STRUCTURE AND FUNCTION CLSS 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 ) 10-44 SK818-5 SK820-5 turbo