STEERING SYSTEM MAINTENANCE
Section I DESCRIPTION AND DATA
This chapter covers maintenance procedures for the steering system components, as well as principles of operation.
PRINCIPLES OF OPERATION
a. System Components The steering system components include steering valve (1), steer select valve (2) and four
steering hydraulic cylinders (3) Additional, related components include the large (3 94 cu in ) section of dual gear pump
(4) and priority valve (5). Making up the emergency steering system are an electric motor driven pump (6) and
pressure switch (7). Pressure switch (7) senses hydraulic pressure in the main steering circuit and closes to turn on the
emergency steering pump motor and a warning light in the cab when main system pressure drops to below
approximately 75 psi
b. Normal System Operation Hydraulic flow from the large section of dual gear pump (4) is directed to the inlet port of
priority valve (5) The function of priority valve (5) is to ensure that sufficient oil flow goes to steering valve (1) to permit
normal steering in the event that any attachment functions are being operated at the same time that steering is
occurring. The priority valve (5) will deprive the attachment functions of oil flow in order to maintain adequate flow for
steering. Component overpressure protection is provided by relief valve (8) which is built into priority valve (5).
As long as the steering wheel is not being turned, sleeve and spool assembly (9) remains centered and gerotor (10)
remains stationary. Priority valve (5) will then direct pump flow to the main control valve The pressure resulting from the
blocking condition of the centered steering valve sleeve and spool assembly (9) keeps priority valve (5) shifted to the
right (as shown) to permit flow to the main valve. The steering cylinders (3) are held stationary by trapped oil in the lines.