Vtu phase 1 report on four wheel steerinfg system

VISVESVARAYA TECHNOLOGICAL UNIVERSITY
“JnanaSangama”, Belgavi
2018-19
A Project Report of Phase-I on
“FOUR WHEEL STEERING SYSTEM”
Submitted in partial fulfillment of the requirements for the award of degree
BACHELOR OF ENGINEERING
IN
MECHANICAL ENGINEERING
BY
KUMAR HARSH 3RB15ME050
PANKAJ CHAUHAN 3RB15ME030
PRAJAWAL SWAMI 3RB15ME086
SANDEEP YADAV 3RB15ME118
Under the esteemed guidance of
Prof. Raj Reddy
(DEPARTMENT OF MECHANICAL ENGINEERING)
BHEEMANNA KHANDRE INSTITUTE OF TECHNOLOGY, BHALKI
Dist. BIDAR, KARNATAKA
BHEEMANNA KHANDRE INSTITUTE OF TECHNOLOGY

Bhalki-585328 (Dist, Bidar) Karnataka
DEPARTMENT OF MECHANICAL ENGINEERING
CERTIFICATE
Certified that the Project work of Phase-I entitled “FOUR WHEEL STEERING
SYSTEM” carried out by Mr./Ms KUMAR HARSH (3RB15ME050), PANKAJ
CHAUHAN (3RB15ME030), PRAJAWAL SWAMI (3RB15ME086) and SANDEEP
YADAV (3RB15ME118) a bonafied students of VII semester Mechanical Engineering in
partial fulfillment for the award of Bachelor of Engineering in Bheemanna Khandre
Institute Of Technology of Visvwswaraiah Technological University, Belagavi during the
year of 2018-19. It is certified that all correction/suggestions indicated for Internal
Assessment have been incorporated in the report.
The project report has been approved as it satisfied the academic requirements in respect
of project work phase-I prescribed for the side degree.
Project Guide HOD
Prof. RAJ REDDY Dr. SANJEEV DOIJODE
Dept. of Mechanical Engineering Dept. of Mechanical Engineering
Project Coordinator:
1. Prof. ANIL KUMAR PATIL
2. Dr. BASWARAJ KAWDI

CONTENTS
Page No.
ABSTRACT 1
CHAPTER 1: INTRODUCTION 2
1.1: STEERING 3
1.1.1: TYPES OF STEERING
1.1.2: FUNCTION OF STEERING SYSTEM
1.2: WORKING OF STEERING 4
1.3: MODES USED IN FOUR WHEEL STEERING 5
CHAPTER 2: LITERATURE REVIEW 6
CHAPTER 3: COMPONENT 16
CHAPTER 4: METHODOLOGY 21
4.1: WORKING MECHANISH
4.2: ADVANTAGES, DISADVANTAGES AND APPLICATIONS 23
REFERENCES 26

FOUR WHEEL STEERING SYSTEM
DEPARTMENT OF MECHANICAL ENGINEERING; BKIT BHALKI Page 1
ABSTRACT
Nowadays, the every vehicle existed mostly still using the two wheel steering system to
control the movement of the vehicle whether it is front wheel drive, rear wheel drive or
all wheel drive. But due to the awareness of safety, four wheel steering vehicles are being
used increasingly due to high performance and stability that they bring to the vehicles. In
this report, the performance of four wheels steered vehicle model is considered which is
optimally controlled during a lane change maneuver in three type of condition which is
low speed maneuver, medium speed maneuver and high speed maneuver. Four-Wheel
Steering – Rear Wheels Control. For parking and low-speed maneuvers, the rear Wheel
steer in the opposite direction of the front wheels, allowing much sharper turns. At higher
speeds, the rest wheels steer in the same direction as the front wheels. The result is more
stability and less body lean during fast lane changes and turns because the front wheels
don’t have to drag non-steering rear wheels onto the path.
KEYWORDS: [ Four-Wheel Steering, 4WS, Rear Wheels Control]

