of the S1 half. Simultaneously, the head of the tubular
All parts referred to in the following paragraphs are
valve (1) contacts the face of the poppet valve (7), thus
identified in figure 8-8. The two halves of the coupling
preventing air from entering the system.
may be connected by placing the tubular valve (1)
within the protruding nose (6) of the mating half, and
Tightening the union nut pulls the coupling halves
rotating the union nut in a clockwise direction. The
together. This causes the nose of the S4 half to push the
union nut must be rotated until its teeth (5) fully engage
sleeve into the S1 half, uncovering the ports to the
the lock spring (8). A properly tightened coupling will
tubular valve. At the same time, the head of the tubular
have compressed the lock spring until a 1/16-inch
valve depresses the poppet valve.
minimum gap exists between the inside lip of the spring
When the coupling halves are fully connected, the
retainer fingers and the spring plate. Figure 8-9 shows
sleeve and poppet valve have reached the positions
the coupling both properly connected and improperly
shown in the left-hand view of figure 8-9. The nose of
connected.
the S4 half has engaged the O-ring packing of the S1
The locking action may be followed by referring to
half, providing a positive seal.
figure 8-8. Positive locking is assured by the locking
NOTE: Do not use a wrench to couple or uncouple
spring (8) with teeth, which engage ratchet teeth on the
series 145 or 155 quick disconnects unless a modified
union nut (5) when the coupling is fully connected. The
union nut is incorporated. Modified union nuts may be
lock spring automatically disengages when the union
identified by the letter C preceding the part number on
nut is unscrewed. An O-ring packing (3) seals against
the nut. On these modified union nuts, a wrench may be
leakage as the coupling halves are joined. Positive
used to assist in tightening the coupling. Torque values
opening of the valves occurs as the halves are
for the various size couplings may be found in the
connected.
aircraft MIM, and should be strictly complied with in
When the coupling halves are joined, the
all instances.
protruding nose (6) of the S4 half contacts the sleeve (4)
Figure 8-9.--Quick disconnects properly and improperly connected.
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