an escapement. The gear train consists of a
primary spur and pinion, a secondary spur and
pinion, an idler wheel, an escapement wheel and
an escapement rocker.
The rack assembly consists of a rack end
screwed into a slotted end. The two components
are secured together with a locking screw. The
upper end of the rack end is shaped to form a
firing pin.
To retain the rack in the cocked position, one
face of a pawl in the bottom housing engages in
the slotted end of the rack assembly. Another face
of the pawl engages in a groove in a gas-operated
Figure 5-15.-Pitot assembly, operation.
piston installed in a housing attached to the lower
part of the unit body. The piston is retained in
position by a frangible disc.
PITOT ASSEMBLIES— Two pitot assemblies
(figs. 5-14 and 5-15) incorporating deployable
pitot heads are mounted on the main beams
behind the parachute container. Removable
covers are provided to prevent entry of foreign
bodies,
The pitot heads are maintained in the stowed
position by locking mechanisms that are released
during seat ejection, as the seat separates from
the catapult,
by gas pressure from the
multipurpose initiator cartridges. When deployed,
the pitot head assemblies supply dynamic pressure
inputs to the electronic sequencer. Static (base)
pressure is supplied to the sequencer from the
voids within the LH and RH main beams.
Each pitot assembly comprises a body, drilled
and plugged to form a series of gas passages, and
two cylinders containing upper and lower pistons.
A deployable pitot arm incorporating a pitot head
is attached to the aft face of a bracket, forming
part of the body. Attached to the forward face
of the bracket is a pitot connector that is
connected to the pitot head. A spring-loaded
locking plunger, which locates in one of two holes
in the body, is installed inside the lower end of
the pitot arm. The locking plunger locks the pitot
arm in the stowed or deployed positions. A
separate passage in the body, incorporating
connectors at each end and a filter, forms part
of the static pressure supply system for the
sequencer.
BALLISTIC MANIFOLDS.— There are two
ballistic manifold assemblies-right-hand and left-
hand.
Manifold Assembly Right-Hand.— The right-
hand (RH) assembly is a gas distribution center
that is connected to the seat bucket trombone
tubes and incorporates the upper harness release
piston, the ejection gas line quick disconnect, and
a housing for the bridle release cartridge. The
assembly also provides a mounting for a delay
cartridge. The drogue bridle release impulse
cartridge is installed in a threaded housing
on the upper face. The upper harness release
piston protrudes from the manifold upper face.
5-15
