Rack and pinion steering is quickly becoming the most common type of
steering on cars, small trucks and SUVs. It is actually a pretty simple
mechanism. 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
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.
On most cars, it takes three to four complete revolutions of the steering wheel to make the wheels turn from lock to lock from far left to far right.
Part of the rack contains a cylinder with a piston in the middle. The piston is connected to the rack. There are two fluid ports, one on either side of the piston. Supplying higher-pressure fluid to one side of the piston forces the piston to move, which in turn moves the rack, providing the power assist.
POWER STEERING PUMP
Describe a Trunion and where it is found?
In older cars, the trunnion
is part of the suspension and either allows free movement of the rear wheel hub
in relation to the chassis or
allows the front wheel hub to rotate with the steering. On many cars the
trunnion is machined from a brass or bronze casting and is prone to failure if
not greased properly, American motors used moulded rubber "Cleve bloc"
bushings on the upper trunnion to seal out dirt and retain silicone lubricant
for the life of the car
One of the most difficult things to design and build on a car is the steering mechanism. The steering mechanism is used to turn the car around the bends in the track. There are many different ways in which this can be done. In this topic I will explain two mechanisms; firstly I will explain a mechanism that is simplest, it's flaws and move to second mechanism, that is little bit complicated.
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The system works in nearly identical fashion to rack-and-pinion. Power steering fluid passes through the steering mechanism, which aids the driver in turning either left or right.Old fluid should never be re-used, and should be disposed of properly. Although power steering, brake, and transmission fluid are all hydraulic fluids, they are not interchangeable.
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