BAIC Power Steering System Manual & Service Guide PDF (EN)

POWER STEERING

POWER STEERING 3B1-1 STEERING, SUSPENSION, WHEELS AND TIRES SECTION 3B1 POWER STEERING Contents GENERAL DESCRIPTION .................................3B1-2 Power Steering Unit.........................................3B1-2 Power Steering Pump......................................3B1-3 Tandem Hydraulic Pump.................................3B1-3 Hydraulic pump................................................3B1-3 ON-VEHICLE SERVICE .....................................3B1-5 Power Steering System...................................3B1-5 Power Steering Unit.........................................3B1-7 Power Steering Pump....................................3B1-10 Tandem Hydraulic Pump...............................3B1-12 UNIT REPAIR ...................................................3B1-14 Power Steering Unit.......................................3B1-14 Power Steering Pump (4J Series Engine).....3B1-27 Power Steering Pump (4H Series Engine without Hy- draulic Booster Brake)...................................3B1-29 Tandem Hydraulic Pump...............................3B1-31

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Operation

POWER STEERING 3B1-3 Power Steering Pump N3A0117E Legend A. 4J series engine B. 4H series engine Tandem Hydraulic Pump the P/S. The hydraulic pump is installed directly to the engine and is driven by gears. It smoothly adapts itself to severe conditions of use, including a wide range of ro- tation speeds, changes in the temperature at which it is used, and frequent changes in load pressure, and it is able to fully perform its functions. A tandem hydraulic pump has two independent hydrau- lic pumps inside one casing. Its main parts can be clas- sified into the following three.

hydraulic pump (vane type) flow control valve pressure relief valve The following is a description of the functions and oper- ation of the main parts. Operation Its drive is transmitted by gears from the engine to the drive shaft of the oil pump, and it turns a rotor that is fit- ted into the spline part of the drive shaft. When the rotor rotates, the ten vanes built into the rotor groove fly out by centrifugal force, are pressed against the inside sur- face of the cam ring, and rotate along the inside surface so that the pump operates. Hydraulic pump Functions The heart of the system, namely the part that supplies hydraulic pressure, which operates the hydro boost and

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Operation

3B1-4 POWER STEERING Suction and discharge of the hydraulic oil is done by a pressure plate and side plate attached to both ends of the cartridge. Suction openings and discharge openings are provided in two locations each in symmetrical positions with re- spect to the axis of rotation, and because the load on the bearings due to the discharge pressure is balanced, a tandem oil pump is also called a balanced hydraulic pump. Because it has a double pump effect per rotation, this pump provides large discharge flow in proportion to the space it occupies.

Also, some of the hydraulic oil that is discharged is led to the base of the vanes and ensures the quality of the seal between the vane tips and the cam, and even if the vanes and cam rings become a lit- tle worn, the seal is hardly affected at all (with respect to discharge, oil tightness).

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System Test Procedure

POWER STEERING 3B1-5 ON-VEHICLE SERVICE Power Steering System N3A0118E Legend 1. From oil pump 2. To steering unit Preparation Inspect the fluid reservoir for proper fluid level. Standard Operating Pressure NQR without HBB: 11,278 kPa (115 kg/cm 2 /1,635 psi) Inspect the pump belt for proper tension. System Test Procedure NPR/NPS/NQR, with HBB: 10,787 kPa (110 kg/ cm 2 /1,563 psi) 1. Place a container under the pump to catch the fluid when disconnecting or connecting the hoses. 2. With the engine NOT running, install the power steering fluid pressure gauge unit between the power steering unit and discharge side of oil pump. The gauge must be between the stop valve and oil pump. Gauge kit:

5-8840-0162-1 3. Check the fluid level. Fill the reservoir with Dexron ® -III to “Full” mark. Check the connections at gauge kit for leakage. 4. Fully open the stop valve, and bleed the system. Refer to “Power Steering System Bleeding” of this section. 5. Start the engine and being idled, and raise oil tem- perature to 50 — 60 ° C (122 — 144 ° F). Check the fluid level again. Fill the reservoir with Dexron ® -III to “Full” mark if required. 6. Hold the steering wheel in the forward position. Fully close the stop valve, and record the highest value of fluid pressure. except Above Models: 10,297 kPa (105 kg/cm 2 / 1,493 psi) HBB:

Hydraulic Booster Brake If the pressure recorded is within specified range, the steering system is functioning within its specifi- cations. If the pressure recorded is higher than specified range, oil pump relief valve is defective. If the pressure recorded is lower than specified range, oil pump or relief valve is defective. 7. Fully open the stop valve and keep engine idled. Turn and hold steering wheel to full left lock, and record the highest value of fluid pressure. Turn and hold steering wheel to full right lock, and record the highest value of fluid pressure. Caution: Do not continue this test. It should be done within 5 sec- onds. Standard Operating Pressure Caution:

Do not continue this test. It should be done within 10 seconds, because otherwise oil temperature would rise to excess to cause trouble. NQR without HBB: 11,278 kPa (115 kg/cm 2 /1,635 psi) NPR/NPS/NQR, with HBB: 10,787 kPa (110 kg/ cm 2 /1,563 psi)

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