oods transportation is growing around the world and road freight is the dominating mode of transportation. Road safety of heavy trucks is therefore an important aspect for society. Despite the fact that the EU target is to reduce traffic fatalities by 50% between 2010 and 2020, the pace of reduction has stagnated, and the target is currently in jeopardy. This work mainly deals with the pneumatic brake system of an Articulated Commercial Vehicles comprising Tractors and Semi-Trailers. When a trailer is attached to the tractor, Firstly, the air brake system of a HGV will be discussed in detail. Then, the mechanism exploited by the tractor to recognise the presence (or malfunction) of the trailer brake system is described. Finally, achilles' heels of HGVs’ Conventional ABS will be discussed before mentioning their remedies. The main contents of the project are as follows, - The future and the worsening situation - Milestones, a glimpse of trailer-tractor-connection history - Trailer presence recognition, SAE J1939 - Data Transmission between tractor and semi-trailer - Power Line Carrier Communication System - Seven-wire trailer electrical cable - Achilles' heels and remedies of HGVs’ Conventional ABS - Stopping Distance -- Conventional ABS control algorithm -- Low-speed pneumatic control circuit of the conventional ABS -- Mechanical limitations of the pneumatic brake system - HGVs Stability beyond a certain speed threshold - Driver interaction *only the first 10 pages of this project are presented here. If you are interested to read the rest of it, please contact me via saeid.ghaffari@studenti.polito.it.

1. Tractor ABS Application
in the presence of a Trailer
Department of
Mechanical and
Aerospace Engineering
Saeid Ghaffari
Automotive Engineering A.Y. 2018-19

2. ABS
1
• Worsening situation
• Small history
• Types of trailers
• Semi trailer
• Air brake system
Trailer recognition
2
•Introduction
•CAN BUS
•SAE J1939
•PLC
•Electrical connection
•Data Transmission
Sending signal
Receiving signal
Achilles' heels and
Remedies
3
• Introduction
• Long Stopping Distance
• Definition
• Conventional ABS control
algorithm
• Sluggish pneumatic control
circuit
• HGVs’ Stability problems
• Jackknifing
• Stretch braking
• Rollover
• ESC
• Driver interaction
• Accident-causing factors
• Interacting with ABS
• ABS makes no difference?!
• People save people
Worsening situation
Rank Disease or Injury
1 Ischaemic heart disease
2 Cerebrovascular disease
3 Lower respiratory infections
4 Chronic obstructive pulmonary disease
5 Diarrhoeal diseases
6 HIV/AIDS
7 Tuberculosis
8 Trachea, bronchus, lung cancer
9 Road traffic injuries
10 Prematurity & low-birth weight
Rank Disease or Injury
1 Ischaemic heart disease
2 Cerebrovascular disease
3 Chronic obstructive pulmonary disease
4 Lower respiratory infections
5 Road traffic injuries
6 Trachea, bronchus, lung cancer
7 Diabetes mellitus
8 Hypertensive heart disease
9 Stomach cancer
10 HIV/AIDS
The EU target is to reduce traffic fatalities by
50% between 2010 and 2020.
The pace of reduction has stagnated, and the target is currently in jeopardy.
Goods transportation
is growing around the world
and road freight is the
dominating mode of
transportation.
Road safety of heavy trucks
is therefore an important
aspect for society.
2011 2020
Top 10 leading causes of death

3. Car and Light Trailer Car Towing a Trailer or Caravan
Rigid Truck Towing a Centre-Axle Trailer Rigid Truck Towing a Chassis Trailer
Trailer (maximum mass not exceeding 0.75 tonnes) is not required by the
European legislation to be fitted with wheel brakes, Most passenger car and
light van manufacturers therefore include the possibility of the extra duty from
towing such a trailer in the design.
Have brakes that are actuated when the towing vehicle’s brakes are applied
Overrun brakes – ‘electric over hydraulic’ system, where the trailer brakes are
separately actuated by hydraulic pressure generated by an electric hydraulic
pump in the trailer braking system.
Brakes are required to be actuated as part of the towing vehicle’s braking system.
Since most commercial road vehicles utilize compressed air (pneumatic) actuation,
this means that the trailer must be fitted with a compatible braking system that is
connected to that of the towing vehicle.
The effect of weight transfer from the trailer to the truck is much smaller
than with a centre-axle trailer because the coupling transmits no vertical
forces arising from the trailer mass) and the only effect arises from the
(assumed horizontal) drawbar force.
Different types of towing and towed vehicle combination

