Attachment - Case CX Series Service Training Manual

HYDRAULICS – CX210/CX240

ATTACHMENT

Boom Raise
1) Two pump flows are combined inside the control valve, when the boom1 and boom2
control spools are shifted.
Oil flow from pump1 (front pump) enters the P1 port of the control valve and oil from pump2
(rear pump) enters the P2 port. When the boom hand control is operated for boom up pilot
pressure is directed through the cushion valve to the boom1 control spool in the main control
valve. The control spool shifts and sends pump2 oil for boom up. Boom up pilot control
pressure is also sent to the boom2 control spool on the pump1 side of the main control valve.
The control spool shifts which directs pump1 oil internally to the boom up circuit at the boom1
spool. This way boom 2-speed is achieved.
Whenever boom up is activated pilot pressure from the boom up pilot control circuit is sent to
the swing priority valve to shift it to unrestricted position to assure pump1 oil for arm circuit
operation.
CX EXCAVATORS
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