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DESIGN AND SIMULATION OF FOUR WHEEL STEERING

SYSTEM

A PROJECT REPORT

Submitted in partial fulfillment for the award of the degree ofBACHELOR OF TECHNOLOGY

in

MECHANICAL ENGINEERING

By

NAVNEET KUMAR (10206173)

D.SATHEESH KUMAR (10206179)

V.P.YUVARAJ (10206200)

Under the guidance of

Mr. ABRAHAM BONIFACE

(ASSISTANT PROFESSOR,Department of AUTOMOBILE ENGINEERING)

FACULTY OF ENGINEERING &TECHNOLOGY

SRM UNIVERSITY

(Under section 3of UGC Act, 1956),

SRM Nagar, Kattankulathur-603203, Kancheepuram District.

APRIL 2010

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BONAFIDE CERTIFICATE

This is to certify that the project report entitledDESIGN AND SIMULATION

OF FOUR WHEEL STEERING SYSTEM submitted by NAVNEET

KUMAR(10206173), D.SATHEESH KUMAR (10206179), YUVARAJ V.P

(10206200), for the award of degree of BACHELOR OF TECHNOLOGY in

Mechanical Engineering, of School of Mechanical, SRM university is a bonafide record

of project work carried out under the supervision of Mr. ABRAHAM BONIFACE The

contents of this report, in full or in parts, have not been submitted to any institute or

university for the award of any degree or diploma.

(Dr. D. Kingsly Jeba Singh) (Mr. ABRAHAM BONIFACE)

HEAD OF THE DEPARTMENT GUIDE

DEANINCHARGE ASSISTANTPROFESSOR

SCHOOLOFMECHANICALENGINERING SCHOOLOFMECHANICALENGINEERING

INTERNAL EXAMINER EXTERNAL EXAMINER

DATE:

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ACKNOWLEDGEMENT

First and foremost, we express our heartfelt and deep sense of gratitude to our

Chancellor Shri. T. R. Pachamuthu, Pro Chancellor Shri. P. Ravi and Vice Chancellor

Shri. P. Sathyanarayanan for providing us the necessary facilities for the completion of

our project. I also acknowledge our Pro- Vice Chancellor Dr. T. P. Ganesan and Registrar

Dr. N. Sethuraman for their constant support and endorsement.

We wish to express our sincere gratitude to our Director (Engineering and

technology) Dr. P.K.A. Muniswaran, Associate Director (Engineering & Technology) Dr.

C. Muthamizhchelvan, for his constant support and encouragement.

We are extremely grateful to Our Head of the Department Dr. Kingsly Jeba Singh

for his invaluable guidance, motivation, timely and insightful technical discussions. We

are immensely grateful to Mr.Abraham Boniface; our internal guide for his constant

encouragement, smooth approach throughout our project period to make this work

possible.

We are indebted to our Project Coordinator Mr. R. Senthil for his valuablesuggestions and motivation. We are deeply indebted to the staff members and lab

assistants of Mechanical Engineering department for extending warm support, constant

encouragement and ideas they shared with us.

We would be failing in our part if we do not acknowledge our family members

and our friends for their constant encouragement and support.

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ABSTRACT

The theme of our project Design and Simulation of Four Wheel Steering

System is to study the characteristics of different modes of four wheel steering

operated under different conditions. The present kind of steering systems that are being

used has certain disadvantages like toppling at higher speeds, skidding of the track,

greater turning radius, etc An extensive research and study has been carried out to

overcome these drawbacks then a suitable and appropriate solution has been found and it

has been simulated in our project.

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TABLE OF CONTENTS

CHAPTER PAGE NO

ACKNOWLEDGEMENT iii

ABSTRACT iv

1. INTRODUCTION 11.1 FUNCTIONS OF STEERING SYSTEM 1

1.2TYPES OF STEERING SYSTEM 11.2.1 FRONT WHEEL STEERING 1

1.2.2 REAR WHEEL STEERING 4

1.2.3 POWER STEERING 5

1.2.4 SPEED ADJUSTABLE STEERING 5

1.2.5 FOUR WHEEL STEERING SYSTEM 5

2. LITERATURE REVIEW 6

3.FOUR WHEEL STEERINING SYSTEM 7

3.1 SLOW SPEED (REAR STEER MODE) 8

3.2 HIGH SPEEDS (CRAB MODE) 83.3 ZERO TURNING CIRCLE RADIUS-360 MODE 9

4. DESIGN OF FOUR WHEEL STEERING SYSTEM 10

4.1 ACKERMAN STEERING MECHANISM

4.2 CONDITION FOR TRUE ROLLING MOTION 12

4.3 BENEFITS OF 4WS STEERING SYSTEM 13

4.4LANE CHANGES 14

4.5 HIGH SPEED STRAIGHT-LINE OPERATION 14

4.6 SIDE WINDS AND OTHER DISTURBANCES 14

4.7 GENTLE CURVES 14

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4.8 PARKING 14

4.9 JUNCTIONS 15

4.10 NARROW ROADS 15

4.11 U-TURNS 15

4.12 CONSTRUCTION AND FUNCTION 16

4.13 STEERING OF REAR WHEEL 16

4.14 PARALLEL PARKING 16

4.15 HIGH SPEED LANE CHANGING 17

4.15.1 RECENT APPLICATION 18

4.15.2 REQURIMENTS OF REAL TIME

IMPLEMENTATION 19

5. TWO DIMENSIONALS DRAWINGS 21

5.1 SHEET NO 1 21

5.2 REDUCTION GEAR BOX 1 22

5.3 REDUCTION GEAR BOX 2 23

5.4 REDUCTION GEAR HOLDER 24

5.5 PINION 24

5.6 RACK AND PINION ASSEMBLY 25

5.7 FRONT GEAR BOX 26

5.8 FRONT GEAR RETAINER 27

5.9 GEAR BOX HOLDER 27 5.10 FRONT RACK 28

5.12 REAR GEAR BOX 29

5.13 PLANTERY GEAR BOX 30

5.14 STROKE ROD ASSEMBELY 32

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5.15 ACKERMANN STEERING GEOMETRY 33

