Accumulators

Figure 9-3.—Typical fluid-pressurized reservoir. threaded openings for connecting fittings and components. Figure 9-4 shows several components installed in lines leading to and from the reservoir; however, this may not be the case in actual installation. The air relief valve, bleeder valve, and soon, may reinstalled directly on the reservoir. Because the reservoir is pressurized, it can normally be installed at any altitude and still maintain a positive flow of fluid to the pump. Figure 9-4.—Air-pressurized reservoir. Some air-pressurized reservoirs also have direct contact of fluid to gas. These reservoirs are installed in large systems and may be cylindrical or rectangular in shape. They contain an oil level indicator, a pump inlet or suction line connection, a return line, a gas pressurization and venting connection, and a drain line connection or a drain plug. These reservoirs are pressurized by air from the ship’s service air system or nitrogen banks. These reservoirs are found on board aircraft carriers and submarines. ACCUMULATORS An accumulator is a pressure storage reservoir in which hydraulic fluid is stored under pressure from an external source. The storage of fluid under pressure serves several purposes in hydraulic systems. In some hydraulic systems it is necessary to maintain the system pressure within a specific pressure range for long periods of time. It is very difficult to maintain a closed system without some leakage, either external or internal. Even a small leak can cause a decrease in pressure. By using an accumulator, leakage can be compensated for 9-3