COVER 2463258 - Caterpillar

Check Valves
The check valves for the lift and tilt circuits prevent the flow of oil in the reverse direction. This will not let the cylinders drift when the main control valves are moved from one direction to another. The valves are closed until the pressure of the pump flow gets high enough to push against the force of the spring and open the valve.Make-Up Valves
The make-up valve opens to add oil to pump flow when the cylinders are returning oil to the tank faster than the pump can supply oil to the cylinders.The make-up valves are held closed by a spring and pressure of the oil in their respective cylinders. If the pressure of the oil in any of the hydraulic circuits becomes less than the pressure in the tank, the make-up valves will open and oil will go from the manifold, through the valves, to the cylinders.The make-up valves, on the main control valves for lift, are vented. The head end make-up valves are vented to let the operator lower the bucket when the engine in the machine is not running. The rod end make-up valves are vented to make a passage to tank when the control lever on the pilot valve is moved to the FLOAT position.Kickout Systems
SCHEMATIC OF BUCKET POSITIONER, DUMP KICKOUT AND LIFT KICKOUT (Tilt and Lift Pilot Control Valves in HOLD Position)
1. Kickout valve for lift circuit. 2. Bucket positioner (tiltback kickout). 3. Kickout valve for dump. 4. Pilot pressure line to float vent valve. 5. Pilot relief valve. 6. Filter for pilot oil. 7. Lift cylinder, left side. 8. Tilt cylinder, right side. 9. Control valve for pilot circuit. 10. Pump for pilot circuit.There are three kickout circuits in the kickout system: the lift kickout, which stops the bucket at a desired height; the dump kickout that stops the bucket at the desired dumping angle; and the bucket positioner (tiltback kickout) that stops the bucket movement at the desired digging angle.The kickout valves are a part of the pilot system. They use pilot oil to move the spools in the pilot control valve to the HOLD position.When either of the valves (lift or tilt) in the pilot valve, is activated by moving the levers, the spools will be held in position by detents. The detents are pistons that are held in position by pilot pressure oil behind them. There are two pistons for each spool. When a kickout valve opens and lets oil go to the kickout inlet on the pilot, the pressure oil in front of the piston is the same as the pressure oil behind the piston. The force of the centering springs on the spool moves it to the HOLD position. There are no springs in back of the detent pistons.Bucket Positioner (Tiltback Kickout)
BUCKET POSITIONER
1. Cam. 2. Cam roller. 3. Positioner valve.In the TILT BACK position, the spool in the pilot valve for the tilt control is held in the detent by two pistons. The master valve for the