Page 267 of 484

SR-11Steering SystemPower Steering (General Introduction)
power steering oil pump
power steering gear steering drive shaft
oil cup
Power steering
Introduction
Principal of Power Steering
The power steering is a kind of hydraulic device that use
the engine power to steer. The engine drive the power
steering oil pump to generate the hydraulic pressure, which
actuates the piston in steering gear, so that the worm shaft
can provide to the piston with a supplementary force, which
has relation with the pressure actuated on the piston.
Therefore, pressure increase is required if larger steering
force is needed, and the pressure variation is accomplished
through the control valve.
Intermediate position (forward straightly)
The liquid from the power steering oil pump is sent to
the control valve, which, if locates at the intermediate, will
allow the liquid to pass and enter into the drain outlet, finally
return the pump. At this time, it is difficult to increase the
pressure; meanwhile, due to the equal pressures at the both
sides of the power piston, it cannot move toward either side.
Steering time
When the steering drive shaft move toward either side,
the control valve will move together with it, in case one oil
passage is shut off, meanwhile open the other larger, the
liquid flow variation will increase the pressure, as result, the
unequal pressure at both sides of piston will make the piston
move toward the side of smaller pressure, therefore, the
liquid is pressed in the pump through the control valve.
pump control valve
drain outlet
power cylinde
power piston
segmental gear shaft worm shaftsteering gear
Pump
Page 269 of 484

SR-13Steering SystemPower Steering (On-Vehicle Inspection)
tensioning wheelpower steering oil
pump
crankshaftOn-vehicle inspection
Inspection on tension of driver conveyor
Measure the tension of drive conveyor.
Drive conveyor tension: under the condition of 98 N.
New conveyor: (5-7)mm
Old conveyor:(7-9)mm
Remark:
ìnew conveyorî means the conveyor that is used on the
machine less than five minutes;
ìold conveyorî means the conveyor that is used on machine
more than five minutes
Check for height of liquid level
1. Keep the body in horizontal status
2. Increase the liquid temperature
When the engine runs idly by 1000 r/m or less, rotate the
steering wheel several times from the locking position to the
reverse locking position to increase the liquid temperature.
3. Check to see whether there is foam or emulsification;
Remark: the foam or emulsification shows there is air in the
system or the liquid level is over-low.
4. Check the liquid level height in oil cup;
Check the liquid level height and, if needed, add the oil.
Page 270 of 484

SR-14Steering SystemPower Steering (On-Vehicle Inspection)
Change of power steering liquid
1. Tear down the oil-returning hose from the oil cup to
drain the liquid into the container;
2. Run the engine in the idle status, and rotate the
steering wheel toward the max rotating angle for
several times in right or left direction while draining the
liquid, until the oil in steering liquid is drained up.
3. Turn off the engine.
4. Connect the oil-returning pipe and inject the new
power steering liquid in the liquid tank;
Hydraulic oil type: No.8 Liquid drive oil (Q/SH003.01.012-88)
5. Start the engine, and make it running in the idle status.
Rotate the steering wheel to the max rotating angle repeatedly
several times, meanwhile, supplement new power steering
liquid in the liquid tank until there is no foam or turbidities in
the liquid tank, and the oil indicating lamp reaches the marked
range when the engine is turned off.
6. Tighten the liquid tank cover
7. Exhaust the air in the power steering system;
Ai-r bleeding in power steering system
1. Check the liquid level height in the liquid tank
Check the liquid level and, if needed, supplement the liquid.
2. Start the engine in the idle status and rotate the
steering wheel repeatedly to the max rotating angle
several times.
3. Turn off the engine and connect the ethane pipe and
bleeding plug.
4. Start the engine and rotate the steering wheel
repeatedly to the max rotating angle several times.
5. Locate the steering wheel at the intermediate position.
Page 271 of 484
SR-15Steering SystemPower Steering (On-Vehicle Inspection)
6. Exhaust the air in steering system:
(a) Loosen the bleeding plug;
(b) Screw up the bleeding plug when there is no air bubble
exhausted from the pipeline.
Notice: take care not let the ethane pipe slide from the
bleeding plug, because the liquid is high in temperature
and pressure.
7. Check to see whether there is air bubble or turbidities
in the oil cup, and ensure the liquid level will not
exceed the max value when the engine stops,
Measure the liquid height under the condition of engine running,
then turn off the engine and measure the liquid height again.
In case any problem is found, repeat the approaches of (5) and
(6) in Power Steering Liquid Change. If the problem still
exists, repair the power steering oil pump.
RPM RPM
Page 272 of 484
SR-16Steering SystemPower Steering (Oil Pump of Power Steering)
Oil Pump of Power Steering
Dismantle and Mount of Oil Pump of Power Steering
Gasoline Engine Series
Diesel Engine Series
power steering oil pump
power steering oil pump bracket
belt pulley
driving beltLP oil pipeHP oil pipe
power steering oil pump bracketHP oil pipe
LP oil pipebelt pulley oil cup
power steering oil pump
Page 310 of 484