VARIABLE PRESSURE RESTRICTIVE VALVE FOR PRESSURE COMPENSATION FOR PNEUMATIC RESCUE HOIST OF CHEETAL HELICOPTER

摘要

Cheetal helicopter is powered by TM 333-2M2 free-turbine turbo shaft engine. The air bleed pressure from the engine compressor is used to power the rescue hoist. The pneumatic rescue hoist requires the input pressure of 2.4 to 3 bars. The TM 333-2M2 Engine variable pressure of 4 to 5 depending on the power/load applied. In order to supply compressed air to the rescue hoist at the required pressure a variable pressure restrictive valve is used in the pneumatic line. The variable pressure restrictive valve is to reduce the engine pressure and supply to the rescue hoist. The valve consists of a fixed part (1) with a window having graduation for pressure setting, from 3 to 6.6 (3). For a given input pressure, increasing the pressure setting of valve will decrease the output pressure and in turn reduce the cable speed and decreasing the pressure setting of valve will increase the output pressure and in turn increase the cable speed.