1. INTRODUCTION
Nowadays, the problem of increased road traffic has made the handling of vehicles
even difficult. Thereby there is a need to find an alternative mechanism for easy steering
(turning) of the vehicles. At times when a vehicle is in a congested or a narrow area
everyone would want to have a better turning response from the vehicle or want the
vehicle to move sideward without much or without any forward movement. Here comes
the application of a Four wheel steered vehicle. It should not be mistaken to a four wheel
drive in which all four wheels of a vehicle are powered. Here, the rear wheels are also
bought into action as they are made to engage their movement in accordance to the front
wheels in the directions required. This makes the vehicle be more precisely controlled
especially during cornering, parking, or when we get into a narrow area. The main
ideology behind this mechanism is that the vehicle requires less driver input for any
steering maneuver when all four wheels are in action. The entire vehicle is made to move
in a direction rather than the rear wheels half attempting to catch u with the front ones.
The vehicle is made to respond even quicker to the steering input as the lag time of the
rear wheel is eliminated here. However, few cars like Honda Prelude, Nissan Skyline GT-
R are available with four wheel steering having their rear wheels steered up to 2 to 3
degrees only as their main aim was to assist the front wheels.
Four Wheel Steering System is employed in vehicles to achieve better
maneuverability at high speeds, reducing the turning circle radius of the car and to reduce
the driver’s steering effort. In most active four wheel steering system, the guiding
computer or electronic equipment play a major role, in our project we have tried to keep
the mechanism as much mechanical as possible which can be easy to manufacturing and
maintenance.

1.1 STEERING:
Steering is the term applied to the collection of components, linkages, etc.
which will allow the vehicle to follow the desired course. Steering system is the
mechanism in a vehicle which makes it possible to steer it in different directions. The
steering system consists of following components:
1. Steering wheel handle the steering operation.
2. Steering column joins the steering wheel and the steering gears
3. Steering gears convert the steering torque and rotational deflection from the
steering wheel.
4. Transmit them to the wheel through the steering linkage, and make the vehicle
turn.
5. Steering linkage a steering linkage is a combination of the rods and arms that
transmit the movement of the steering gear to the left and right front wheels.
1.1.1 TYPES OF STEERING SYSTEM:
a. CONVENTIONAL STEERING SYSTEM:
In that steering system, only the front wheels are steered
towards right or left According to the requirement because of at rear their dead axle is
present.
b. FOUR WHEEL STEERING SYSTEM:
In that steering system, the all four wheels are to be steered according
to the steer perform to drive towards left or right. Four wheel steering, 4WS, also called
rear-wheel steering or all-wheel steering, provides a means to actively steer the rear
wheels during turning maneuvers. It should not be confused with four-wheel drive in
which all four wheels of a vehicle are powered. It improves handling and helps the
vehicle make tighter turns. Production-built cars tend to under steer or, in few instances,
over steer. If a car could automatically compensate for an under steer /over steer problem,
the driver would enjoy nearly neutral steering under varying conditions. In most active
four wheel steering system, the rear wheels are steered by a computer and actuators, the
rear wheels generally cannot turn as far as the front wheels. Some systems including
Delphi’s Quadra steer and the system in Honda’s Prelude line allow the rear wheels to be
steered in the opposite direction as the front wheels during low speeds. This allows the

vehicle to turn in a significantly smaller radius sometimes critical for large tucks or
tractors and vehicles with trailers.
Fig. 1: Four wheel steering
1.1.2 Functions of steering system:
a. To provide directional stability of vehicle.
b. To facilitate straight ahead recovery.
c. To minimize tire wear.
d. To absorb major parts of the road shocks.
e. To provide perfect rolling motions of the road wheels.
1.2 WORKING OF STEERING:
The basic aim of steering is to ensure that the wheels are pointing in the desired
directions. This is typically achieved by a series of linkages, rods, pivots and gears. One
of the fundamental concepts is that of caster angle. Each wheel is steered with a pivot
point ahead of the wheel; this makes the steering tend to be self-centering towards the
direction of travel.

