STRUCTURE AND FUNCTION CLSS 3.1 SERIES CIRCUIT Function Return flow rate from the lift arm is recirculated to the bucket. 2 a F 3 4 d b c P1 Q1 P2 D A C B 1 Q2 5 6 E RKS00720 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. 10-41 SK818-5 SK820-5 turbo