TM 5-3805-281-24-1
Theory of Operation
SWING MOTOR MAKE-UP VALVE OPERATION
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pressure the other side of motor until cavitation starts.
While stopping the swing function the control valve
When cavitation starts the make-up poppet (C) is
spools go to neutral and the lines to inlet ports (D) at
pushed open by the return oil in the make-up oil port.
the swing motor are blocked at the control valve.
The return oil flows in and prevent cavitation. The
Because of the inertia of the upperstructure the oil
make-up oil port in connected to the return passage in
pressure in one side of the swing motor becomes high.
the control valve. The return oil pressure is maintain by
For a few seconds the motor acts like a pump. The
the restriction valve located downstream of the oil
relief poppet in the crossover relief valve opens to
cooler.
relieve the high pressure oil to the make-up oil port
(B).
Because the lines to the motor are blocked the
continued rotation of the upperstructure lowers the
TX,05,GG2196 1904JUN981/1