6. CALCULATION 35

7. THREE DIMENSIONAL PART DRAWINGS 38

7.1 ANNULAR GEAR 38

7.2 DISC 38

7.3 FRONT GEAR BOX 38

7.4 FRONT STUD AXEL 38

7.5 FRONT TIE ROD 38

7.6 FRONT TOP WISH BONE 38

7.7 REAR GEAR BOX 38

7.8 REAR LEFT HUB 38

7.9 REAR TOP WISHBONE 38

7.10 SLIDER GEAR 39

7.11 SLIDER PLATE 39

7.12 STROKE ROD 39

7.13 ECCENTRIC SHAFT 39

7.14 UNIVERSAL COUPLING 39

7.15 STEERING HADLE 39

7.16 PINION 39

7.17 REAR RIGHT HUB 39

7.18 FRONT RACK 39

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8. ASSEMBLY DRAWINGS 41

8.1 FRONT GEAR BOX ASSEMBLY 41

8.2 PLANETARY BOX ASSEMBELY GEAR 42

8.3 REAR TRACK ROD ASSEMBLY 42

8.4 REAR ASSEMBLY 43

8.5 OVERALL STEERING ASSYMBLY 44

8.6 FRONT VIEW OF THE VEHICLE 45

8.7 TOP VIEW OF THE VEHICLE 45

8.8 RIGHT SIDE VIEW OF THE VEHICLE 46

8.9 3D VIEW OF THE VEHICLE 46

9. PRODUCTION CARS WITH ACTIVE 4WS SYSTEM 47

10. RESULT 49

11. CONCLUSION 51

REFERENCES 52

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CHAPTER -1

INTRODUCTION TO STEERING SYSTEM

1.1 Functions of the steering system

The various functions of the steering wheel are:

1. To control the angular motion the wheels and thus the direction of motion of thevehicle.

2. To provide directional stability of the vehicle while going straight ahead3. To facilitate straight ahead condition of the vehicle after completing a turn4. The road irregularities must be damped to the maximum possible extent. This should

co-exist with the road feel for the driver so that he can feel the road condition withoutexperiencing the effects of moving over it

5. To minimize tyre wear and increase the life ofthe tyres1.2 Types of steering

Depending on the number and position of the wheels being steered, steering

systems can be classified as follows:

1.2.1 Front wheel steering

The most commonly used type of steering, only the two front wheels of the

vehicle are used to steer the vehicle. This type of steering suffers from the comparatively

larger turning circle and the extra effort required by the driver to negotiate the turn A

typical front wheel steering mechanism layout is given in FIG 1.1.

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1.2.2 Rear wheel steering

o

i

Some

nly the two

unsuitable

types of in

rear wheels

for high spe

dustry batte

control the

ed purposes

ry trucks a

steering. It

and for eas

d backhoe

an produce

of use

loaders use

d smaller tu

ack and pin

ack and pin

FIG 1.

ion, recircul

ion

- Conventi

ating ball,

x

onal Front

orm and se

heel Steer

tor

ng System

this type,

rning circle

here

, but

http://en.wikipedia.org/wiki/File:WrightspeedStearingRack4888.JPGhttp://en.wikipedia.org/wiki/File:Rack_and_pinion_animation.gif

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Rack and pinion unit mounted in the cockpit of an Ariel Atomsports car chassis. For

most high volume production, this is usually mounted on the other side of this panel

Many modern cars use rack and pinionsteering mechanisms, where the steering wheel

turns the pinion gear; the pinion moves the rack, which is a linear gear that meshes withthe pinion, converting circular motion into linear motion along the transverse axis of the

car (side to side motion). This motion applies steering torqueto the swivel pin ball joints

that replaced previously used kingpinsof the stub axle of the steered wheels via tie rods

and a short leverarm called the steering arm.

The rack and pinion design has the advantages of a large degree of feedback and direct

steering "feel". A disadvantage is that it is not adjustable, so that when it does wear and

develop lash, the only cure is replacement.

Older designs often use the recirculating ballmechanism, which is still found on trucks

and utility vehicles. This is a variation on the older worm and sectordesign; the steering

column turns a large screw (the "worm gear") which meshes with a sector of a gear,

causing it to rotate about its axis as the worm gear is turned; an arm attached to the axis

of the sector moves the Pitman arm, which is connected to the steering linkageand thus

steers the wheels. The recirculating ball version of this apparatus reduces the

considerable friction by placing large ball bearings between the teeth of the worm and

those of the screw; at either end of the apparatus the balls exit from between the two

pieces into a channel internal to the box which connects them with the other end of the

apparatus, thus they are "recirculated".

The recirculating ball mechanism has the advantage of a much greater mechanical

advantage, so that it was found on larger, heavier vehicles while the rack and pinion was

originally limited to smaller and lighter ones; due to the almost universal adoption of

power steering, however, this is no longer an important advantage, leading to the

increasing use of rack and pinion on newer cars. The recirculating ball design also has a

perceptible lash, or "dead spot" on center, where a minute turn of the steering wheel in

either direction does not move the steering apparatus; this is easily adjustable via a screw

on the end of the steering box to account for wear, but it cannot be entirely eliminated

because it will create excessive internal forces at other positions and the mechanism will

