In high pressure hydraulic systems, pumps are often required to intermittently supply high pressure fluid to loads, such as accumulators, when the system requires replenishing. In order to allow the pump to come up to speed at light loads before the load of the high pressure accumulator is placed on the system, unloading valves are utilized. These valves controllably impose the hydraulic load on the pump at start-up and controllably release the load before the pump shuts down. Unloading valves require a source of motive power for their operation, and it has been conventional to utilize pressure taken from the high pressure system itself. This type of operation requires one or more lines from the high pressure system through a filter and a solenoid valve in order to supply adequate pressure to operate the unloading valve. These lines deliver high pressure fluid through a filtering system to a solenoid valve, which directs the flow of the fluid to the unloading valve to operate it. The use of high pressure lines can make installation, especially in the field, difficult and time consuming. Additionally, high pressure lines add to the overall cost of the valve, as well as the cost of initial or field installation. Furthermore, such a complex maze of high pressure lines can be dangerous in that the lines present unnecessary obstructions in the work place. An inadvertently disengaged line may expel high pressure hydraulic fluid and result in undesirable system down time required to repair the connection. Such disengagement also results in unreliable operation of the unloading valve, and, therefore, the high pressure loading system.