THEORY OF OPERATION (CONT)
Oil Flow with Lift Spool Actuated.
In this example,
lift spool is moved out of con-
trol valve assembly to raise loader frame.
Lift spool stops oil flow through open
center passage. When pressure in the open center passage increases, load check valve
opens and lets oil flow to B port. Oil is sent from B port to closed end of lift
At the same time,
oil that is pushed out of rod end of lift cylinders enters control
valve assembly at A port.
This oil flows through return passage to outlet port.