Fig-2: Rack and pinion steering
Many modern cars use rack and pinion steering mechanisms, where the steering wheel
turns the pinion gear; the pinion moves the rack, which is a linear gear that meshes with
the pinion, converting circular motion into linear motion along the transverse axis of the
car (side to side motion). This motion applies steering torque to the swivel pin ball joints
that replaced previously used kingpins of the stub axle of the steered wheels via tie rods
and a short lever arm called the steering arm.
1.3 MODES USED IN FOUR WHEEL STEERING
Two modes are generally used in four wheel steering which are as follows:
1) Slow Speeds - Rear Steer Mode:
At slow speeds, the rear wheels turn in the direction opposite to the front wheels. It can
reduce the turning circle radius by 25%, and can be equally effective in congested city
conditions, where U-turns and tight streets are made easier to navigate.
2) High Speeds – Crab Mode:
In high speeds, turning the rear wheels through an angle opposite to front wheels might
lead to vehicle instability and is thus unsuitable. Hence, at speeds above 80 kmph, the rear
wheels are turned in the same direction of front wheels in four wheel steering systems.

2. LITERATURE REVIEW
Literature survey is an assignment of previous task done by some authors and collection
of information or data from research papers published in journals to progress our task. It
is a way through which we can find new ideas, concept. There is lot of literatures
published before on the same task; some papers are taken into considerations from which
gives the ideas of the project is taken.
2.1: TITLE: DEVELOPMENT OF FOUR WHEEL STEERING SYSTEM FOR A
CAR
Author: K. Lohith, Dr. S. R. Shankapal, M. H. Monish Gowda
Publisher: AUTOMOTIVE AND AERONAUTICAL ENGINEERING
DEPARTMENT, M. S. RAMAIAH SCHOOL OF ADVANCED STUDIES,
BANGALORE Volume 12, Issue 1, April 2013
In this project Maruti Suzuki 800 is considered as a benchmark
vehicle. The main aim of this project is to turn the rear wheels out of phase to the front
wheels. In order to achieve this, a mechanism which consists of two bevel gears and
intermediate shaft which transmit 100% torque as well turns rear wheels in out of phase
was developed. The mechanism was modeled using CATIA and the motion simulation
was done using ADAMS. A physical prototype was released. The prototype was tested
for its cornering ability through constant radius test and was found 50% reduction in
turning radius and the vehicle was operated at low speed of 10 kmph.
By the analytical and experimental analysis Working prototype
was built to carry out CRC tests and to find the reduction in turning radius with four
wheel steering when compared to two wheel steering. The results from CRC tests was
that the turning radius achieved with two wheel steering is 5.75m and turning radius
achieved with four wheel steering is 2.85m. By experiment the reduction in turning radius
with four wheel steering when compared to two wheel steering is 50.43%.

2.2: TITLE: DESIGN OF FOUR WHEEL STEERING SYSTEM OF CAR
Author: Dishank Bari
Publisher: INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
& ADVANCED TECHNOLOGY Volume-4, Issue-6, 536-54, 2014
Production cars are designed to under steer and rarely do them over steer. If a car
could automatically compensate for an under steer/over steer problem, the driver would
enjoy nearly neutral steering under varying operating conditions. Four-wheel steering is a
serious effort on the part of automotive design engineers to provide near-neutral steering.
Also in situations like low speed cornering, vehicle parking and driving in city conditions
with heavy traffic in tight spaces, driving would be very difficult due to vehicle’s larger
wheelbase and track width. Hence there is a requirement of a mechanism which result in
less turning radius and it can be achieved by implementing four wheel steering
mechanism instead of regular two wheel steering. Our 4 Wheel Steering System gives
39.56% reduction in turning circle radius of a hatchback which is reduced from 4.6 m to
2.78 m, considering Maruti Suzuki ALTO 800 Turning Radius Four wheel steering Two
wheel steering By calculation 2.78 m 4.6 m 4. From the kinematic analysis it is evident
that the turning radius of the vehicle can be reduced up to 39.56% by using four wheel
symmetric steering system without crossing the practical limitations.

