Mine locomotive ppt (under ground transport system )

Thursday, May 16, 2019MINE LOCOMOTIVES 1

Syllabus
locomotive haulage and calculations based on it, track
laying, mine cars.
Practical
• Study of Exhaust Conditioner on a diesel locomotive
Thursday, May 16, 2019 2

Locomotive haulage
Chief Underground methods for transportation of mineral
are:
1. Rope haulages
2. Locomotive haulages
3. Conveyor haulages
The rope haulage provide intermittent production and are
not flexible. The conveyor haulage has a high capacity but
it is also not flexible. The locomotive provides the
flexibility in both directions and can be utilised for
transportation of men, material and mineral.

Application of locomotives
The mine locomotives are principally used in two areas:
1. Gathering haulage: The gathering work involves short
hauls with relatively few tubs and demands a
locomotive having a speed of nearly 5 kmph. Since
the gathering work is done near the face, therefore
trolley wire and diesel locomotives are ruled out and
the automatic choice falls on the battery locomotives.
2. Main road haulage: The haulage involves long hauls
at higher speeds. The trolley wire and diesel
locomotives therefore become the natural choice.

Application of locomotives (contd.)
A locomotive haulage can be used in a mine:
1. Where the gradient is mild. The flat gradients are
preferable. A gradient of 1 in 15 against the load is
considered as limiting
2. Where the locomotive track is not subjected to
movement due to mining.
3. Sufficient ventilation must be available to dilute the
percentage of methane and other harmful gases like
carbon–di-oxide and carbon monoxide given of by the
diesel locomotive.
4. Where haul roads are reasonably high and wide.

Types of locomotives
The locomotives are classified in the following categories:
1. Trolley-wire locomotive
2. Diesel locomotive
3. Battery locomotive
4. Battery/trolley-wire locomotives
5. Pneumatically powered locomotives
Out of the above the last one is used on a scanty
basis because of its low efficiency.

Types of locomotives (contd.)
The locomotives can also be classified as :
1. Traction: The tractive effort in this type of locomotive
is effected by the friction between the wheels and
rails.
2. Induced Traction: The tractive effort is effected by the
wheel forcibly held against the rail by an externally
applied force.
3. Rack: The tractive effort is effected through a spur
wheel on the locomotive and a rack mounted between
the rails.

Definitions of some important terms
1. Tractive force: It is effort required to cause the
movement. The tractive force is generated by the
locomotive. The force is partly used by the locomotive
for overcoming the friction in itself and accelerating
the same. The remainder is used for the movement of
the train. The tractive effort is calculated by the
simple formula:
P = μ × W
where P is tractive force in kN; W is the weight of
locomotive in kN and μ is the coefficient of adhesion
between the rails and locomotive wheels

Definitions of some important terms (contd.)
2. Coefficient of adhesion: The coefficient of adhesion is
the coefficient of static friction between the rails and
wheels of the locomotive. The value of the coefficient
of adhesion depends on the nature of surfaces in
contact with each other. If the surfaces are dry; then
the value is high and for the wet surfaces its value
reduces. In mine locomotives; a high value of the
coefficient is maintained by spreading sand on the
rails so usually the value of coefficient comes out to
be in between 0.2 to 0.25. For breaking the value is
taken as 0.16 as the friction is less while locomotive is
in movement.

Definitions of some important terms (contd.)
3. Draw bar pull: It is force which remains available to
pull the train. It is thus the difference between the
total tractive force generated by the locomotive and
the force required to propel the locomotive itself.
4. Optimum gardient: The gradient on which a full train
can be started and safely stopped under emergency
breaking conditions.
5. Stopping distance: It is the distance at which a train
stops after the application of breaks.

Locomotive calculations
• When a locomotive and a train starts moving; it is
acted upon the tractive force which it has generated.
In addition to this force; a few resistances have also
an influence upon it. The resistances are of four
types:
1. Rolling Resistance.
2. Inertia Resistance.
3. Grade Resistance.
4. Curve Resistance

Locomotive calculations (contd.)
• Rolling resistance: The reason for the rolling resistance is
the bearing friction for the locomotive and train together
with a degree of flange rub on the rails. The lower the
standard of track laying higher is the value. Even on
exceptionally good track there will be always some
resistance.
• Inertia Resistance: This resistance is the force required to
accelerate (retard) the locomotive and train. The value
can be found by multiplying the mass of the locomotive
and train with acceleration (retardation). The normal
values of acceleration (retardation) are 0.045 m/s2 to 0.09
m/s2.