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http://en.wikipedia.org/wiki/Ariel_Atomhttp://en.wikipedia.org/wiki/Rack_and_pinionhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Kingpin_(mechanics)http://en.wikipedia.org/wiki/Tie_rodhttp://en.wikipedia.org/wiki/Leverhttp://en.wikipedia.org/wiki/Backlash_(engineering)http://en.wikipedia.org/wiki/Recirculating_ballhttp://en.wikipedia.org/wiki/Worm_and_sectorhttp://en.wikipedia.org/wiki/Worm_gearhttp://en.wikipedia.org/wiki/Pitman_armhttp://en.wikipedia.org/wiki/Linkage_(mechanical)#Types_of_linkageshttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Power_steeringhttp://en.wikipedia.org/w/index.php?title=Steering_box&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Steering_box&action=edit&redlink=1http://en.wikipedia.org/wiki/Power_steeringhttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Mechanical_advantagehttp://en.wikipedia.org/wiki/Linkage_(mechanical)#Types_of_linkageshttp://en.wikipedia.org/wiki/Pitman_armhttp://en.wikipedia.org/wiki/Worm_gearhttp://en.wikipedia.org/wiki/Worm_and_sectorhttp://en.wikipedia.org/wiki/Recirculating_ballhttp://en.wikipedia.org/wiki/Backlash_(engineering)http://en.wikipedia.org/wiki/Leverhttp://en.wikipedia.org/wiki/Tie_rodhttp://en.wikipedia.org/wiki/Kingpin_(mechanics)http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Rack_and_pinionhttp://en.wikipedia.org/wiki/Ariel_Atom

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wear very rapidly. This design is still in use in trucks and other large vehicles, where

rapidity of steering and direct feel are less important than robustness, maintainability, and

mechanical advantage. The much smaller degree of feedback with this design can also

sometimes be an advantage; drivers of vehicles with rack and pinion steering can have

their thumbs broken when a front wheel hits a bump, causing the steering wheel to kick

to one side suddenly (leading to driving instructors telling students to keep their thumbs

on the front of the steering wheel, rather than wrapping around the inside of the rim).

This effect is even stronger with a heavy vehicle like a truck; recirculating ball steering

prevents this degree of feedback, just as it prevents desirable feedback under normal

circumstances.

The steering linkage connecting the steering box and the wheels usually conforms to a

variation of Ackermann steering geometry, to account for the fact that in a turn, the inner

wheel is actually travelling a path of smaller radius than the outer wheel, so that the

degree of toesuitable for driving in a straight path is not suitable for turns.

The worm and sector was an older design, used for example in Willys and Chrysler

vehicles, and the Ford Falcon.

Other systems for steering exist, but are uncommon on road vehicles. Children's toys and

go kartsoften use a very direct linkage in the form of abell crank(also commonly known

as a Pitman arm) attached directly between the steering column and the steering arms,

and the use of cable-operated steering linkages (e.g. the Capstan and Bowstring

mechanism) is also found on some home-built vehicles such as soapbox cars and

recumbent tricycles.

1.2.3 Power steering

Power steering assists the driver of an automobile in steering by directing a

portion of the vehicle's power to traverse the axis of one or more of the road wheels. As

vehicles have become heavier and switched to front wheel drive, particularly using

negative offset geometry, along with increases in tyre width and diameter, the effort

needed to turn the steering wheel manually has increased - often to the point where major

physical exertion is required. To alleviate this, auto makers have developed power

steeringsystems: or more correctly power assisted steering - on road going vehicles there

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http://en.wikipedia.org/wiki/Ackermann_steering_geometryhttp://en.wikipedia.org/wiki/Toe_(automotive)http://en.wikipedia.org/wiki/Go_karthttp://en.wikipedia.org/wiki/Bellcrankhttp://en.wikipedia.org/wiki/Pitman_armhttp://en.wikipedia.org/wiki/Capstan_and_Bowstringhttp://en.wikipedia.org/wiki/Soapbox_carhttp://en.wikipedia.org/wiki/Recumbent_tricyclehttp://en.wikipedia.org/wiki/Front_wheel_drivehttp://en.wikipedia.org/wiki/Auto_makerhttp://en.wikipedia.org/wiki/Power_steeringhttp://en.wikipedia.org/wiki/Power_steeringhttp://en.wikipedia.org/wiki/Power_steeringhttp://en.wikipedia.org/wiki/Power_steeringhttp://en.wikipedia.org/wiki/Auto_makerhttp://en.wikipedia.org/wiki/Front_wheel_drivehttp://en.wikipedia.org/wiki/Recumbent_tricyclehttp://en.wikipedia.org/wiki/Soapbox_carhttp://en.wikipedia.org/wiki/Capstan_and_Bowstringhttp://en.wikipedia.org/wiki/Pitman_armhttp://en.wikipedia.org/wiki/Bellcrankhttp://en.wikipedia.org/wiki/Go_karthttp://en.wikipedia.org/wiki/Toe_(automotive)http://en.wikipedia.org/wiki/Ackermann_steering_geometry

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has to be a mechanical linkage as a failsafe. There are two types of power steering

systemshydraulic and electric/electronic. A hydraulic-electric hybrid system is also

possible.

A hydraulic power steering(HPS) uses hydraulic pressure supplied by an engine-drivenpump to assist the motion of turning the steering wheel. Electric power steering(EPS) is

more efficient than the hydraulic power steering, since the electric power steering motor

only needs to provide assistance when the steering wheel is turned, whereas the hydraulic

pump must run constantly. In EPS the assist level is easily tunable to the vehicle type,

road speed, and even driver preference. An added benefit is the elimination of

environmental hazard posed by leakage and disposal of hydraulic power steering fluid.

1.2.4 Speed adjustable steering

An outgrowth of power steering is speed adjustable steering, where the steering is

heavily assisted at low speed and lightly assisted at high speed. The auto makers perceive

that motorists might need to make large steering inputs while maneuvering for parking,

but not while traveling at high speed. The first vehicle with this feature was the Citron

SMwith its Derive layout, although rather than altering the amount of assistance as in

modern power steering systems, it altered the pressure on a centering cam which made

the steering wheel try to "spring" back to the straight-ahead position. Modern speed-

adjustable power steering systems reduce the pressure fed to the ram as the speed

increases, giving a more direct feel. This feature is gradually becoming commonplace

across all new vehicles.