2.3:TITLE: DEVELOPMENT OF ACTIVE FOUR WHEEL STEERING SYSTEM
Author: Ajay Kumar, Abhishek Gaur, Sachchida Nand
Publisher: INTERNATIONAL JOURNAL OF ADVANCE RESEARCH IN
SCIENCE AND ENGINEERING Volume No.7,Special IssueNo.1, April 2018
This paper report on four wheel steering system by using rack and pinion mechanism.
This system converts the steering rotational motion into linear motion to turn the wheels.
The four wheel steering system is completely different from two wheel steering system.
In this system, power transferred from front axle to rear axle by using rack and pinion
method with rod. It reduces the turning radius and also space required for turning. Four
wheel steering is a system employed by some vehicles to improve steering response,
increase vehicle stability while steering at high speed and to decrease turning radius at
low speed. It is helpful in avoiding skidding as well as parking problems occurs in metro
cities, in traffic and in rural areas. A four wheel steering system is superior to a two wheel
steering system. This type of system can be applicable to all types of special utility
vehicles. In most active four wheel steering systems, the rear wheels are steered by
activators and coupling arrangement. Because of large work load on front wheels and
uneven tire wears of vehicle this system does not getting popularity. In order to achieve
this, a mechanism which consists of two rack and pinion and intermediate shaft which
transmit 100% torque as well turns rear wheels in out of phase was developed. The
mechanism was modeled using SOLID WORK and the motion simulation and analysis
was done using SOLID WORK and ANSYS.

2.4:TITLE: Design and Development of Active Four Wheel
Steering System
Author: Ketul B. Patel, Nirmal M. Patel, Akshay S. Patel, Ujas R. Patel, Diptesh
Patel
Publisher: INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN
SCIENCE, ENGINEERING AND TECHNOLOGY
Vol. 5, Issue 4, April 2016
In recent time, an automobile industry is widely used two wheel steering system. But,
four wheel steering system has many advantages which are very useful as compared to
two wheel steering system still 4WS has not widely used. In four wheel steering system,
all the four wheels are steered by driver to take a sharp turn for parking purpose or in a
traffic situation. Four wheel steering system is not a new technology but it has not gained
more popularity than two wheel steering system even though experimental results has told
that four wheel steering system is more suitable than two wheel steering system. Because
the turning radius of any four wheel vehicle is decreased by the implementation of four
wheel steering system. Four wheel steering system has excellent maneuverability, high
stability and it is a solution to over steer/under steer. Due to four wheel steering system,
driver can easily control and steer the car and decrease the driver effort.

2.5:TITLE: Design and Simulation of 4 Wheel Steering System
Author: Saket Bhishikar, Vatsal Gudhka, Neel Dalal, Paarth Mehta, Sunil Bhil, A.C.
Mehta
Publisher:INTERNATIONAL JOURNAL OF ENGINEERING AND
INNOVATIVE TECHNOLOGY (IJEIT) Volume 3, Issue 12, June 2014
We have developed an innovative 4 wheel steering design to implement a mechanism that
can serve the purpose of changing in-phase and counter-phase steering of rear wheels
depending upon the conditions of turning and lane changing with respect to front wheels,
thus enhancing the maneuverability of a sedan in accordance with its speed. The
movement of the rear wheels is done by the movement of the rear pinions which in turn
move the newly designed spindle to achieve the required movement of the rear wheels.

