Komatsu Galeo PC138US-8 Shop Manual page 169

10 Structure, function and maintenance standard
Boom regeneration circuit
1. At boom lower and own weight fall
Function
When the boom is lowered and falls due to its
q
own weight because the bottom pressure (A)
in the cylinder (1) is higher than the head pres-
sure (B), this circuit brings the return flow on
the bottom side to the head side to increase
the cylinder speed.
Operation
When the boom is lowered and falls due to its
q
own weight, the bottom side pressure (A) in the
boom cylinder (1) will rise above the head side
pressure (B).
PC138US, USLC-8
At the time, part of the return flow on the bot-
q
tom side passes through the regeneration pas-
sage (a) of the boom spool (2), pushes the
check valve (3) to open it and flows to the head
side.
This increases the boom lower speed.
q
SEN02549-02
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