Light Bus-EN QR.pdf

October - 2020
Issue v1.1
This handbook covers the additional information a professional driver needs to know when driving a light bus
and should be seen as a complement to the light vehicle Emirates Driving Handbook.
Light Bus
Handbook
BOOK
11

TABLE OF CONTENTS
BUS DRIVING 013
1.1 Different types of buses 014
1.1.1 Double-Deckers 014
1.1.2 Heavy rigid Body buses 014
1.1.3 Articulated buses 015
1.1.4 Tri-axle buses 015
1.1.5 Light buses 016
1.1.6 Minibuses 016
1.1.7 School bus 017
1.1.8 Urban public transport buses 017
1.1.9 Mid-size buses 017
1.2 Reserved Lanes 018
1.3 Vehicle turning radius 019
1.4 Roadway characteristics 020
1.4.1 Road barriers 020
1.4.2 Pavement 020
1.4.3 Curb height 020
1.4.4 Intersection radius 021
1.4.5 Bus turnouts 021
1.4.6 Bus berths 022
1.4.7 Bus turnaround 023
1.5 Passenger facilities 024
1.5.1 Bus stop zones 024
1.5.2 Bus stop spacing 024
1.5.3 Bus stop location 025
1.5.4 Near-Side bus stops location 025
1.5.5 Far-side bus stops location 026
1.5.6 Mid-block bus stops location 026
1.5.7 Passenger waiting area 026
1.6 Emergency equipment and exits 027
1.7 Baggage 027
VEHICLE KNOWLEDGE 031
2.1 Driving physics 032
2.1.1 Electrical voltage 032
2.1.2 Electric current 032
2.1.3 Electric power 032
2.1.4 Battery capacity 032
2.1.5 Engine power 033
2.1.6 Engine revolutions 033
2.1.7 Engine torque 033
2.1.8 Engine cylinder volume 033
2.1.9 Speed 033
2.1.10 Air pressure 033
2.1.11 The torque 033
2.1.12 Friction 033
2.2 Forces affecting a vehicle 034
2.2.1 Friction 034
2.2.2 Kinetic energy 035
2.2.3 Gravity 035
2.2.4 Centrifugal force 035
2.3 Wind and rolling resistant 036
2.3.1 Aerodynamic drag 036
2.3.2 Mechanical drag 036
2.4 Vehicle-Lights 037
2.4.1 Head lights 037
2.4.1.1 Full beam 038
2.4.1.2 Dipped beam 038
2.4.1.3 Parking Lights 038
2.4.1.4 Rear lights / Taillights 038
2.4.1.5 Side lights 039
2.4.1.6 Revers lights 039
2.4.1.7 Stop lights 039
2.4.1.8 Indicators 039
2.4.1.9 Registration plate light 039
2.4.1.10 Reflectors 040
2.5 Vehicle-Suspension 041
2.5.1 Leaf springs 041
2.5.2 Shock absorbers 042
BUSES AND BASIC PARTS 046
3.1 Be careful with your vehicle 047
3.2 Chassis and chassis frame 047
3.3 Engines 048
3.3.1 Understanding internal combustion engines 048
3.3.2 Four stroke engine 048
3.4 Engine parts 050
3.4.1 Cylinder block 050
3.4.2 Oil sump 050
3.4.3 Camshaft 050
3.4.4 Cylinder head 050
3.4.5 Pistons 050
3.4.6 Air intake and exhaust manifold 050
3.4.7 Crankshaft 050
3.5 Diesel engine 051
3.5.1 Diesel engine advantage and disadvantage 052
3.6 The fuel system 052
3.6.1 Fuel filters 052
TABLE OF CONTENTS

3.6.2 Fuel pump 053
3.6.3 Electronic fuel system 055
3.6.4 Cold start device 056
3.6.5 Bleeding the fuel system 056
3.7 Air filter 057
3.7.1 Paper air filter 057
3.8 Turbo charger 058
3.8.1 Intercooler 058
3.9 Exhaust system 059
3.9.1 Silencer 059
3.9.2 Catalytic converter 059
3.9.3 Particle filter 060
3.9.4 Exhaust pressure regulator (EPR) 060
3.10 Smoking engine 061
3.10.1 Black smoke 062
3.10.2 Blue smoke 062
3.10.3 White smoke 062
3.11 Environment and exhaust gases 063
3.12 Vehicle’s lubrication system 064
3.12.1 Mineral oil or synthetic oil 065
3.12.2 Advantages with synthetic oil 065
3.13 Cooling system 066
3.13.1 Liquid cooling 066
3.13.2 Radiator 067
3.13.3 Cooling liquid 067
3.14 Electrical system 068
3.14.1 Batteries 068
3.14.2 Generator 068
3.14.3 Relays 069
3.14.4 Fuses 069
3.15 Jump starting 070
TRANSMISSION AND BRAKE SYSTEMS 075
4.1 Clutch 076
4.1.1 Mechanical clutch 076
4.2 Hydraulic coupling 076
4.3 Hydraulic torque converter 077
4.4 Gearbox 078
4.4.1 Different types of gear boxes 079
4.4.1.1 Manual gearbox 079
4.4.1.2 Automatic gearbox 080
4.5 Rear axle and differential 081
4.6 Steering system 082
4.6.1 Steering box 082
4.6.2 Power steering 083
4.7
Automatic Traction Control (ASR) 084
4.8
Electronic Stability Program (ESP) 084
4.9
Anti-overturn Control System (ARP) 085
4.10
Lane Assistant 085
4.11 Wheels and Tires 086
4.11.1 Radial / Diagonal 086
4.11.2 Tube and tubeless tires 087
4.11.3 Grip 087
4.11.4 Remolded tires 088
4.11.5 Regroovable tires 089
4.11.6 Tire tread 089
4.11.7 Tire wear indicator 089
4.11.8 Twin tires 090
4.11.9 Right tire air pressure 090
4.11.9.1 Hot tires 090
4.11.10 Age of tires 090
4.11.11 Re-tightening wheel nuts 091
4.11.12 Wheel alignment 091
4.11.13 Tire markings 092
4.12 Braking system 093
4.12.1 Foot brake 093
4.12.2 Parking brake 093
4.12.3 Hydraulic brakes 094
4.12.4 Drum brake 095
4.12.5 Disc brake 096
4.13 ABS brakes (Anti-locking brake system) 097
BUS SAFETY 102
5.1 Bus Safety check 103
5.1.1 Before you enter the bus 103
5.1.2 When you are on the driver’s seat 103
5.1.3 Step out of the vehicle again 104
5.1.4 While you walk around the vehicle 104
5.1.5 Get back in the driver’s seat 104
5.2 Driver’s Environment 105
5.3 Before you start driving 106
5.3.1 Seat adjustment 106
5.3.1.1 How to adjust your seat 106
5.3.2 Adjusting the seatbelt 107
5.3.3 Bus mirror adjustment 108
5.4 Blind spots 109
5.4.1 Direct vision distance at the front of the bus 110
5.4.2 Blind spot area behind the bus 110
5.5 Systematic mirror check 111
TABLE OF CONTENTS

5.6 Post - Trip Inspection 111
5.7 Fitness to drive 112
5.7.1 Vision 112
5.7.2 Alcohol 112
5.7.3 Drugs and medicines 113
5.7.4 Fatigue 113
5.8 Driving at night 114
5.9 Personal protection 115
5.9.1 Reflective vest 115
5.9.2 Seatbelt 115
5.10 Working hours, breaks and sleep `116
5.11 Passengers safety 116
5.11.1 Loading and unloading passengers on roadside 117
5.11.2 Focus on driving 117
5.12
Passengers refusal 117
5.13
Transporting people of determination 118
5.14 Bus lighting 119
5.15
Vehicle cleanliness and inspection 119
5.16 Route planning 120
5.16.1 Routes to avoid 120
5.16.1.1 Time plan for the trip 120
5.16.2 Refueling 121
5.17 When driving a new bus 122
BUS ACCIDENT AND PASSENGERS 126
6.1 Common bus accident injuries 127
6.1.1 Whiplash injury 127
6.1.2 Head and spinal cord injury 127
6.1.3 Broken bones 127
6.1.4 Deep Cuts 127
6.2 Crash risk 128
6.2.1 Speed 128
6.3 Passengers 130
6.4 Transporting children 132
6.4.1 Children behavior management 132
6.4.2 Safety, Order Rights 133
6.4.2.1 Safety 133
6.4.2.2 Order 133
6.4.2.3 Rights 133
6.5 School buses 134
6.5.1 Loading and unloading procedures 135
6.5.2 Loading procedures 135
6.5.3 Bus stops 137
TABLE OF CONTENTS
6.5.4 School campus 138
6.5.5 Unloading procedures on the route 138
6.5.6 Crossing The Street (Guard Present) 139
6.5.7 Unloading procedures at school 140
6.6 Special dangers of loading and unloading 142
6.6.1 Dropped or forgotten objects `142
6.6.2 Electric doors 142
6.6.3 Handrail hang-ups 142
6.7 Dangers Zones and use of mirrors 143
6.7.1 Danger Zones 143
6.8
Emergency evacuation and moving to a safe distance 144
6.8.1 Planning for emergencies: 144
6.8.2 Evacuation procedures 145
6.8.3 General procedures 147
6.8.4 Event of Fire 149
DRIVING A BUS 152
7.1 Driving a bus 153
7.2 Before you drive 154
7.2.1 The vehicle 154
7.2.2 Instruments and control leavers 154
7.3 How to maneuver a large bus? 154
7.4 Mirrors 155
7.5 Before you move 156
7.6 Changing gears 156
7.7 The Clutch 157
7.8 Brake the right way 158
7.8.1 Use the right brakes 158
7.8.2 Foot brake 158
7.8.3 Emergency brake 158
7.8.4 ABS brakes (Anti-locking brake system) 158
7.9 Moving off 159
7.9.1 Leaving the curb 159
7.10 Signaling 160
7.11 Passing parked cars 162
7.12 Bus braking / stopping 163
7.13 Bus following distance 163
7.14 Yielding and the right-of-way 164
7.15 Positioning the vehicle 165
7.16 Junctions 166
7.17 Roundabouts 169
7.17.1 Give way rules 169
7.17.2 Positioning and signaling in roundabouts 169
7.18 Following distances 171
7.18.1 Stopping distances 172

7.18.2 Braking and stopping 173
7.18.3 Emergency braking 173
7.19 Reversing 174
7.19.1 Reversing on Level Ground 174
7.19.2 Reversing Downhill 174
7.19.3 Reversing Uphill 174
7.20 Parking 175
7.20.1 Parking at night 175
7.21 Overtaking 176
7.22 Speed and speed limits 178
DRIVING UNDER DIFFICULT CONDITIONS 182
8.1 Difficult driving conditions 183
8.1.1 Driving under sunshine 183
8.1.2 Wind 183
8.1.3 Dust 184
8.1.4 Driving in fog 184
8.1.5 Rain 185
8.2 Driving on difficult roads 186
8.2.1 Soft road shoulders 186
8.2.2 Driving in curves 186
8.2.3 Hills 187
8.2.4 Going downhill 187
8.2.5 Going uphill 187
8.2.6 Single lane roads 187
8.2.7 Narrow bridges 188
8.2.8 Floods 188
8.3 Night driving 189
8.3.1 Lights 189
8.4 Towing 191
8.5 ECO driving 191
8.6 Alternative fuels 192
8.6.1 Bio diesel 192
8.6.2 Vegetable oil 192

