Komatsu Galeo PC800-8 Shop Manual page 184

Hydraulic excavator

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When the travel is operated at the same time as

the boom, arm, or bucket, the pressure oil flow-

ing to the left and right travel circuits is divided

and sent to the boom, arm, or bucket circuit. If

the oil in one travel circuit is divided off, the

amount of oil supplied to the travel motor will be

less than in the travel circuit which is not divided,

so the drop in the supply of oil to the travel motor

will cause the machine to deviate.

To prevent this, the straight-travel valve is

switched to interconnect the left and right travel

circuits. This ensures that the amount of oil sup-

plied to the left and right travel motors is equal,

so the left and right travel motors both rotate at

the same speed, and this prevents any travel de-

When travel is operated independently (straight-

travel solenoid valve de-energized)

The straight-travel solenoid valve is de-ener-

gized, so no pilot pressure flows, and spool (6)

remains pushed to the right.

Because of this, port P2 (left travel circuit) and

port P1 (right travel circuit) are not interconnect-

ed, and each circuit remains independent.

When travel and work equipment are operated at

same time (straigh t- travel solen oid valve

The straight-travel solenoid valve is excited, so

the pilot pressure flows and spool (6) is pushed

to the left.

Because of this, port P2 and port P1 are inter-

connected, so the amount of oil supplied to the

left and right travel motors is the same. As a re-

sult, the left and right travel motors both rotate at

the same speed, so there is no travel deviation.

10 Structure, function and maintenance standard

PC800, 850-8

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