The exhaust-valve hydraulic lock valve (fig. 4-18)
opens and closes the exhaust valve by controlling the
flow of hydraulic fluid to the exhaust-valve actuator.
When the exhaust-valve open solenoid is energized, air
pressure is directed to the opening side of the lock
valve, causing it to shift. This allows fluid to flow from
port A, out port B, through the keeper valve, and into
the opening chamber of the actuator. Fluid also flows
from port D to lock the valve in the OPEN position.
When the exhaust-valve closed solenoid is energized,
air pressure shifts the lock valve to the closed position,
allowing fluid to flow from port A, out port C, and into
the closing chamber of the exhaust-valve actuator. The
valve is locked in this position by pressure from port A
acting on the larger working area of the lock valve
piston.
LAUNCHING ENGINE CYLINDERS
Each catapult has two rows of launching engine
cylinders (see fig. 4-4) mounted parallel to each other in
the catapult trough. Each row of cylinders is made up of
sections that are slotted on the top and flanged at each
end, with the number of sections determined by the
overall length of the catapult. The cylinder sections are
bolted together at their flanges (fig. 4-19) by means of
long stud bolts, spacers, and nuts. The spacers and long
stud bolts are designed to minimize bolt failure due to
uneven thermal stress within the cylinders during pre-
heating and operation. Each cylinder is identified by a
serial number stamped on the outer surface of its flange.
Base pads are welded in the bottom of the catapult
trough at specified intervals to match the bearing pads
fastened to the cylinder bases. Shims are then used to
properly align each cylinder section, and then the
cylinder sections are secured to the trough base pads by
bolts and clamps, which prevent the lateral movement
of the cylinders while allowing smooth elongation of
the cylinders due to thermal expansion. Lubricator
fittings are provided for lubrication of the sliding
surfaces.
CYLINDER COVERS
The cylinder cover (fig. 4-20) acts as clamps
holding the slotted portion of the cylinder in position to
prevent radial spreading when steam pressure is
applied. Space is provided in the cylinder covers for the
sealing strip. Lubrication oil is supplied to the
launching engine cylinders through lubrication ports
and lubricators in each cover. Cylinder cover support
brackets, screwed to the cylinder, hold the cylinder
cover in place. Cover seals are used to seal and maintain
alignment of each cylinder cover section.
4-15
COVER SUPPORT
BRACKET
TIE BOLT
PLUGGED PORT
PLUGGED PORT
PLUGGED PORT
LUBRICATOR
LUBRICATOR
LUBRICATOR
REAR COVER
CYLINDER
COVER SEAL
SCREW
67-INCH
INTERMEDIATE
COVER
FORWARD
COVER
12-FOOT
INTERMEDIATE
COVER
ABEf0421
Figure 4-20.—Launching engine cylinder covers.