An attempt to increase the value beyond this causes the
slipping of the wheels. To counter this; sand is often
sprinkled on the track. In spite of this, there will always a
limit on the value of the acceleration.
So far we have considered the translational motion of the
train. In addition there are several rotating parts in the
locomotive and the train. To make an allowance for the
acceleration (retardation) of such parts, it is customary, to
add an additional 5% to the masses.

• Grade Resistance: The gradient resistance is due to the
component of weight of locomotive and train acting
parallel to the inclined plane. The component is always
directed downwards. For a train moving up the incline;
the component will oppose the motion whereas if the
train is moving down the gradient the component will
assist the motion. The component is given by the simple
formula Mg sinθ.

• Curve Resistance: Travelling round curves requires
additional force to overcome the greater resistance due to
the heavier rubbing of wheel flanges against the rails. A
general value of the curve resistance is
N/te
Where G is the gauge in m and B is wheel base in m

• Normally the radius of the curves on a locomotive haulage
road should not be less than 25 m. Assuming that
adequate super elevation has been provided; the limiting
speeds and various radii of the curves should be as given
below in the table:
Speed, kmph Radius of the curve, m
Up to 8 30
8-16 30-60
16-24 60-90

• The following sketch shows the forces acting on a
locomotive which has just started moving on a level.
P = Tractive Force; f = Frictional Resistance
Therefore Drawbar pull = P-f
P
f

• Locomotive has just started moving up the gradient:
P = Tractive Force;
f = Frictional Resistance;
Mg sinθ is the gravity component
Therefore Drawbar pull
= P-f-Mg sinθ

• Locomotive has just started moving down the gradient:
P = Tractive Force;
f = Frictional Resistance;
Mg sinθ is the gravity component
Therefore Drawbar pull
= P-f + Mg sinθ

• Frictional (running or rolling) resistance (f) is normally
expressed in N/tef of locomotive weight. To find the total
resistance multiply the value in N/tef by the locomotive
weight. The normal values of the resistance at the time of
starting are 70 to 90 N/tef whereas for the running
conditions they are 25 to 35 N/tef. However some times
instead of providing the value in N/tef; a coefficient is
provided. In such case to find the total frictional
resistance you have to first convert the coefficient by
multiplying it with 9810 to get frictional resistance in
N/tef e.g. If the frictional coefficient is given as 0.0070
then frictional resistance is 0.0070 × 9810 ≈ 69 N/tef

• Ideal gradient: The gradient of the roadway on which a
locomotive has to operate must be an optimum one as far
as possible.
The gradient is said to be ideal if the effort to pull the full
trains outbye is equal to that required for haul empties
inbye. This requires that full tubs must be hauled down
the gradient and the empties up the gradient.

Calculation of ideal gradient:
Let
Ml be the mass of locomotive, te;
Mf be the mass of full tubs, te;
Me be the mass of empty tubs, te;
Rr be the rolling resistance in N/te
1/G be the ideal gradient

Effort required to pull the full tubs =
Effort required to haul the empty tubs =

• For an ideal gradient; the two efforts must be equal;
Therefore
=

• On simplifying, we get

Minimum mass (weight) of the locomotive:
1. Locomotive working on level gradient: Let WL tebe the
mass of locomotive, μ be the coefficient of adhesion,
WT te be the trailing load, RL N/te be the running
resistance of the locomotive and RT N/te be the
running resistance of the trailing load.
Now, 9810 × μ × WL - RL× WL = RT × WT