015
014 Bus Driving
Bus Driving
1.1 Different types of buses
The double Decker is a bus designed in two decks in order
to accommodate more passengers. Some have an open rear
platform for passengers' entry and exit
When operating public
Transport buses on
roads the vehicle
characteristics should
be considered.
Bus height, width, weight,
number of seats and
turning radius are among
the items that will help
operators to determine
which bus could operate
effectively and efficiently
in a specific area.
A too big bus will most of
the time not be used to
its capacity and can also
be difficult to maneuver
where space is limited.
On the other hand,
a too small bus will
not cope with the
demand and leave
passengers stranded
during peak hours.
Proper and efficient
public transport supports
the community, reduce
the number of ordinary
cars and increase
movability for all.
A motor coach is a large bus that usually travels
between cities, often country to countries.
The buses found in U.A.E are normally 12 meter-buses that
hold 27 passengers and above except the driver, having
undercarriage luggage compartments, and lavatories.
These buses often travel millions of miles during their service
lifetimes due to their rugged steel and aluminum construction.
Emirates Driving Company buses
Joint or articulated buses
are another common
type of bus for increasing
passenger capacity around
the world. This type of bus
is used exclusively for public
transport purpose. These
buses are long and fitted
with an extra pair of wheels
Tri-axle buses can have a
higher capacity than buses
with only two axles. The load
of the bus will be distributed
over three instead of two
axles. An alternative to
three-axle buses is the
articulated buses.
and a flexible joint usually
located slightly behind the
midpoint of the bus, behind
the second pair of wheels.
Some models of articulated
buses have a steering
arrangement on the
rearmost axle, which turns
slightly in opposition to
the front steering axle.
Some buses have two
flexible joints, and these
are called bi-articulated.
Some rare combinations
between double-decker and
articulated buses also exist,
but neither is in common use.
1.1.1 Double-Deckers
1.1.2 Heavy rigid Body buses
1.1.3 Articulated buses
1.1.4 Tri-axle buses
An alternative
to three-axle
buses is
the articulated
buses.
Proper and
efficient
public
transport
supports the
community.

017
016 Bus Driving
Bus Driving
1.1.5 Light buses
Light buses are smaller
than the ordinary tourist
or public transport buses,
and are intended to carry
up to 15 – 26 people
except the driver.
They are normally used for
the types of transportation
like inside city, schools
and for limited numbers
of company-employees
or students. Due to their
smaller size, they are
often used on routes with
a few passengers, on
narrow rural roads, or on
routes where the service
frequency is high.
Minibuses can carry a
maximum of 9 people
except the
driver; no standing
passengers are allowed.
Minibuses typically offer a
faster and more efficient
transportation solution
due to their small size,
limited carrying capacity,
frequency and diverse
range of routes.
The minibus is categorized
as a light motor-
car in the UAE.
A driver holding the light
vehicle driver's license is
legally permitted to drive
the minibus in the UAE.
A school bus transports
children to and from the
school. In the UAE, a
school bus is usually of
a distinctive yellow color,
equipped with traffic
warning lights, stop arm
and other safety equipment
for loading and unloading of
children safely.
These buses are generally
rigid body heavy buses
operated by the school
authorities. The safety of
school children is considered
to be the key-priority.
This type of buses are
specially constructed for
urban transport. They can
take many passengers as
standees are allowed. The
bus is low and easy to enter
and leave. Big doors make
loading and unloading time
short at the bus stops.
These buses are common
for companies to
transport people from
accommodation to work
and vice versa.
They normally have
less seats, luxuries and
one door entry.
1.1.6 Minibuses
1.1.7 School bus
1.1.8 Urban public transport buses
1.1.9 Mid-size buses
1.1 Different types of buses
It is not permissible under the law to write phrases or place stickers on the
vehilce without the permission of the official authorities.

019
018 Bus Driving
Bus Driving
1.2 Reserved Lanes
BUS
STOP
In some counties, one or
more lanes are reserved
for Public Transport
buses and other traffic is
prohibited on it.
These reserved lanes
are identified by the
help of Traffic signs and
road markings.
The road´s turning radius should be considered when driving a heavy bus full of passengers. It needs
high concentration when dealing with different types of roads, intersections and other transit facilities.
If the bend is very sharp the driver should be more careful and the speed slower.
In the bends and intersections where the turning of the bus is not sharp, the buses can
be driven at a more reasonable speed through the bend and the passenger will be more
comfortable.
Modern buses often have a smaller turning radius
1.3 Vehicle turning radius

021
020 Bus Driving
Bus Driving
For efficient and effective operation of public buses, roadway width, grade, pavement
design and curb detail are important.
As a driver of transportation buses you should judge in advance the level of tire-grip
and surface of the road. Especially when turning, a high natural force is accrued which
is compensated by the road design having slope to reduce centrifugal force. The turns
without slopes are very dangerous.
Transportation drivers should always keep the roadways characteristicsconsideration.
1.4 Roadway characteristics
A road barrier is a physical division (median) between opposing traffic or separate
access ramps to and from the highway, which are more widely separated than
connections on a standard road.
These barriers are commonly found on roadways especially in tunnels, under
bridges and on highways to prohibit pedestrians’ access and limit only to the
vehicular movement.
Pavement is usually considered as the footpath at the side of
a road but can also mean the hard surface put on
top of a road.
The most common modern paving methods are asphalt and concrete. Also, in some
countries bricks are extensively used.
For bus stop areas, including bus turnouts and terminals, a rigid design is strongly
recommended which can bear loads and shear forces applied to paved surfaces at
the time of starting and stopping of the buses. This pavement surface has the best
potential to retain its shape.
The curb heights on the bus stops are mostly of 15 cm.
This curb height is appropriate for the step-heights of
public buses. This curb height also allows transportation
vehicle users to board and alight the bus easily. But for the
passengers to be able to utilize the curb, the bus must stop
next to the curb. If drivers hit the curbstone while stopping
on the bus stops it can cause damage to the tires and even
sometimes to the body of the bus.
1.4.1 Road barriers
1.4.2 Pavement
1.4.3 Curb height
The radius of an intersection
should be designed in
a way to facilitate the
turning movement of the
bus using only one lane
without having to straddle
to other tracks. Proper
maneuvering will decrease
the conflicts between
buses and other vehicles
at intersections, reduce the
travel-time and improve the
passenger comfort.
Pedestrian crossings are often
at intersections, but may also
be at other points on busy
roads that would otherwise
be dangerous to attempt to
cross. They are common
near schools or in other
areas where there is a large
number of children.
1.4.4 Intersection radius
Bus turnouts are bus stop
areas that are recessed
from the thoroughfare. The
turnout provides the bus
with an off-street service
point that does not interfere
with traffic movement and
provides a safe waiting area
for transit passengers. These
facilities should be utilized
so that bus drivers have
clear rear vision capabilities
necessary for safe re-entry
into traffic. The normal width
for turnout is 5-6 meters on
major roads inside cities.
These dimensions provide bus
drivers with enough space to
properly maneuver and stop
their vehicles. Bus turnouts
are mostly located in areas
where passenger volumes
are high and the flow of traffic
could be significantly impeded
by stopped transportation
vehicle. The bus drivers
should use the right lane of
the road to enter and exit the
traffic smoothly. Acceleration,
deceleration and indicators
are highly considered while
using turnouts.
During turning movements,
the bus should avoid using
adjacent lanes of traffic
whenever possible to reduce
vehicle conflicts.
Bus turnouts where
passengers can wait safely
far away from the fast
traffic on the main road.
1.4.5 Bus turnout

023
022 Bus Driving
Bus Driving
Bus berths are reserved
bus stop areas designed to
accommodate more than
one transit bus.
They are mostly found at
bus-terminals.
Similar in concept to
bus turnouts, bus berths
provide convenient, off-
street service points
and bus staging areas
that do not interfere with
traffic movement.
Bus berths are located in
areas where transit routes
intersect and along bus
waiting areas
are appropriate.
Bus drivers should use these
facilities to avoid conflicts
with turning vehicles and
to take advantage of gaps
in traffic produced by
traffic signals.
The bus drivers should
focus on the traffic
moving around the bus to
avoid danger.
The most common accident
on the bus-berth is hitting
the passengers while
reversing or adjusting,
opening or closing doors
and leaving from the
bus-berth, etc.
1.4.6 Bus berths
Bus berths are reserved bus stop areas designed
to accommodate more than one transit bus.
Bus turnarounds can be
specially constructed to
make it possible for buses
to turn around at the end of
the route in a safe manner.
Turnarounds improve
schedule adherence and
service reliability since
continuous route is available
for the transit bus. These
turn around facilities also
provide effective, off- street
waiting and service areas for
transit users.
Bus turnarounds should be
designed so that the bus
can be turned in a counter-
clockwise direction to improve
the drivers’ visual capabilities.
The Jug-handle bus-turnouts
can be found either at the
end of a particular route or
en route to a final destination
while both round and loop
shape bus-turnaround are
found at the end of bus-routs.
Proper maneuvering may be
needed for vehicle control and
to expedite the return of the
transit vehicle to its route.
1.4.7 Bus turnarounds
Bus drivers should be highly alert while exiting the road, maneuvering in turnarounds and
joining the road.
Bus turnarounds should be designed so that
the bus can be turned in a counter-clockwise
direction to improve the drivers’ visual
capabilities.

025
024 Bus Driving
Bus Driving
A bus stop is a place where
a public transport bus
stops for the purpose of
allowing passengers to
board or leave the bus. The
simplest type has just a
sign saying “bus stop”, but
often rout-numbers and/or
destinations are indicated
on the time tables.
The bus stops can be
equipped with access ramps
for the disabled, shelters,
benches, natural windbreaks
and route schedule or
information displays.
A bus stop is often a
request stop where a bus
does not stop unless it is
requested. Someone waiting
at the stop has to signal the
bus to stop for boarding and
someone inside has to press
a request button or ask the
driver to stop for alighting.
1.5 Passenger facilities
Bus stop spacing is based on population densities. Bus stops should be placed after every
500 meters, if an area is primarily commercial or population density is high. Special bus stop
spacing is considered at employment centers and high-density residential areas.
Bus-stops can also be put up in response to the request by the passengers. In UAE the
municipality designs the bus stop spacing according to the population and employees' density.
The public transport operators should be aware of bus stop locations. The drivers should
prepare for stopping in the limited distance.
The bus driver should give special consideration for
people of determination.
This valuable service will present quality service of public
transport as a viable alternative to the private automobile.
ONLY FOR BUSES. No other
vehicle should stop or wait
at this place.
Rout-schedule displayed at
the bus-stops.
1.5.1 Bus stop zones
1.5.2 Bus stop spacing
In UAE the municipality design the bus stop
spacing according to the population and
employment density
Generally, bus-stops are
placed in three locations:
Near Side (located
immediately before an
intersection).
Far Side (located im-
mediately after an
intersection).
Mid-Block (located between
intersections).
All bus-stops are provided
with the bus-stop signs.
Each of these locations
offers great advantages
to both drivers
and passengers.
However, bus-stop location
depends on ease of
operation, space availability
and traffic volume.
Near-Side (located immediately before an intersection)
Mid-Block (located between intersections)
Far-Side (located immediately after an intersection)
1.5.3 Bus stop location
Nearside locations offer
a number of features to
passengers and vehicle
drivers. This location allows
transit users to board and
alight from buses close
to crosswalks.
1.5.4 Near-Side bus
stops location
1.5 Passenger facilities

