Power steering pump location/task/design/function - GF46.30-P-2100A
MODEL 129 except CODE (216c) adaptive damping system (ADS II) with electronic level control
MODEL 140, 210 except CODE (217a) level control on rear axle with ADS
MODEL 202, 208 except CODE (480) level control on rear axle
MODEL 170
Scheme 168
Location On front side of engine Task Supplies the steering gear with pressure oil irrespective of engine speed Design Principle of the vane-type pump Power steering pump function GF46.30-P-2100-01A
Steering tandem pump/suspension system ADS location/task/design/function - GF46.30-P-2200A
MODEL 129 as of 1.9.95 with CODE (216c) adaptive damping system (ADS II) with electronic level control
MODEL 140, 210 with CODE (217a) level control on rear axle with ADS
MODEL 202, 208 with CODE (480) level control on rear axle
Scheme 169
Location On front side of engine Task Produce different oil pressures and volume flows irrespective of engine speed, for: the steering system for vehicles with level control or ADS Design Two independent oil pumps are driven by one drive shaft for the smallest installation conditions Power steering pump section (30) Radial-piston pump section (49) They are protected from one another by a shear bridge (shear pin or sleeve) Power steering pump function GF46.30-P-2100-01A Radial-piston pump function With level control, ADS GF46.30-P-2200-01A
Scheme 170
Oil delivery
The spring-loaded pistons (49c) undergo a lift motion due to the rotation of the cam (49a) on the drive shaft (30r). When the piston is travelling towards bottom dead center a vacuum occurs due to the increase in space in the piston chamber. This causes the oil to flow in through the cross bores in the piston which connects the cylinder chamber with the inlet side shortly before bottom dead center.
On the working stroke the filled cylinder chamber is sealed due to overlap of the bores shortly after bottom dead center. The oil is pushed out towards the pressure side via the spring-loaded outlet valves.
The constant oil flow at variable speed is achieved by the suction control. As the speed increases the opening time of the cross bores in the piston reduces so that the vacuum is not longer sufficient to completely fill the cylinder chamber in the short time interval. The reducing partial filling causes the volume flow and the required power to remain almost constant as speed increases.
Pressure limitation
The pressure of the radial-piston pump is limited by pressure relief valves in the control units of the connected systems.
Scheme 171
An output and pressure test must therefore not be carried out directly at the radial-piston pump section of the tandem pump.
SPS solenoid valve, location/task/design/function - GF46.50-P-5000A
MODEL 140, 210 with CODE (213a) Speed-sensitive power steering
Model 140
Scheme 172
Model 210
Scheme 173
| SPS solenoid valve, location | Model 140: On steering gear housing. Model 210: On rotary valve housing of steering gear | ||
|---|---|---|---|
| SPS solenoid valve, task | Regulates the steering wheel torque in the speed range of: 0-80 km/h on model 140 0-100 km/h on model 210. | ||
| SPS solenoid valve, design | Current-controlled proportional valve. | ||
| SPS solenoid valve, function | GF46.50-P-5000-01A |
Scheme 174
Scheme 175
Scheme 176
The P-valve is actuated in cycles with approx. 6V by the ETS, ASR or ESP control module (N47-1, N47-2, N47-5). As vehicle speed increases the current flow reduces and the P-valve opens the control restrictor continuously in accordance with a characteristic (K) defined in the control module. Consequently the oil flow is controlled and also the steering wheel torque.
If the valve is fully energized, (v= 0 km/h), the control restrictor is closed.
Consequently there is no oil flow and the lowest steering wheel torque is adjusted (parking situation).