positive flow of fluid to the pump suction ports. The
pressurization is derived from thermal expansion of
fluid and the return of fluid to the reservoir from the
Most reservoirs of this type are vented directly to
the atmosphere or cabin with only a check valve and
filter to control the outside air source. The reservoir
system includes a pressure and vacuum relief valve.
The valve, as shown in figure 7-5, has two reservoir
ports, and it is connected between and serves both
main system reservoirs. The purpose of the valve is
to maintain a differential pressure range between the
reservoir and cabin.
RESERVOIR MANUAL AIR BLEED (VENT)
VALVE.A vent valve is provided to vent the
This valve is connected to the reservoir
vent line to allow depressurization of the reservoir.
The valve is actuated prior to servicing the
reservoir to prevent fluid from being blown out of the
filler as the cap is being removed. Figure 7-6 shows a
full sectional view of a manual air bleed valve.
Pressing the slide valve opens a passage to vent the
Air-pressurized reservoirs are currently used in
many high-performance naval aircraft. Figure 7-7
Figure 7-7.Air-pressurized reservoir and components.
Figure 7-6.Manual air bleed valve.