Figure 4-44.—C-13 retraction engine control valves.
the shuttle, hydraulic fluid is admitted to the retraction
end of the retraction engine cylinder. The motion of the
crosshead is then reversed, and the grab brings the
shuttle and piston assemblies to the BATTERY (AFT)
position. The retract buffer slows and stops the motion
of the shuttle and piston assemblies, grab, crosshead,
and piston in the retraction engine cylinder at the end
of the stroke. For additional information on these
components and systems see the appropriate NAVAIR
technical manuals.
HYDRAULIC SYSTEM
The hydraulic system supplies pressurized fluid to
the hydraulic components of the catapult (see figs. 4-45
and 4-46). The main pumps of the hydraulic system
draw fluid from the gravity tank. The fluid is then
directed into the main hydraulic accumulator, where the
pressure is kept constant.
Hydraulic Fluid
The red-colored hydraulic fluid, NAEC P/N
217768-3, is 50 percent water, which provides its fire
resistance. The remaining 50 percent is composed of a
water-soluble polymer, which increases the viscosity of
the water; a freezing point depressant; and selected
additives that impart lubricant and corrosion protection.
With use, the fluid loses water and volatile inhibitors.
Water loss is indicated by an increase in the fluid
viscosity. Loss of inhibitors is indicated by a change in
the pH number of the fluid. (External contamination
4-34