4. Articulated Commercial Vehicles comprising Tractors and Semi-Trailers
• The ‘articulated lorry’ or ‘tractor and semi-trailer’ combination represents the largest group of heavy commercial
vehicles on modern roads.
• The tractor and trailer are connected through the coupling (‘kingpin’ or the ‘fifth wheel’), which transmits horizontal
and vertical forces between the two parts of the vehicle.
• The tractor is designed to carry a substantial proportion of the weight of the trailer via the coupling, and the retardation
forces provided by its brakes must be capable of decelerating both the tractor mass and this proportion of the trailer
mass.
ABS
1
•Worsening situation
Small history
Types of trailers
Semi trailer
Air brake system
Trailer recognition
2
•Introduction
•CAN BUS
•SAE J1939
•PLC
•Electrical connection
•Data Transmission
Sending signal
Receiving signal
Achilles' heels and
Remedies
3
• Introduction
• Long Stopping Distance
• Definition
• Conventional ABS control
algorithm
• Sluggish pneumatic control
circuit
• HGVs’ Stability problems
• Jackknifing
• Stretch braking
• Rollover
• ESC
• Driver interaction
• Accident-causing factors
• Interacting with ABS
• ABS makes no difference?!
• People save people

5. ABS
1
•Worsening situation
•Small history
•Types of trailers
•Semi trailer
•Air brake system
Trailer recognition
2
•Introduction
•CAN BUS
•SAE J1939
•PLC
•Electrical connection
•Data Transmission
Sending signal
Receiving signal
Achilles' heels and
Remedies
3
• Introduction
• Long Stopping Distance
• Definition
• Conventional ABS control
algorithm
• Sluggish pneumatic control
circuit
• HGVs’ Stability problems
• Jackknifing
• Stretch braking
• Rollover
• ESC
• Driver interaction
• Accident-causing factors
• Interacting with ABS
• ABS makes no difference?!
• People save people
Air brake system

6. PLC over AC,
Edward Davy,
UK, 1838
ABS were
developed
during the
1970s
Introduction and
further refinement of
ABS for air braked
commercial vehicles,
by Mercedes-Benz,
Wabco, MAN and
Knorr Bremse, 1981
PLC was
used to
permit
trailer-to-
truck ABS
communic
ations,
1985
CAN
Protocol
developed
by Robert
Bosch
1986
Daimler-
Benz and
Scania
presented
the first
EBS in
their
towing
vehicles,
1996
Introductio
n of
mandatory
ABS for
trailers,
USA,1998
Mandatory
use of
PLC
communic
ations,
2001
Mandatory
status
check light
for trailer
ABS in the
IPC, 2001
A glimpse of trailer-tractor-connection history
ABS
1
•Worsening situation
•Small history
•Types of trailers
•Semi trailer
•Air brake system
Trailer recognition
2
•Introduction
•CAN BUS
•SAE J1939
•PLC
•Electrical connection
•Data Transmission
Sending signal
Receiving signal
Achilles' heels and
Remedies
3
• Introduction
• Long Stopping Distance
• Definition
• Conventional ABS control
algorithm
• Sluggish pneumatic control
circuit
• HGVs’ Stability problems
• Jackknifing
• Stretch braking
• Rollover
• ESC
• Driver interaction
• Accident-causing factors
• Interacting with ABS
• ABS makes no difference?!
• People save people