2.6:TITLE: RECENT DEVELOPMENT OF FOUR WHEEL STEERING SYSTEM
Author: VINAYAK SHIRKE, SHRIDHYEY GUPTA, VARUN YEOLE, VARUN
SHROTRI, SUNIL K. YADAV
Publisher: INTERNATIONAL JOURNAL OF RESEARCH PUBLICATIONS IN
ENGINEERING AND TECHNOLOGY [IJRPET] VOLUME 3, ISSUE 4, Apr.-2017
The driving circumstances of the vehicle with higher Wheelbase and track
breadth face problems of turning as space is captive, the same problem is faced in low
speed to gain control over Four wheel steering is a method developed in the automobile
industry for the effective turning of the vehicle and to increase the flexibility. For a
vehicle, working on all wheel drive (AWD) it is necessary to achieve adjustability. This
calls for a continuous need and demand of a car to attain flexibility. With this attribute,
handling and operating at the minimum speed achieved is till 6.2 mph. The main aim is to
come up with effective steering response resulting increase in vehicle adjustability while
manoeuvring at high speed and to decrease turning radius at low speed with keeping up as
less weight as possible of the vehicle.
Four wheel steering system is not a new technology but it has not gained
more popularity than two wheel steering system even though experimental results has told
that four wheel steering system is more suitable than two wheel steering system. Because
the turning radius of any four wheel vehicle is decreased by the implementation of four
wheel steering system.
Four wheel steering system has excellent maneuverability, high stability and it
is a solution to over steer/under steer. Due to four wheel steering system, driver can
easily control and steer the car and decrease the driver effort.

2.7:TITLE: RECENT DEVELOPMENT OF FOUR WHEEL STEERING SYSTEM
Author: PROF. MILIND S. DEOTALE
Publisher: INTERNATIONAL JOURNAL OF RESEARCH PUBLICATIONS IN
ENGINEERING AND TECHNOLOGY [IJRPET] VOLUME 3, ISSUE 4, Apr.-2017
The study of various four wheel steering system shows that the flexibility of the
vehicle majorly increases at low as well as high speeds. By using electronic steering, the
steering response can be further improved. The different types of four wheel steering
perform their functions effectively, such as the crab steering improves manoeuvrability in
cramped spaces, active four wheel steering improves handling of cars at various speeds
and eliminates over steer and articulated steering reduces effort and improves cornering
of segmented vehicles. However, that being said, the four wheel steering system is
complex and its implementation is expensive and is yet to be available in all markets. But
given the recent advancements in automobile industry, it is safe to assume that the system
will become more commonplace.

2.8:TITLE: FOUR WHEEL STEERING SYSTEM FOR AUTOMOBILE
Author: Mr. Krishna Bevinkatti, Mr. Atul Mali, Mr. Rahulsingh Bayas, Mr. Abhijit
Ghadage
Publisher: INTERNATIONAL JOURNAL OF INNOVATIONS IN
ENGINEERING RESEARCH AND TECHNOLOGY [IJIERT] VOLUME 2, ISSUE
4APR.-2015
A Four wheel steering system also known as Quadra steering system. In this paper,
both front wheel and rear wheels can be steered according to speed other vehicle and
space available for turning. Quadra steer gives full size vehicle greater ease while driving
at low speed, improves stability, handling and control at higher speed. Production-built
cars tend to under steer or, in few instances, overseer. If a car could automatically
compensate for an under steer overseer problem, the driver would enjoy nearly neutral
steering under varying conditions. Four wheel systems is a serious effort on the part of
automotive design engineers to provide near-neutral steering. This system finds
application in off-highway vehicles such as forklifts, agricultural and construction
equipment mining machinery also in Heavy Motor Vehicles. It is also useful in passenger
cars. It improves handling and helps the vehicle make tighter turns. This system is used to
minimize the turning radius. It is observed that when Maruti 800 during turning actual
turning radius is 14.70ft. But after making modification in the four wheel steering system
it is measured as 5.14ft hence we conclude that after making modification the turning
radius is reduced more than half.

