STICK GP-HOE 8U3238 - Caterpillar

Installation Procedure
1. Disconnect the bottom hoses from both hoist cylinders and remove the existing adapter from both ports.2. Install 6U9503 Elbows and reconnect the bottom hoses as shown in Illustration 1.
Illustration 1. Hoist Overrun Attachment (Right Hand Side).3. Disconnect the transfer pipe from both hoist cylinder top ports and remove the existing adapters. Keep the adapters.4. Install 2U637 Valves using 2U680 Fittings, 2U96 Seals, and 2U97 Seals as shown in Illustration 2.
Illustration 2. Sealing Arrangement For 2U637 Valve.5. Install a 5M6213 Plug in each fitting as shown, then install the existing transfer pipe using the adapters previously removed.6. Install 6U6667 Hoses.Operation
When pressurized oil is directed to the head end of the hoist cylinders (bottom ports), the new 6U6667 Hoses direct some of this oil to the pilot ports on 2U637 Valves. The valves are then opened which allows oil from the rod end of the hoist cylinders to return to the tank. The dump body is then powered up in the normal way. The pressure in the head end of the cylinders will be high in order to raise the loaded body. The pressure in the pilot lines (6U6667 Hoses) will be the same.
If the pressure in the head end suddenly decreases, the pilot pressure will decrease also. This can happen if sticky material suddenly hits the rear of the body (duck tail) or the body goes over center causing the piston rod assembly to move faster than oil is being supplied to it. When the pilot pressure decreases, the valves close and prevent oil from escaping from the rod ends of the cylinders. The valves remain closed until pressure in the head ends (and hence pilot pressure) increases again. In this way the body moves in a controlled manner. The 2U637 Valves contain integral check valves which allow free flow into the rod end of the hoist cylinders to power the body down.