TM 5-3895-359-14&P
In situations where other than basic engine equipment is
a.
Oil pressure gage installed in one of the
used during the test, proper record of this fact should be
engine main oil galleries.
made on the Engine Test Report. The effects of this
b.
Oil temperature gage installed in the oil
additional equipment on engine performance should
pan, or thermometer installed in the dipstick
then be considered when evaluating test results.
hole in the oil pan.
c.
Adaptor for connecting a pressure gage
Dynamometer
or mercury manometer to the engine air box.
d.
Water temperature gage installed in the
The function of the dynamometer is to absorb and
thermostat housing or water outlet manifold.
measure the engine output. Its basic components are a
e.
Adaptor for connecting a pressure gage
frame, engine mounts, the absorption unit, a heat
or water manometer to the crankcase.
exchanger, and a torque loading and measuring device.
f.
Adaptor for connecting a pressure gage
or mercury manometer to the exhaust manifold
The engine is connected through a universal coupling to
at the flange.
the absorption unit. The load on the engine may be
varied from zero to maximum by decreasing or
g.
Adaptor for connecting a vacuum gage
increasing the resistance in the unit. The amount of
or water manometer to the blower inlet.
power absorbed in a water brake type dynamometer, as
h.
Adaptor for connecting a fuel pressure
an example, is governed by the volume of fluid within
gage to the fuel manifold inlet passage.
the working system. The fluid offers resistance to a
rotating motion. By controlling the volume of water in
In some cases, gages reading in pounds per square inch
the absorption unit, the load may be increased or
are used for determining pressures while standard
decreased as required.
characteristics are given in inches of mercury or inches
of water. It is extremely important that the scale of such
The power absorbed is generally measured in torque
a gage be of low range and finely divided if accuracy is
(Ib-ft) on a suitable scale. This value for a given engine
desired. This is especially true of a gage reading in psi,
speed will show the brake horsepower developed in the
the reading of which is to be converted to inches of
engine by the following formula:
water. The following conversion factors may be helpful.
BHP = (T x RPM)/5250
Inches of water = psi x 27.7"
Where:
Inches of mercury = psi x 2.04"
BHP = brake horsepower
NOTE: Before starting the Run-In or
T = torque in lb-ft
starting the engine for any reason
RPM = revolutions per minute
following an overhaul, it is of
extreme importance to observe the
Some dynamometers indicate direct brake horsepower
instructions on Engine Run-in
readings. Therefore, the use of the formula is not
Instructions on Page 10-9-2.
required when using these units.
Run-In Procedure
During the actual operation, all data taken should be
recorded immediately on an Engine Test Report (see
The procedure outlined below will follow the order of the
sample on Page 10-94).
sample Engine Test Report.
A. PRE-STARTING
Certain instrumentation is necessary so that data
1.
Fill the lubrication system as outlined under
required to complete the Engine Test Report may be
Lubrication System on Page 10-5-1.
obtained. The following list contains both the minimum
amount of instruments and the proper location of the
2. Prime the fuel system as outlined under Fuel System
fittings on the engine so that the readings represent a
on Page 10-3-1.
true evaluation of engine conditions.
10-9-3
