ROAD AND WORKSHOP by HANDYMAN
Page 35
If you've noticed an error in this article please click here to report it so we can fix it.
About Power Steering
DRE and more use is being made of hydraulic power for steering assise—and as with all such aids to efiicy and comfort there can be a :wash of silly mechanical problems )wing along some way behind.
rst of all, there is nothing rm,sterious A. the power-steering mechanism. It features quite similar to hydraulic .ing mechanism and calls for the e. care and cleanliness during repair, the emphasis very much on the Jval of all grit, mud, and so on from area housing the equipment.
ery briefly, the system consists of a .aulic pump (usually of the hi-rotor ) with a combined flow control and f valve, this permitting a steady piesat all revs. The pump is supplied a hydraulic oil reservoir and the
power produced is delivered to a doubleacting ram which, contrary to expectations, moves the cylinder and not the ram.
Obviously, the steering wheel is coupled to a control that will apply power to either side of the ram, and it is desirable that some resistance is felt when moving the steering wheel. This light effort enables the driver to move the road wheels in determined amounts; thus, on setting the steering wheel for a curve, a slight easing back from this resistance will halt the steering movement, and hold it there until the opposite wheel is put on. Should the power fail for any reason, the vehicle is then steered manually, as by loading the control in either threedon, the h■draulic oil is free to move.
Use only hydraulic oil specified for power steering and change the oil annually. On filling up after draining it is necessary to prime the system, and the normal procedure is to jack up the front wheels, fill the reservoir to within 2in. of the reservoir neck, and run the engine just above tick-over. All that is then needed is to swing the steering from lock to lock until the oil in the reservoir is clear of turbulence.
Do not bold the steering hard in either lock, otherwise strain may be placed on the mechanism because of pressure build up. Similarly, at no time should the steering be held hard in either lock on the road, or the wheels forced against the kerb. unless the steering wheel can be eased back and the operatine port closed. The fight resistance mentioned on moving the wheel is the effort needed to open the port against spring tension—just enough to indicate to the driver whether the port is open or shut and to permit graduated control.
Referring to the faults one max expect to meet, the main one can be heavy steering. Long life can be expected from the pump,but if it is suspect the answer is to insert a pressure gauge in between pump and ram and move the steering wheel each way enough to pressurize the system and take a reading. A pump in good order will show between 600 and 700 lb. p.s,i. If a low reading is being obtained, blank off between gauge and ram: if the pressure is then correct, the fault is in the ram section.
Where the pump is positively faulted. it is still wise to first of all strip and examine the relief and control valves before condemning the pump. However, the equipment is very reliable, and any undue stiffness is far more likely to be zi shortage of lubrication at swivel assemblies and ball joints—where all too often the easy assisted steering has deceived the driver into thinking that all is well— until complete seizure takes place.
To avoid this rather odd situation, it is wise to lubricate at four-weekly intervals when the vehicle is in regular use.