FABRICATION OF OPTIONALFOUR WHEEL STEERING SYSTEM

SIR C.R REDDY COLLEGE OF ENGINEERING, ELURU

K.S. SARAN KUMAR(315277133004)

M.E (Machine Design)

CONTENTS INTRODUCTION AND SYNOPSIS TYPES OF STEERING

FABRICATION OF FOUR WHEEL STEERING SYSTEM

MECHANISM USED IN FOUR WHEEL STEERING

WORKING OF FOUR WHEEL STEERING MECHANISM

ADVANTAGES

CONCLUSION

AimDevelopment of Four Wheel Steering System

Introduction

4 Wheel Steering System is employed in vehicles to achieve better manoeuvrability at reducing the turning radius of the car and to reduce the driver's steering effort. In most active 4 wheel steering system, the guiding computer or electronic equipment play a major role, in our project we have tried to keep the mechanism only by mechanical aid which can be easy to manufacturing and maintenance.

SYNOPSIS 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.

If a car could automatically compensate for an under steer/over steer problem, the driver would enjoy nearly neutral steering under varying operating conditions.

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 a sedan’s larger wheelbase and track width.

Steering Types The 4WS system performs two distinct operations:

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

• Counter phase steering, whereby the rear wheels are turned in the opposite direction

In-Phase ModeAt High Speeds, turning the rear wheels through

an angle opposite to front wheels might lead to vehicle instability and is thus unsuitable.

Hence the rear wheelsare turned in the same direction of front wheels in four-wheel steering systems.

Counter-Phase ModeAt Slow Speeds rear wheels turn in direction opposite

to that of front wheels.

This mode is used for navigating through hilly areas and in congested city where better cornering is required for U turn and tight streets with low turning circle which can be reduced.

Rear Frame Transformation

The rear frame for the type-1 MARUTHI 800 is altered.

The wheel disc with drum brakes has taken out  Coil spring with gas-filled shock absorbers has to

be retainedAlteration has to be done between the flat plate

clamp and wheeler drum

FabricationThe front axle of TATA ACE is dissembled and

the wheel discs are fitted to MARUTHI 800To the rear axle two inches of seamless rod is

welded on either ends.To this rear wheels are fixed.

Mechanism of four wheel steeringThe steering column with universal joint has to be altered.

Bevel gears are fitted to the steering linkage.

Mechanism of Four wheel steeringThe model consists of front rack and pinion

mechanism assisted by two bevel gears of which one is connected to

a)Telescopic shaftb)one is connected to steering rod in which input is given by the driver .

Mechanism usedo To the telescopic shaft a yoke and teeth is

welded . It is used for engaging and disengaging.o Since it is an optional four wheel steering , two

wheel steering or four wheel steering can be obtained by just adjusting the lever.

Mechanism Used At the rear end, Another Rack and Pinion

mechanism is used to change the direction of the wheels from the feed rod.

MechanismTo the rear end, a rack and pinion is attached .The movement for the pinion is achieved from

the steering wheel. Rack and pinion is supported by the L-shaped

frames and is fixed to rear axle.

WorkingIN-PHASE is achieved when the yoke and teeth is

engaged to Telescopic shaft

In IN-PHASE, angle turned by rear wheels will be similar to that of front wheels because the function of rear steering system is to assist the motion of front wheels and not provide its own direction.

Incase of In phase , the front and rear wheels will turn in 1:1 ratio.

WorkingCounter phase is achieved by paralleling the

wheels and then disengaging the yoke and teeth and then changing the direction of the front wheels.

AdvantagesThe 4WS system is effective in the following situations:

Lane Changes Gentle Curves Junctions Narrow Roads U-Turns

ConclusionThis type of steering is much preferable in heavy

traffics and congested roads.

Parallel parking is the most adoptable mechanism for the Indian roads.

If everything goes well , this type of steering will be implemented in all the future cars to achieve better maneuverability.

Thank You