1.2.5 Four wheel steering

The most effective type of steering, this type has all the four wheels of the vehicle

used for steering purpose. A detailed description of this type follows

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CHAPTER 2

LITERATURE REVIEW

Contemporary rear axles allows for coincidental steering through the influence of

variation of elasto kinematic steering; rear wheels rotate, due to an influence of variation

of vertical load of wheels (tilting), in the same direction as front wheels. Nevertheless,

such a turn of rear wheels is very small and drivers will-independent. A disadvantage of

this so-called passive steering system is that it operates even when driving in straight

direction when single wheel of an axle hits surface irregularity (deterioration of

directional stability).New generation of active steering systems distinguishes a need of

steering of rear wheels for the reason of directional stability from a need of steering of

rear wheels for the reason of cornering at slow speed. Therefore, the active system means

that rear wheels are possible to be turned either coincidently or non-coincidently The

increase of the manoeuvrability when parking the vehicle is achieved by means of

disconcordant steering, meanwhile the increase of the driving stability at higher speeds is

achieved through concordant.

Dr. N. K. Giri, Automotive Mechanics

The basic steering calculations like basic formula for true rolling condition, formula

for finding out turning radius of each wheel,etc..are done by referring this book.

Heinz Heisler, Advanced Vehicle Technology

The basic constructional details of planetary gear box and stroke rod assembly are

being done by referring this book.

Design data data book of engineers PSG college of technology.

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Rack construction, formula to find minimum number of teeth to avoid interference,

gear materials and basic gear calculations are done by referring this book.

Theory of machines, S.Rattan

Gear train construction for gear box, speed ratio and the speed of revolutions obtained

by each pinion in the gear box are calculated by referring this book.

CHAPTER -3

FOUR WHEEL STEERING

Contemporary rear axles allows for coincidental steering through the influence of

variation of elasto kinematic steering; rear wheels rotate, due to an influence of variationof vertical load of wheels (tilting), in the same direction as front wheels. Nevertheless,

such a turn of rear wheels is very small and drivers will-independent. A disadvantage of

this so-called passive steering system is that it operates even when driving in straight

direction when single wheel of an axle hits surface irregularity (deterioration of

directional stability). New generation of active steering systems distinguishes a need of

steering of rear wheels for the reason of directional stability from a need of steering of

rear wheels for the reason of cornering at slow speed. Therefore, the active system

means that rear wheels are possible to be turned either coincidently or non-coincidently.

The increase of the maneuverability when parking the vehicle is achieved by means of

disconcordant steering, meanwhile the increase of the driving stability at higher speeds

is achieved through concordant steering.

In a typical front wheel steering system, the rear wheels do not turn in the direction of

the curve, and thus curb on the efficiency of the steering. Normally, this system has not

been the preferred choice due to the complexity of conventional mechanical four wheel

steering systems. However, a few cars like the Honda Prelude, Nissan Skyline GT-R have

been available with four wheel steering systems, where the rear wheels turn by a small

angle to aid the front wheels in steering. However, these systems had the rear wheels

steered by only 2 or 3 degrees, as their main aim was to assist the front wheels rather than

steer by themselves.

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xvii

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Such a system requires precise calculation from a servo motor with real-time feedback to

make certain that all three steering modes function perfectly. The concept didnt make it

to production, possibly due to the high costs involved in the power train layout. But the

idea presented by the concept continues to find importance. The only major problem

posed by this layout is that a conventional rack-and-pinion steering with pitman arms

would not be suitable for this mode, since the two front wheels are steered in opposite

directions. Steer-by-wire systems would work fine, however, since independent control

can be achieved.

CHAPTER -4

DESIGN OF FOUR WHEEL STEERING SYSTEM

It is to be remembered that both the steered wheels do not turn in the same

direction, since the inner wheels travel by a longer distance than the outer wheels, as

described in FIG 2.1.

FIG 2.1 - Variation in steer angles for left and right wheels

4.1 Ackerman steering mechanism

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Shown in FIG 2.2, Ackermann steering geometry is a geometric arrangement of

linkages in the steeringof a caror other vehicledesigned to solve the problem of wheels

on the inside and outside of a turn needing to trace out circles of different radii. The

steering pivot points are joined by a rigid bar called the tie rod which is also a part of the

steering mechanism. With perfect Ackermann, at any angle of steering, the centre point

of all of the circles traced by all wheels will lie at a common point. But this may be

difficult to arrange in practice with simple linkages, and designers draw or analyze their

steering systems over the full range of steering angles. Hence, modern cars do not use

pure Ackermann steering, partly because it ignores important dynamic and compliant

effects, but the principle is sound for low speed maneuvers, and the right and left wheels

do not turn by the same angle, be it any cornering speed.

FIG 2.2 - Ackerman steering geometry

This presents a difficult problem for vehicles with independent steering, as the

wheels cannot be easily given the correct Ackerman turning angles. This would directly

affect the dynamic handling of the car, making it impossible to control properly. With all

the four wheels steered, the problem gets compounded, since the appropriate steering

angles for all four wheels need to be calculated. It is to be noted that the variation in

steering angles as a result of Ackerman geometry is progressive and not fixed, hence they

have to be pre-calculated and stored by the controller. This dictates that the control of

xix

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four-wheel steering systems be very precise, and consequently, complex. This is another

reason why manufacturers have not preferred the use of such systems in their vehicles,

even with recent advances in technology. The cost of such systems can be high, and a

good amount of research & development is required upfront. Nevertheless, the benefits

that engineers can reap out of this technology are significant enough to work around these

obstacles.

We chose to use a simple control circuit to demonstrate the effectiveness of a four

wheel steering system, and at the same time, simulated the suspension-steering assembly

of a typical car to predict the Ackerman angles for corresponding steer angles. The design

calculation for the model follows shortly.

