TRUCK SERVICE MANUAL
Calibration Test Equipment
Cummins ST-848, ST-775, and ST-445 (with ST-773
calibrating the PT fuel pump, but due to some older
conversion) fuel pump test stands have the following
engines being built on special, "one time" orders cannot
features to provide accuracy:
be applied to all engines which have been built with PT
fuel pumps.
1. Large dial, laboratory accurate gauges. However,
gauges are only accurate if properly maintained and
Test Oil
should, therefore, be checked at regular intervals.
Cummins fuel pump test stands must be filled with clean
Cummins Test Oil No. 99011-68 or equivalent since all
2. Accurate tachometers, either electric on ST-445, ST-
calibration data has been established using this test oil.
775 and ST-848 or hand tachometer ST-774 for use with
ST-445. A digital tachometer is now In ST-848.
Note: Hydraulic oils are not suitable to use as test oils in
Cummins test stands.
3. A flow-meter, which permits the tester to adjust each
fuel pump for total flow and correlate it with pressure
Duplication of factory test methods and materials is the
calibration. The "fuel manifold pressure" thus obtained
key to correct calibration and insures uniform results
on the test stand will duplicate fuel manifold pressure on
wherever the fuel pump is adjusted.
the engine.
General Requirements
Test Stands
Cummins fuel pump test stands equipped with a flow-
The material shall be a straight oil or a blend of oils
meter are ST-848,ST-775 and ST-445 (with ST-773
containing parafinic, aromatic or naphenic compounds,
conversion kit.) These test stands provide the most
but not olefininc compounds, which show little or no
accurate method of
change in physical properties during storage or use. The
use of various additives and/or inhibitors to stabilize the
oil is left
Fig. 5-1-1, F5100. Cummins ST-848 Fuel pump test stand
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