SUPPLEMENTAL STEERING SYSTEM
As soon as steering wheel (7) is turned, the relief valve
(4) closes and supplemental steering pump (8) again
sends oil to metering valve (9).
Dump (Unloading) Valve
RELIEF AND BY-PASS VALVES
2. Oil cooler by-pass valve. 4. Relief valve. 13. Check
16. Dump (unloading) valve.
valve. 17. Line to steering metering valve. 18. Line to
hydraulic tank. 19. Line from cooler pump and tank. 20.
Line from supplemental pump. 21. Line from cooler. 22.
Line to cooler.
DUMP VALVE SWITCH
During cold weather engine starting, dump
(unloading) valve (16) is normally used to divert primary
system hydraulic oil back to hydraulic tank (3). This
removes the power loss created by the implement pump
on the starter while cranking the engine. When this valve
(16) is pushed down, it closes a normally open switch
HYDRAULIC OIL COOLER
(15) which keeps the supplemental steering motor/ pump
1. Hydraulic oil cooler.
from operating. (For more information on the hydraulic
If the vehicle direction is not being changed, steering
and steering systems, see the following Systems
metering valve (9) will block oil flow to the head and rod
Operation, Testing and Adjusting forms.
ends of the steering cylinders. When the pressure of the
blocked oil increases to approximately 12 600 kPa (1825
psi), a relief valve (4) will open. Oil is then sent through
the oil cooler by-pass valve (2). It combines with the oil
cooler return oil and is sent to hydraulic tank (3). From
hydraulic tank (3), the oil goes to oil cooler pump (5),
then to oil cooler (I) and/or through relief valve (2)
(depending on the temperature of the oil) back to
hydraulic tank (3).