Komatsu Galeo PC138US-8 Shop Manual page 171

10 Structure, function and maintenance standard
Arm regeneration circuit
1. At arm in and own weight fall
A : Head circuit
B : Bottom circuit
PP : Pump circuit
Function
When the arm falls due to its own weight
q
because the head pressure (A) in the arm cyl-
inder (1) is higher than the bottom pressure (B)
during arm digging, this circuit brings the return
flow on the head side to the bottom side to
increase the cylinder speed.
Operation
When the arm falls for digging due to its own
q
weight, the head side pressure (A) in the arm
cylinder (1) will rise above the bottom side
pressure (B).
PC138US, USLC-8
1. Arm cylinder
2. Arm spool
3. Check valve
At the time, part of the return flow on the head
q
side passes through the regeneration passage
(a) of the arm spool (2), pushes the check
valve (3) to open it and flows to the bottom
side.
This increases the arm digging speed.
q
SEN02549-02
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