1) SERVICE BRAKE RELEASED SERVICE BRAKE RELEASED 19 Front P1 T1 A1 20 40 P2 T2 A2 16 17 16 Rear S2 B2 B1 S1 S3 18 G1 PS Parking Return line B3 41 T/M 18 18 PS G2 PS 22 23 24 2 29 30 D Return line P B B A A 21 25 B T Main pump L S 740F4BS02 When the pedal of brake valve (19) is released, the operating force is eliminated by the force of the spring, and the spool is returned. When the spool removes up, the drain port is opened and the hydraulic oil in the piston of axles return to the tank (21). Therefore, the service brake is kept released. 4-4 P PS 26 26