Komatsu PC200-8M0, Shop Manual

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SEN06120-00
10-402
42
PC200, 200LC, 220, 220LC-8M0
402 Hydraulic system, Part 2
Functions and operation by valve
Travel PPC shuttle valve
PPC: Abbreviation for Proportional Pressure Control
Function
q
If boom RAISE, arm IN or OUT, bucket CURL or DUMP operation is performed when the machine is
traveling up a steep, the pilot pressure from the travel PPC valve serves to restrict the travel of respec-
tive spools of boom, arm and bucket valves so that the oil flow rates to respective cylinders are
restricted.
q
To limit the travel of the boom, arm or bucket spool, the pilot pressure from the travel PPC valve passes
through the internal circuit of respective control valves and acts on the spool.
Operation
When travel levers are in NEUTRAL
q
The oil in the stroke limiting signal chamber (a) passes through orifices (5) and (6) of respective pistons
(3) and (4) build in the travel spring case, and then is drained through the travel PPC valve.
q
When boom RAISE (or arm IN or OUT, bucket CURL or DUMP) operation is performed, spool (1) moves
to the left until it contacts the end face of spring case (2) (st0).