027
026 Bus Driving
Bus Driving
Long bus-stops are easy for the bus drivers to enter without
having to slow down drastically.
A short bus-stop makes
it difficult for the buses to
enter the stop.
Usually waiting passengers
do not have enough facilities
in the bus-stops found along
the main road.
1.5.5 Far-side bus
stops location
Far-side bus stop locations
are found on routes in which
buses make left turns at next
intersections.
It also provides a more
appropriate service point for
the buses that take a left turn
from the next intersection.
A mid-block location is
generally less congested
than those at an intersection.
Bus turnouts are most
effectively located in a mid-
block bus stop zone.
Mid-block stops are
applicable at locations
generating a large number
of passengers.
The public transport drivers
should be aware of the
different locations of the
bus stops on the routes
to prepare for proper
positioning in time.
A variety of amenities can be found at some bus-stops to
enhance the attractiveness of public transportation. Bus-
stops with modern amenities increase passengers' comfort
level and their feeling of security. Bus-stops can be designed
with paved waiting pads, shelters, benches windbreaks
and adequate lighting for the safety and comfort of the
transit users.
1.5.6 Mid-block bus
stops location
1.5.7 Passenger
waiting area
A short
bus-stop
makes it
difficult for the
buses to enter
the stop.
Every public or limited
passenger vehicle that has
a seating capacity of more
than 10 occupants, including
the driver, must have:
1.6 Emergency
equipment
and exits
• A first-aid kit
• A spare tire
• At least one fire
extinguisher
• A warning triangle
The driver is responsible for
ensuring these emergency
equipments are available
in working condition. In
addition, passenger vehicles
that have a seating capacity
of more than 12, including
the driver, must be equipped
with an emergency exit door
or emergency windows.
The driver is responsible for loading all pieces of
baggage safely.
Do not strain yourself by lifting or moving heavy baggage.
Load all pieces of baggage in the luggage compartment so
that they do not interfere with the passengers getting on
and off the bus. Baggage or cargo must not block entirely or
partially any aisle or exit.
The cargo must be stored in specified places so that they
do not fall on or against any passenger during the journey.
Also, it is important to protect the cargo from the dust
and moisture.
1. The floor
Baggage must be stored under the seats against a barrier that
prevents its forward movement.
1.7 Baggage

What are the different types of passenger facilities
found in the UAE?
When you have studied this chapter try to answer these questions.
1
If you are not sure about the
answer go back and read
that part again. Be aware
that the questions are not
cover-ing the whole content
of the chapter.
What are the risks with
standing passengers?
3
What dangers can the baggage cause for
the passengers?
5
Where can baggage be
stored in a bus?
4
2 How many fire extinguisher should be there in the vehicle
with more than 10 seats?

033
032 Vehicle knowledge
Vehicle knowledge
As a Bus Driver you are handling a large complicated
machine. The construction of a modern bus is much
more complicated than a car. Many buses are large and
the forces acting on it can easily take over if you are not
careful. It is very important that you understand how a
bus is constructed and what forces act on it when driving.
2.1 Driving physics
is measured in Volts. Small
vehicles normally have 12 V
(V= Volts) batteries, Large
buses use two batteries in
series and therefore have 24
V electrical system.
The household voltage in the
UAE is between 220 - 240 V.
is the flow of electric charge
going through a wire. It is
measured in Amperes (A).
If the wire is thick more
current can go through it.
is the amount of power
consumed and measured in
Watts (W). If you multiply the
Voltage with the current, you
get the power (V x A = W).
is measured in AH (Ampere
x hours). If a battery has
100 AH you can theoretically
take out 10 A continuously
for 10 hours.
Some deﬁnitions:
When you work with vehicles
you will hear about different
measurements.
Here is a list of the most
common ones for vehicles:
2.1.1 Electrical voltage
2.1.2 Electric current
2.1.3 Electric power
2.1.4 Battery capacity
is measured in kW (kilo
Watts = 1000 watts).
An old way of measuring
engine power was hp
(horse power).
One hp is the same as 0.736
kW. If a vehicle got a 100 kW
engine it has 135 hp.
2.1.5 Engine power
are measured in revolutions
per minute (RPM).
2.1.6 Engine revolutions
is measured in Nm and is
the moment of force given
by the engine. It is good to
know at what revolution
the engine gives the
highest torque.
2.1.7 Engine torque
for how hard a bolt should
be tightened is measured in
Nm (Newton meter).
Earlier kpm (kilopond meter)
was used. 1kpm =9.81 Nm.
The piston moves up and
down inside the cylinder from
Top Dead Centre (TDC) to
Bottom Dead Centre(BDC).
The distance it travels
vertically from TDC to BDC
or from BDC to TDC is
known as a stroke.
Displacement of space in
cylinder is known as volume
and is measured in (CC) Cubic
centimeter or in liters (L).
1 liter = 1000cc
is measured in km/h
(kilometers per hour)
or sometimes m/h
(mile per hour)
2.1.8 Engine
cylinder volume
is measured as friction
coefficient (µ). If µ=1 it
needs the same force as the
weight of the object to move
it on a surface and if µ=0.5 it
needs half the weight of the
object to move it.
is nowadays measured
in Pascal (Pa).
1 kilo Pascal (kPa)= 1000 Pa.
100 kPa = 1 bar
1 bar = 1.02 kg/cm2
2.1.9 Speed
2.1.10 Air
pressure
2.1.11 The torque
2.1.12 Dynamic
Friction

035
Vehicle knowledge
Skid marks from tire.
2.2 Forces affecting a vehicle
Friction is the resistance relative lateral motion
of two solid surfaces in contact.
Friction is a resistance force produced when two surfaces
rub or slide.
The tire has a friction towards the road surface (the grip).
The friction can vary depending on the type of tire and type of
road surface.
A wet road surface has less friction than a dry surface.
Traction is the friction between a drive wheel and the road
surface which can be reduced by mud and sand on the road.
The forces acting on a bus are much more than a small car and will affect your driving significantly.
2.2.1 Friction
Rolling tires on the road
surface have higher friction
than a skidding tire.
Braking so hard not only
locks your tires causing
a skid as shown in the
picture below but also
uneconomical due to
excessive tire-wear.
Kinetic energy is the energy
a vehicle gains from its
speed and weight.
The higher the speed and
more the weight the higher
is the kinetic energy.
The kinetic energy has
to be absorbed by the
brakes when stopping.
In an accident the kinetic
energy is taken up by
the deformation of
the vehicles.
2.2.2 Kinetic energy
Gravity is the force that
attracts a body towards the
center of the earth. To make
it easy to understand how
gravity affects a vehicle,
we can use the definition
“center of gravity”. The
lower the center of gravity
the more stable is a vehicle.
Sports cars, for example,
always have a very low
center of gravity while trucks
with high, heavy loads have
a higher center of gravity.
If a vehicle with high center
of gravity is driven fast
through a bend, it can
easily turn over.
If the load is movable, for
example half a tank with
liquid, the center of mass
will move as the liquid
moves and the vehicle are
more prone to roll over.
Centrifugal force is the side force on a vehicle when driving
in a bend. The higher the speed and the sharper the curve the
greater the centrifugal force on the vehicle. If the centrifugal
force is high and the center of gravity is high above ground the
vehicle can turn over. If the center of gravity is near the ground,
the vehicle will just slide off the road Rather than overturning.
Centripetal
force
Centrifugal
force
Bus accident. The kinetic energy has been absorbed by
the bus body.
2.2.3 Gravity 2.2.4 Centrifugal force

037
Vehicle knowledge
2.3 Wind and rolling resistant
Drag exists from two different sources.
2.3.1 Aerodynamic drag
is the force of wind or air-
resistance pushing a vehicle
in the opposite direction
of its motion.
To make the buses aerodynamic, they are designed more circular. This design is always the
compromise between interior space and good air
2.3.2 Mechanical drag
is due to all the moving
mechanisms in the vehicle
that have frictional losses,
most specifically the
wheel bearings, but is
almost entirely due to the
action of the tires on the
road surface.
Drag exists
from two
different
sources.
2.4 Vehicle-Lights
A motor vehicle must have headlights. Both dipped and full beam headlights can be in the
same unit or separate units for each headlight.
2.4.1 Head lights

039
Vehicle knowledge
2.4.1.3 Parking Lights
20m
30m
60m
2.4.1.1 Full beam
2.4.1.2 Dipped beam
Full beam shall reach from 100 to 150 meters. Additional
lights can be used along with the full beam.
The switch of this light
activates the parking lights
in front and tail-lights at the
back at the same time.
Parking light should be
used only in stationary
vehicles at night or when
the visibility is poor.
Every motor vehicle must
have at least two red tail-
lights, one at each side at the
back of the vehicle.
If the vehicle got more than
two taillights, they should be
symmetrically distributed on
both side at the back.
Dipped beam is also called low beam headlight. It does not
dazzle other road users and should be used when meeting or
driving behind other vehicles.
The standard dipped headlights are designed slanting
downwards and adjusted slightly more towards the right side
so that the right edge of the road can be seen clearly.
The H4 lamp for the headlights have two filaments.
The rear one is used for main beam and the front one is
for dipped beam.
The front one has a metal cup under the filament so that
the rays are only going upwards. The asymmetric beam of
dipped headlight gives better illumination on the right side
of the road without dazzling the oncoming vehicles.
2.4.1.4 Rear lights/taillights
2.4.1.7 Stop Lights
2.4.1.5 Side lights
Long vehicles are equipped
with yellow sidelights and
reflectors. In many countries
it is a law to have both
sidelights and reflectors and
some countries regulate
the reflectors only. Side
markings are very important
especially when the long
vehicle has to cross another
road at night.
Reverse lights help you
when reversing at night.
They are designed to work
only when the reverse
gear is engaged.
Reverse gear produces an
alarm to inform the driver
and people around when the
gear is engaged.
Stop lights are also known as the brake light.
The stop or brake light is always brighter than the tile light.
Operate with the start of pressing the brake.
Direction indicators must be functioning at both the front
and rear of the vehicle. The indicators are, of course, of extra
importance on large vehicles as there may be road users
hidden from the drivers' vision.
Rear registration plates must be illuminated when the vehicle
lights are on.
2.4.1.6 Reverse Lights 2.4.1.8 Indicators
2.4.1.9 Registration Plate Light
2.4 Vehicle-Lights

041
Vehicle knowledge
2.4.1.10 Reflectors
All motor vehicles and
trailers must have red
reflectors at the back.
And, any vehicle longer
than 6 meters must have
side reflectors. The rear
reflectors are often found in
the tail-light frame.
Reflectors work by sending
the incoming light straight
back to its source.
INCIDENT
LIGHT
INCIDENT
LIGHT
REFLECTED
LIGHT
REFLECTED
LIGHT
REFLECTED
LIGHT
INCIDENT
LIGHT
Smooth Surface
Specular
Reflection
Rough Surface
Diffuse
Reflection
Beaded Surface
Retro-Reflection
2.4 Vehicle-Lights 2.5 Vehicle-Suspension
2.5.1 Leaf springs
Leaf springs are the
most common type of
suspension-springs on
large vehicles.
They are simple and easy to
repair. The older types can
actually be used without
shock absorbers.
A modern implementation of
the traditional leaf spring is
the parabolic leaf spring. They
have fewer leaves whose
thickness varies from center
to ends following a parabolic
curve. Inter-leaf friction is
avoided, and therefore there
is only contact between the
springs at the ends and at
the center where the axle is
connected. Spacers prevent
contact at other points.
Aside from weight saving,
the main advantage of
parabolic springs is that
they are more flexible to
improve ride quality and
have greater load-bearing
capacity as compared to
that of coil springs.
Keep on checking the
leaf spring to see that
none is broken.
If main leaf(s) are broken
(the leaf that secure the
position of the axle) you
cannot drive the vehicle.
If any of the other leafs are
broken you can drive with
reduced load and speed to a
workshop for repair.
Leaf spring on the rear axle on a light bus
Parabolic leaf

