hydraulically pressurized reservoir used in the CH-47 hydraulic system is shown in Figure 1-2.
This reservoir, or tank as it is referred to by Boeing-Vertol, is constructed of a metal housing with
two internal pistons, one fixed and the other a floating piston which slides along a central tube.
Attached to the floating piston is a larger tube that projects through the forward end of the tank and is
calibrated to indicate FULL and REFILL fluid levels for ramp-up and ramp-down positions.
Figure 1-1. Typical Hydraulic Reservoirs.
Hydraulic fluid at 3,000 psi flows into the central tube as shown in Figure 1-2, passes through two
outlet holes, and applies pressure at the piston area between the two tubes. Because the smaller piston
has a .5-square-inch (sq in) exposed surface and the floating piston has a 30-sq-in exposed surface, the
3,000-psi pressure acting upon the smaller forward area produces an opposing pressure of 50 psi on the
return fluid stored at the rear of the piston.