Chevrolet 10 Series 1970 Service Manual page 292

BRAKES 5-54
Inspection
It is of the utmost im portance that the co m p re s s o r is
taking in clean a ir. The a ir s tra in er must be p ro p e rly
in stalled and kept clean.
connected to the engine a ir clean er, etc., these connec­
tions must be p ro p e rly in stalled and maintained.
Check c o m p resso r mountings to be sure they a re se ­
cure. Check d riv e fo r p ro p e r alignm ent, b elt tension,
etc. Inspect o il supply and return lines.
lin es a re p ro p e rly in stalled and that the c o m p resso r is
getting the p ro p er supply of oil, and just as important,
that the o il is returning to the engine p rop erly.
Check w ater lin es to and fro m co m p ressor if a w a ter-
cooled type.
If the com p resso r is a ir-c o o le d ,
the engine fan b l a s t is flow ing by the com p resso r
unrestricted.
Check unloader m echanism fo r operation.
Tests (A ir Leakage)
Leakage past the discharge va lv e s can be detected by
rem ovin g the disch arge
through the discharge port and listening fo r escaping a ir.
A ls o the discharge v a lv e s and the unloader pistons can
be checked fo r leakage by building up the a ir system until
the go vern o r cuts out, then stopping the engine. W ith the
engine stopped, c a re fu lly listen fo r escaping a ir at the in­
take. T o pin-point leakage i f noted, squirt soapy w ater
around the load er pistons. If there is no noticeable leak­
age at the unloader pistons, the discharge v a lv e s may be
leaking.
If the co m p ressor does not function as d escrib ed above,
Fig . 9 6 —A ir Brake C ir c u it —C o n v e n tio n a l
If the com p ressor intake is
Be sure these
check to be sure
line, applying shop a ir back
o r leakage is ex c ess ive, the co m p resso r should be r e ­
p a ired with genuine s e rv ic e parts, in which case the fo l­
low ing inform ation should prove helpful.
F ig . 9 7 —R elay V a lv e
CHEVROLET TRUCK SERVICE MANUAL