TM 9-2330-294-14
n. One-Way Check Valve Operation and Test.
line if suspension springs inflate in (f ) but not in (i )
(1) Operation (fig. 4-27 and 4-28). The one-way
above.
check valve permits air to fill the fail-safe release air
l. Auxiliary Air Supply Valve Operation and
tank at the same pressure that exists in the main
Test.
reservoir. However, it prevents air from returning to
(1) Operation. This valve is a manually con-
the main reservoir when air pressure is lost in the
trolled air supply valve. It is provided so that
reservoir air line.
auxiliary air-powered equipment may be operated
(2) Test.
from the semitrailer air system. This includes tire
(a ) Pressurize trailer air system.
inflation equipment and other air-powered items.
(b ) Open drain cock on fail-safe release air
(2) Test.
tank until a loss of 20-30 psi is registered on an air
(a ) Pressurized air system. Remove air
gage at the air tank fill tank valve.
supply outlet cap (fig. 4-54).
(b ) Place handle of valve in normal operating
(c ) Close drain cock. Air pressure at the air
tank fill should build up to its original pressure.
position (parallel to valve body). No air should
escape from the air supply outlet (fig. 4-54), but
(d ) Close air supply line from towing vehicle
and open drain cocks on main reservoir air tanks.
system air should be available at the air valve-check
with the towing vehicle tire air gage.
(e ) After reservoir air line has drained apply
(c ) Turn the valve handle at right angles to
tire air gage to air valve on auxiliary air supply
valve. A pressure increase indicates a faulty one-way
the valve body. Air should be available at the air
check valve.
supply outlet. The air valve (tank valve) should be
without air.
(d ) Place handle in normal operating
WARNING
position and coat entire valve with soapsuds.
Depressurize air system prior to removal of
Leakage at any part of the valve should not exceed 1-
any brake or air system component. If
inch soap bubble in five seconds.
loaded, rear of semitrailer will sink as air is
(e ) Replace the valve if excessive leakage
purged from air bags.
occurs in (d ) above or if air is not supplied at the air
a. Place air control handle in LIGHT LOAD
supply outlet, when the valve handle is in its proper
position to ensure all axles are on ground.
position (c ) above.
b. Open drain cock on bottom of each air tank
m. Air Control Valve Operation and Test.
assembly and fail-safe release reservoir.
c. After all repairs are completed, close drain
manually controlled air valve directs air from the
cocks on all air tanks and fail-safe reservoir.
semitrailer air system reservoir to one of four
pressure regulator valves in the suspension system.
The three air lines from the control valve to the
regulators that are not in use are vented to the at-
before replacing any air lines. Copper and/or nylon
mosphere through the control valve.
tubing is used in the air system for semitrailer No. 1
(2) Test.
through 200 and nylon tubing for semitrailer No. 201
(a ) Pressurize semitrailer air system.
and cm. When replacing copper and/or nylon tubing,
CAUTION
use new fittings.
Do not use pliers to loosen fittings. Use only
proper wrench. Unscrew fitting only several
41 through 4-44 for location and replacement of
threads.
copper tubing and fittings, For preformed
(b ) Loosen a fitting on one air line from the
replacement copper tubing, notify direct support
vehicle reservoir to the control valve and verify that
personnel. Organizational maintenance personnel are
air is available to the valve (fig. 4-59 and 4-60).
only authorized to replace fittings and install tubing.
(c ) Select each of the four control valve
To install copper tubing, assemble nut over tube,
output positions in turn and check to see if air is
open end out, then put sleeve (ferrule) on tube.
being delivered to the proper suspension pressure
Lubricate sleeve and threads of fitting and nut with
regulator valve. This can be checked by applying the
oil (OE /HDO). Insert tube straight and square all
towing vehicle tire gage to the air test valves on each
the way into male fitting. Run down nut and thread
regulator valve (fig. 2-8).
it on, then tighten nut until sleeve just grips tube
(d ) Replace the valve if it fails to supply air
(moving tube while turning nut until you can no
to the regulator valves (pare 4-49) or if it supplies
longer turn or move tube). After sleeve grips tube,
other than the designated regulator pressure.
tighten nut turn.
