Figure 2-39.—Series 145 and 155 quick-disconnect couplings.
beams, which are used for the same purpose in rigid
control systems.
AIRCRAFT HYDRAULIC HARDWARE
AND SEALS
Learning Objective:
Identify the various
hydraulic hardware and seals used in naval
aircraft.
Hardware, such as the quick-disconnect coupling,
and seals and packings are used throughout the
aircraft. They are essential for safe and proper
operation of aircraft systems. You must be familiar
with the various types used on naval aircraft.
QUICK-DISCONNECT COUPLINGS
Quick-disconnect couplings provide a means of
quickly disconnecting a line without the loss of
hydraulic fluid or entrance of air into the system.
Each coupling assembly consists of two halves, held
together by a union nut. Each half contains a valve,
which is held open when the coupling is connected.
This action allows fluid to flow in either direction
through the coupling.
When the coupling is
disconnected, a spring in each half closes the valve,
preventing the loss of fluid and entrance of air.
The union nut has a quick-lead thread that permits
connecting or disconnecting the coupling by turning
the nut. The amount the nut must be turned varies
with different styles of couplings. For one style, a
quarter turn of the union nut locks or unlocks the
coupling. For another style, a full turn is required.
Some couplings require wrench tightening; others are
connected and disconnected by hand. Some
installations require that the coupling be safetied with
safety wire; others do not require any form of
safetying. Because of these individual differences, all
quick disconnects should be installed in accordance
with the instructions in the applicable MIM.
The series 145 and 155 (Aeroquip) couplings
make up one type of quick-disconnect coupling found
on naval aircraft. These couplings may be identified
by the part number (145 or 155) stamped on the face
of the union nut.
Each quick-disconnect coupling consists of two
halves, referred to as S1 half and S4 half. See figure 2-39.
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