ONE WAY CHECK VALVE
The one-way check valves (Fig. 1 and 2) are used to
permit passage of air pressure through the valve in one
direction only as indicated by the arrow on the side of the
valve. They are installed in both primary and secondary
reservoirs to maintain the air supply in both reservoirs if
an air loss should occur ahead of the valve.
Fig. 1 Cross Sectional View of One- Way Check Valve
The 900 angle check valve shown in Fig. 2 is used in
applications where clearance conditions exist on various
Air flow in direction of arrow moves the seal from its seat
and the air flow is unobstructed. Flow in reverse
direction is prevented by seating of the seal by the
upstream air pressure and assistance of spring.
Once each year or every 160,000 km (100,000 miles)
check operation (see SERVICE CHECKS).
Depending upon installation, it may be easier or
necessary to completely remove check valve so that the
following checks may be made. If checking valves at
primary and secondary reservoirs, bleed air supply
reservoir and disconnect air inlet to valve and proceed as
Fig. 2 90o Angle Check Valve
Be sure to set parking brake or block
wheels to prevent vehicle from moving.
With air pressure present at outlet side of check valve
and inlet open to atmosphere, use leak detector tester to
test for leakage. Leakage should not exceed 25.4 mm (1
in.) soap bubble in 5 seconds, slight leakage is
permitted. However, if valve leaks excessively, the valve
should be repaired or replaced.
Apply parking brake or block wheels to prevent
vehicle from moving.
Drain all air reservoirs.
Disconnect air lines and remove check valve.
Check and, if required, clean or replace air line
Install valve making certain that it is installed
correctly. Arrow on outside of body indicates
direction of air flow through valve.
Check valve for leakage.
CTS -4079-CHAPTER III
PRINTED IN UNTIED STATES OF AMERICA