HARNESS AS 5524722 - Caterpillar

2-2-5 Function of high pressure selector valve
Main function is to select high pressure oil from either of Port Am or Port Bm in valve cover and lead the high pressure oil to Port P in the selector valve. Stopper, ball and seat are incorporated in the valve cover and also plugs and O-rings are installed to seal up.Seat has a hole at the center and its one end is conical. Stopper has two flats. Ball is put in position between the seat and the stopper. These three parts function as a check valve.The high pressure oil freely goes through the seat and flows to the stopper. (Shown at the left on above figure.) On the opposite side, the oilflow is blocked since ball is forced against seat.1. Orifice 1) Orifice is screwed into valve cover, forms a passage to lead high pressure oil from the brake valve to the brake piston chamber, and works as a throttle.2. Auxiliary pressure relief valve Since it is constructed to prevent circuit pressure acting on brake piston chamber when the brake valve counter-balance spool is in neutral, the main function is to lead high pressure oil from the brake piston chamber into motor casing.1) Spring guide is press fitted in bushing, and the bushing is press fitted in valve cover respectively.2) Spool contains spring, and spool moves inside bushing according to pressure difference between chambers A and B.3) If spool moves against the spring force, throttle hole area of bushing becomes small, raising pressure of chamber B and spool moves upward.2-3 Operation
2-3-1 Operating principle of generating rotating force
1. High pressure hydraulic oil sent from the hydraulic pump enters inlet at the motor valve cover, flows through valve plate and is led into cylinder. 1) At this time, high pressure oil acts on brake piston of negative brake releasing the brake.2) The above figure stands for the case that the external pilot pressure is "O" and the inclination angle of the swash plate is the largest for low speed circuit. 2. This high pressure oil acts on the piston and shoe assembly and generates force F1 (F1 = P × A). P: Working pressure, A: piston cross section3. This force F1 is divided into thrust component force F2 and radial component force F3 by the swash plate with tilting angle α. 4. Force F33 generates torque T = F3 × Y against line Y-Y connecting the top and bottom dead points of piston. This torque generates rotation forces by forming composition of forces of torque generated by each piston and shoe assembly (4 or 5) on one side in connection with high pressure oil. 5. Rotating force generated by the piston and shoe assemblies is transmitted as rotating force without any change to the cylinder.6. Since the cylinder and the shaft are spline-coupled, the rotating force of cylinder is transmitted to the shaft as rotating force without any change.7. This rotating force is transmitted to the reducer as the output for hydraulic motor.2-3-2