A - Piston that
moves up and
down when the
suspension
is active
B - Cylinder for the
piston connected
to the wheel
C - Piston rod
connected to the
vehicle body
D - Oil
2.5.2 Shock absorbers
A shock absorber is a
mechanical device designed
to smooth out or damp
shock impulses when the
axle is moving up and
down. Shock absorb-
ers are constructed as a
closed cylinder filled with
oil. The cylinder is fitted
with a movable piston. The
piston’s movements are
restricted by the oil.
The picture shows a shock
absorber cut open to see
how it works.
The cylinder
is fitted with
a movable
piston.
A
B
C
D
What will be the result if you are driving a vehicle with high
center of gravity fast?
1
of the chapter.
Can you drive with a bus
even if the air suspension
bag is punctured?
4
What is the
centrifugal force?
3
Some buses can be equipped with a lift gate. Why?
6
What is kinetic energy?
2
Where can you find
Side reflectors?
5

BUSES AND
BASIC PARTS
Chapter Three

047
046 Buses and basic parts
Buses and basic parts
3.1 Be careful with your vehicle
Light buses are expensive and advanced. As a driver you have responsibility over the vehicle
and of the passengers as well as their luggage. Good maintenance of the vehicle is essential
for reducing repair costs and avoids breakdowns.
• Buses are built on a
chassis frame. The
engine, transmission
and suspension are
fixed to the frame and
the body is mounted
on top of it.
• The frame is strong but
also flexible.
• The bus chassis
is often made of
two U-shaped side
members hold together
by cross members.
• This is a typical
chassis for a light bus.
This is how the frame
is delivered to the
coach builder. They
will extend the chassis
between front and rear
axle when they build
the bus.
3.2 Chassis and chassis frame
3.3 Engines
Almost
all petrol
and diesel
engines are
four stroke
engines.
A four-stroke engine is
an internal combustion
engine in which the piston
completes four separate
strokes for turning
a crankshaft.
A stroke refers to the
full travel of the piston
along the cylinder, in
either direction.
Almost all petrol and
diesel engines are four
stroke engines. The inlet
and exhaust valves are
operated by a camshaft
and rocker arm.
The
principle behind any internal combustion engine: If you
put a tiny amount of high-energy fuel in a small, enclosed
space and ignite it, an incredible amount of energy is released
in the form of expanding gas. In this case, the energy can be
translated into motion.
1. Intake stroke
2. Compression
stroke
3. Power stroke
4. Exhaust stroke
3.3.1 Understanding internal combustion engines 3.3.2 Four stroke engine
In this engine the working
cycle has four strokes:

049
Power stroke
At the end of the
compression stroke, the
fuel mixture is ignited.
The fuel charge in the
cylinder explodes, driving
the piston down.
Exhaust stroke
Once the piston hits the
bottom of the power stroke,
the exhaust valve opens and
the exhaust gases leave the
cylinder to go out through
the tailpipe.
Compression stroke
In compression stroke, the
piston moves back to the
top compressing the air
when the fuel is sprayed
in. Compression makes the
explosion more powerful.
Intake stroke
When the piston moves
from the top to down, the
intake valve opens to let the
engine take in the air from
the atmosphere.
(NB: In diesel engines,
only air is taken by the
intake-stroke and the
fuel is injected during the
compression stoke)
This is the intake stroke.
Only the very small drop of
fuel needs to be mixed into
the air for this to work.
Crankshaft Connecting rod
Piston
Intake valve Exhaust valve
3.3 Engines
1
2 3 4
3.4 Engine parts
The cylinder head sits on top of the cylinder block. It closes in
the top of the cylinder, forming the combustion chamber. This
joint is sealed by a head gasket. In most engines, the head also
provides space for the passages that feed air and fuel to the
cylinder, and that allow the exhaust to escape.
Fitted to the cylinder block normally opposite each other. The
air intake sends air to the engine and the exhaust manifold
send the exhaust gases from the engine to the exhaust pipe.
The main part of the
engine made of cast
steel or aluminum.
3.4.1 Cylinder block
It is fitted under the cylinder
block and hold the lubri-
cating oil for the engine.
Camshaft is driven by the
crank-shaft by gear,belt or
chain to operate the valves.
(In heavy vehicles, timing
gear is used).
Pistons move up and
down in the cylinders. The
pistons have piston rings to
prevent leaks between the
cylinder and piston.
3.4.2 Oil sump 3.4.3 Camshaft
3.4.4 Cylinder head 3.4.5 Pistons
3.4.6 Air intake and exhaust manifold
Crankshaft is fitted just
above the oil-sump and the
pistons are connected to
the crankshaft.
3.4.7 Crankshaft

051
3.5 Diesel engine
The diesel internal combustion engine differs from the petrol-
powered engine by using a higher compression of the air/
fuel mixture to ignite the fuel rather than using a spark plug
(compression ignition rather than spark ignition). In the
diesel engine, air is compressed with a compression ratio
typically between 14:1 and 25:1. This compression raises the
temperature to the ignition temperature of the fuel mixture,
which is formed by injecting fuel once the air is compressed.
Therefore, the diesel engine got no spark plugs.
In modern engines, the fuel is injected directly into cylinders
using computers to deliver precisely the right amount of fuel
the instant it is needed.
All functions in a modern
diesel engine are controlled
by an electronic control
module that communicates
with an elaborate array of
sensors placed at strategic
locations throughout the
engine to monitor everything
from engine speed to coolant
and oil temperatures and
even piston position. Tight
electronic control means that
fuel burns more thoroughly,
delivering more power,
greater fuel economy, and
fewer emissions than older
diesel engines could achieve.
Modern direct-injection diesel
engines produce low amounts
of carbon dioxide, carbon
monoxide, and unburned
hydrocarbons. Emissions of
reactive nitrogen compounds
(commonly spoken of as
NOx) and particulate matter
(PM) have been reduced
by over 90 percent since
1980. Nevertheless, NOx
and PM emissions remain
at relatively high levels.
NOx contributes to acid rain
and smog, while adverse
health effects have been
associated with exposures to
high PM amounts.
All heavy buses
diesel engines got
several cylinders.
If the cylinders are in a line
the engine will be longer
than if the cylinders are
arranged as a V. Many large
buses have 6, 8 or even
10 cylinders.
• Works at low engine
revolutions
• Has high
compression
pressure in the
cylinders
• Gives high torque
• Does not need an
ignition system
• Needs to be made
much stronger
because of the high
compression
• Make more noise
• Use less fuel
The fuel tank stores fuel for the engine. Baffles inside the tank
ensure that the fuel always reaches the engine even if the
vehicle is leaning to one side and stops air entering the system.
Fuel filters remove abrasive particles and water.
All functions
in a modern
diesel
engine are
controlled by
an electronic
control
module.
3.5.1 Diesel engine
advantage and
disadvantage
3.6 The fuel system
3.6.1 Fuel filters
3.5 Diesel engine

053
The fuel
pump can be
a diaphragm
type lift pump
mounted on
the engine,
or a separate
electric pump.
A pump is mounted on the
in-line injection pump, and
driven by a cam inside the in-
line injection pump housing.
This pump gives a very high
pressure to the injectors.
Standard type of fuel
injector cut open to see the
inner parts. The injector
is made with very small
tolerances and even very
little dirt in the fuel will stop it
working properly.
In some diesel vehicles, a
priming pump is used to
remove air from the fuel
system. Otherwise if air has
entered the fuel system, the
engine would have to be
cranked over with the starter
motor, to bleed and prime the
system or the fuel system
has to be bled manually.
3.6.2 Fuel pump
The fuel tank stores fuel for the engine. Baffles inside the tank ensure that the fuel always
reaches the tank even if the vehicle is leaning to one side and stops air entering the system.
Fuel filters remove abrasive particles and water. A fuel pump sends the fuel from the tank to
the high-pressure diesel pump. The fuel pump can be a diaphragm-type lift pump mounted on
the engine, or a separate electric pump. The diaphragm-type pump has an eccentric camshaft
that pushes on a rocker arm. It acts on a diaphragm that will move up and down to create a
pressure difference, which lifts fuel from the tank to the injection system.
Fuel tank
Fuel pump
Injector Fuel filter
Diesel Fuel
Fuel level sensor
Fuel
Filter
High-Pressure
Injection
Pump
Excess Fuel Return Line
Fuel Supply Lines
1 per cylinder
Diesel Engine
«Power» Stroke
Intake
Valve
Fuel
Injector
Open
Fuel
Exhaust
Valve
Basic Fuel Injection System
To get the right amount of fuel to the cylinder a distributor-type pump uses a transfer pump to
fill the single pumping element. This raises fuel pressure to injection pressure. A distribution
system then distributes fuel to each cylinder, in the firing order of the engine. As fuel pressure
rises, it acts on the needle valve in the injector, eventually lifting it from its seat. Fuel under high
pressure enters the engine in an atomized spray at a high speed.
Fuel injectors are designed with high sensitivity to prevent any impurities in diesel fuel from
entering combustion chambers. Any dirt that can damage engine components.
3.6 The fuel system

055
3.6.3 Electronic fuel system
by the injection pressure
setting in the engine control
unit), independently of
the engine speed and the
quantity of fuel injected.
The fuel is fed through rigid
pipes to the injectors, which
inject the correct amount of
fuel in a fine spray into the
combustion chambers.
The Electronic Diesel
Control (EDC) controls
Many new buses have a more
modern fuel system called
common rail fuel injection.
In the modern common rail
accumulator injection system,
the generation of the injection
pressure is separate from the
injection itself.
A high-pressure pump
generates in an accumulator
– the rail – a pressure of
up to 1,600 bar (determined
Common Rail
Pressure Limiter
EDU
EDU- Electronic Driver Unit
Injectors
ECU
ECU - Electronic Control Unit
Fuel Tank
Supply Pump
Filter
Pressure Sensor
extremely precisely all
the injection parameters
– such as the pressure in
the Rail and the timing and
duration of injection – as
well as performing other
engine functions.
The common rail fuel
injection system reduces
fuel consumption and
the exhaust gases
will be cleaner.
When a diesel engine is cold,
the compression process
may not raise the air to a
high enough temperature
to ignite the fuel. Therefore,
some diesel engines are
fitted with glow plugs. The
glow plug has an electrically
heated wire that heats the
combustion chambers and
raises the air temperature
when the engine is cold so
that the engine can start.
3.6.4 Cold start device
If the diesel engine stops because the vehicle runs out of fuel
it will often not be enough to just fill up the tank again.
The fuel system must be bled before it can start. On many
vehicles a bleeding valve has to be opened and fuel must be
pumped by hand until all air is gone and clear fuel is coming
out of the bleeder valve.Some vehicles have got a self-
bleeding system and then it will bleed itself just by cranking
the engine with the starter motor.
But the bleeding can take up to 1 - 2 minutes before the
engine starts. As vehicles are bled differently always check in
the driver’s manual how to do it on your vehicle.
Bleeding pump mounted on top of the fuel filter. The pump is
on top and the circled valve to the left is the bleeding valve.
Open the valve
Instead of glow plugs some
vehicles have a pre-heater
that heats up the incoming
air to the engine when start-
ing in cold weather.
Pre-heater
Glow plugs
3.6 The fuel system
3.6.5 Bleeding the fuel system