2.9:TITLE: A REVIEW ON MECHANICAL DESIGN OF A FOUR WHEEL
STEERING SYSTEM
Author: Vipin Singh, Sharad Sharma
Publisher: INTERNATIONAL JOURNAL ONLINE OF SCIENCE Volume III,
Issue VI July 2017
The controlling behavior of a vehicle is influenced by the performance of its
steering system. The steering system consists of steering wheel, steering column, rack and
pinion, steering gearbox, and a linkage system. The vehicle is controlled by the behavior
of the steering gear with the spring loaded rack and pinion. In standard 2 Wheel Steering
System, the rear set of wheels are always directed forward and do not play an active role
in controlling the steering. While in 4 Wheel Steering System, the rear wheels do play an
active role for steering, which can be guided at high as well as low speeds. Production
cars are designed to under steer and rarely do they over steer. Production cars are
designed to under steer and rarely do they over steer. If a car could automatically
compensate for an under steer/over steer problem, the driver would enjoy nearly neutral
steering under varying operating conditions. Four-wheel steering is a serious effort on the
part of automotive design engineers to provide near neutral steering. Also in situations
like low speed cornering, vehicle parking and driving in city conditions with heavy traffic
in tight spaces, driving would be very difficult due to vehicle’s larger wheelbase and track
width. Hence there is a requirement of a mechanism which result in less turning radius
and it can be achieved by implementing four wheel steering mechanism instead of regular
two wheel steering.

2.10:TITLE: ACTIVE FOUR WHEEL STEERING
Publisher: IMPERIAL JOURNAL OF INTERDISCIPLINARY RESEARCH
(IJIR)Vol-3, Issue-4, 2017
Author: Shaikh Mohammad Shakir, Shashank Mahadik, Praveen Singh, Abhishek
Sawant, Sarjeel Sayyed
The implementation of four wheel steering improved the overall performance of
vehicle especially in steering and stability. Four wheel steering is a relatively new
technology. The rear set of wheels are always directed forward therefore and do not play
an active role in controlling the steering in four wheel steering system the rear wheel can
turn left and right. The aim of 4WS system is a better stability during overtaking
maneuvers, reduction of vehicle oscillation around its vertical axis, reduced sensibility to
lateral wind, neutral behavior during cornering. Even though it is advantageous over the
conventional two wheel steering system, 4-Wheel Steering is complex and expensive. It is
not economically viable to replace two wheel steering with 4-Wheel Steering in cars
where the consumer expects more from the technology for the extra cost, but in heavy
truck and towing vehicles it gives more driving advantage over cost. Both 2WS and 4WS
have their own advantages and disadvantages. Hence, by use of convertible steering
system, we can use any of them according to the situation.

3. COMPONENT
The four wheel steering require the following main components to obtain higher
manoeuvrability:
1. Frame
2. Rack and pinion
3. Spur gear
4. Chain drive
5. Steering System
6. Wheels
1. FRAME:
For building the proto type model, the designed model is considered along with
that a frame is built to support the steering, suspension and seat.
The frame is designed considering the wheelbase and track width of Maruti Suzuki 800
and also it has to support for the suspension part as the suspension is welded to the frame,
seat is also welded to the frame. The frame also takes the road load and load of driver, so
considering all the factors the frame is designed and developed.
Fig-3.1: Base Frame Structure

2. RACK AND PINION:
A rack and pinion is a type of linear actuator that comprises a pair of gears which
convert rotational motion into linear motion. A circular gear called “the pinion”
engages teeth on a linear “gear” bar called “rack”; rotational motion applied to the
pinion causes the rack to move relative to the pinion, thereby translating the
rotational motion of the pinion into linear motion.
Fig-3.2: Rack and Pinion
3. SPUR GEAR:
Spur gears teeth are manufactured by either involute profile or cycloidal profile.
Most of the gears are manufactured by involute profile with 200 pressure angle.
When two gears are in mesh at one instant there is a chance to mate involute
portion with non-involute portion of mating gear. This phenomenon is known as
“interference” and occurs when the number of teeth on the smaller of the two
meshing gears is less than a required minimum. To avoid interference we can
have undercutting, but this is not a suitable solution as undercutting leads to
weakening of tooth at its base.

