Figure 4-16.-Clinder elongation indicator installation
and upper and lower cover support bars (see fig. 4-17).
The trough is of welded construction, made of steel
plates, and is reinforced on the outside. The troughs are
built with voids outside the trough walls. The bolted
down access plates for these voids form the flight deck
at both sides of the bow catapults. The access to the
voids on waist catapults is from below deck through the
sides of the voids. The trough contains heaters used to
preheat the catapult and to maintain minimum catapult
operating temperature during all weather conditions.
The launching engine cylinders rest on lubricated
bearing pads mounted in the trough. The only points at
which the launching engine is secured to the ship
structure are at the thrust unit at the aft end of the
launching engine and at the forward or buttress plate
end of the water-brake cylinders. The forwardmost
launching engine cylinders telescope over the
water-brake cylinders.
This allows longitudinal
expansion and contraction during catapult heating and
cooling.
Catapult Trough Covers
The trough covers perform a dual function. They
cover the catapult trough which accommodates the
launching cylinders, and they form a shuttle track,
which supports and guides the shuttle and grab during
catapult operation (fig. 4-17). All covers are designed
to withstand a vertical rolling shuttle load of 264,000
pounds total (132,000 pounds to each cover) in upward
directional force and 100,000 pounds wheel-load in
downward directional force. The standard trough covers
are
made in
various lengths: the 6-foot-long
intermediate and aft covers, the 4-foot forward cover
4-15