4.2 Condition for true rolling motion

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FIG 2.3 - Fundamental condition for true rolling motion

As observed from FIG 2.3, perfect steering of the wheels can be achieved only

when all four wheels are rolling perfectly for all dynamic conditions. While tackling a

turn, the condition of perfect rolling motion will be satisfied if all the four wheel axes

when projected at one point called the instantaneous centre, and when the following

equation is satisfied:

Cot cot = c / b (1)

c

WheelBase

b

WheelTrack

t

It is seen that the inside wheel is required to turn through a greater angle than the

outer wheel. The larger the steering angle, the smaller the turning circle. It has been

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found that the steering angle can have a maximum value of about 44 degrees under

dynamic conditions. The extreme positions on either side are called lock positions. The

diameter of the smallest circle which the outer front wheel of the car can traverse and

obtained when the wheels are at their extreme positions is known as the turning circle.

4.3 Benefits of four wheel steering

With the 360 mode, the vehicle can quickly turn around at the press of a button and ablip of the throttle. Complicated three-point steering maneuvers and huge space

requirements to park the vehicle are entirely phased out with this.

Crab mode helps simplify the lane changing procedure. In conjunction with rear steer mode, four-wheel steering can significantly improve the

vehicle handling at both high and low speeds.

Due to the better handling and easier steering capability, driver fatigue can be reducedeven over long drives.

The only major restriction for a vehicle to sport four-wheel steering is that it shouldhave four or more wheels. Hence, every kind of private and public transport vehicle,

be it cars, vans, buses, can benefit from this technology.

Military reconnaissance and combat vehicles can benefit to a great extent from 360mode, since the steering system can be purpose built for their application and are of

immense help in navigating difficult terrain.

Applications

By steering a vehicles rear wheels as well as its front wheels, a four-wheel steering

system, either mechanical or electrical, offers improved handling stability and other

benefits. The 4WS/E-4WS system used by Honda performs two distinct operations: in-

phase steering, whereby the rear wheels are turned in the same direction as the front

wheels, and counter phase steering, whereby the rear wheels are turned in the opposite

direction.TheHonda4WS/E-4WS system is effective in the following situations:

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4.4 Lane changes

During lane-change maneuvers at high speed, the system performs in-phase

steering. This operation enables the vehicle to move in a crab-like manner rather than in a

curved path. As a result, the vehicle is more stable and controllable.

4.5 High speed straight line operation

Even when travelling in a straight line at high speed, a vehicles driver frequently

needs to make small steering corrections to maintain his/her desired course. With the

Honda 4WS/E-4WS system, in-phase steering of the rear wheels minimizes these

corrective steering inputs.

4.6 Side wind sand other disturbance

When a vehicle is subjected to side winds, bumpy road surfaces, or other externaldisturbances, the driver needs to make steering corrections to maintain his/her desired

course. The Honda 4WS/E-4WS system enables the driver to make these corrective

steering inputs without causing significant changes in the vehicles body attitude .

4.7 Gentle curves

On gentle curves; in-phase steering of the rear wheels improves the vehicles

stability.

4.8ParkingDuring a parking maneuver, a vehicles driver typically turns the steering wheel

through a large angle to achieve a small turning radius. By performing counter-phase

steering of the rear wheels, the Honda 4WS/E-4WS system realizes a smaller turning

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radius than is possible with a two-wheel steering (2WS) system. As a result, the vehicle is

easier to maneuver into garages and other parking spaces.

4.9Junctions

On a crossroads or other junction where roads intersect at 90 degrees or tighterangles, counter-phase steering of the rear wheels causes the front and rear wheels to

follow more-or-less the same path. As a result, the vehicle can be turned more tightly as it

negotiates the junction. With a 2WS system, the vehicle would need to follow a relatively

curved path.

4.10 Narrow road

On narrow roads with tight bends, counter-phase steering of the rear wheels

minimizes the vehicles turning radius, thereby reducing side-to-side rotation of the

steering wheel and making the vehicle easier to maneuver.

4.11 U-Turns

By minimizing the vehicles turning radius, counter-phase steering of the rear wheels

enables U-turns to be performed easily on narrow roads.

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4.12 Construction and function

The main components of a Honda 4WS system are the front steering gearbox, which

turns the front wheels, the rear steering gearbox, which turns the rear wheels, and thecenter steering shaft, which links the two gearboxes. When the steering wheel is turned,

the front wheels are steered in the same way as with a 2WS system. A rack-and-pinion

mechanism in the front steering gearbox transmits this movement to the rear steering

gearbox via the center shaft. (The rack-and-pinion mechanism is separate from the one to

which the steering wheel is connected.) Via the rear tie rods, the rear steering gearbox

steers the rear wheels by the appropriate angle and in the appropriate direction.

4.13 Steering of rear wheels

When the steering wheel is turned from its straight-ahead position by an angle of 120

degree or smaller, the 4WS system performs to increase in-phase steering of the rear

wheels angle.

When the steering wheel angle exceeds 120 degree, the rear wheels gradually straighten

up then turn in the opposite direction.

Application of four wheel steering with 360 mode

4.14 Parallel parking

As has been discussed previously, zero steer can significantly ease the parking

process, due to its extremely short turning footprint. This is exemplified by the parallel

parking scenario, which is common in foreign countries and is pretty relevant to our

cities. Here, a car has to park it between two other cars parked on the service lane. This

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i

1

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t

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xxvii

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http://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Monster_truckshttp://en.wikipedia.org/wiki/Monster_truckshttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Monster_truckshttp://en.wikipedia.org/wiki/Monster_truckshttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Travel_trailerhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Motorwayhttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Yaw_angle

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in large farm vehicles and trucks. Some of the modern European Intercity buses also

utilize four-wheel steering to assist maneuverability in bus terminals, and also to improve

road stability.

General Motors offers Delphi's Quadra steer in their consumer Silverado/Sierra andSuburban/Yukon. However, only 16,500 vehicles have been sold with this system since

its introduction in 2002 through 2004. Due to this low demand, GM will not offer the

technology on the 2007 update to these vehicles.

Previously, Hondahad four-wheel steering as an option in their 1987-2000 Prelude, and

Mazdaalso offered four-wheel steering on the 626and MX6in 1988.

