Troubleshooting
Problem
Possible cause
Solution
Air motor is not operating, air is coming
from exhaust
Inadequate air supply to air motor
Check air supply and adjust to minimum
recommended level Check air supply hose
and piping for minimum recommended size
Ensure FRL and quick disconnect couplings
meet or exceed minimum specified sizes and
do not restrict airflow to air motor
Erratic or accelerated operation with short
stroking Air motor hesitates on up or down stroke
Dirty or damaged relay valve (
17
) or air signal
valve (
20
) or stop valve assembly (
60
)
Check valves and clean if necessary
Replace any damaged seals or worn parts
Pump cavitation
Check fluid level Ensure pump inlet is not
blocked or restricted or is large enough to
handle flow into pump inlet
Air brake trips off even though air motor is
operating below set trip speed (trips after
three or more strokes)
Dirty or blocked labyrinth plate or components
Clean or replace labyrinth components
Check for grease or oil blocking air passages
in labyrinth subassembly Blocked labyrinth
may be confirmed (in quiet locations) by
turning selector knob to
RUN
mode setting
immediately after air motor has stopped If sudden
rush of air escaping is heard, labyrinth
is either blocked or installed incorrectly
Grease or dirt on balls (
81
) in labyrinth cover (
78
) Clean balls and labyrinth cover with solvent
Coat with very light film of light grease to hold balls
in cover
Air brake trips even though air motor is
operating below set trip speed (within
three strokes)
Leaking diaphragm (
58
)
Replace diaphragm
Leaking upper gasket (
51
)
Replace upper and lower gaskets (
51
and
53
)
Upper piston quad ring (
64
) is leaking
Replace quad ring
Laminated labyrinth plate (
77
) is installed
incorrectly
Observe laminated labyrinth plate and find
single hole (
76
) and align with hole (
75
) (
Fig. 3
)
Air brake trips at proper speed (as
indicated by sound of air surging into
diaphragm chamber), but air motor
does not stop Indicator pin does not
pop out
Stop valve vent hole in lower body (
54
) is clogged
or blocked (
Fig. 17
)
Unclog vent hole in lower body
Stop valve (
60
) is damaged
Check stop valve and replace if worn or
damaged
Diaphragm seal is damaged, worn, deformed or
improperly installed
Replace damaged or worn diaphragm seal
If not damaged, reinstall into diaphragm (
58
)
with twisting action to fully seat in mating hole
Inadequate air supply to air motor
See above for checking air supply Ensure that
air regulator is set to air pressure at or greater than
minimum recommended air pressure for
air motor installed
Air brake will not trip even though air motor
has been running above trip speed for more
than 1 minute
Discharge umbrella valve (
63
) is damaged or worn Replace both umbrella valves
Diaphragm seal is damaged, worn deformed or
improperly installed
Replace damaged or worn diaphragm seal
If not damaged, reinstall into diaphragm (
58
)
with twisting action to fully seat in mating hole
Leaking upper gasket (
51
) or lower gasket (
53
)
Replace gaskets (
51
and
53
)
Stuck metering pump piston (
55
)
Install air pump repair kit, replacing items
55
,
56
,
63
,
64
and
65
Inlet air filter (
40
) is completely or partially clogged Clean or replace inlet air filter
19
