STRUCTURE AND FUNCTION CLSS 3.2 SELF LEVELING FUNCTION Function When the only lever of the lift arm raise is operated, the lift arm raise and the bucket dump are worked. When this happens, the work equipment can raise with constant bucket bottom angle. (Only the lift arm raise).. F 2 a 3 4 d b c P1 Q1 P2 D A C B 1 Q2 5 6 E RKS00720 Operation When the lift arm raise is operated individually. The lift arm spool (1) strokes fully and the bucket spool strokes 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 raise PPC pressure is sent by passage E . Then the leveling circulating valve strokes 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 (3). When this happens, the flow divider (5) is operated as P1=P2 , so flow rate ( Q1 , Q2 ) is divided to B and C in prportion to the area of opening of notch ( b ) and ( c ) as below expression. Q1:Q2 = notch ( b ):notch ( C ) Q1 passes through the check valve (6) and then supplies to the bucket cylinder. 10-42 SK818-5 SK820-5 turbo