A new "Active Drive" system is introduced on the 2008 version of the Renault Laguna

line. It was designed as one of several measures to increase security and stability. The

Active Drive should lower the effects of under steer and decrease the chances of spinning

by diverting part of the G-forces generated in a turn from the front to the rear tires. At

low speeds the turning circle can be tightened so parking and maneuvering is easier.

4.15.2 Requirement for real-time implementation

Since our application was carried out on a scale model, there were bound to be a

number of modifications as the project scales up to its true size. Following are some the

requirements/modifications needed in a car to use four wheel steering with 360 mode:

Replacing the rack and pinion steering mechanism up front with a fully electronicservo-motor controlled steering front and rear, since both the right and left wheels

face in opposing directions. If it is possible to get opposing steer angles with a

rack and pinion system, it may be used for the front wheels

Increasing the suspension travel on all four struts. Since the wheels turn by closeto 50 degrees for 360 mode, it is imperative that an extra load acts on the

suspension. Hence, the suspension travel has to be increased by close to 25%

In case of four-wheel drive vehicles, all four wheels must have constant velocityjoints to handle both traction and steering purposes

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An advanced steering controller circuit with steering angle sensor must beinstalled to continuously monitor the vehicles dynamic condition and adjust the

steering angles accordingly. The 360 mode can be activated/deactivated at the

press of a button, and the ECU must handle the other two modes depending on

vehicle speed

Manual override should be provided to use conventional two-wheel steering whendemanded by the driver. This would be useful for experienced drivers who may

not need the assistance of 4WS for most of their daily run

The four-wheel steering system has to implemented in the vehicle right from thedesign stage, as it cannot be retrofitted in existing vehicles. Space constraints and

lack of electronic processing capability and power supply might act as deterrentshere

A mechanism should be provided to reverse the drive on any one side (right/left)wheel, to achieve 360 mode

To provide for the power requirement of high-torque steering servos, the batterywill have to be updated with a higher voltage and ampere-hour rating

The current traffic scenario demands a revolution, rather than an evolution, and

the zero turning circle four-wheel steering system can prove to be a panacea for the

people. With its tight parking circles and improved high speed handling, it is well worth

the extra effort required in design and any extra cost that might have to be paid by the end

consumer. A precise control strategy and dynamic handling solutions are the only

roadblocks that prevent this system from reaching the people. But time and technology

will soon help it get past these hurdles.

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CHAPTER -5

All the given drawings are first drawn in 3d using a software called Pro-E

Wildfire.2 then it is converted into 2d drawings in AutoCAD for preparing

manufacturing prints for proper manufacture.

2D DRAWINGS FOR SINGLE MODE STEERING

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2D DRAWINGS FOR DUAL MODE STEERING

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STROKE ROD ASSEMBELY

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CHAPTER -6

CALCULATION

a=wheel track, mm

b=wheel base, mm

c=distance between kingpin axis, mm

y= shown in above figure.

All the below values are obtained from steering geometry

a=1300

b=2000

c=1151.72

y=3357.98 (true rolling condition)

2 8= 1 2 1 . 5 2) For inner fron wheel=

1 t

=

- .

= 4185 mm

2) For outer front wheel= + .

= +=5531.15 mm

3) For inner rear wheel= =

-

.

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=3687 mm

4) For outer rear wheel= +

= + .

cot- cot =

=5151 mm

Steering ratio =

=

= 6.43

Camber = 1(positive)

aster = 4(positive)

R=10.5 m)

2) Rear steer mode (TR=3.6 m)R=4.2 m)

TR= Turning Radius

King pin inclination = 10

C

Scrub radius= 40mm

1) Same steer mode (T

3) True rolling condition (T

% Reduction =..

. 100 19% (Rear steer mode compared with true rolling)

% Reduction = ... 100= 65% (Rear steer mode compared with crab mode)

Gea

1)Module = 2 mm

r specification:

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2)Pressure angle = 20 mm

3)No.of.teeth = 14 = External gear

No.of.teeth = 28 = External gear

No.of.teeth =30 = External gear

4) No.of.teeth = 45 = Internal gear

No of teeth calculation on rack

PCD of pinion = 28No.of.teeth =

=

= 14

For 360 L-L movement the pinion has to be given one full rotation,

o.of.teeth on rack = 14 + 6 =20 teeth (6 teeth allowance on either side)

minimum number of teeth to avoid interference

2 1 2

N

With rack & pinion, formula for

1 2 13.8614

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CHAPTER -7

3D DRAWING

7.1 Annular gear 7.2 Disc 7.3 Front gear box

7.4 Front stud axle 7.5 F 7.6 Front top wishbone

7.7 Rear gear box 7.8 Rear left hub 7.9 Rear top wishbone

ront tie rod

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7.10 Slider gear 7.11 Slider plate 7.12 Stroke rod

7.13 Eccentric shaft 7.14 Universal coupling 7.15 Steering handle

7.16 T 14 Pinion 7.17 Rear right hub 7.18 Fron t rack

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Gear box constructional details of four wheel steering

1 Front rack

5 4 3 2

he gears are listed in the figure from 1 to 7.

(T2 * T4 / T3 * T5)

ise the speed of the input shaft}

h) PCD(inmm) O.D(inmm)

6 5 Steeringwheel

Module (m)=2,

FrontGearbox

PlanetaryGearbox7

Reartrackrod

SliderplatePressure angle()= 20 deg,

T

Front gear box (train value) e =2 =

{ The output shaft is tw

Gear(no.ofteet

N1=14 28 32

N2=28 56 60

N3=14 28 32

N4=14 28 32

N5=14 28 32

N6=45(InternalGear) 90 94

N7=30 60 64

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CHAPTER-8

For the perfect working of planetary gear box, the required revolutins of the shaft

t

a

ASSEMBLY DRAWINGS

8.1 FRONT GEAR BOX ASSEMBLY

must be 2 i.e. 720, but in the front the required revolution is 1 i.e. 360(for 360 lock to

lock steering). Therefore front to rear gear ratio is 1:2. This ratio is achieved with a

simple gear train in the front gear box with a driving pinion of PCD 56 mm and a driven

pinion of PCD 28 mm, with two idle gears of PCD 28 mm. The idle gears are used to ge

suffic

ient gap between the two shaft of the front gear box so that the Universal

couplings coupled with the shafts are free to rotate without hitting each other.

