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TM 10-3930-671-24
SECTION 7
TEST BENCH REQUIREMENTS & PROCEDURES
SPECIAL TEST BENCH REQUIREMENTS
Any test is only as good as the testing equipment
employed. Incorporation of quality test equipment and
adherence to specifications and the following test
procedures
will
reduce
testing
inaccuracies
to
a
minimum.
a) Calibrating Nozzles: Several different types of
calibrating nozzles will be required for testing the various
DB2 pump models. Be sure to use only the type of
nozzle called for on the individual specification. Some of
the permissible types are listed below:
TYPE
OPENING PRESSURE -p.s.i.
DN12SD12
2500 - (170 ATS)
AMBAC PCU25DO50.5
Orifice Plate (SAE Std.)
3000 - (204 ATS)
AMBAC TSE77110 - 518
.5 Orifice Plate
1700 - (116 ATS)
Use of the SAE 1150 orifice plate nozzle is described in
SAE recommended practices J968c and J969b.
b) Injection Lines: Several injection line sizes (length
and I.D.) have been released for service use. Use test
injection lines equal in diameter to those installed on the
TMD 27 engine.
c) Calibrating Oil: Use calibrating fluid or injector test oil
listed in Appendix C. Calibrating oil should be changed
every three months or 200 pumps (whichever comes
first).
d) Calibrating Oil Temperature: The temperature of the
oil in the test bench must be maintained within
1100115°F while testing Roosa Master fuel injection
equipment.
NOTE
This reading should be taken as close
to inlet as possible. The test bench
should be equipped with a heater and
thermostatic control to maintain this
temperature.
e) Test Bench: Mount and drive the DB2 pump models
according to the test bench manufacturer's instructions.
In addition, the test stand coupling should be of the self-
aligning, 'zero" backlash type; similar to the Thomas
Coupling types or Robert Bosch (SAEJ969b).
GENERAL TEST PROCEDURE
a)
Install applicable transfer pump inlet connector,
using two (2) wrenches so that the pump outlet fitting
does not get moved at the same time. Install transfer
pressure gauge connector. Install a shutoff valve to
isolate the gauge when not in use. Connect a pressure
gauge to the 21900 adapter. Some automotive DB2
pumps require 114 of one degree setting accuracy. If so
specified, remove the timing line cover and replace with
the advance gauge. If the advance gauge is not
required, replace the timing line cover with the advance
test window.
b)
Determine proper direction of pump rotation from the
specification. Rotation is determined as viewed from the
drive end of the pump.
c)
If the pump is equipped with an "Energized-to-
Run" electric shutoff device, energize it at the lowest
speed with 12 volts. Move pump throttle lever to full load
position. When transfer pump is primed, allow fuel to
bleed for several seconds from loosened injection line
nuts at the nozzles. Tighten line nuts securely.
NOTE
Roosa Master pump specifications
list
fuel
delivery
in
cubic
millimeters/stroke.
Some
test
benches measure fuel flows in cubic
centimeters (milliliters). To convert
from mm3/stroke to CC’s use the
following formula:
Delivery in CC’ s = mm3/Stroke x No. of Strokes
1000
EXAMPLE:
If
the
Specification
calls
for
72
mm3/stroke and the test stand counter has been set
for 500 strokes, simply substitute these numbers
into the formula and calculate as follows:
72x500
Delivery in CC’s =
= 36 CC's
1000
Bear in mind when testing Roosa Master pumps that
our specifications refer to engine RPM (ERPM) and
that most test bench tachometers register pump
RPM which is 1/2 engine speed for four stroke cycle
engines.
F-249
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