HYDRAULICS – CX130/CX160
5 - 12
CX EXCAVATORS
TRAVEL
Straight Travel
1) When performing travel operation + attachment operation or travel operations + swing
operation, one pump is dedicated to the travel motors. The other pump will supply oil
to the other functions.
An example of straight travel is explained using the example of travel + boom raise
operation. During travel operation, oil flow from pump1 (front pump) enters the PR port of the
control valve and oil flow from pump2 (rear pump) enters the PL port of the control valve.
When the right and left travel spools are shifted, oil flow is directed to the travel motors for
forward or reverse operation. At this time each pump is dedicated to a travel motor. When
the boom raise operation is executed, the return circuit for the upper pilot pressure circuit is
blocked. The resulting pressure rise in the upper pilot pressure circuit shifts the straight travel
pilot valve. This in turn shifts the straight travel valve. Which directs flow from pump1 for
boom operation and flow from pump2 is directed to both travel motors. This way boom raise
operation is performed and straight travel is maintained. Oil from pump1 not needed by the
upper attachment is routed to the pump2 travel circuit through an orifice and check valve to
assist in travel speed during straight travel.
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