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8.2 PLANETARY BOX ASSEMBELY GEAR

8.3 REAR TRACK ROD ASSEMBLY

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8.4 REAR ASSEMBLY

The rear steering box is basically formed from an epicyclic gear set consisting of

a fixed internally toothed annular ring gear in which a planetary gear driven by an

eccentric shaft revolves. Motion is transferred fron the input eccentric shaft to theplanetary gear through an offset peg attatched to a disc which is mounted centrally on the

eccentric shaft. Rotation of the input eccentric shaft imparts movement to the planetary

gear which is forced to orbit around the inside of the annular gear. At the same time

motion is conveyed to the guide fork via a second peg mounted eccentrically on the face

of the planetary gear and the slider plate which fits over the peg. Since the slider plate is

located between the fork fingers, the rotation of the planetary gear and peg causes the

slider plate to move in both a vertical and horizontal direction. Due to the construction of

the guide fork, the slider plate is free to move vertically up an down but is constrained in

the horizontal direction so that the stroke rod is compelled to move transversely to and

fro according to the angular position of the planetary gear and peg.

Adopting this combined epicyclic gear set with a slider fork mechanism enables a small

same direction steer movement of the rear wheels to take place for small deviation of the

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steering wheel from the straight ahead position. The rear wheels then progressively

change from a same direction steer movement into an opposite steer displacement with a

large steering angles.

8.5 OVERALL STEERING ASSYMBLY

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8.6 FRONT VIEW OF THE VEHICLE

8.7 TOP VIEW OF THE VEHICLE

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8.8 RIGHT SIDE VIEW OF THE VEHICLE

8.9 3D VIEW OF THE VEHICLE

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CHAPTER-9

PRODUCTION CARS WITH ACTIVE FOUR WHEEL

STEERING

Chevrolet Silverado(20022006) (high and low speed) Efini MS-9(high and low speed) GMC Sierra(2002) (high and low speed) Honda Prelude (high and low speed, mechanical from 1987 to 1991,

computerized from 1992-2001)

Honda Accord(1991) (high and low speed, mechanical) Infiniti FX50 AWD (option on Sports package) (2008Present) (high and low

speed, fully electronic)

Infiniti G35 Sedan(option on Sport models) (2007Present) (high speed only?) Infiniti G35 Coupe(option on Sport models) (2006Present) (high speed only) Infiniti J30t(touring package) (19931994) Infiniti M35(option on Sport models) (2006Present) (high speed only?) Infiniti M45(option on Sport models) (2006Present) (high speed only?) Infiniti Q45t(19891994) (high speed only?) Mazda 929(19921995)(computerized, high and low speed)(all models) Mazda 626(1988) (high and low speed) Mazda MX-6(19891997) (high and low speed)

Mazda RX-7(optional, computerized, high and low speed)

Mazda Eunos 800(19962003) (Optional, computerized, high and low speed) Mitsubishi Galant/Sigma (high speed only) Mitsubishi GTO (also sold as the Mitsubishi 3000GT and the Dodge Stealth)

(Mechanical) (high speed only)

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http://en.wikipedia.org/wiki/Chevrolet_Silveradohttp://en.wikipedia.org/wiki/Efini_MS-9http://en.wikipedia.org/wiki/GMC_Sierrahttp://en.wikipedia.org/wiki/Honda_Preludehttp://en.wikipedia.org/wiki/Honda_Accordhttp://en.wikipedia.org/w/index.php?title=Infiniti_FX50_AWD&action=edit&redlink=1http://en.wikipedia.org/wiki/Infiniti_Ghttp://en.wikipedia.org/wiki/Infiniti_Ghttp://en.wikipedia.org/wiki/Infiniti_J30http://en.wikipedia.org/wiki/Infiniti_M35http://en.wikipedia.org/wiki/Infiniti_M45http://en.wikipedia.org/wiki/Infiniti_Q45http://en.wikipedia.org/wiki/Mazda_929http://en.wikipedia.org/wiki/Mazda_626http://en.wikipedia.org/wiki/Mazda_MX-6http://en.wikipedia.org/wiki/Mazda_RX-7http://en.wikipedia.org/wiki/Mazda_Eunos_800http://en.wikipedia.org/wiki/Mitsubishi_Galanthttp://en.wikipedia.org/wiki/Mitsubishi_GTOhttp://en.wikipedia.org/wiki/Mitsubishi_GTOhttp://en.wikipedia.org/wiki/Mitsubishi_Galanthttp://en.wikipedia.org/wiki/Mazda_Eunos_800http://en.wikipedia.org/wiki/Mazda_RX-7http://en.wikipedia.org/wiki/Mazda_MX-6http://en.wikipedia.org/wiki/Mazda_626http://en.wikipedia.org/wiki/Mazda_929http://en.wikipedia.org/wiki/Infiniti_Q45http://en.wikipedia.org/wiki/Infiniti_M45http://en.wikipedia.org/wiki/Infiniti_M35http://en.wikipedia.org/wiki/Infiniti_J30http://en.wikipedia.org/wiki/Infiniti_Ghttp://en.wikipedia.org/wiki/Infiniti_Ghttp://en.wikipedia.org/w/index.php?title=Infiniti_FX50_AWD&action=edit&redlink=1http://en.wikipedia.org/wiki/Honda_Accordhttp://en.wikipedia.org/wiki/Honda_Preludehttp://en.wikipedia.org/wiki/GMC_Sierrahttp://en.wikipedia.org/wiki/Efini_MS-9http://en.wikipedia.org/wiki/Chevrolet_Silverado

