prevents a hard impact between the two as the
pistons bottom against the flanges.
The sole function of the cushioning piston is to
prevent the operating piston from slamming into the
opposite end of the cable anchor damper assembly
if the purchase cable should break or in the event of
an extreme off-center landing. In either situation,
the operating piston accelerates away from its
BATTERY position and rams the cushioning piston.
The battery positioner (fig. 3-19) functions to
return the cable anchor damper piston to its
BATTERY position during the retracting cycle of
the arresting engine.
The battery positioner includes a three-way air
valve (3), which is connected to a 100-psi air supply
and to the air container mounted on the cushioning
end of each damper assembly. An air strainer (4) is
located in the supply line ahead of the three-way
valve. The three-way air valve is mounted on a base
plate (5), secured to the arresting engine retracting
valve, and operated by means of a cam (1) mounted
on the retracting valve actuating lever.
When the actuating lever is moved to its retract
position, the cam positions the three-way air valve
to admit 100-psi air to the air containers. From the
air container, the 100-psi air passes through a hole
in the cushioning piston rod and acts against the
operating piston, moving it to its fully retracted
position. As soon as the actuating lever is released,
the air pressure is shut off, and the air container is
vented through an exhaust line (2) at the three-way
air valve. A line containing a liquid sight indicator
(7) and a drain plug (6) is provided at each
The fluid sight indicator permits
detection of fluid leakage into the air container.
Figure 3-19.Battery positioner.