TM 5-3810-300-24&P-3
13.2.1 Run-In Instructions
In situations where other than basic engine equipment is
c. Adaptor for connecting a pressure gage or
used during the test, proper record of this fact should be
mercury manometer to the engine air box.
made on the Engine Test Report. The effects of this
d. Water temperature gage installed in the water
additional equipment on engine performance should then
outlet manifold.
be considered when evaluating test results.
Dynamometer
e. Adaptor for connecting a pressure gage or water
manometer to the crankcase.
The function of the dynamometer is to absorb and
measure the engine output. Its basic components are a
f. Adaptor for connecting a pressure gage or
frame, engine mounts, the absorption unit, a heat
mercury manometer to the exhaust manifold at
exchanger, and a torque loading and measuring device.
the flange.
The engine is connected through a universal coupling to
g. Adaptor for connecting a vacuum gage or water
the absorption unit. The load on the engine may be
manometer to the blower inlet.
varied from zero to maximum by decreasing or
increasing the resistance in the unit. The amount of
h. Adaptor for connecting a fuel pressure gage to
power absorbed in a water brake type dynamometer, as
the fuel manifold inlet passage.
an example, is governed by the volume of fluid within the
working system. The fluid offers resistance to a rotating
i. Adaptor for connecting a pressure gage or
motion. By controlling the volume of water in the
mercury manometer to the turbocharger.
absorption unit, the load may be increased or decreased
as required.
In some cases, gages reading in pounds per square inch
are used for determining pressures while standard
The power absorbed is generally measured in torque (lb-
characteristics are given in inches of mercury or inches
ft) on a suitable scale. This value for a given engine
of water. It is extremely important that the scale of such
speed will show the brake horsepower developed in the
a gage be of low range and finely divided if accuracy is
engine by the following formula:
desired. This is especially true of a gage reading in psi,
the reading of which is to be converted to inches of
BHP = (T x RPM)/5250
water. The following conversion factors may be helpful.
Where:
BHP = brake horsepower
Inches of water = psi x 27.7"
T - torque in lb-ft
Inches of mercury = psi x 2.04"
RPM = revolutions per minute
NOTE: Before starting the Run-In or starting the
Some dynamometers indicate direct brake horsepower
engine for any reason following an overhaul, it is
readings. Therefore, the use of the formula is not
of extreme importance to observe the
required when using these units.
instructions on Preparation for Starting Engine
First Time in Section 13.1.
During the actual operation, all data taken should be
recorded immediately on an Engine Test Report (see
Run- In Procedure
sample on page 3).
The procedure outlined below will follow the order of the
sample Engine Test Report.
Certain instrumentation is necessary so that daia
required to complete the Engine Test Report may be
A. PRE-STARTING
obtained. The following list contains both the minimum
amount of instruments and the proper location of the
1. Fill the lubrication system as outlined under
fittings on the engine so that the readings represent a
Lubrication System--Preparation for Starting Engine
true evaluation of engine conditions.
First Time in Section 13.1.
a. Oil pressure gage installed in one of the engine
2. Prime the fuel system as outlined under Fuel System
main oil galleries.
-- Preparation for Starting Engine First Time in Section
b. Oil temperature gage installed in the oil pan, or
thermometer installed in the dipstick hole in the
oil pan.
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