Mounting The Dynamometer To The Test Bench; Aligning The Dynamometers On The Test Bench; Vibrations Induced By The Test Bench - Magtrol WB Series User Manual

Magtrol WB/PB Dynamometers
2.2

MOUNTING THE DYNAMOMETER TO THE TEST BENCH

The dynamometer should be placed on a stable horizontal base plate—preferably constructed of cast
iron, steel or aluminum—in order to eliminate vibrations to the greatest extend possible. Flatness
defects should not exceed 0.05 mm. In addition, the dynamometer frame must withstand the torque
transmitted by the dynamometer without deformation.
The dynamometer is mounted onto the bench by means of four screws. The size of these screws
depends on the dynamometer model. Tandem dynamometers require stronger screws than single
dynamometers. Refer to the data sheet of the corresponding dynamometer (see Section 1.2) for
additional information on the screw type and size.
2.2.1 A
ligning the dynAmometerS on the teSt Bench
The proper alignment of the dynamometer with the motor under test is very important. The higher
the speed of the test, the more care must be taken when performing the alignment. The maximum
tolerated misalignment depends on the selected coupling.
With high-speed Eddy-current dynamometers (WB-HS), 0.01 mm may be tolerated. With magnetic
powder dynamometers (PB) operating at lower maximum speeds, a misalignment of up to 0.1 mm
is acceptable.
2.2.2 V
iBrAtionS induced By the teSt Bench
Vibrations generate premature wear of the bearings. Since modifying the motor under test in order
to prevent any vibration is not feasible, measures will have to be taken to forestall any damage to
the dynamometer.
In order to evaluate motors producing vibrations (for instance, combustion engines), the motors
must be mounted on a heavyweight base plate equipped with vibration mounts. By doing this, the
vibrations transmitted from the motor to the dynamometer will be reduced considerably.
Height differences due to varying motor loading must be taken into account. The vibration mounts
should not be compressed, creating a misalignment between the motor and the dynamometer. This
would affect the measurement results and damage the dynamometer.
Note: Magtrol offers standard and custom dynamometer tables specially
designed to support the entire range of Magtrol dynamometers.
C : o
aution perating at the resonanCe frequenCy of the measuring Chain
will severely damage the dynamometer
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Chapter 2 – Installation / Mounting
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