THEORY OF OPERATION: IMPLEMENT AND STEERING HYDRAULIC
IMPLEMENT AND STEERING HYDRAULIC SYSTEM
The hydraulic system controls the steering, the bulldozer, and the ripper or winch (depending on which implement
is installed). The hydraulic system is a load sensing, pressure compensated system. In a load sensing, pressure
compensated system, oil flow does not change according to the load conditions. Cylinder speeds remain constant
under all load conditions.
Hydraulic pump (Figure 1, Item 1) is a variable displacement piston pump. The pump provides oil for all implement
circuits and for the steering circuit. The pump is oversized so that the steering circuit and the implement circuit can
be operated simultaneously. The maximum pump flow is set at 76 US gal/min (289 L/min).
The pump destrokes to keep the pressure in the system at a minimum. When a control lever is moved to an
operating position, higher oil pressure is needed in the system. The destroked pump compensates for system
leakage with a small output and maintains an approximate system pressure of 525 psi (3,620 kPa).
Figure 1. Hydraulic Pump.