Engineering workshop

Although the hydraulic systems used aboard vary widely. They may, however, be grouped into the three basic set ups. Constant flow For a constant flow pump it is possible to vary the flow to a load by varying the outlet from the load. The major components are the fixed delivery pump, unloading valve, and accumulator. The accumulator consists of a steel pressure vessel within which is a rubber bag. The space between the bag and the steel walls is filled with nitrogen at a set pressure. When the constant delivery pump is started, oil is supplied to the accumulator inflating the bag with oil against the nitrogen pressure. When the set system pressure is reached the unloader valve will open maintaining system pressure at a set amount. The check valve maintains the pressure in the accumulator giving a ready reserve on demand. An alternative to this is to have a pressure cut out switch for the pump with a suitable dead band to prevent cycling. When a throttle or control valve