Figure 4-10.—Shuttle.
shuttle track. The nose gear launch spreader is attached
to the shuttle blade.
Water-Brake Cylinders
The water brakes stop the forward motion of the
shuttle and pistons at the end of the catapult power
stroke. The water-brake cylinders (fig. 4-11 ) are
installed at the forward end of the launching engine
cylinders. The after end of each water-brake cylinder is
supported and aligned by the most forward section of
each launching engine cylinder, which fits closely
around the end of the water-brake cylinder. The forward
end of each cylinder is anchored in place by an upper
bracket and lower support saddle and chock.
The open end of each cylinder holds four rings.
They are the choke ring, the annulus ring, the jet ring,
and the striker ring.
The choke ring is the innermost ring and is
threaded into the cylinder to form the water-brake
cylinder mouth. The annulus ring has angled holes
machined in it to direct pressurized water into the
cylinder and forms a vortex (whirlpool) at the open end
of the cylinder. The jet ring is bolted to the end of the
cylinder and holds the annulus ring in place. The striker
ring, the outermost of the four rings, prevents damage
to the other three rings and the end of the cylinder
when the piston assemblies are maneuvered or advanced
into the water brakes.
WARNING
To prevent damage to the water brakes and
piston assembly components, a water-brake
pump must be running any time the shuttle and
piston assemblies are not fully bottomed in the
water brakes.
A vane is keyed to the end plug (see fig. 4-11). Its
purpose is to breakup the vortex caused by the annulus
ring and to create a solid head of water in the cylinder,
which is maintained by the continued vortex action at
the mouth of the cylinder.
Braking action occurs at the end of the power run
when the tapered spear on the piston assembly enters
the water brake. Water in the brake is displaced by the
spear and forced out the after end of the cylinder
between the choke ring and the spear. (See fig. 4-2.)
Since the spear is tapered, the space between the choke
ring and the spear is gradually decreased as the spear
moves into the brake cylinder. This arrangement
provides a controlled deceleration and energy absorp-
tion, which stops the piston assembly within a distance
of about 5 feet without damage to the ship’s structure.
4-10
