Komatsu ecot3 PC300LC-8 Shop Manual page 167

10 Structure, function and maintenance standard
Travel PPC shuttle valve
1. When travel lever is in neutral
Function
q Regulates flow to each cylinder by controlling
the stroke of each spool of the boom, arm, and
bucket using the pilot pressure of travel PPC
valve while climbing a steep grade, raising the
boom, digging with arm, dumping, bucket-dig-
ging or operating dump.
q When controlling the stroke of the boom, arm
and/or bucket, pilot pressure of travel PPC
valve passes through the circuit inside the con-
trol valves to actuate the system.
PC300, 350-8
Operation
q The oil in stroke regulation signal chamber (a)
is drained through orifices (5) and (6) of pis-
tons (3) and (4) in the travel spring case and
the travel PPC valve.
q When operated for boom raising (or arm dig-
ging, dumping, bucket digging, dumping),
spool (1) moves to the left until it makes con-
tact with the end face of spring casing (2) (st0).
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