Form No. 29703
The swing transmission is a double reduction planetary-type transmission. It is bolted to the upper main frame and
has an output pinion that engages the bull gear of the swing bearing. When this pinion rotates, it turns the
upperstructure in relation to the undercarriage.
A pressure reducing valve is installed in the swing circuit.
See Figure 32 & 34
Its primary purpose is to provide
makeup fluid to the charge circuit in extreme conditions. Under some conditions, more fluid is required in the swing
loop than can be provided by the internal charge circuit. A pressure reducing valve is tied into the pilot circuit. It is
equipped with a 350 PSI relief valve. A check valve isolates the output of the pressure reducing valve from the
charge circuit. Dump fluid from the valve returns to tank through the pump case. When charge circuit pressure drops
below relief setting in the pressure reducing valve, fluid from the pressure reducing valve provides make up fluid into
the charge circuit until the momentary need for extra fluid passes.
XI. Swing Circuit
(continued)
FIGURE 31
SWING MOTOR
Reaction Plate
Relating Plate
Tapered Pistons
Drive Shaft
Center Pin
Port Plate
Barrel
Pin
FIGURE 32
PRESSURE REDUCING VALVE
(LOCATION)
Pressure Reducing
Valve Assembly
FIGURE 33
SWING CHARGE RELIEF VALVE
Swing Charge
Relief Valve
FIGURE 34
PRESSURE REDUCING
VALVE
Pressure
Reducing Relief
Relief 350 PSI
Left Side Of
Machine
Low Pressure Pilot
Charge Test Port
LP Swing
Charge Test
Port
32
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