PS Magazine - TB 43-PS-570
PS, The Preventative Maintenance Monthly
ISSUE 570
MAY 2000
ry air is a must for the compressed air system on your M1070 HET tractor
and M1074 or M1075 PLS tractor. That’s why there are so many filters and
dryers installed in the system. But one of these moisture-stoppers isn’t getting
the PM it must have.
The coalescing filter
is the second stop for
air after it leaves the
compressor. (The
first stop is the
aftercooler.) The
filter removes oil
and moisture from
pressurized air before
it goes to the air dryers.
In regular use, the
coalescing filter must be drained every
week, according to the PMCS for all
three tractors. Depending on operating
conditions, there can be lots of oil and
moisture collected in the filter.
The draining is not happening, however. Over time, as the filter fills up with
oil and moisture, less filtering is done. That passes oil to the air dryers, causing
them to get dirty and clogged quicker than normal.
M1070 HET, M1074/1075 PLS . . .
When the air dryers can’t handle the wet, oily air coming from the coalescing
filter, they just pass it on to the reservoirs. Assuming the reservoirs are drained
daily as required by PMCS, operators will notice more and more water coming
from them.
Regardless, in operation the wet air gets passed through the entire compressed
air system, including the air system of any trailer hooked up to the tractors.
This has caused clogging of the spider valves on the M1000 HET trailer,
which defeats the suspension system that makes the trailer so valuable in hauling
tanks. It can also cause brake failure.
Wet air will also clog the air system on M1076
PLS trailers, reducing their braking capabilities.
You can stop all this damage by draining the
coalescing filter weekly as called for in your
truck’s PMCS. If you haven’t drained it lately,
don’t be surprised if you get a slimy mess in the
container you use. A little bit is OK. The filter’s
doing its job.
Let your mechanic know if you get a steady
stream of this stuff coming from the filter. He’ll
need to check the other air filtering and drying
components in the system for damage.
Coalescing filter will
discharge water
and
oil
Drain coalescing filter every week.
..
check
all
the filters
to
keep me
haulin
'!
...to keep air
dryers clean
PS 570
2
MAY 00
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