Steering System

1. STEERING SYSTEM

2. STEERING SYSTEM
 Steering is the term applied to the collection of components,
linkages, etc. which will allow a vehicle to follow the desired
direction.
 An automobile is steered with the help of steering gears and
linkages, which transfer the motion of the hand operated
steering wheel to the pivoted front wheel hubs via steering
column.
 The other parts that are used for steering a vehicle are steering
wheel pads, steering shafts, steering boxes, steering arms and
steering stabilizers. These parts are made of durable materials
like stainless steel, iron, aluminum, copper, magnesium,
titanium, platinum, rubber, and plastics.

3. NEEDS OF STEERING SYSTEM
 It should multiply the turning effort applied on the steering
wheel by the driver.
 It should be to a certain extent irreversible. In other words, the
shocks of the road surface encountered by the wheels should
not be transmitted to the driver’s hands.
 The mechanism should have self rightening effect i.e., when the
driver releases the steering wheel after negotiating the turn, the
wheel should try to achieve straight ahead position.

4. Function of Steering System
•Control of front wheel (sometimes
rear wheel) direction.
•Maintain correct amount of effort
needed to turn the wheels.
•Transmit road feel (slight steering
wheel pull caused by the road surface)
to the drivers hand.
•Absorb most of the shock going to the
steering wheel as the tire hits holes
and bumps in the road.
•Allow for suspension action.

5. LAYOUT OF A STEERING SYSTEM
A typical steering system consists of
Steering wheel
Steering shaft
 Steering gear box
 Pitman arm
Drag link
 Steering knuckle arm,
Tie rod
Track rod arm

6. Tire rod
Steering arm
Drag link
Pitman arm
Gearbox

7. Turning the Car (when turning, front wheels don’t point the same direction)
•Inside wheel turns at a smaller radius, hence the inside wheel turns at a
steeper angle then the outside wheel.

8. Linkage Steering System (Worm Gear)

9. Linkage Steering System (Worm Gear) Parts
•Steering Wheel – used by the driver to rotate a
steering shaft that passes through the steering
column.
•Steering Shaft – transfers turning motion from
the steering wheel to the steering gearbox.
•Steering Column – supports the steering column
and steering shaft.

10. STEERING GEARS
 The steering gear is a device for converting the rotary motion
of the steering wheel into straight line motion of the linkage
with a mechanical advantage.
 If the steering wheel is connected directly to the steering
linkage it would require a great effort to move the front
wheels. Therefore, to assist the driver, a reduction system is
used having a steering ratio.
Most useful steering gear system are as follows:
1) Recirculation ball type steering gear.
2) Rack-and-pinion steering.
3) Hydraulic power steering.

11. RECIRCULATING BALL TYPE STEERING GEAR
 It consists of a worm at the end of steering rod. A nut is mounted on the
worm with two sets of balls is the grooves of the worm, in between the nut
and, the worm. The balls reduce the friction during the movement of the nut
on the worm. The nut has a number of teeth on outside, which mesh with
the teeth on a worm wheel sector, on which is further mounted the drop arm.
 When the steering wheel is turned, the balls in the worm roll in the grooves
and cause the nut to travel along the length of the worm. The balls, which
are in 2 sets, are recirculated through the guides. The movement of the nut
causes the wheel sector to turn at an angle and actuate the link rod through
the drop arm, resulting in the desired steering of the wheels. The end play of
the worm can be adjusted by means of the adjuster nut provided.
 To compensate for the wear of the teeth on the nut and the worm, the two
have to be brought nearer bodily. To achieve this, the teeth on the nut are
made tapered in the plane perpendicular to the plane of Figure.

12. RECIRCULATING BALL TYPE STEERING GEAR

13. Linkage Steering System (Worm Gear) Parts
•Steering Gearbox) – changes turning motion
into a straight-line motion to the left or right.
•Steering gear box ratios range from 15:1 to
24:1 (with 15:1, the worm gear turns 15 times
to turn the selector shaft once).
•Steering linkage – connects the steering
gearbox to the steering knuckles and wheels.

