7.2 Hydraulic Power Steering System

7.2.1 Specifications
7.2.1.1 Fastener Tightening Specifications

Applications

Model

Specifications

Metric (Nm)

US English (lb-ft)

Intermediate Shaft Assembly
Bolt

M8 × 30

25-28

18.5-20.7

Power Steering Assembly Tie
Rod Right Assembly Bolt

M12 × 58

53-63

39.2-46.6

Power Steering Assembly Tie
Rod Left Assembly Bolt

M12 × 33

53-58

39.2-43.0

Steering Tie Rod End Lock Nut

M12

69-79

50.9-58.3

Steering Tie Rod Ball Joint
Locking Nut

M12

33-43

24.4-31.9

Power Steering Outlet Pipe to
Subframe and Crossmember
Retaining Bolts

M6 × 14

10-12

7.4-8.9

Power Steering Pipe to
Crossmember Retaining Bolts

M6 × 30

10-12

7.4-8.9

Power Steering High Pressure
Pipe to Power Steering Pump
Retaining Bolts

M6 × 20

10-12

7.4-8.9

Power Steering Assembly
Bolts

M10 × 122

50-55

37.0-40.7

Power Steering Pump
Assembly Nuts

M10

50-55

37.0-40.7

Inlet Pipe Connecting Nut (to
Power Steering Pump
Assembly)

M16

38-44

28.1-32.6

Inlet Pipe Connecting Nut (to
Steering)

M16

41-49

30.2-36.1

Outlet Pipe Connecting Nut (to
Steering)

M17

41-49

30.2-36.1

Power Steering Pump
Assembly Pulley Assembly
Retaining Nut

M12

72-92

53.1-67.7

7.2.1.2 General Specifications

Steering System

Hydraulic Power Steering System

7-3

Applications

Specifications

Metric

US English

System Pressure Difference (Straight
Direction)

490 kPa or less

71 psi or less

Idle System Pressure (Full Turn Position)

Greater Than or Equal To 8,000 kPa

Greater Than or Equal To 928 psi

Approximate Fluid Capacity (Entire Power
Steering System)

0.9 L

4.58 pt

Applications

Type

Specifications

Fluid

Power Steering Fluid

DEXRON III

7-4

Hydraulic Power Steering System

Steering System

7.2.2 Description and Operation
7.2.2.1 Description and Operation

Warning!

Refer to "Steering Wheel in the Full Turn Position Notice"
in "Warnings and Notices".

Warning!

Before  disconnecting  the  mechanical  steering  column
assembly  with  the  power  steering  gear,  the  wheels
should  be  kept  in  the  straight  front  positions  and  the
mechanical  steering  column  assembly  must  be  in  the
LOCK (lock) position.

After disconnecting the above components, do not move
front tires and wheels, otherwise it will cause some parts
are  not  positioned  correctly  during  the  installation
process and lead to mechanical steering column airbag
assembly  spiral  off  center  position,  and  damage  the
airbag spiral coil.

Power Steering Pump Assembly Instructions

Power steering pump assembly provides hydraulic pressure for
the whole steering system, and it is a vane-type pump.

Power  steering  pump  assembly  consists  the  following
components:

–

Pump Housing

–

Impeller Pump Rotor

–

Pump Impeller Blades

–

Impeller Pump Front Side Panel

–

Impeller Shaft

–

Impeller Shaft Bearings

–

Fluid Pressure Switch Assembly

–

Flow Control Valve Assembly

–

Fluid Pipe

–

Fluid Seals and O-ring

Following components are installed in the pump housing side
hole :

–

Fluid Pipe

–

Fluid Pressure Switch Assembly

–

Flow Control Valve Assembly

Flow  control  valve  assembly  consists  of  the  following
components:

–

Filling Joints

–

Flow Control Valve

–

Flow Control Valve Compression Spring

Flow  control  valve  hole  and  the  outlet  connector  is  an
integrated part. Flow control valve's primary role is to prevent
high steering pump pressure.

Power Steering Gear Assembly Instructions

Power  steering  gear  assembly  uses  the  rack  and  pinion
hydraulic power steering.

When turning the steering wheel, steering wheel movement is
passed  to  the  steering  control  valve  shaft,  steering  control
valve axle pinion and rack mesh, so the rack moves left and
right.

Power  steering  gear  assembly  has  a  steering  control  valve.
Steering control valve assembly introduces high pressure fluid
from the power steering pump to both sides of the rack piston
to move the rack piston. Integral power cylinder piston and rack
connection can convert rack piston hydraulic pressure to linear
force and move the rack. linear force is transmitted to the inner
and  outer  steering  tie  rod,  and  then  passed  to  the  steering
knuckle, which turns the wheel.

If  the  auxiliary  hydraulic  fails,  manually  control  steering  will
require much greater effort.

Power Steering Fluid Description

Warning!

After  adding  or  completely  replace  the  power  steering
fluid,  make  sure  use  the  correct  power  steering  fluid.
using  the  incorrect  power  steering  fluid  will  cause
damage to hoses and seals, and oil leaks. Refer to this
chapter for recommended power steering fluid.

Power steering fluid reservoir and pipe assembly is made from
plastic, and the fluid level within the reservoir can be seen from
outside. There are fluid level mark on the fluid reservoir side.
The marks are used to indicate the power steering fluid level.

Make sure use proper power steering fluid. Refer to .

–

After preheating the power steering fluid, its temperature is
about 75 °C -80 °C (167-176 ºF). Power steering fluid level
should be between "HOT-MAX" and "HOT-MIN".

–

After  cooling  the  power  steering  fluid,  its  temperature  is
about 20 °C -25 °C (68-77 ºF). Power steering fluid level
should be between "COLD-MAX" and "COLD-MIN".

Steering System

Hydraulic Power Steering System

7-5

7.2.3 System Working Principle
7.2.3.1  Hydraulic  Power  Rack  and  Pinion
Steering Working Principle

Intermediate Shaft

Pinion

Steering Tie Rod

Rack

Steering 

Tie Rod

Pinion Rotation

Rack Movement

FE07-1001b

When there is no hydraulic pressure assistance, the steering
working principle is as shown in the graphic. The torque applied
on the steering wheel, passes through the intermediate shaft
to the steering drive gear (steering control valve gear), because
the drive gear tooth (steering control valve gear tooth) and the
rack teeth are in meshing state, it will convert the torque to rack
linear force, move the rack. Linear force passes through the
inner and outer steering tie rod, to the steering knuckle, which
steers the wheel.

PAS 

Pump

Power Assisted Steering 

(PAS) Fluid Reservoir

Return Hose

Pressure 

Hose

Valve 

Assembly

Steering System Assembly

FE07-1002b

Rack and pinion with hydraulic pressure assistance steering
system is as shown in the graphic. The mechanical rack and
pinion steering, steering cylinder and steering control valve are
designed to be integrated to form the integral power steering
system. Power cylinder piston and the rack is made as a whole,
the power cylinder is divided into about two chambers.

Steering Control 

Valve Gear

Shaft

Valve Core

FE07-1003b

When  the  steering  wheel  is  not  turned,  the  steering  control
valve is in the middle position, fluid the master cylinder flows
through the steering control valve inlet into the valve cavity. As
the  steering  control  valve  is  in  the  middle  position,  so  that
power  cylinder  two  chamber  are  connected.  The  fluid  flows
from the steering control valve outlet to to the fluid reservoir, so
the hydraulic power does not work.

7-6

Hydraulic Power Steering System

Steering System