057
3.7 Air filter
The engine is using a lot of air and to stop dust entering the engine all the air must go through
an air filter. It is good economy to change the filter often.
Pleated paper filter elements are now the most common vehicle engine air cleaners, because
they are efficient, easy to service, and cost-effective. As long as a pleated-paper filter is sized
appropriately for the airflow volumes for a particular engine, such filters present very little
restriction to flow until the filter has become significantly clogged with dirt.
3.7.1 Paper air filter
3.8 Turbo charger
Cooler air is denser than hot
air. In the intercooler air from
the turbo is cooled down
before entering the cylin-
ders. Denser air can burn
more fuel and the engine
can be made more powerful.
The intercooler can increase
the possible power of the
engine up to 10%.
Many diesel engines are
equipped with a turbo to
give them more power. The
turbo is driven by the exhaust
gases and pump in extra air
to the engine. With more air to
the engine more fuel can be
added and the engine will give
more power. The turbo runs
with very high revolutions
often 75,000 to 130,000.
Therefore, the turbo must
at all times get sufficient oil
to the bearings. The oil to
the turbo is pumped by the
engine’s lubrication system.
If the vehicle has been
driven hard (the turbo is
running fast) do not switch
off the engine immediately
when you stop the vehicle.
Wait 1-2 minutes and let
the turbo slow down before
switching off the engine
to avoid running the turbo
without proper lubrication.
Some new buses are
equipped with an electric
turbo. The exhaust
gases turn the turbo and
electricity is generated
by the combined electric
motor/generator.
When extra power is needed,
the turbo can speed up by
the electric motor and give
more air to the engine.
3.8.1 Intercooler

059
3.9 Exhaust system
3.9.1 Silencer
3.9.2 Catalytic
converter
Following items can be found along the exhaust system.
The exhaust pipe is
equipped with a silencer
that reduces the noise
from the engine.
A catalytic converter
converts toxic exhaust
gases from the engine into
non-toxic substances.
The catalytic converter is
described in “Environment
and Exhaust Gases”
3.9.3 Particle filter
3.9.4 Exhaust pressure regulator (EPR)
A diesel particle filter,
sometimes called a DPF,
removes particles or soot
from the exhaust gas of a
diesel engine.
Diesel particle filters usually
remove about
85% of the soot.
A diesel vehicle equipped
with a functioning filter will
emit no visible smoke from
its exhaust pipe.
In addition to collecting the
particles, there must be a
method to clean the filter.
Some filters are single-use
(disposable), while others
are designed to burn off
the accumulated particles,
either through the use
of a catalyst (passive),
or through an active
technology, such as a fuel
burner which heats the
filter to soot combustion
temperatures, through
engine modifications or
through other methods.
This is known as filter
regeneration.
A warm engine produces much less harmful exhaust gases than a cold one. Therefore, it is
good if the engine reaches at working temperatures as fast as possible.
The EPR is a valve that closes to increase the pressure in the exhaust system in order to heat
up the engine to the working temperature faster.
This will reduce bad exhaust gases.
The EPR is often combined with the exhaust brake.
Exhaust gases are dangerous. NEVER run an engine in a
closed area with poor ventilation
The exhaust pipe on a bus is normally directed backwards or
to the left so that passengers entering or leaving the bus will
not be exposed to the exhaust gases.
3.9 Exhaust system

061
3.10 Smoking engine
A diesel engine should not smoke. If your bus is smoking there is something wrong with
the engine. A smoking vehicle produces exhaust gases that are harmful to humans and for
the environment.
An engine in proper condition should not smoke.
Black smoke is the most
common smoke emitted
from diesel engines.
It indicates poor and
incomplete combustion of
the diesel fuel.
There are many
causes, including:
Blue smoke is an indication
of oil being burnt.
The oil can enter the
combustion chamber for
several reasons:
White smoke occurs when
raw diesel comes through
the exhaust completely
intact and unburned or
when the coolant gets
burned with fuel.
Some causes of this include:
• Incorrecttiming
• Dirtyor
worninjectors
• Faultyturbocharger
(i.e.notenoughair
tomatchthefuel)
• Incorrect
valveclearance
• Incorrectair/
fuelratio
• Lowcylinder
compressiondue
tostickingpiston
ringsorworn
components.
• Dirtyaircleaner
• Restrictedair
inlet(e.g.airfilter
blockedorkinked
inletpiping)
• Poorqualityfuel
• Lowoperating
temperature.
• More oil pressure.
• Worn valve
guides or seals
• Wear in power
assemblies
(i.e. cylinders,
piston rings,
ring grooves)
• Cylinder glaze
• Piston
rings stuck
• Incorrect grade
of oil (e.g. oil
too thin, and
migrating past
the rings)
• Fuel dilution in
the oil (oil thinned
out with diesel)
• Faulty
or damaged
injectors
• Incorrect
injection timing
(could be
a worn
timing gear or
damaged
crankshaft
keyway).
• Low cylinder
compression
(e.g. caused
by leaking or
broken valves,
piston
ring sticking,
cylinder
and/or ring
wear, or
cylinder glaze)
Black smoke is the most
common smoke emitted
from diesel engines.
3.10.1 Black smoke 3.10.2 Blue smoke 3.10.3 White smoke
3.10 Smoking engine

063
hydrocarbon (HC) but not
nitrogen oxides (NOx) and
particles (soot). Catalytic
converters for petrol engine
reduce CO, NOx and HC.
Carbon monoxide is a
colorless, odorless, and
tasteless gas that is
slightly lighter than air. It
is highly toxic to humans
and. Hydrocarbon in the
exhaust gases is burned
or partially burned fuel.
Hydrocarbons are poisonous
and are a major contributor
to smog a major problem
in urban areas. Prolonged
exposure to hydrocarbons
contributes to asthma, liver
disease, and cancer.
Nitrogen oxides are 300
times more potent than
carbon dioxide as a
greenhouse gas. NO2 makes
up about 7.2 percent of the
gases that cause global
warming. Petrol vehicles
with catalytic converters
reduce the amount of NO2
substantially.
The exhaust gases from
vehicles are not good
for humans and for the
environment. It is im-
portant that the engine
is in good condition and
well-adjusted to avoid
unnecessary pollution.
Today many vehicles
have a catalytic converter
connected to the exhaust
system. The catalytic
converter for diesel engines
reduces the amount of
carbon monoxide (CO) and
3.11 Environment and exhaust gases 3.12 Vehicle’s lubrication system
vehicle manual informs
about oil and oil filter
change intervals.
It is always good to change
the oil and oil-filter as
recommended in the manual
Never overfill the engine
oil. Always keep the oil
level within the maximum
and minimum markings.
If there is too much oil in
the engine the oil seals can
start leaking. Some modern
vehicles got special oil
cooler fitted. It works like
the ordinary radiator but
All moving parts in the
engine and transmis-
sion must be constantly
lubricated. The engine
got an oil sump filled with
oil and an oil pump that
transport the oil to different
parts of the engine. The
steering box, gear-box
and the differential on the
driving axles are also filled
with oil. Grease is applied
on many places.
It is essential that the
right type of oil is used
and that oil levels are
checked regularly. The
Relief valve
Lines and jets
Filter
Oil sump
Strainer
Pressure
regulator
valve
Oil pump
instead of cooling “water”
the engine oil pass through
the oil cooler. This is of
course to help cooling the
oil so that it will work better
as lubricant.
Oil cooler

065
3.12.1 Mineral oil or synthetic oil
3.12.2 Advantages with synthetic oil
There are a number of
different types of engine
oils on the market. The
mineral oil has been the
standard oil but today
you can buy synthetic oils
and mixtures of synthetic
and mineral oils. In the
driver’s manual for the
vehicle you will find what
type of oil the vehicle
manufacturer recommends.
Remember that when you
top up always use the
same type of oil.
Avoid mixing different
types of oil.
The modern synthetic oil is
often the better choice even
though it is more expensive.
The best protection under extreme temperatures within the
engine and the best protection against hot spots for less oil burn.
• Measurably
better low and
high temperature
viscosity
performance
• Better chemical
shear stability
• Decreased
evaporative loss
• Resistance to
oxidation, thermal
breakdown and oil
sludge problems
• Extended drain
intervals with the
environmental
benefit of
less oil waste
• Improved fuel
economy in
certain engine
configurations
• Better lubrication
on cold starts
• Longer engine life
Synthetic oil Mineral oil
3.13 Cooling system
Less than half of the used fuel energy is transferred to the vehicle movement. The rest creates
heat in the engine. As the engine should not work at too high temperature there must be
cooling system taking care of the heat.
This is the cooling system
on almost every car, bus
and truck today.
The engine is cooled by
liquid circulating through
the engine and cooled off in
the radiator. A water pump
pumps the cooling liquid
and a thermostat adjust
the flow to keep the engine
temperature at a fixed level.
The engine runs best and
uses least fuel when it is not
too cold nor too hot (about
80-90 degrees C is normally
the best engine temperature).
The cooling system works
under pressure to stop it
from boiling even at higher
temperatures. It is fitted with
an expansion container that
takes up the change of liquid
volume when the engine
is hot or cold.
Never open the radiator cap
when the engine is hot and
never fill cold water in to a
hot radiator.
3.13.1 Liquid cooling

067
3.13.2 Radiator 3.13.3 Cooling liquid
In the radiator the cooling
liquid is cooled down by
the wind passing through
the radiator.
Never block the air from
freely entering and going
through the radiator.
When the vehicle is moving
air is forced through the
radiator and when the vehicle
is stationary or moving
slowly a fan behind the
radiator draws air through it.
Nowadays a thermostat
normally controls
the cooling fan.
The cooling liquid must not freeze to ice in cold weather and
should also minimize rust in the engine. Therefore, the liquid
is not just pure water but water mixed with some other liquid.
Most common is either ethylene glycol(ENG) or propylene gly-
col (PGW). Look in the vehicle manual to see what is recom-
mended for your vehicle.
When the
vehicle is
moving air
is forced
through
the radiator.
3.14 Electrical system
3.14.1 Batteries
The electrical system in a vehicle traditionally supplied electricity to the starter motor and to
the lights. Nowadays a vehicle has electronic equipment, computerized systems, sensors and
electrically controlled maneuver systems. A modern vehicle uses a lot of electricity and if the
electrical system is malfunctioning it can often be impossible to drive the vehicle.
The electrical system on a bus is very complicated. Computerized systems have made it very
difficult to fully understand what to do if something is wrong.
The battery stores the
electrical energy while the
generator charges it. Avoid
draining the battery. A
battery will last long if only
10-20 % of its capacity is
used and if it as much of
the time as possible is fully
charged. A stored battery
needs to be charged at
least every month.
The batteries can be sealed
or open. The sealed ones
are maintenance free but
the open ones should be
topped up with distilled
water when needed.
The sulphuric acid in
the batteries is very
harmful and you should
avoid getting it on your
skin or clothes.
The generator is producing the electricity for the vehicle. It is
driven by a belt connected to the engine.
The generator is producing alternative current and must have
a rectifier to give the direct current needed for the batteries.
As the generator produces alternative current it is often
called alternator. Modern alternators have a voltage regulator
built into them.
3.14.2 Generator

069
3.14.3 Relays
3.14.4 Fuses
A relay is an electric switch.
With a small amount
of electricity, the relay
can switch on and off
high currents.
You will find many different
relays the vehicle.
They control all electrical
equipment that needs
moderate to large amount
of electricity.
Fuses protect the electrical system from break down. If there is a short circuit somewhere in
the electrical system a fuse will blow to protect the system from major damage.
You will find several different fuse boxes on a vehicle.
Look in the manual to see where they are and what the different fuses are for. Always replace a
fuse with one with the same Ampere rating.
3.15 Jump starting
If your vehicle’s batteries are flat, you can jump-start the vehicle using jump lead connected to
another vehicle.
• On the vehicle
with the dead
battery, make
sure everything is
turned off (lights,
Radio, etc.)
• Check the batteries
of both vehicles.
Make sure you
can clearly
identify which
is the positive
(red) terminal
and which is the
negative (black
or blue) terminal.
If you get these
mixed up, you can
fry both vehicles
electronics.

