Komatsu Utility SK714-5, Shop Manual

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10-48 SK714-5 SK815-5 SK815-5 turbo
Operation
When the lift arm raise and the bucket digging are operated at the same time.
• The lift arm spool (1) and the bucket spool (2) stroke fully.
• When this happens, the bucket digging PPC pressure is sent by passage H .
Then the combination circulating valve (3) strokes fully to the right and also the lift arm raise PPC pressure is sent
by passage E .
Then the leveling circulating valve (4) strokes fully to the left.
• 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 as below expression.
Q1:Q2 = (notch ( b ) + notch ( d )): notch ( C )
Q1 = flow rate flows to B
Q2 =flow rate flows to C
• If the bucket load becomes beyond a certain valve by influences of digging, the series-parallel switching valve (7)
strokes to the right.
Then it passes thorough passage
G by opening notch ( e ).
And then the spring chamber of flow divider (5) is connected to tank.
• As a result, flow divider strokes fully to the right, and P2=T
Return flow rate from the lift arm is connected with tank totally, and Q1 =0L/min.
• When this happens, notch ( f ) of the lift arm spool and notch ( a ) of the bucket spool open, so the lift arm and the bucket
become parallel circuit ( CLSS ).
And flow rate of the lift arm raise ( Q3 ) and teh bucket digging flow rate are divided as below expression.
Q3:Q4 = notch ( f ): notch ( a )
STRUCTURE AND FUNCTION
CLSS