L
TT
L
R9810
RW
W




2. Locomotive working on an unfavourable gradient: Let
WL tebe the mass of locomotive, μ be the coefficient
of adhesion, WT te be the trailing load, RL N/te be the
running resistance of the locomotive and RT N/te be
the running resistance of the trailing load. Further the
train is operating on an gradient of 1 in n.
Now, 9810 × μ × WL - RL× WL - = RT × WT
WL=
n
1W9810 L 









n
9810
R9810
WR
L
TT

3. Locomotive working on a favourable gradient: Let WL
te be the mass of locomotive, μ be the coefficient of
adhesion, WT te be the trailing load, RL N/te be the
running resistance of the locomotive and RT N/te be
the running resistance of the trailing load. Further the
train is operating on an gradient of 1 in n.
Now, 9810 × μ × WL - RL× WL + = RT × WT
WL=
n
1W9810 L 








n
9810
R9810
WR
L
TT

Locomotive numericals
• A 10 te diesel locomotive hauls 15 mine cars having a tare
of 2 te and a capacity of 4 te. Assuming that the rolling
resistance for all the vehicles to be 80 N/te; calculate the
power required to operate at 24 kmph.
Solution:
• Mass of locomotive, Ml = 10 te;
• Mass of empty cars, Me = 15 × 2 = 30 te
• Mass of full cars, Mf = 15 × (2+4) = 90 te
• Rolling Resistance Rr = 80 N/te

Locomotive numericals (contd.)

Power = Te × Velocity
Te =
Substituting the values,
Te =

Te = 8000 - 3383
= 4617 N
Velocity = 24 kmph = 24 × = 6.67 m/s
Power = Te × V
= 4617 × 6.67 = 30.8 kW.
Assuming the efficiency @ 70%; the engine power is
44 kW (Ans.)
18
5

2. A locomotive weighs 15 tef and adhesion to the tracks
is 2246 N/te. Find
a. The coefficient of adhesion.
b. Find the draw bar pull while the locomotive is
working on a level track; on adverse gradient of 1
in 100; 1 in 15.
Assume that the running resistance of the locomotive
is 67 N/te.

Solution:
229.0=
9810
2246
=adhesionoftCoefficien
N9810=
15
9810×15
=15in1oncomponentGravity
N5.1471=
100
9810×15
=100in1oncomponentGravity
N1005=15×67=resistanceRunning
N33690=2246×15=effortTractive

Draw bar pull on level gradient = 33690 - 1005 = 32685 N.
Draw bar pull on an adverse gradient of 1 in 100 =
33690-1005-1471.5 = 31213.5 N
Draw bar pull on an adverse gradient of 1 in 15 =
33690-1005-9810 = 22875 N

3. A locomotive weighing 10 tef is pulling a train on a
favourable gradient of 1 in 100. The speed of the
train is 18 kmph. The rolling resistance of the system
is 80 N/te. The headlight beam is 60 m long and the
driver’s reaction time is 1 s. Calculate the safe trailing
load. Assume the coefficient of breaking adhesion as
0.1.

Solution:
Let m be trailing load
Speed of the train is 18 kmph = 5 m/s.
Stopping distance = 60-5 = 55 m.
The work done during breaking is equal to the change in
K.E.
Force acting on the train during breaking = Breaking force
+ Rolling Resistance – Gravity component

Breaking Force = 0.1 × 10 × 9810 = 9810 N
Rolling Resistance = 80 × m + 80 × 10 = 80 m + 800 N
N
100
9810)10(
componentGravity


m





 

100
)10(9810
80080981055
m
m
The work done during breaking
= 529595 – 995.5 m

Change in K.E. =
2
1
× (m + 10) × 25 × 1000
Equating the two we get m = 30 te

A 12 te locomotive hauls a train of 24 unbreaked cars on a
gradient favourable to the load of 1 in 110 which
incorporates an adverse gradient 1 in 60 at the outbye
end. Each car has a tare of 1.5 te and capacity of 3 te. The
following coefficients apply to the system:
Rolling friction for locomotive: 0.03; Rolling friction for
empty cars: 0.03; Rolling friction for loaded cars: 0.04;
Breaking adhesion for the locomotive: 0.16.
Determine the power to haul empties at 15 kmph on 1 in
110. What is stopping distance while breaking on 1 in 110
and 1 in 60 at 15 kmph. Driver’s reaction time is 1 s. KE of
rotating parts is 10% of linear KE