Make sure the vehicle with
the good battery is running,
and then connect the cables!
This must be done in the
following order:
Once they are connected properly, wait a minute or so (the
healthy battery will slightly charge the weak battery). If the
cables are connected correctly, the interior lights and other
things on the weak battery should work.
Start the vehicle with the weak battery. If it doesn't start
within 30 seconds, stop cranking and give it a break. If you
crank too long, you can burn out your starter.
Once the vehicle is started, disconnect the jumper cables in
the reverse order:
• Connect one
red clamp to the
positive terminal of
the healthy battery
• Connect the other
red clamp to the
positive terminal of
the weak battery
• Connect the
black clamp to
the negative
terminal of the
healthy battery
• Connect the
remaining black
clamp to a ground
of some sort
on the vehicle
with the weak
battery. Do not
connect it directly
to the negative
terminal. Sparks
may detonate
the hydrogen gas
which formed
around the battery.
• Examples of good
grounds are: clean,
metal surfaces
(bolts or brackets).
Note that you may
get a small spark
when you connect
this final clamp.
It's a good idea to let the vehicle with the weak battery run for
a few minutes, and then do the following test.
Turn the vehicle off, and see if it can start on its own. If it can,
great! You are on your way. If not, you'll need to boost it again
and have the charging system checked out.
Be careful.
When a battery is being charged it will produce oxy-hydrogen
gas that is explosive.
1. Remove the
negative cable
from the weak
battery vehicle
2. Remove the
negative
cable from the
healthy battery
3. Remove the
positive cable from
the weak battery
4. Remove the
positive cable from
the healthy battery.
If your vehicle’s batteries are
flat, you can jump-start the
vehicle using jump-leads
connected to another vehicle.
Describe what are the four strokes.
1
answer go back and read that
part again. Be aware that the
questions are not covering the
whole content of the chapter.
What is
electrical fuel system?
4
What is the major
difference between petrol
and diesel engine?
3
What is the purpose of
oil in the engine?
Why do we use coolant
liquid in the engine?
6 7
What minimize
leaks between the
cylinder and piston?
2
How a
turbocharger works?
5

TRANSMISSION
AND BRAKE
SYSTEMS
Chapter Four

075
074 Transmission and Brake systems
Transmission and Brake systems
4.1 Clutch
4.1.1 Mechanical clutch
4.2 Hydraulic
coupling
The engine is running all the time when you drive even when
you change gear or when the vehicle has stopped. Therefore,
a vehicle must have a device that can disconnect the engine
from the wheels. The clutch is that device.
The clutch connects the
engine to the gearbox.
When you press down the
clutch pedal the engine
gets disconnected from
the gearbox. The clutch
plate has a lining made of
the same type of material
Flywheel
Clutch lining
Clutch disc
Gear Casting
Pressure Plate
Plate spring
Thurst bearing
Clutch lever
Fulcrum
Drive shaft
The hydraulic coupling
has an impeller connected
to the engine and turbine
connected to the gearbox.
Both are mounted near
each other in a closed
compartment; shell, filled
with hydraulic oil.
When the impellor start
rotating it will force the
turbine to follow. At idling
the impeller is not able to
turn the turbine. Vehicle with
automatic gear-boxes have
this type of clutch.
as on the brake pads.
You can therefore engage
and disengage the clutch
smoothly by letting the
clutch plate slip towards the
flywheel. Be careful and avoid
slipping the clutch as much
as possible to minimize wear.
Cut open hydraulic coupling.
When the
impellor
start rotating
it will force
the turbine
to follow.
4.3 Hydraulic torque converter
The torque converter is a more sophisticated type of
hydraulic clutch.
Like a basic hydraulic coupling, the torque converter
normally takes the place of a mechanical clutch, allowing the
load to be separated from the power source.
However, a torque converter is able to multiply torque
when there is a substantial difference between input and
output rotational speed, thus providing the equivalent of a
reduction gear.
Effectively changing the converter into a purely
mechanical coupling.
The result is no slippage, and virtually no power loss.
This coupling has a stator
mounted between the
impellor and the turbine
that raise the torque.
There is also a mechanical
clutch to avoid slip in the
clutch when driving.

077
4.4.1 Different types of gear boxes
There are two common
types of gearboxes:
4.4.1.1 Manual gearbox
The manual gearbox has
different size of gears that
will be connected when
the gear lever is moved. In
modern gearboxes the gears
have sync-built in. This
device adjusts the speed of
the gears before they are
connected and makes it
easier to change gear.
A basic layout of a 5 peed
manual gear box. The gear-
lever connects the different
gears. In first gear the
outgoing gear is big (1) and
in fifth gear small (5).
From
Engine
Gear
Selector
Fork
To
Differential
Idler
Gear
Layshaft
1 2 3 4 5 R
4.4 Gearbox
The gearbox changes the revolutions of the engine to suit the changing driving conditions.
A diesel engine for large vehicles works best within a narrow revolution range (for example
between 1000-2000 rpm) that can be chived by using the appropriate gear, the driver can
maintain the engine most of the time within this range. A low gear will give high torque to the
driving wheels but the speed will be low.
Modern gearbox

079
4.4.1.2 Automatic gearbox
With an automatic gearbox
the vehicle automatically
changes the gears when
needed. Some buses are
fitted with a gearbox that
works as an ordinary
manual gearbox but can
also be set to change the
gears automatically. There
are two different types of
Auto Shift Transmissions,
those with a clutch pedal
and those without one.
These transmissions are
still manual gearboxes
and there is little difference
between the manual shifted
transmission and the auto
shift except that the auto
shifts are controlled by
computer and shifted by
solenoids rather than using
the gearshift lever.
The same thing with the
clutch pedal, one is manually
operated, and the other is
controlled by computer.
4.5 Rear axle and differential
Ring gear
Axle shaft
side gear
Axle shaft
Axle housing
Differential
side gear
Universal
joint
Pinion shaft
Pinion gear
Axle shaft
When a vehicle is turning the outer wheels travel a longer distance than the inner wheels.
In the middle of the driving
axle is a differential that
accommodates for the
different speed of left and
right wheels when turning.
Some vehicles have a
differential lock that can
be engaged when there
is risk of getting stuck in
mud. The differential lock
should only be used on
slippery roads. The power
is transferred from the
differential to the wheels
through drive shafts.
4.4 Gearbox

081
4.6 Steering system
The steering box transfers the turning of the steering wheel
to the drop arm, draglink, tie rods and steering arms mounted
on the front wheels and turn the wheels. There are two main
different types of steering boxes. The most common type of
steering box on cars is the rack and pinion box.
Light buses have a steering box with recirculating balls. This
type of box is less sensitive to the road.
A play in the steering (back lash) can be adjusted. Play should
never be more than 5 cm.
Steering
Arms
Steering
Wheel
Steering
Wheel
Shaft
Tie Rod
Spindle
Steering Ring
Knuckle
Drag
Link
Pitman
Arm
Steering
Gear
Box
Rotary valve
Steering gear
Pump
Pulley
4.6.1 Steering box 4.6.2 Power steering
Basic components on a power steering
All modern buses are equipped with power steering.
The power steering helps the driver to turn the steering
wheel more easily.
The engine drives a hydraulic pump and the hydraulic oil that
is under pressure works on pistons inside the steering box
when the steering wheel is turned.
The steering will still work even if the power steering is not
working (if the engine is not running) but the vehicle will be
very hard to turn.
Shake the steering wheel
and measure how much the
play is before the wheels
start turning. It should not
be more than 5 cm.

083
4.7
Automatic
Traction
Control (ASR)
Electronic stability control
(ESC) is a computerized
system that improves
safety of a vehicle's
stability by detecting and
minimizing skids.
When ESC detects loss
of steering control, it
automatically applies the
brakes to help steer the
vehicle where the driver
intends to go. Braking is
automatically applied to
wheels individually, such
as the outer front wheel to
counter over steer or the
inner rear wheel to counter
under steer. ESC does
not improve a vehicle's
cornering performance; it
only helps to minimize the
loss of control.
Some research shows that
one-third of fatal accidents
could have been prevented
by this technology. ESP is
an additional feature that
uses the ABS system for
controlling the brakes.
When the traction control
computer detects one or
more drive wheels spinning
significantly faster than
the others, it will use the
ABS to apply brake friction
to the wheels that are
spinning too fast.
This braking action on
the slipping wheel(s)
will cause power to be
transferred to the wheels
that got traction.
4.8
Electronic
Stability
Program (ESP)
Sensor types:
Driving too fast in a corner
or roundabout may result
in a rollover because of the
vehicle center of gravity. The
ARP system automatically
detects an unstable
condition that could lead
to a potential rollover. ARP
rapidly applies the brakes
with a high burst of pressure
to the appropriate wheels
to interrupt the rollover
before it occurs.
Rollovers can also occur
when the vehicle is knocked
into a stationary object
such as a curb. To avoid roll
over, new rollover stability
systems incorporate
an active suspension
system to the rollover
protection apparatus.
When the ARP system
determines that the vehicle
is at risk of rollover, it
calculates the direction
of roll and activates the
active suspension system
so that it counteract the
roll over forces.
4.9
Anti-overturn
Control
System (ARP)
A lane departure warning system is a mechanism that warns a
driver when the vehicle begins to move out of its lane (unless
a turn signal is on in that direction). A sensor detects the
white or yellow side marking on the road and send a signal if
the vehicle crosses the side marking.
There are two main types of systems:
1. Which warn the driver (lane departure warning,
LDW) if the vehicle is leaving its lane. (visual,
audible, and/or vibration warnings).
2. Which warn the driver and if no action is taken
automatically take steps to ensure the vehicle
stays in its lane (lane keeping system, LKS).
• Video sensors in visual domain (mounted behind
the windshield, typically integrated beside the
rear mirror)
• Laser sensors mounted in the vehicle front
• Infrared sensors (mounted either behind the
windshield or under the vehicle)
Driving too
fast in a
corner or
roundabout
may result
in a rollover.
4.10 Lane
Assistant
This braking
action on
the slipping
wheel(s)
will cause
power to be
transferred
to the
wheels that
got traction.
High buses can be unstable
when driving in bends.

