Technical data

28
Park the vehicle on level ground and chock wheels. Build system pressure to governor cut-out
and allow the pressure to stabilize for one minute.
1: Observe the dash gauges for two additional minutes without the service brakes applied.
2: Apply service brakes for two minutes (allow pressure to stabilize) and observe the dash
gauges.
If you see any noticeable decrease of the dash air gauge readings, repair leaks. Repeat this
test to confirm that air leaks have been repaired and return vehicle to service. Please repeat
BASIC test at next service interval. Note: Air leaks can also be found in the charging system,
parking brakes, and/or other components - inspect and repair as necessary.
STEP E - If no air leakage was detected in Step D
STEP D - Air Brake System Leakage Test
STEP C - How to Use the BASIC Test
Sixty days since last air
tank draining
Decision point
The Technician uses the chart (label) on the BASIC
test cup to help decide the action to take, based on
the amount of oil found. Use the lower acceptance
line for low air use vehicles, and upper line for high
air use vehicles (from Step A).
If no air leakage was detected, and if you are conducting
this test after completing Step C, go to Step E.
BASIC Test Example
An oil level of 4 units in a sixty-day period is within the
acceptance area (at or below the line) for both low and
high air use vehicles. Return the vehicle to service.
1. Record days since air
tanks were last drained.



3. Action to
take
2. Record amount
of oil found:
If number of days is:
30-60 days (high air
use) or
30-90 days (low air
use)

if oil level is at or below
acceptance line for number
of days
if oil level is above
acceptance line for number
of days 
System OK.
Return to service.
Otherwise . . .

(if the number of days is
unknown, or outside the
limits above)
if oil level is at or below
30-day acceptance line 
if oil level is above 30-day
acceptance line 
STOP
TEST
Stop inspection.
Test again
after 30 days.
See Footnote 2.
_________ days
_________ units
Go to Step D
System OK.
Return to service.
STOP
TEST
STOP
+ CK.
The Technician looks for the point where the number
of days since the air tanks were drained meets the
oil level. If it is at or below the (low or high use)
acceptance line, the vehicle has passed the test. If
the point is above the line then go to the leakage
test.
Air leakage is the number one
cause of compressors having
to pump excessive amounts of
air, in turn run too hot and pass
oil vapor along into the system.
Here the Technician conducts
a four-minute test to see if
leakage is a problem with the
vehicle being tested.
The Technician only reaches
Step E if the amount of oil
found, for the amount of
time since the air tanks were
last drained exceeds the
acceptance level, AND the
vehicle passes the four-minute
leakage test (no noticeable
leakage was detected).
Replace the compressor.
Note: If the compressor is within warranty period,
please follow standard warranty procedures. Attach
the completed checklist to warranty claim.
Filling in the Checklist for the Bendix
®
Air System Inspection Cup (BASIC) Test
Note: Follow all standard safety precautions. For vehicles using a desiccant air dryer.
Appendix A continued: Information about the BASIC Test Kit (Bendix P/N 5013711)
Oil
Level
X
Acceptance
Lines