industrial arts

1. Automotive Steering System
Purposeof SteeringSystem:
 The steering system allows the driver to control the direction of the vehicle travel. This is
made possible by linkage that connects the steering wheel to the steerable wheels and tires.
 The steering system may be either manual or power:
1. When the only energy source for the steering system is the force the driver applies to the
steering wheel, the vehicle has manual steering.
2. Power steering uses a hydraulic pump or electric motor to assist the driver’s effort.
Steering System Components:
1. The steering wheel and steering shaft that transmit the driver’s movement to the steering
gear.
2. The steering gear that increases the mechanical advantage while changing the rotary
motion of the steering wheel to linear motion.
3. The steering linkage that carries the linear motion to the steering arms.
Types of Steering Gears:

2. • Two types of steering gears widely used in automotive vehicles.
• The recirculating ball steering gear
• The rack and pinion steering gear
Recirculating Ball Steering Gear - Trucks and large cars often have a recirculating
ball steering gear. It has sector gear on the inner end of the output shaft. A sector gear is a section
teeth from a gear wheel. The output shaft is called the sector gear mesh with the teeth of ball nut.
Rack And Pinion SteeringSystem - Smaller and down sized vehicles use this steering gear.
It has a pinion gear on the end of the steering shaft meshes with a flat rack of gear teeth. Tie rods
connect the end of the rack to the steering arms. As the steering wheel turns, the pinion gear moves
the rack to the right or left.
SteeringRatio:
• Mechanical advantage is the ratio of the output force to a mechanical device. With the
mechanical advantage, a small input force can produce a large output force. In the
steering system, the driver applies a relatively small force to the steering wheel. For
example a 10 pound force applied to the steering wheel may produce up to 270 pounds
or higher at the wheels. This increase is due to the mechanical advantage or steering
ratio of the steering gear.
Power Steering:
• A vehicle with power steering has an energy source that aids the driver in turning the
wheels for steering. Most automotive power steering systems are hydraulic. A pump
supplies high pressure fluid when the driver turns the steering wheel. This provides
most of the required steering effort.
Power SteeringSystem Components:
Power SteeringPump – The pump usually mounts at the front of the engine and is driven by a
belt from the engine crankshaft pulley. The pump can produce high pressure.
Hoses and Fittings - Most power steering systems have a pressure hose and return hose. The
hoses and fittings provide the fluid path between the power steering pump and the control valve.
They are made to take high pressures, temperature extremes and continual stretching and flexing.
The hoses also help reduce noise from the pump pulsations.
Fluid Cooler - Some vehicles with air conditioning and high under hood temperatures have a
small power steering fluid cooler. It prevents excessive fluid temperature that could damage seals,
vanes and other parts.
Power SteeringFluid - Several different hydraulic fluids are used as power steering fluid. Some
manufacturers specify either type F or dexron II automatic transmission fluid. Others manufacturers

3. use a high temperature and pressure. Only the fluid recommend by the manufacturer should be used
in a power steering system.
Power SteeringPressureSwitch - Some vehicles have a power steering switch in the
pressure line between the pump and the steering gear. The switch signals the engine control module
(ECM) to increase engine idle speed when pump pressure or steering load is high.
Four Wheel Steering:
• PURPOSE OF FOUR WHEEL STEERING
1. A variety of military vehicles have had four wheel steering. When the front wheels
pivot for steering, the rear wheels also pivot and steer the rear end of the vehicle.
This improves handling and allows tighter turns.
2. The system automaticallysteers the rear wheels according to the speed of the vehicle
and the steering angle of the front wheels. For increased maneuverability at low
speeds, the rear wheels may steer in the opposite direction of the front wheels steer
in the same direction as the front wheels. This provides greater stability during
cornering and high speed lane changes.
Mechanical Four Wheel Steering:
• A mechanicalfour wheelsteering system uses a steering shaft to carry the
rotary motion of the steering wheel to the rear steering gear.
• After studying this lesson, you should able to:
•
• Explain the purpose,construction,and operationof automotive steering
system.
• Describe the constructionand operation of manualand power
recirculating steering gears.
• Describe the constructionand operation of manualand powerrack and
pinion steering gears.
• Explain the operation of variable ratio steering,variable powersteering and
four wheelsteering.
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