PS Magazine - TB 43-PS-727
PS, The Preventative Maintenance Monthly
ISSUE 727
JUNE 2013
16
PS 727
JUN 13
Dear Editor,
A problem with an M1075A1 PLS was recently brought to my attention.
The truck had low miles, but it kept dumping air out of the tire on the front
passenger side of the vehicle.
At first, we thought it was a tire leak because only the front passenger
tire deflated to 25 psi after shutting down the vehicle. We followed the
troubleshooting guidance in the TM and still couldn’t find the solution.
After swapping out the pneumatic control unit, quick-release valve, wheel
valve, wet tank transducer, pneumatic brake valve, and the CTIS controller,
the problem didn’t go away. We even swapped out wheel seals, hubs and
tires, but the front passenger tire still deflated to 25 psi.
Finally, the truck’s front axle was taken apart down to the spindle. We
found that one of the three holes drilled on the back side of the spindle for
the central tire inflation system (CTIS) had a check ball that was depressed
into its machined hole. The spindle was compared to a known good one, and
its check balls were
not
depressed into the machined holes.
We replaced the spindle on the truck and the problem was corrected.
This has happened with a few other trucks Army-wide, so your readers can
save a lot of trouble by checking the spindle if they ever get a slow leak that
won’t go away with normal troubleshooting.
David M. Watts
TACOM Automotive LAR
2/25 SBCT BLST
Schofield Barracks, HI
Editor’s note:
Thanks, Mr. Watts. Your letter
may keep others from spinning their wheels over
a faulty spindle! By the way, TACOM tells us that
this problem may affect M1074A1 trucks, also.
Spindle Is Key to
Tire Leak Mystery!
PLS…
Good spindles won’t have check ball
depressed into machine hole
Bad spindles have check balls
pushed into machine hole
I
don’t
get
it,
bonnie!
nope, that
didn’t work.
strike
one!
nope, that didn’t
work either.
strike
two!
here’s a new
tire…now
let’s hit the
road!
so far so
good…
so far so
good…
so far so
good…
{sigh} here’s
another new
tire…now let’s
try again!
and here’s
another
new
tire!
ggrrrr!
strike
three!
all of my
replacement
tires end up
flat!
we just
heard
from a LAR
on that.
here’s his
solution…
727 16-17.indd
1-2
5/2/13
10:47 AM
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