TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
0003 00
STEERING SYSTEM
0003 00
1.
General.
a.
Hydraulic steering system changes machine's angle of articulation. Main steering system components are piston
pump, metering pump, and steering cylinders. A secondary steering system is an option for this machine. If
machine is equipped with secondary steering system, secondary steering pump, electric motor for secondary steer-
ing pump, and relief valve for secondary steering system are part of steering system.
b.
Piston pump is a pressure-compensated, variable displacement axial piston pump which provides flow to steering
cylinders. Metering pump sends a signal to piston pump indicating amount of flow needed.
c.
Piston pump is located on left side of machine under operator's platform. Piston pump and vane pump (implement)
are mounted to transmission. Piston pump is driven by vane pump. Piston pump and vane pump have separate
hydraulic lines. Access to piston pump is gained by removing side panels on machine. Piston and vane pumps are
mounted to top of transmission housing. Transmission pump drives piston and vane pumps. Manifold is mounted
on top of transmission. Access is gained by articulating machine, or removing side panels.
d.
Metering pump controls oil flow from piston pump to steering cylinders. Metering pump is located under opera-
tor's platform above articulation pin. Access to metering pump is underneath operator platform.
e.
Metering pump contains a control valve section and a metering section. Metering pump contains several valves.
Control valve section of metering pump connects to steering wheel through a mechanical linkage.
f.
Steering cylinders change fluid energy from piston pump into mechanical energy. Mechanical energy changes
machine's angle of articulation. Steering cylinders are located on each side of machine near articulation hitch.
Access to steering cylinders is gained from sides of machine.
g.
Secondary steering pump is a gear pump. Secondary steering pump and electric motor for secondary steering pump
are located under engine in front of fuel tank. Access to secondary steering pump is underneath machine. Second-
ary steering pump and motor and secondary steering relief valve are beneath hydraulic tank. Secondary steering
pressure switch will detect a decrease in steering system pressure. Pressure switch will then send a signal to ECM
to activate secondary steering system.
h.
Hydraulic tank and hydraulic tank breather are located at rear of machine. Hydraulic oil is added to tank by remov-
ing filler cap.