Fig-3.3: Spur Gear
4. CHAIN DRIVE:
Chain drive is a way of transmitting mechanical power from one place to another. It is
often used to convey power to the wheels of a vehicle, particularly bicycles and
motorcycles. It is also used in a wide variety of machines besides vehicles.
Fig-3.4: Chain Drive

5. STEERING:
Steering is the term applied to the collection of components, linkages, etc. which will
allow a vessel (ship, boat) or vehicle (car, motorcycle, and bicycle) to follow the desired
course. An exception is the case of rail transport by which rail tracks combined together
with railroad switches provide the steering function. The most conventional steering
arrangement is to turn the front wheels using a hand–operated steering wheel which is
positioned in front of the driver, via the steering column, which may contain universal
joints, to allow it to deviate somewhat from a straight line.
Fig-3.5: Steering
1. Steering wheel
2. Steering column
3. Rack and pinion
4. Tie rod
5. Kingpin.

6. WHEELS:
Wheel is the circular block of a hard and durable material at whose center has been bored
a circular hole through which is placed an axle bearing about which the wheel rotates
when a moment is applied by gravity or torque to the wheel about its axis, wheel and axle
thereby making together one of the six simple machines.
Fig.3.6: Wheel

4. METHODOLOGY
In this project working of four wheel steering system with the help of rack and pinion
mechanism to reduce the turning radius and increase the stability at the time of drive or
turning. A steering wheel connected with shaft, which is attached with the pinion which is
connected to rack. In a model use two rack and three pinion .when steer the steering then
a rack and pinion mechanism work with the help of shaft.
4.1WORKING MECHANISH:
1. Consists of a rack-and-pinion front steering system that is hydraulically assisted by
twin tandem pump main power source.
2. The rear wheel steering mechanism is also hydraulically assisted by the main pump and
electronically controlled - according to the front steering angle and vehicle speed.
3. The rear steering shaft extends from the rack bar of the front steering gear assembly to
the rear steering-phase control unit.
4. The rear steering system is comprised of the input end of the rear steering shaft, vehicle
speed sensors, a steering-phase control unit (determining direction and degree), a power
cylinder and an output rod
5. A centering lock spring is incorporated, which locks the rear system in a neutral
(straightforward) position in the event of hydraulic failure. Additionally, a solenoid valve
that disengages hydraulic assist (thereby activating the centering lock spring) in case of
an electrical failure is included.
6. The 4WS system varies the phase and ratio of the rear-wheel steering to the front
wheels, according to the vehicle speed.
7. It steers the rear wheels toward the opposite phase (direction) of the front wheel during
speeds less than 35km/h (22mph) for a tighter turn and "neutralizes" them (to a
straightforward direction, as in a conventional two-wheel steering principle) at 35km/h
(22mph).
8. Above the speed of 35 km/h, the system steers toward the same phase-direction as the
front wheels, thereby generating an increased cornering force for stability.
9. The maximum steering angle of the rear wheels extends 10 degrees.

