SEAL- 2566959 - Caterpillar

Operation
There is a relief valve in each of these circuits: head end of the tilt cylinder, rod end of the tilt cylinder, head end of attachment or third cylinders and rod end of attachment cylinders. These valves are the same in construction and operation.When either valve spool (tilt control or third control) is in HOLD position, the relief valves in the head and rod ends limit the maximum amount of pressure in the cylinder lines. If an outside (external) force on the bucket or ripper becomes too high, the relief valve will permit movement of the cylinder piston. This prevents damage to the machine components.The relief valve for the rod end of the tilt cylinder also releases the rod end pressure when the lift arms are lifted or lowered and the tilt control valve spool is in HOLD position.Oil from either the head end or rod end of the cylinders is in passage (5). When the pressure of the oil becomes greater than the force of springs (3), valve (2) will move off its seat and let the oil in passage (5) go back into the oil tank through passages (1) and (6).
RELIEF VALVE
1. Passage. 2. Valve. 3. Springs. 4. Nut. 5. Passage from cylinder. 6. Passage. 7. Adjustment screw.Pressure Tests
Use only high pressure test equipment; pressure can exceed 27 500 kPa (4000 psi). Before installation of test equipment, place the bucket flat on the ground. With the engine shut off, move the lift and tilt control levers to all positions to release pressure in the hydraulic lines. Return the control levers to the HOLD position. Loosen the filler cap on the oil supply tank to release tank pressure. Tighten the cap.
6V4161 Pressure Gauge Kit.Head End Tilt Relief Valve
1. At the tilt cylinder, remove