085
4.11 Wheels and Tires
Today all modern tires of radial type.
Tubeless tire has a special rubber lining inside
to make it air tight. You can always have a
tube in a tubeless tire.
The wheels have a rim and mounted on that a tire. The rim is made of pressed steel or of cast
aluminum alloy. The rim is fixed to the wheel hub with wheel nuts.
Today almost all modern tires are of radial type. They have soft sides and a rigid surface. They
run a little bit cooler than diagonal tires and last longer.
In the diagonal tire, the plies are crossing each other. The radial tire has the plies going
only in one direction. The belt gives a rigid surface for the part of the tire that is in contact
with the road.
Diagonal Tire Radial Tire
Belt Belt
Diagonal plies Radial plies
Diagonal Tire Radial Tire
Belt Belt
Diagonal plies Radial plies
The tire’s grip towards the road is of course essential. Tires must work in cold and warm
weather, when the road is wet or dry and on asphalt as well as on gravel roads. It is not possible
to make a tire that is optimized for all these different conditions.
Therefore, there are many different types of tires made for different conditions and most of
them are made to work reasonably well in all ordinary situations.
The wheels can have tires with a tube inside or tires without tube. Tubeless tires can only be fitted
on rims made for tubeless tires. Tubeless tire has a special rubber lining inside to make it air
tight. You can always have a tube in a tubeless tire.
Standard
Tubeless
Standard
Tubeless
4.11.2 Tube and
tubeless tires
4.11.1 Radial / Diagonal
4.11.3 Grip

087
4.11.4 Remolded tires
In some countries worn out tires can be remolded. A new tread surface is vulcanized on the old
tire. This remolded tire is if made professionally very strong and both save money and rubber.
Tread proﬁle
Carcass
Additional tread
available as a
result of
regrooving
2.0mm
of under
tread
Additional
steel belt
Steel belt
Regularly check that the new surface is not getting loose.
Some tires have a
thicker tread surface and
are constructed to be
regrooved when the original
tread is worn out.
These tires are marked
“Regroovable”
No other tires should be re
grooved and even tires that
are regroovable must only
be re grooved in accordance
with the tire manufacturer’s
recommendations
(not too deep).
The depth of the tread is
important when driving
on wet roads and on
gravel or in mud.
The minimum tread must be
at least 1.6 mm in normal
conditions and 3.2 in
rainy weather.
4.11.5 Regroovable tires
4.11.6 Tire tread
Many tires have molded ribs
crossing the tread.
These ribs are 1.6 mm
high and indicate if
a tire is worn out.
The TWI and the ∆ marking
show were to find the tire
tread indicators.
4.11.7 Tire
wear indicator

089
Twin tires should always be of the same size and have the same air pressure so that the load is
equally distributed between the two tires.
4.11.8 Twin tires
The tire air pressure must
follow the manufacturer’s
recommendations.
A tire with low pressure
wears out faster And
consume more fuel,
increases the rolling
resistance and builds up
more heat. Tire air pressure
should always be checked
when the tire is cold.
Hot tires wear out faster
and are more prone to burst.
High speed, overload and
low air pressure build up
heat in the tire.
When changing the tires, check and tighten the wheel nuts after driving a few
kilometers if needed.
4.11.9.1 Hot tires
When tires get old the rubber gets harder and loose some of
the grip and flexibility.
Tires age faster in hot weather and in sunshine.
4.11.11 Re-tightening wheel nuts
4.11.12 Wheel alignment
There are a number of different front wheel angels to consider like toe-in/out, kingpin
inclination, caster and camber angles. If any of these angels is incorrect the vehicle will not
function correctly and the tires will wear out faster.
Check that stones are not stuck in between the tires.
4.11.9 Right tire
air pressure
4.11.10 Age of tires

091
4.11.13 Tire markings
The tire got many different markings that can be of interest for you as a driver.
Ratio of height to
width (aspect ratio)
Radial
tire
Rim diameter
code
Load index and
speed symbol
Severe snow conditions
U.S. DOT tire
identiﬁcation number
The Nominal width of
tire in millimeters
Passenger
car tire
Max.
permissaable
inﬂation
pressure
Max. load
rating
Treadwear, traction
and temperature grades
Tire ply
composition
and materials
used
Section width (SW)
Section
height
(SH)
Outside
diameter
(OD)
WEAR 220 TRACTION AA
TEMPERATURE A
DOT U2LL LML R5107
4.12 Braking system
The ordinary foot brake works on all wheels and is the main
and most efficient brake system
The brake system controls
all the wheels when driving.
All vehicles must also
have a parking brake that
can hold the vehicle when
parked. The parking brake
works mechanically and
is independent from the
main foot brake.
4.12.1 Foot brake
The ordinary
foot brake
works on all
wheels and is
the main and
most efficient
brake system.
Different types of brakes
The last four digits in the DOT number indicates when the tire was manufactured. 51 is the
week number and 07 is the year 2007.
This brake works on some of the wheels on the bus.
Traditionally, in old model buses, a large lever is used
to activate the parking brake that holds the vehicle
stationary when parked.
Modern buses have small knobs or switches to apply the
parking brake.
4.12.2 Parking brake

093
4.12.3 Hydraulic brakes
Most of the vehicles are
equipped with hydraulic
brake system.
When the brake pedal is
pressed down brake fluid
from the master cylinder
actuates the brakes
on all wheels.
In a modern brake system,
the hydraulic bakes are
divided in to two separate
circuits. If one of the circuits
stops working (for example
because of a leak in the
hydraulic system) the other
circuit will still be intact.
With only one of the two
circuits working the brake
force will be reduced but
it will be possible to stop
the vehicle.
In the hydraulic brake
system, the brakes at the
wheels can be either drum
brakes or disk brakes.
Front Brakes
Typical Disk Brake
Brake Lines
Brake Pedal
Master Cyinder
Rear Brakes
Typical Drum Brake
4.12 Braking system
4.12.4 Drum brake
Drum brakes have been the
standard for wheel brakes
before disk brakes appeared.
They are still the most
common types of brakes on
heavy buses.
They are mounted on the
wheels behind the rim.
The drum brakes have two
brake shoes inside the drum
that are pressed out on the
drum when braking.
Brake drum
Brake lining material Shoe returning
springs
Shoe
Shoe
Hold-down springs
Hold-down pin
Shoe adjustment
Bleed nipple
Hydraulic slave cylinder
A drum brake for light bus
with hydraulic brake system.
The hydraulic slave
cylinder pistons push the
brake shoes towards the
rotating drum.

095
4.12.5 Disc brake
The modern type of wheel brake is the disc brake. A caliper with two brake pads presses the pads
against both sides of a disc when braking. They are mounted on the wheels behind the rims.
4.12 Braking system 4.13 ABS brakes (Anti-locking brake system)
An anti-lock braking system
(ABS) is a safety mechanism
that allows the wheels on a
motor vehicle to continue
to roll on the road surface
while braking, preventing
the wheels from locking up
(that is, cease to rotate) and
therefore avoid skidding.
An ABS generally offers
improved vehicle control
and decreases stopping
distances on dry and
slippery surfaces, however,
on loose surfaces like gravel
or sand-covered roads, an
ABS can increase braking
distance, although still
improving vehicle control.
The warning light on the
dashboard normally lights
up when the vehicle is
started and the system
is checking that the
ABS is in order. If the
light does not switch off
something is wrong and
the vehicle brake should be
checked at a garage
The warning light on the dashboard normally
lights up when the vehicle is started.

097
What is the purpose of the clutch?
1
of the chapter.
What is Electronic
Stability Program (ESP)?
4
What is an Automatic
Traction Control (ASR)?
3
How much play is acceptable in the steering system?
6
What is the
automatic gearbox?
2
When do you need to
change a tire?
5
How worn tires are acceptable?
8
What is ABS brake
system and how
does it work?
7

101
100 Bus Safety
Bus Safety
5.1 Bus Safety check
5.1.1 Before you
enter the bus
• Windscreen
washer
• Engine oil level
• Engine
cooling liquid
• Check that all
instruments and
control levers/
knobs are working
• Check that the low
pressure indicator
for the brakes
is working
• Start the engine
and check:
• ABS control
indicator (if fitted)
• Never rev the
engine when it is
still cold
• Check rear
view mirrors,
windscreen wipers
and washers,
Indicators horn
• Turn on the
driving lights
• Check steering
wheel play and
the function of the
steering servo
5.1.3 Step out of the
vehicle again
5.1.4 While you walk around the vehicle
• Check under the
engine for any oil
or water leakage
• Check the lights
at the front
• Take a piece
of cloth with
you when you
walk around
the vehicle
• Adjust the seat
so that you are
comfortable
• Start driving slowly
and check that
the foot brake and
parking brake are
working properly
• Wipe off all lights, reflectors and signs on the
bus and check that the lights are working at
the same time
• Check for any damage on the tires and that no
stones are stuck between the twin tires
• Check all mud guards
• Check that the emergency equipment are there,
e.g. warning triangles, fire extinguisher and
first aid kit.
Check:
5.1.2 When you are on the driver’s seat
Check engine oil level radiator coolant level and wind screen washer level.
5.1.5 Get back in the driver’s seat
Never rev the
engine when
it is still cold.

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5.2 Driver’s Environment
• Heating,
ventilation
and air conditioning
• Dashboard with a number
of important
gauges
and indicator lamps
• Switches for doors, lighting, public
address system, entertainment
systems (TV, radio, video)
• Sometimes equipment for handling
tickets and collecting of fees
5.3 Before you start driving
• You should be
seated in a normal
driving position
• Place your
right foot on the
service brake and
depress it.
Move the seat
forward if you
have to stretch to
reach the pedal
• Your feet should rest
flat on the floor. If
not, then adjust the
height of the seat
• Adjust the tilt of
the steering wheel,
if available. Hands
should be at 10
and 2 or 9 and 3
o’clock position
and arms bent
• Your back should
be flat against
the backrest to
ensure proper
back support.
• You should be
able to reach
all pedals
and controls
with your
seatbelt on
5.3.1.1 How to adjust your seat?
A modern bus has a very comfortable driver cabin. It has:
Many of these different systems can be quite complicated to handle and you will have to learn
to understand and maneuver all these items.
Before you start your work-shift always make a safety check of the bus.
It is very important to adjust your seat before adjusting your mirrors. If you move your seat, then
your view of the mirrors will change simultaneously.
5.3.1 Seat adjustment

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104 Bus Safety
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5.3.2 Adjusting the seatbelt
• Ensure that the belt is not twisted
• Adjust the height of the belt by
placing it on the shoulder and
not the arm (too low) or the neck
(too high)
• Belt should run smoothly across
the shoulder closer to the neck.
• Belt should not constrict the
throat or neck
• Lap belt should fit snugly over
the hip bone rather than
the stomach
• Double check the belt (pull the belt)
to ensure the belt is not Loose
5.3.3 Bus mirror adjustment
After positioning the
driver’s seat and adjusting
the left and right hand
external mirrors, the
drivers should be correctly
positioned so as to have a
full view of the road ahead,
to the sides and clear
view in the external rear
vision mirrors.
The mirrors should be
secure enough to ensure
that they do not vibrate and
make it impossible to see
anything in them and solid
enough that they do not
swing about or move due to
transmitted shock from the
road surface.
Rear vision mirrors can
often be used to check
the side of a bus to see if
anything is hanging out or
blowing about, especially
a kid's hands.
All of a driver’s vision
should be unobstructed.
Items should not be
hanging from the inside
of the vehicle that could
distract the driver’s
attention, nor should
stickers etc. block vision
through the windows.
All windows and mirrors
should be clean and free of
cracks or other damage that
could interfere with vision.
Modern advanced type of side view mirrors. The upper mirror
is showing what happens near the front side of the bus. These
mirrors can be adjusted with an electrical switch.
Mirrors mounted like this
reduce the blind spots
Standard type of
side view mirror
The drivers should be correctly positioned so
as to have a full view of the road ahead.
5.3 Before you start driving

