Contents: Power steering system ⇩ Power steering gear housing…⇩ Power steering system ⇩ Operation of the spool valve ⇩ Operation of the pump and control…⇩
Power steering system
| Pos. | Spare part number | Name |
| 1. | - | Hydraulic pump |
| 2. | - | Liquid tank |
| 3. | - | Steering gear housing |
| 4. | - | Upper section of the column |
| 5. | - | Cardan joints |
| 6. | - | Lower shaft |
| 7. | - | Crimp connection |
| 8. | - | Longitudinal steering rod |
Power steering gear housing components
| Pos. | Spare part number | Name |
| 1. | - | Crankcase with sector shaft bearings |
| 2. | - | Cover with bearing |
| 3. | - | Sector shaft |
| 4. | - | Hydraulic piston/rack |
| 5. | - | Worm/valve assembly with torsion bar |
| 6. | - | Worm/Valve Centering Shims |
| 7. | - | Ball bearing |
| 8. | - | Teflon seals for valve core |
| 9. | - | Bearing adjuster, lock nut and seal |
| 10. | - | Worm shaft seal, retaining ring and dirt trap |
| 11. | - | Teflon and rubber piston seal |
| 12. | - | End Cap Seal and Retaining Ring |
| 13. | - | Adjusting elements for piston/rack |
| 14. | - | Hydraulic pipeline |
| 15. | - | Air bleed nipple |
| 16. | - | Sector shaft adjustment lock nut with seal |
| 17. | - | Cover bolts |
| 18. | - | Lid seal |
| 19. | - | Seal, washer and backup seal |
| 20. | - | Retaining ring and dust cover |
The lower shaft of the steering system has a crimped connection. It is designed to be crushed in a collision. The misalignment of the upper section of the steering column and the steering gear housing and the presence of two universal joints are also designed to prevent the column from moving toward the driver in a frontal collision.
The steering gear housing is located behind the first chassis cross member and is connected to the steering knuckles of the wheels by means of a longitudinal steering rod and a transverse steering rod. A hydraulic shock absorber absorbs steering shocks caused by wheel deflection when driving on uneven road surfaces.
Power steering system
The power steering system includes a hydraulic pump that is belt driven from the engine and receives power steering fluid from a reservoir that also acts as a cooler.
The steering gear housing contains a self-centering spool valve, which is part of the worm/valve and hydraulic piston/rack, to facilitate mechanical operation. The spool valve, which is activated by moving the steering wheel, directs fluid pressure to the corresponding side of the hydraulic piston/rack to provide assistance.
Operation of the spool valve
Spool valve in neutral position
The spool valve assembly includes a worm (1), a spool (2), an input shaft (4) and a torsion bar (5).
The spool is held inside the worm by an adjusting screw (3). On its inner wall are valve ports. The input shaft is connected to the steering wheel by means of the steering shaft and steering column and has valve ports on the outside diameter that are aligned with the ports in the spool.
When there is no demand for power, a torsion bar, which is attached to the worm and input shaft by means of pins (6) located at each end, holds the valve ports in a neutral position.
When there is no demand for boost, the torsion bar holds the input shaft and spool valve ports in a neutral position relative to each other, allowing equal pressure to be supplied from the pump (A) to both sides of the piston/rack (9). Any excess fluid from the pump returns to the reservoir through (B).
The spool valve is offset
When the steering wheel and input shaft are turned, the resistance to steering action transmitted to the worm causes the torsion bar to twist and the valve ports to shift to turn right or left. The shifting of the valve ports directs all fluid pressure to only one side of the piston and allows fluid B to move to the other side.
When maximum boost is requested, all excess fluid leaving the pump, due to the high pump speed, will circulate through the control valve located in the pump, causing a rapid rise in fluid and pump temperature.
CAUTION: To avoid elevated fluid temperatures which could damage the oil seals, the steering should not be held in the stop for more than 30 seconds within one minute.
Only after the steering wheel is released and assistance is requested will the torsion bar return the valve to the neutral position, allowing the fluid to circulate through the reservoir where it is cooled.
In the unlikely event of a mechanical failure of the torsion bar, the large spline connection (7) between the input shaft and the worm ensures that the steering function can be maintained to regain control of the vehicle.
Operation of the pump and control valve
No request for reinforcement
Details can be found on the website lrman.ru
| Pos. | Spare part number | Name |
| 1. | - | Tank |
| 2. | - | Pump |
| 3. | - | Pressure control ball valve and spring |
| 4. | - | Flow control valve and spring |
| 4. | - | A plug that can be installed by pressing the fit (ball bearing) |
| 5. | - | Limiter |
The pump, which is belt driven by the engine, is an eccentric roller pump. It also contains a pressure regulator and a flow control valve. The pressure is controlled by a spring-loaded ball valve (3), which is located inside the piston of the flow control valve (4).
When there is no demand for power, the spool valve in the steering gear housing acts as a relief valve, allowing fluid (A) to flow freely through the steering gear housing and back to the reservoir and pump inlet (B).
When the steering wheel is turned, the spool valve effectively stops all fluid flow through the steering gear housing, thus causing an increase in pressure (A). This increase in pressure is sensed in the flow control valve spring chamber where, at a given pressure, the relief valve (3) opens, allowing the pressure to be released. The drop in pressure in the spring chamber allows the flow control valve to move to the right, which in turn allows fluid exiting the pump (A) to flow directly into the pump inlet (B).
Request for reinforcement
Once the steering wheel is released after a turn has been made, the system returns to the state shown in J6292 and the wheels are returned to the straight ahead position by the geometry of the steering design.
In the event of any hydraulic failure, steering control will be maintained by mechanical elements in the steering gear housing, but the effort on the steering wheel will be very high.
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