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12-14
Measure the oil pressure with the gauge
valve fully open. 7.
Pressure at no load
3 to 5 bar
If the pump pressure is in specified range,
the pump is normal. If not, replace the
power steering pump 8.
Turn the steering wheel righ or left until it
stops with the engine idling ans valve fully
open. 9.
Oil pressure78 to 83 bar
To prevent the internal damage, do not
close the gauge valve for over 10
seconds.
Keep the oil temperature at proper range. -
-
Page 741 of 828

12-154610-01
1. SYSTEM DESCRIPTION
The power steering has been designed to make the wheel move more easily than in a manual
steering system. The hydraulic power assists the process utilizing hydraulic fluid. The fluid
increases pressure in the power steering pump and aids the movement of the steering
mechanism. The power steering system consists of pump, oil reservoir, rack and gear box. The
power steering pump is a vane type and delivers hydraulic pressure to operate the power steering
system. The pressure relief valve in the pump controls the discharging pressure. The rotary valve
in the rack and the pinion gear directs the oil from the power steering pump to one side of the
rack piston. The integrated rack piston converts the hydraulic pressure to linear movement. The
operating force of the rack moves the wheels through the tie rod, the tie rod end and the steering
knuckle. Even though the hydraulic pressure cannot be generated, a driver can steer the vehicle
without power assist but it needs very high steering force. In this case, the operating force of the
steering wheel is conveyed to the pinion, and the movement of the pinion moves the rack through
the pinion gear combined to the rack gear.
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12-16
2. SYSTEM LAYOUT
The steering pump is driven by the engine power through a belt. This pump circulates the power
steering oil from the reservoir -> steering pump -> oil supply pipe -> steering gear box -> oil
return pipe -> reservoir to perform steering operations
Steering pump Steering return pipe Steering cylinder
Return line
High pressure line
Return hose & tube
Steering pump &
reservoir
High pressure hose
Linkage gear box Steering wheel
Lower shaft Column & shaft
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