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5.4 Blind spots
Blind spots can be
found with any vehicle
regardless of its size.
To be safe and competent, a
driver needs to be aware of
a bus’s blind spots and look
to those areas as often as
possible. Good drivers look
in their rear vision mirrors
every few seconds to be
aware of the traffic behind.
When checking mirrors,
drivers should remember
that at 60km/h the vehicle
would travel 17 meters
in one second; therefore,
a driver should not look
into the mirrors for longer.
A good mirror system,
with a combination of the
flat and convex exterior
rearview mirrors, can have
good results in reducing
the blind spots areas
around the bus.
5.4.1 Direct vision
distance at the
front of the bus
The clear direct visible
distance in front of the
bus allows the driver to
maneuver in the soft manner
to avoid front collision or
emergency braking.
Bus drivers should always
keep more safe distance
(Space Cushion) at all
sides of the vehicle to avoid
sudden maneuvers. Space
cushion is a clear area in
front of, at the sides and
behind a vehicle that drivers
should try hard to maintain
wherever possible.
This will allow room to
maneuver or swerve
slightly if required.
Bus drivers usually have
the advantage of their extra
high position allowing them
to see over the vehicles
in front, giving them early
warning of problems ahead.
Drivers should never forget
the need to have a space
cushion above the vehicle.
This can be done by always
being aware of the height
of a vehicle.
Even an adult standing just
in front of the bus can hardly
be seen by the driver. A
child will be totally hidden
5.4.2 Blind spot area behind the bus
Blind Area behind the Bus is very dangerous because of
non-visibility. In the interior rear view mirror you can see the
passenger but you cannot see behind the bus. As the transit
buses stop on berth, bus stops and hard shoulder of the road,
passengers walking around the bus are not visible.
If possible reverse to the parking bay so that when leaving
you can drive straight out without reversing. Some buses are
equipped with mirrors placed over the rear windshield to cover
a part of the rear blind spot behind the bus.
Some buses are equipped with mirrors placed
over the rear windshield.

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5.5 Systematic mirror check
The systematic mirror check is the key to quickly finding
problem objects in your mirrors. You should think and develop
a systematic mirror check.
Procedure
Here is an example of a systematic mirror check:
• Scan up left
exterior mirrors
• Check for the
traffic ahead.
• Scan down right
exterior mirrors
• Articles left
on the bus
• Sleeping
passenger
• Open windows
and doors
• Damage
or vandalism
• Mechanical
/ operational
problems with
the bus with
special attention
to items that
are unique, for
example school
buses, mirrors,
flashing warning
lamps and stop
signal arms
The bus driver can use the example above or one they have
developed and feel more comfortable with. The order in which
the drivers check their mirrors is not necessarily the same
way each and every time.
5.6 Post - Trip
Inspection
When your route/trip is
finished, you should conduct
a post-trip inspection
of the bus. You should
walk through the bus and
around the bus looking for
the following:
Any problems or
special situations
should be reported
immediately to your
supervisor.
5.7 Fitness to drive
Most of the information
that a driver needs comes
through his eyes. Good
vision is therefore essential
for safe driving.
There is a legal minimum
standard of eyesight
for bus drivers.
Make sure that you meet
these standards at all times.
Have you had your eyesight
checked recently?
As people get older, their
eyesight tends to get
worse. Regular eye checks
are essential.
If you need to wear glasses
for driving, make sure that
you always wear them.
Use sun glasses in bright
sunlight only. NEVER use
them at night.
• Take
LONGER to react
• Take MORE risks
• LOSE control
• LOSE your memory
• LOSE
consciousness
• DIE
Alcohol may give you a feeling of wellbeing but, in fact, it is
a depressant.
Even at low levels, it worsens your judgment and your driving
performance. At higher levels, the risk of being involved in an
accident increases dramatically.
NEVER drink alcohol and Drive
Alcohol is a major cause of traffic accidents in many
countries. Even small amounts of alcohol can affect your
driving. It is not just people who are obviously drunk who
cause accidents.
The effects of alcohol on driving vary but, in general, they
follow the pattern below.
With increasing amounts of alcohol, you are likely to:
5.7.1 Vision 5.7.2 Alcohol
What you can see in the left view mirror. The vehicle passing
next to you can easily be seen but vehicles in the next lane to
the left are hidden
Alcohol
is a major
cause
of traffic
accidents in
many
countries.

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110 Bus Safety
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5.7.3 Drugs and medicines
Many drivers need to take
prescription drugs at some
time in their lives. Only a
few realize how the drugs
can affect their driving.
Drugs may be taken for
many reasons. Some
medical drugs, such as
mild Painkillers taken for
headaches, are unlikely
to affect most drivers
seriously. Others, such as
antihistamines taken for hay
fever, can cause drowsiness
and are therefore dangerous
if taken before driving.
Drugs prescribed for serious
medical conditions may have
side effects, which can affect
driving. So check with your
doctor and follow his advice.
A very common reason for
accidents is that the driver
has been tired and fatigued. It
is not uncommon that drivers
fall asleep when driving.
This type of micro sleep
maybe lasts a split-second
only but that is enough to
lose control of the vehicle.
It is dangerous to try to
keep awake only by turning
the radio on, opening
the window while you
continue driving.
If you feel tired stop and take
rest for sometime, stretch
your legs, take a walk round
the vehicle and you will soon
feel much better. Eat carefully before and during a journey.
A large meal can make you feel drowsy. Eating nothing at all
is equally bad.
NEVER take drugs or medicines to help you to keep awake
There are many factors that contribute to make you tired or
fatigued and unable to drive.
Non-medical drugs or medical drugs taken for non-medical
reasons (such as amphetamines to stay awake) are illegal and
dangerous to all drivers.
Never drive after taking the drugs unless they have been
prescribed by a doctor and are confident that it is safe to drive.
5.7.4 Fatigue
5.8 Driving at night
Night driving can be particularly dangerous if you are not familiar with it. Both driving in heavy
traffic and driving along a straight road for a long time at night can be quite tiring.
The worst time is the early morning hours when your body normally wants to sleep. If you feel
sleepy, have a break.
Avoid driving for more than 4 hours without a break.
5.7 Fitness to drive

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5.9 Personal protection
5.9.1 Reflective vest
5.9.2 Seatbelt
Always wear
the seatbelt
when driving.
If you have to leave the bus in traffic always wear the fluorescent coloring jacket/vest with
reflective materials so that you are visible.
Always wear the seatbelt
when driving.
The seatbelt is the most
effective device for reducing
injuries and fatalities in
road accidents.
5.10 Working hours, breaks and sleep
Many countries have special
regulations controlling the
time a driver is allowed to
drive without a break, how
long a break must be and
how many hours sleep the
driver must have between
each daily shift.
To control the working
hours, the driver has
to fill in the time when
driving and resting.
Obey the national laws
regarding driving time.
As a general rule, don’t drive
for more than four hours
before taking a break. In a
period of 24 hours, don't
drive more than a total of
10 hours. When you have a
break, get out of the cab and
go for a short walk.
One of the causes of
Buses accidents is the
sleepiness of the driver
because of driving for very
long hours without getting
proper breaks.
Drowsiness during driving
causes inability to make
correct decisions and
adversely affects the speed
of the driver's reaction to
the risks he may face while
driving the bus, All these
things can cause loss of
control over the vehicle
and the occurrence of
fatal accidents.
The risk of increased sleep
during driving increases
the normal sleep times
5.11 Passengers safety
Your most important concern
must be the safety of your
passengers. Ensuring
your passengers’ safety is
always more important than
meeting schedules. You can
protect your passengers
best by making certain
that the vehicle you use to
transport them is safe and by
operating it properly.
When bus passengers
are injured, it is typically
because the driver:
• Stops too quickly
or suddenly
• Starts too quickly
• Turns too quickly
or suddenly
• Opens or closes
the doors
too quickly
• Fails to check
on passengers
frequently
enough
while driving.
You can prevent many
passenger injuries by
driving defensively. Keep a
safe distance behind other
vehicles so you won’t be
forced to stop quickly.
If the vehicle in front of you
stops suddenly, passengers
may be jolted and injured
during a quick stop. Avoid
getting blocked in by other
vehicles so you have an
escape route if trouble
develops ahead of you.
Use the controls on your
bus carefully.
Make your starts, stops and
turns smoothly. Check on
your passengers. Ensure
that they are not moving
about in the aisle when
the bus is moving and that
they are completely on
or off the bus before you
close the doors.
Keep a safe
distancebehind
other vehicles.
of drivers, especially in the hours before sunrise. There is
an increased risk of accidents during the afternoon and
after lunch hours.
Legal reference
Driving while feeling tired is not only dangerous but also
illegal The law states that driving, or continuing to drive a
commercial vehicle, is not required during feeling or getting
close to feeling tired.

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• Signal to warn
others that you
are stopping
to let off
passengers
• Leave at least 3
meters between
the bus and
the road on
the left Side to
allow vehicles
on the road to
continue Without
hindrance
• Stop in a place
that allows other
drivers to see
your vehicle
from a distance
of at least 60
meters in front
and behind
• Whenever it is
safe to do so,
pull your vehicle
off the travel
portion of the
road while your
passengers are
getting on or off
5.11.1 Loading and
unloading
passengers
on roadside
When you are loading or
unloading passengers on
the road, you must:
5.11.2 Focus on driving
The safety of your passengers is your first priority.
This means that any time
your vehicle is moving you
must not collect fares, take
on or let off passengers.
You should also save any
unnecessary conversation
with your passengers
until you have stopped
your vehicle.
You must ensure that
nothing or no one in your
vehicle gets in your way, not
allowing you to do a safe job.
You must be able to see
clearly ahead, to the right
and to the left.
You must be able to move
your arms and legs at all
times and be ready to reach
for emergency equipment.
Some modern buses
are equipped with video
cameras inside the bus to
help the driver to watch
the passengers.
5.12 Passengers
refusal
It is your duty to provide
transportation to all
paying customers.
However, you may refuse to
transport a passenger if:
1. Sick or
intoxicated
2. Boisterous,
disorderly
or using
bad language
3. Offensive or
dangerous
to others or
their property
• Your vehicle is
already carrying
the maximum
allowed number
of passengers
• Speak directly to the person with the disability, not to their companion or assistant.
• Do not assume that a disabled person needs your help. Always ask before
extending your help.
• Remember that every person is unique and people’s needs and abilities vary greatly.
• Be patient, flexible and creative in the way you communicate.
5.13
Transporting people of determination.
You need special skills, knowledge and sensitivity to transport the people of determination. You
cannot refuse to transport an individual just because that person has a disability.
Some people of determination travel with an assistant. You must keep special care to provide
them comfortable ride.
Remember these tips when transporting the people of determination.
If the passenger is:
It is your duty to provide
transportation to all
paying customers.
5.11 Passengers safety

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