14. RACK-AND-PINION STEERING
 Rack-and-pinion steering is quickly becoming the most common type of
steering on cars, small trucks and SUVs.
The rack-and-pinion gear set does two things:
 It converts the rotational motion of the steering wheel into the linear motion
needed to turn the wheels.
 It provides a gear reduction, making it easier to turn the wheels.
 A rack-and-pinion gear set is enclosed in a metal tube, with each end of the
rack protruding from the tube. A rod, called a tie rod, connects to each end
of the rack. The pinion gear is attached to the steering shaft. When you turn
the steering wheel, the gear spins, moving the rack. The tie rod at each end
of the rack connects to the steering arm on the spindle.

15.  Some cars have variable-ratio steering, which uses a rack-and-pinion gear
set that has a different tooth pitch (number of teeth per inch) in the center
than it has on the outside. This makes the car respond quickly when starting
a turn (the rack is near the center), and also reduces effort near the wheel's
turning limits.

16. Basic Rack-and-Pinion Steering

17. Basic Rack-and-Pinion Steering
•Pinion Gear- rotated by the steering wheel and steering shaft; it’s teeth mesh
with the teeth on the rack.
•Rack- long steel bar with teeth along one section; slides sideways as the pinion
gear turns.

18. Basic Rack-and-Pinion Steering
•Gear Housing- holds the pinion
gear and rack.
•Tie-rods- connects the rack with
steering knuckles.

19. Basic Rack-and-Pinion Steering
•Part of rack contains a piston
•Two fluid ports, one on each side.
•The side with high pressure pushes the piston to the
opposite side (turning the wheel).

20. Steering Linkage
Pitman Arm transfers gearbox motion to the steering linkage.
•Pitman arm is splined to the gearbox.

21. Steering Linkage
Center Link (Relay Rod) steel bar connects the right and
left side of the steering linkage.
•Connects to Pitman arm, Tie rod ends, and Idler arm.

22. Steering Linkage
Idler Arm supports the end of the center link on
the passenger side of the vehicle.
•Bolts to the vehicle’s frame.
•If worn, will cause excessive steering play.

23. Steering Linkage
Tie-Rod Assemblies: Two tie-rod assemblies are used
to fasten the center link to steering knuckles.
•Assembly is consist of inner tie-rod end, outer tie-rod end,
and a toe adjustment sleeve.
•Be sure to check the toe setting after replacing the
tie-rod ends.

24. Steering Linkage
Rack-and-pinion outer tie-rod end is similar to
the regular tie-rod end, but the inner tie-rod end
sits inside the rack assembly.

25.  HYDRAULIC POWER STEERING : is a hydraulic system for reducing
the steering effort on vehicles by using hydraulic pressure to assist in
turning the wheels. It is intended to provide for easier driving direction
control of the car while preserving "feedback", stability and unambiguity of
the trajectory specified. The steering booster is arranged so that should the
booster fail, the steering will continue to work (although the wheel will feel
heavier).
The steering booster consists of the following basic elements:
 Steer torque detector
 Controlled pressure distributor case
 Hydraulic booster pump
 Tank with a working liquid
 Connection hoses
The working liquid, also called "hydraulic fluid" or "oil", is the medium by
which pressure is transmitted. Common working liquids are based on
mineral oil. For pressure restriction in the pump there is a restrictive valve,
which is adjusted on different cars in a range from 7 to 13 MPa.
HYDRAULIC POWER STEERING

27. Power Steering normally use an engine driven pump and a hydraulic
system to assist steering action.
Three major types of power steering systems:
•Integral-piston linkage system.
•External power steering system.
•Rack-and-pinion system
•Integral power piston.
•External power piston.
Integral Rack-and-pinion system
is the most common.

28. Power steering pump is driven by the engine produces the hydraulic
pressure for steering system operation.
Four basic pumps:
•Roller pump.
•Vane pump.
•Slipper pump.
•Gear pump.

29. Steering System Diagnosis
Steering Wheel Play is the most common problem.
Should not be able to turn the steering wheel
more than 1 ½’’ (33mm) without causing
movement of the front wheels.
Move the wheel side-to-side,
should have no play.

30. Steering System Diagnosis
Hard Steering (steering wheel requires excessive turning effort)
•Low power steering fluid.
•Pump belt broken or slipping.
Steering System Noise
•Belt squeal is a loud screeching sound produced by a worn belt.
•Power steering pump noise is usually a loud whine that only occurs when
the steering wheel is turned.
•Low fluid level and air in the system.
Check fluid with engine turned off.