Solution:
Speed = 15 kmph = 4.17 m/s.
Friction force = (0.03 × 12 × 9.81) + (0.03 × 36 × 9.81)
= 14.126 kN
Gravity component= = 4.24 kN
Tractive effort = 14.126 + 4.24 = 18. 366 kN
110
81.9×48

Power = 18.366 × 4.17 = 76.59 kW.
To find the stopping distance:
a. favourable gradient 1 in 110.
Breaking effort = 0.16 × 12 × 9.81 = 18.835 kN
Gravity component = = 10.71 kN
Friction force = (0.03 × 12 × 9.81) + (0.04 × 108 × 9.81)
= 45.91 kN
110
81.9×120

Total Retarding Force = 18.835 - 10.71 + 45.91
= 54.035 kN
Stopping distance × Retarding force = Change in KE
S × 54.035 = 1.07 × × 120 × (4.17)2 => S = 20.66 m
Distance travelled during reaction time = 4.17 m
Stopping distance = 24.83 m
2
1

b. Adverse gradient of 1 in 60
Breaking force = 18.835 kN
Gravity component = = 19.62 kN
Friction force = 45.91 kN
Total Retarding Force = 18.835 + 19.62 + 45.91
= 84.365 kN
60
81.9×120

Stopping distance × Retarding force = Change in KE
S × 84.365 = 1.07 × × 120 × (4.17)2 => S = 13.23 m
Distance travelled during reaction time = 4.17 m
Stopping distance = 17.40 m
2
1

Problems for Practice
1. A train of 200 te is drawn up a slope of 1 in 200
against a resistance 60 N/te with uniform acceleration
which in a distance of 2 km increases its speed from
36 kmph to 54 kmph. Find the power the at which
locomotive is working.
2. Find the maximum load that can be started up a
gradient of 1 in 100 at an acceleration of 0.045 m/s2
by a locomotive of 10 te. Assume the coefficient of
adhesion and friction as 0.2 and 0.01.

Problems for Practice (contd.)
3. A locomotive has a mass of 50 te and the connected
load is 250 te. The train moves the load up a gradient
of 1 in 120 at a speed of 40 kmph with an acceleration
of 0.20 m/s2. Resistance on account of friction and
other causes is 70 N/te. Calculate the power that the
locomotive develops.
4. A locomotive of 10 tef hauls a train of 50 tef down a
gradient of 1 in 100 at 16 kmph. Brakes are applied to
bring the train to the rest. Find (a) Gross braking effort
(b) Net retarding force (c) Rate of retardation (d) The
time taken to stop the train (e) Stopping distance.
Assume braking adhesion as 0.16 and running
resistance as 70 N/tef.

Construction of locomotives
Although we have got locomotives of various types,
however, the main constructional features of all of them
are similar. Whatever difference in the construction is
there; is because of the type of prime mover that is being
used and other associated parts which are required in
commensuration with a particular prime mover.
Mine locomotives are light weight type having mass 2 to 5
te and heavy weight type having mass 8 to 13 te.

Construction of locomotives (contd.)
Every locomotive consists of
1. A chassis which is a rigid frame work of rolled steel
sections.
2. Traction (Driving) wheels on axels, springs and break
blocks mounted underneath the chassis.
3. A power unit, which may either be a electric DC motor,
or diesel engine or compressed air motor. Prior
permission from DGMS is necessary to use a diesel
engine in the underground.

Construction of locomotives (contd.)
4. Operator’s cabin equipped with controls, break
operating system, sand boxes, horns etc.
5. An air compressor on medium and large sized
locomotives for powered breaks.
6. Lights at both ends.
7. A hand screw break for emergency.

Diesel Locomotive
• The majority of diesel engines used on underground
locomotives are 4-stroke, naturally aspirated, water-
cooled with fuel cut-off arrangement.
• The diesel engine is a compression-ignition engine where
power output depends upon the quantity of fuel injected.
This is sprayed into the chamber just before the end of
compression stroke.
• Due to its high compression ration, the efficiency of the
diesel engine is better than that of the petrol engine and
is more economical in fuel consumption. The diesel has a
higher flash point 50 to 110O C and therefore is much safe.

