Right Side of Machine Under Operator Platform
Charge oil is delivered through propel charge filter (7) before
entering the propel circuit. The charge oil is supplied by the
return oil from the steering circuit through line (5) and (6). The
flow from the propel pumps is controlled by the propel control
lever on the operator console.
The return oil from the steering pump also serves as charge
pressure for the propel system. The charge oil flows through
propel charge filter (7). This oil continues to flow to the propel
Left Side of Machine Under Operator Platform
(19) Thermal pass valve. (22) Return manifold.
Case drain oil and all returning oil flows to thermal bypass
valve (19). Thermal bypass valve (19) is a cartridge type valve
that controls the oil to the oil cooler. The thermal bypass valve
is wide open until the hydraulic oil temperature reaches 65C
(149F). When the thermal bypass valve is open, the oil is
bypassed around the oil cooler and the oil flows to the
hydraulic oil tank in order to increase the temperature of the oil.
When the temperature reaches 65 C (149F), the thermal
bypass valve shifts and the oil flow increases, to the oil cooler.
The thermal bypass valve closes at 71C (159F) and all of the
oil is directed through the oil cooler. A small amount of oil
constantly flows to the oil cooler when the thermal bypass
valve is open.
(13) Drum propel pump. (16) Axle propel pump.
Drum propel pump (13) is mounted to the end of axle propel
pump (16). These pumps are located beneath the operator
platform. The propel pumps are variable displacement pumps.
The propel pumps provide hydraulic oil for the propel system
and the brake release systems. Quick disconnects are located
at the end of the balance lines for measuring the closed loop
system pressure. The axle hydraulic system and the drum
hydraulic system are connected by two balance lines with a 1.6
mm (0.063 inch) orifice. The balance lines equalize the
pressures that are between the two propel circuits that are
caused by terrain and rolling resistance.