Komatsu Utility SK714-5, Shop Manual

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10-45 SK714-5 SK815-5 SK815-5 turbo
3.1 SERIES CIRCUIT
Function
• Return flow rate from the lift arm is recirculated to the bucket.
Operation
When the lift arm raise and the bucket dump are operated at the same time.
• The lift arm spool (1) strokes fully and the bucket spool (2) stokes by half.
• When this happens, notch ( a ) doesn’t open, so all flow rate from pump supplies to the lift arm raise.
• The lift arm and the bucket PPC pressure are sent by passage E and F .
Then the leveling circulating valve (3) and the combination circulating valve (4) stroke fully.
• Return flow rate from the lift arm cylinder passes through passage A .
Then it is divided to passage B and C , by the leveling circulating valve (4) and the combination circulating valve (3).
• When this happens, the flow divider (5) is operated as P1=P2 , so flow rate ( Q1 , Q2 ) is divided to passage B and C
in proportion to the area of opening of notch ( b ) and ( c ) as below expression.
Q1:Q2= (notch ( b ) + notch ( d ) ): notch ( C )
Q1 = flow rate flows to B , Q2 = flow rate flows to C
• Q1 passes through the check valve (6) and then supplies to the bucket cylinder.
RKS00720
P2
P1
Q1
Q2
5
6
2
1
3
4
d
F
b
a
D
c
C
B
E
A
STRUCTURE AND FUNCTION
CLSS