Diesel Locomotive (contd.)
• The diesel engine does not have a electric ignition system.
Therefore it is much easier for making it flame-proof and
useful in wet conditions.
• Advantages of diesel engine as a power source:
1. Freedom from restraints on the movement of tubs.
2. High specific storage energy (@42.48 MJ/kg) causing
reduction in size.
3. rapid refueling and longer intervals between refueling.
4. Wide range of units available.

• The disadvantages of diesel engine:
1. A need of complex flame-proofing required when used
in a gassy mine.
2. Inevitable environmental pollution in the form of
exhaust gases, heat and noise.
3. The need of a high level of maintenance both in terms
of skill and frequency.
4. The upper power limit is much reduced due to size and
weight of protective equipment.

Power transmission: The power transmission in a diesel
locomotive is done by either a mechanical means, semi-
automatic with fluid coupling, torque and hydrostatic
means.
a. Mechanical transmission: It employs a complete dry
friction clutch and some form of the gear box.
Benefits of mechanical transmission
I. Simple to maintain.
II. Low consumption of fuel and high overall efficiency
for a predefined work load.

III. Mechanical transmission allows positive braking giving
a better control of the locomotive and reduces the
chances of slip.
IV. Gives the same number of speed variations in both
directions.
The driving of this locomotive requires more skills.

b. Semi-automatic mechanical transmission with fluid
coupling:
The transmission employees a fluid coupling between
the engine and gear box together with a clutch
c. Hydro-kinetic transmission:
The transmission includes a torque converter instead
of a fluid coupling. The smoother speed variation
makes it easy to drive the locomotive. However it
suffers from the disadvantage that the transmission
has a low efficiency because of the torque converter.

d. Hydro-static transmission:
The hydrostatic transmission also provides a smooth
transmission of power.

Wheel arrangements: Internationally the locomotive
wheel arrangements are classified by leading carrying
wheels, the driving wheels and the trailing carrying
wheels. The normal configuration is 0-4-0 up to 12 te
locomotive. For the higher capacities a twin axel bogie is
attached at each end of the locomotive.

The engine is placed in a flame-proof enclosure as a
safeguard against the firedamp explosion. The intake air
passes over the filter and the flame trap.
A flame trap consists of a number of stainless steel plates
contained within a stainless steel housing.
The plates are 50 mm wide and welded into position with
gaps of 0.5 mm between adjacent plates.
On the exhaust side the diesel locomotive has an exhaust
conditioner.

Need and construction of exhaust conditioner:
The diesel on combustion gives off oxygen, nitrogen,
carbon monoxide, carbon-di-oxide, oxides of nitrogen and
sulphur mixed with aldehydes.
Most of these gases are harmful for the human beings. So
these gases must be removed/diluted before they mix
with the air. This requires that combustion of diesel must
be satisfactory and diesel should not have a flash point
more than 65o C.
To remove these gases an exhaust conditioner is fitted on
a diesel locomotive on its exhaust side.

The principle of exhaust conditioner is displayed in the
next slide. The quantity of exhaust gases is nearly 0.085
m3/bhp/min. The exhaust gases are conducted to the
bottom of the conditioning chamber. The exhaust
impinges on surface of the water in the base. This traps
hot particles, and washes away the sulphur and nitrogen
oxides and aldehydes. The gases the pass through a flame-
proof slag wool. While passing through the slag-wool
filter, the incandescent particles are entrapped. The
process is repeated in the second chamber.

Exhaust Conditioner in an Underground Diesel Locomotive
Exhaust
fumes of
Locomotive
To
Mine Atmosphere
Fan
Water Water
Flame Trap
FilterFilter
Mixing Chamber

After the second chamber, the exhaust passes over the
flame trap. The MS flame trap conducts away the heat of
incandescent particles which might of escaped the two
chambers. A clean flame trap is a prerequisite for the
conduction of heat. It is therefore necessary that flame
trap be cleaned at least once in every day. The exhaust is
then mixed with fresh air 30 to 40 times the volume and
then given off to the atmosphere. The exhaust
conditioner is fitted with float switch for indicating the
water level. Should the water level falls beyond a certain
level, the switch operates and cuts off the fuel supply to
the locomotive.

The next slide shows the lay out of an underground
garage for a diesel locomotive. The garage is provided
with facilities like inspection pit, stores, fitting shop, fire
extinguishers, fuel pump etc. The garage must be provided
in an independent split.

