Service Pressure Lock Pins

Spool valves P3 and P4 are fitted with an anti-spill valve device that can be operated externally via the pressure lock pins. The anti-spill valves block the ports and enable the hydraulic pipes and RDU to be removed or serviced, without loss of hydraulic fluid from the reservoir. To open the anti-spill valves once servicing is complete, the bleeding procedure must be run. Pressure is applied to both P3 and P4 ports forcing the spill valves to open. This can be verified by checking that the pins are now in the fully extended position. During normal operation, the pins should be visible, protruding from the valve block body.

The RDU pump is located in the pump housing and secured with two screws. The pump drive shaft engages on the electric actuator output shaft. The pump housing is attached to the valve body, secured with three screws and sealed with an O ring seal. The pump output port connects with a pressure adaptor within the valve body. Pressure from the pump flows through the pressure adaptor and into drillings in the valve body to supply each of the four spool valves.