Four-wheel steering (4WS) allows rear wheels to turn for improved maneuverability, reducing the turning radius by 20% and enhancing stability at high speeds. Different types of 4WS include mechanical, hydraulic, and electro/hydraulic systems, each offering distinct advantages in various driving conditions. Modern vehicles utilizing active 4WS technology include models from Acura, BMW, and Toyota, providing greater steering efficiency and stability.

1. SUBMITTED BY: -
ARPIT GUPTA
(1409140037)

2. FOUR WHEEL STEERING
&
FOUR WHEEL DRIVE

3. INTRODUCTION
 Four wheel steering is a system employed by vehicles
that allows the rear wheels to turn for maneuvering,
rather than just follow the front wheels.
 It reduces the turning radius by 20% as well as the space
required for turning. It also enables to change road lane
while driving even at high speed.
 At lower speeds, turning the rear wheels in the opposite
direction to the front wheels results in a smaller turning
radius and faster cornering responses. At high speeds,
turning all four wheels in concert improves high-speed
stability.

4. 2 WHEEL STEERING

5. 4 WHEEL STEERING (4WS)

7. CONTROLLING OF REAR WHEELS
 At slow speeds, the rear
wheels are turned in the
opposite direction of the front
wheels. This can lessen the
turning radius by
approximately 20%.
LOW SPEEDS(0-40 km/h)

8. CONTROLLING OF REAR WHEELS
At faster speeds on the
highway, the rear wheels
are turned in the same
direction as the front
wheels. This improves
lane changing
maneuverability and is
particularly beneficial
for vehicles towing a
trailer. HIGHER SPEEDS
(GREATER THAN 80 km/h)

9. DIFFERENT SPEED WHEELS CONFIGURATION
0-40km/h 40-80km/h >80km/h

11. TYPES OF 4WS
MECHANICAL 4WS
HYDRAULIC 4WS
ELECTRO/HYDRAULIC 4WS

12. MECHANICAL 4WS
• The mechanical 4WS
uses two separate
steering gears to
control the front and
rear wheels.

13. HYDRAULIC 4WS
 The hydraulic 4WS
uses a two-way
hydraulic cylinder to
turn both the
wheels in the same
direction.

14. ELECTROHYDRAULIC 4WS
 The electro/hydraulic
4WS combine
computer electronic
controls with
hydraulics to make the
system sensitive to
both steering angle
and road speeds

15. ZERO TURNING RADIUS
 Zero turning radius
 Require no space for
turning
 On-spot Turning

17. MODERN CARS WITH ACTIVE FOUR WHEEL
STEERING: -
•Acura RLX (P-AWS)
•BMW 850CSi (only Euro spec models)
•BMW 7-Series (2009 onward, part of sport package)
•BMW 5-series (2011 onwards, Integral Active Steering
option)
•Toyota Camry / Vista JDM 1988–1999 (Optional)
•Toyota Carina ED / Toyota Corona EXiV (world's first
dual-mode switchable 2WS to 4WS)
•Toyota Celica (option on 5th and 6th generation, 1990–
1993 ST183 and 1994–1997 ST203) (Dual-mode, high and
low speed)
•Toyota Soarer (UZZ32)

18. CONCLUSION
 Requires less steering input for corrections.
 Entire vehicle moves in one direction.
 Greater Stability in maneuvers.
 Turn in crab like manner rather than curve.
 Reduces effecting turning radius.
 4WS is complex and expensive.

19. REFERENCES
 Suspension and Steering Systems, Design of modern
terrain vehicles
By- Shpetim lajqi
Stanislav Pehan
 Automotive Mechanics
BY- Crouse and Anglin