Bench . Bench Bench
Bench
Fire
Station
Stores
Oil Tanker
Sand Car
Sill
VentilationRepair track
Sand bucket and fire
extinguishers
Metal sliding doors
Filling station
Locomotive inspection pits
Telephone call-bellFitting shop
Regulator doors
Sill
Fuel oil pump
Underground Diesel Locomotive Garage

Battery locomotives
The battery locomotives have the same mobility as to that
of the diesel locomotive. The parts like frame, gear box
and wheel-axel assembly are same. The battery
locomotive because of its ease of control, maneuverability
and lower headroom makes it ideal for gathering purpose.
Advantages of battery locomotives:
• It is clean, silent and pollution free in operation.
• It is reliable and requires a low order of maintenance.

Battery locomotives (contd.)
• Although the initial costs may be higher as compared
to a diesel locomotive because of the standby battery
and charger, however its operation and maintenance
costs will be lower.
Disadvantages of battery locomotives:
• Emission of highly inflammable gas hydrogen takes
place during charging.
• Flameproofing of battery is difficult. This leads to
considerable reservations to its use in underground
coal mines.

The power of the battery locomotive ranges from 4 to 70
kW. Normally each battery locomotive has two batteries
which normally constitutes 60% of the weight of
locomotive. The batteries normally consists of 2- V lead-
acid type cells. There may be nearly 40-70 cells in a
battery. A fully charged battery gives service for nearly 8
hours and also takes nearly 8 hours for its charging. The
next slide shows the layout of a underground battery
locomotive garage having the facility of battery charging.

Bench
Inspection pits
telephone Fire stationStores and recordsMotor
generators
or rectifiers
Charging
tables
Regulator
to return
airway
Battery service benches Parking space
Sand buckets
and fire
extinguishers
Underground Battery Locomotive Garage

• The efficiency of the battery is expressed in terms of
ampere-hours or watt-hours.
The ampere-hour efficiency is defined as the ampere-
hours taken from the battery to the ampere-hours
required to be put in the battery in normal working
conditions. The normal value is 90 to 95%.
The watt-hour efficiency is defined as the watt-hours
given out by the battery during discharge to the watt-
hours put in the battery during its charging. The
average value of the watt-hour efficiency is 72 to 75%.

• Watt-hour is given by the following formula:
Watt-hour = Average voltage (V) × Current (A) × Time (h)
Types of batteries:
The different types of batteries available for the
locomotive are
• Lead-acid
• Nickel - zinc
• Nickel-iron
• Sodium-sulphur

The lead-acid cell is one of the most popular cell. The cell
suffers from a disadvantage that it has a low specific
energy storage capacity.
This leads to
• High weight
• Limited energy storage capacity between recharges.
• Limited power output
• Long charging time.
The first three disadvantages can be quantified by two of
the commonly used parameters of energy storage systems
viz. specific energy storage density ( Wh/kg) and

• Specific power density (W/kg). The normal values are 40-
50 Wh/kg And 160 W/kg.
e.g. A 3.5 te has two batteries each having 57 cells
supplying a voltage of 114 V, has a capacity of 219 Ah or
24.97 kWh. Assuming a specific energy storage density of
40 Wh/kg, the mass of the battery comes out to be 624
kg. The mass of casing is nearly 50% of the battery. So the
total of the one battery mass is nearly 29% of locomotive.
The two such batteries constitute nearly 60% the battery
weight.

The lead-acid battery scores over the point that the
energy density by volume is high and is nearly 100
kW/m3. This causes the minimum volume of the battery
which is of importance in the underground mine.
The advantages of lead-acid battery are:
• It has the lowest initial cost employing the cheapest
and readily available materials.
• It can operate over a large range temperature i.e.-18
to 56OC.
• It has a high power to weight ratio.

• Electro-chemical reactions produce a little effect on
the plates.
• It has the highest electrical efficiency.

Nickel-zinc battery has a high energy storage capacity of
299 W/kg and a high power density. They are however
are not so rugged as the other battery.
Nickel-iron battery has a long-life capability. However, it
is more expensive and gives off more hydrogen.
Sodium-sulphur battery has a liquid electrode and a solid
electrolyte. The battery needs more maintenance and its
volume is more as compared to lead-acid battery.
The disadvantages with the batteries make it lead-acid
battery as a widely used one.