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Nissan Cefiro(A31) (high speed only) Nissan 240SX/Silvia (option on SE models) (high speed only) Nissan 300ZX(all Twin-Turbo Z32 models) (high speed only) Nissan Laurel(later versions) (high speed only) Nissan Fuga/Infiniti M(high speed only) Nissan Silvia(option on all S13 models) (high speed only) Nissan SkylineGTS, GTS-R, GTS-X (1986) (high speed only) Nissan Skyline GT-R(high and low speed) Renault Laguna (only in GT version of 3rd generation which was launched

October 2007, GT launched on April 2008)

Subaru Alcyone SVXJDM (19911996) (Japanese version: "L-CDX" only) (highspeed only)

Toyota Aristo(1997) (high and low speed?) Toyota CamryJDM 1990-1992 Camry Prominent (Optional)(high and low speed) Toyota Celica (option on 5th and 6th generation, 1990-1993 ST183 and 1994-

1997 ST203) (Dual-mode, high and low speed)

Toyota Soarer(UZZ32)

lviii

http://en.wikipedia.org/wiki/Nissan_Cefirohttp://en.wikipedia.org/wiki/Nissan_240SXhttp://en.wikipedia.org/wiki/Nissan_300ZXhttp://en.wikipedia.org/wiki/Nissan_Laurelhttp://en.wikipedia.org/wiki/Nissan_Fugahttp://en.wikipedia.org/wiki/Infiniti_Mhttp://en.wikipedia.org/wiki/Nissan_Silviahttp://en.wikipedia.org/wiki/Nissan_Skylinehttp://en.wikipedia.org/wiki/Nissan_Skyline_GT-Rhttp://en.wikipedia.org/wiki/Renault_Lagunahttp://en.wikipedia.org/wiki/Subaru_Alcyone_SVXhttp://en.wikipedia.org/wiki/Toyota_Aristohttp://en.wikipedia.org/wiki/Toyota_Camryhttp://en.wikipedia.org/wiki/Toyota_Celicahttp://en.wikipedia.org/wiki/Toyota_Soarerhttp://en.wikipedia.org/wiki/Toyota_Soarerhttp://en.wikipedia.org/wiki/Toyota_Celicahttp://en.wikipedia.org/wiki/Toyota_Camryhttp://en.wikipedia.org/wiki/Toyota_Aristohttp://en.wikipedia.org/wiki/Subaru_Alcyone_SVXhttp://en.wikipedia.org/wiki/Renault_Lagunahttp://en.wikipedia.org/wiki/Nissan_Skyline_GT-Rhttp://en.wikipedia.org/wiki/Nissan_Skylinehttp://en.wikipedia.org/wiki/Nissan_Silviahttp://en.wikipedia.org/wiki/Infiniti_Mhttp://en.wikipedia.org/wiki/Nissan_Fugahttp://en.wikipedia.org/wiki/Nissan_Laurelhttp://en.wikipedia.org/wiki/Nissan_300ZXhttp://en.wikipedia.org/wiki/Nissan_240SXhttp://en.wikipedia.org/wiki/Nissan_Cefiro

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CHAPTER-10

RESULT

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A planetary type of gear box has been designed to get both same side steer andopposite side steer to combine the advantage of both the modes.

el turns 90 the front road wheel turns

and the rear

ns 180 the front wheel turns 28 and the rear wheel

comes back to 0 at this stage true rolling condition is being achieved with a

turning radius of 4.2 meter.

A graph has been plotted by taking Steering wheel angle in X-axis and Frontand Rear road wheel angle in y-axis

The graph shows the variations in steering wheel angle and the correspondingvariations in the front and rear road wheel angles.

It has been found that when the steering whe12 and rear road wheel turns 6.5 in the same direction as that of the front road

wheel thus providing same side steer mode.

When the steering wheel turns 135 the front road wheel turns 19 road wheel turns 12.5 in the direction opposite to the front road wheel thus

providing rear steer mode with a reduced turning radius of 3.6 meter.

When the steering wheel tur

lx

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lxi

CHAPTER-11

CO

f maneuvering the

e these problems, both the modes have been introduced together in a

locomotive and its performance has been simulated and shown.

NCLUSION

There are three modes in 4-wheel steering each of which is individually implemented in

most of the 4 wheel steering cars. Each one has its own disadvantage like use of crab

mode increases the turning radius which is turn decreases the ease o

vehicle at sharp bends, similarly rear steer mode decreases the turning radius to a greater

extent, thus increases the risk of toppling of the vehicle at high speed.

Hence to overcom

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Vehicle Technology Second edition.

f technology, published by

obile Engineering), Madras Institute of Technology, guided by Dr. P.

Mannar Jawahar

e Concept

System

10.

VPD Discussion Forum

12.www.rctek.com Ackerman Steering Principles and control of steering arms.

REFERENCES

1. Dr. N. K. Giri, Automotive Mechanics, Khanna Publishers, 2-B, Nath Market,th

Nai Sarak, New Delhi 111006. (1996) , 7 Edition

2. Heinz Heisler, Advanced3. Design data data book of engineers PSG college o

Kalaikathir Achchagam.

4. Theory of machines, S.Rattan, Khanna publications.5. Thomas. D. Gillespie, Fundamentals of Vehicle Dynamics, Society of

Automotive Engineers, Warrendale. (2000) Online Edition

6.

Hiroshi Ohmura (1990) Rear wheel steering apparatus, Mazda MotorCorporation, U.S patent No. 4,953,648

7. (Autom

Websites:

8. http://www.jeep.com/en/autoshow/concept_vehicles/hurricane/ - The JeepHurrican

9. auto.howstuffworks.com/jeep-hurricane.htm Working of the Hurricane 4WS

www.carbible.com Basics of 4-wheel Steering

11.http://forums.mscsoftware.com/adams/ubbthreads.php - ADAMS / Car Software

http://forums.mscsoftware.com/adams/ubbthreads.phphttp://www.rctek.com/http://www.rctek.com/http://forums.mscsoftware.com/adams/ubbthreads.php