Fig-4.1: Wheel Steering Mechanism

4.2:ADVANTAGES, DISADVANTAGES AND
APPLICATIONS
 ADVANTAGES:
1. Superior cornering stability: The vehicle cornering behavior becomes more
stable and controllable at high speed as well as on wet slippering road surfaces.
2. Improved steering response and precision: The vehicle response to steering
input becomes quicker and more precise throughout the vehicle enter speed range.
3. High speed straight line stability: The vehicle’s straight –line stability at high
speed is improved. Negative effects of road irregularities and crosswinds on the vehicles
stability are minimized.
4. Improved rapid lane-changing maneuvers: This is stability in lane changing
at high speed is improved. In high speed type operation become easier. The vehicle is less
likely to go into a spin even in situations in which the driver must make a sudden and
relatively large change of direction.
5. Smaller turning radius: By steering the rear wheels in the duration opposite the
front wheels at low speed, the vehicle’s turning circle is greatly reduced. Therefore,
vehicle maneuvering on narrow roads and during parking become easier.
6. Controlling: Computer-controlled Quadrasteer can be switched on and off and has
an effective trailer towing mode.
 DISADVANTAGES:
1. The four wheel steering, due to construction of many new components, the system
becomes more expensive.
2. The system includes as many components (especially electronically) there is always a
chance to get any of the part inactive, thus the system becomes in operative.
3. The system is not stable at high speed gets overpowered and topple in some cases.
4. Pump and sensors should be checked regularly to avoid its failure.

 APPLICATION:
1. Parking: During a parking a vehicles driver typically turns the steering wheels
through a large angle to achieve a small tuning radius. By counter phase steering of the
rear wheels, 4ws system realizes a smaller turning radius then is possible with 2ws
system. As a result vehicle is turned in small radius at parking.
2. Junctions: On a cross roads or other junction where roads intersect at 900 degrees or
tighter angles, counter phase steering of the rear wheels causes the front and rear wheels
to follow more or less path. As a result the vehicle can be turned easily at a junction.
3. Slippery road surfaces: During steering operation on low friction surfaces,
steering of the rear wheels suppress sideways drift of the vehicle’s rear end. As a result
the vehicles direction is easier to control.
4. High speed straight line operation: When traveling in a straight line at high
speed, a vehicle’s driver frequently needs to make small steering correction to maintain
the desired direction, in phase steering of the rear wheels minimizes these corrective
steering inputs.
5. Narrow roads: On narrow roads with tight bends, counter-phase steering of the rear
wheels minimizes the vehicle’s turning radius, thereby reducing side-to –side rotation of
the steering wheels and making the vehicle easier to turn.
6. U-Turns: By minimizing the vehicle’s turning radius, counter –phase steering of the
rear wheels enables U-turns to be performed easily on narrow roads.

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http://www.scribd.com/doc/58682411/Ackerman-Steering-For mula-
Derivation, June 2011
5. V. B. Bhandari “ Design of Machine Elements” McGraw Hill
Education India Pvt. Ltd., vol. 3, 11th Edition, 2013
6. Unknown, Four wheel steering, http://www.wisegeek.com/what-is-
four-wheelsteering.htm, Retrived on 13th Sep 2012.
7. Prakashan”, New Delhi, pp 3-8 and 571-579, 2007 R. B. Gupta,
“Automobile Engineering College”, Satya
8. K. Singh, “Automobile Engineering Vol. 1, Standard Publishers
Distributors, New Delhi, pp 448-453, 463-471, 2008
9. R. S. Khurmi, J. K. Gupta, “A text book ofMachine Design. Eurasia
Publishing house(PVT.) Ltd”, First multi color edition, pp 576-586
658-679, 1037-1040, 2005
10. Johnson Erik (2007), “2008 Infiniti G37 Sport Coupe-Suspension,
Handling and Four-Wheel Steering”.

WEBSITES:
1. http://seminarprojects.com/Thread-fourwheel- steering-system-full
report— 6172#ixzz1tn3wSWNO.
2. http://seminarprojects.com/Thread-fourwheel- steering-system-full
report—26172#ixzz1tn3wSWNO.
3. http://trucks.about.com/cs/4ws/a/ 4wheel_steering.htm
4. http://www.delphiauto.com
5. http://www.howhurricaneworks.com

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