Battery maintenance: The economics of battery operation
depends upon the care that battery locomotive receives.
The following precautions must be observed while
operation:
1. Correct topping up: The sulphuric acid must have its
correct level in the battery which should be above the
plates. If the strength becomes too high then the
hydrogen emission increases during charging. The
normal density of the acid should be in the range of
1.25 to 1.27. Any variation within 10 points indicates
that the acid is healthy.

Any variation beyond 20 points indicates that the
charging is at fault or there is loss of acid due to over
charging, leakage, spillage etc.
2. The life of positive plate depends upon the corrosion
it undergoes. The corrosion is accelerated if the if the
overcharging occurs.
3. The life of the battery is reduced if there is sulphation
of the plates since this reduces the amount of active
material. This may happen if the battery is left for a
long time in discharged condition.

• A fully discharged battery requires 15 % more Ah to
put it back to its normal position.

• Electric motor: The locomotive uses a DC series motor.
The small locomotives have a single motor and the drive
being supplied to each axel by gears. On medium and
large locomotives there are two motors providing torque
to each axel. The motors are totally enclosed, dust and
weather proof and have a 20% overload capacity.
Since series motor has both the windings in series. At
smaller loads, the flux and hence the current is less. This
causes a high speed on light loads. Since the torque is
built up rapidly therefore DC series motor is used.

Speed
Load Current

• The speed control of the motor is effected by the voltage
applied to the motor terminals. If two motors are used;
then they will be used first will be connected in series and
then in parallel. The series connection causes the speed to
be half and parallel connection leads to full speed.

Trolley-wire locomotives
Benefits of trolley-wire locomotives:
1. High efficiency: Of all the types; the trolley wire
locomotive is the most efficient.
2. High overloading capacity: The locomotive can take up
an overload for a short duration without any problem.
3. Simple maintenance.
4. High power/weight ratio.
5. Reliability and good control.

Trolley-wire locomotives (contd.)
The high investment cost of overhead lines requires that
traffic density and total power requirement is high.
As a rule of thumb; the trolley wire locomotive should be
used when the power requirement is more than 200 kW,
the length of haulage is more than 5 km and the life
expectancy is more than 10 years. The trolley wire
locomotives are used for mineral transportation. The
transportation of materials and men can be effected by a
battery locomotive.

The motor can be operated by either by AC or DC. The use
of DC requires installation of conversion equipment. The
shock hazards are less with DC. The bare overhead wires
are of hard drawn copper which is suspended at a height
of not less than 2 m. The conductors are suspended
through insulators from short cross-wires. Earth leakage
wire is connected to each cross-wire. The rail track forms
the return. The rail joints must therefore be suitable
bridged.

Limitations of trolley-wire locomotives:
1. The roadways must be sufficiently wide and high to
provide sufficient clearances.
2. Branch roadways can not be served by trolley-wire
locomotives unless they are so equipped.

Haulage track
Requirement of haulage track

Thursday, May 16, 2019
Fire StationD.C. Generator Set
D.C. Generator Set
Charging Bay
Charging Bay
Battery charging station in Underground
88

Exhaust Conditioner in an Underground Diesel Locomotive
Exhaust
fumes of
Locomotive
To
Mine Atmosphere
Fan
Water Water
Flame Trap
FilterFilter
Mixing Chamber
89

Bench . Bench Bench
Bench
Fire
Station
Stores
Oil Tanker
Sand Car
Sill
VentilationRepair track
Sand bucket and fire
extinguishers
Metal sliding doors
Filling station
Locomotive inspection pits
Telephone call-bellFitting shop
Regulator doors
Sill
Fuel oil pump
Underground Diesel Locomotive Garage
90

Bench
Inspection pits
telephone Fire stationStores and recordsMotor
generators
or rectifiers
Charging
tables
Regulator
to return
airway
Battery service benches Parking space
Sand buckets
and fire
extinguishers
Underground Battery Locomotive Garage
91

Mine locomotive ppt (under ground transport system )

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