TM 1-1500-204-23-2
Figure 4-129. Landing Gear System Using Mechanically Actuated Sequence Valves
e.
Priority Valves. Priority valves are installed in hydraulic systems to provide adequate fluid flow to units
requiring immediate completion of action. Figure 4-131 illustrates the operation of a priority valve. The priority valve is
installed in the line between an actuating unit in which completion of action can be delayed and its source of operating
pressure As long as system pressure is normal, the flow of fluid to the delayable unit is unrestrained. When system
pressure drops below normal, the priority valve automatically reduces the rate of flow to the unit not requiring Immediate
completion of action. Priority valves are used in hydraulic systems to give operating priority to such units as brakes,
landing gear, and flaps
f.
Shuttle Valves. In some cases, two sources of operating pressure are connected to a single component
or system One of the pressure sources will be reserved for emergency use Provisions are usually
Figure 4-130. Pressure-Actuated Sequence Valve
Figure 4-131. Priority Valve
4-132