7. Chapter 2
Trailer Recognition
ABS
1
•Worsening situation
Small history
Types of trailers
Semi trailer
Air brake system
Trailer recognition
2
•Introduction
•CAN BUS
•SAE J1939
•PLC
•Electrical connection
•Data Transmission
Sending signal
Receiving signal
Achilles' heels and
Remedies
3
• Introduction
• Long Stopping Distance
• Definition
• Conventional ABS control
algorithm
• Sluggish pneumatic control
circuit
• HGVs’ Stability problems
• Jackknifing
• Stretch braking
• Rollover
• ESC
• Driver interaction
• Accident-causing factors
• Interacting with ABS
• ABS makes no difference?!
• People save people

8. Trailer Recognition
What is CAN BUS?
A Controller Area Network (CAN) Bus is a communication system made for vehicle intercommunication in real time and
without a host computer.
This bus allows many microcontrollers and different types of devices to communicate with each other.
An Analogy between a Vehicle and the Human body
CAN bus
Nervous System
Enables Communication Between
Nodes of the Nervous System
ECUs of the vehicle
Enables Communication Between
However, CAN bus only provides a "tool" for communication (like a telephone) - not the "language" you
need to have a conversation.
ABS
1
•Worsening situation
Small history
Types of trailers
Semi trailer
Air brake system
Trailer recognition
2
•Introduction
•CAN BUS
•SAE J1939
•PLC
•Electrical connection
•Data Transmission
Sending signal
Receiving signal
Achilles' heels and
Remedies
3
• Introduction
• Long Stopping Distance
• Definition
• Conventional ABS control
algorithm
• Sluggish pneumatic control
circuit
• HGVs’ Stability problems
• Jackknifing
• Stretch braking
• Rollover
• ESC
• Driver interaction
• Accident-causing factors
• Interacting with ABS
• ABS makes no difference?!
• People save people

9. J1939 is a set of standards defining how ECUs communicate in HDVs.
J1939 is standardized, i.e. ECUs can communicate across manufacturers.
In most commercial vehicles, this language is the SAE J1939 standard.
In more technical terms,
J1939 provides a higher layer protocol (HLP) using CAN as the "physical layer" basis.
SAE J1939, One Language
Trailer Recognition
Using a technology known as Multiplexing.
This allows multiple electrical loads to communicate through
one pair of wire compared with having several wires to
accomplish the same job.
How do multiple messages can be sent through a single pair of wire?
A primitive form of multiplexing known as power line carrier
(PLC) has been used to permit trailer-to-truck ABS
communications since 1985.
ABS
1
•Worsening situation
Small history
Types of trailers
Semi trailer
Air brake system
Trailer recognition
2
•Introduction
•CAN BUS
•SAE J1939
•PLC
•Electrical connection
•Data Transmission
Sending signal
Receiving signal
Achilles' heels and
Remedies
3
• Introduction
• Long Stopping Distance
• Definition
• Conventional ABS control
algorithm
• Sluggish pneumatic control
circuit
• HGVs’ Stability problems
• Jackknifing
• Stretch braking
• Rollover
• ESC
• Driver interaction
• Accident-causing factors
• Interacting with ABS
• ABS makes no difference?!
• People save people

10. Power Line Carrier Communication Systems
Trailer Recognition
Power line communication technology over the AC line was firstly proposed in the UK for remote
electricity supply metering in 1838.
Like any other Data Transmission Technology :
• A sender modulates the data to be sent,
• The sender injects the data onto medium, and
• The receiver de-modulates the data to read it.
The major difference with many other communication technology is:
PLC does not need extra cabling. It transmits message/information through the Existing High-voltage
Power Grids. Different types of PLC use different frequency band depending on the transmission
characteristic of the power wiring.
How does PLC work in general?
ABS
1
•Worsening situation
Small history
Types of trailers
Semi trailer
Air brake system
Trailer recognition
2
•Introduction
•CAN BUS
•SAE J1939
•PLC
•Electrical connection
•Data Transmission
Sending signal
Receiving signal
Achilles' heels and
Remedies
3
• Introduction
• Long Stopping Distance
• Definition
• Conventional ABS control
algorithm
• Sluggish pneumatic control
circuit
• HGVs’ Stability problems
• Jackknifing
• Stretch braking
• Rollover
• ESC
• Driver interaction
• Accident-causing factors
• Interacting with ABS
• ABS makes no difference?!
• People save people