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8.1
TORQUE READOUT PROBLEMS
8.1.1
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ynaMoMeTer
If the dynamometer is new (never operated before) and the torque reading is near full scale and
constant, the probable cause is failure to remove the shipping restraining bolt. This applies to all
dynamometers with model numbers from 106 to 715. For further instruction refer to Section 3.1
– Removal of the Load Cell/Shipping Restraining Bolt.
8.1.2
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ero
alanCe
Zero balance is usually attained by the ZERO control potentiometer on the rear panel of the
dynamometer. Refer to Section 6.2 – Calibration Procedure. If you cannot obtain a zero torque
reading with zero applied torque, you will need to first make sure that your load cell is functional.
To verify that the strain gauge is stable under stress, complete the following steps.
1. Install the calibration beam.
2. Set the power supply for full current.
3. Install a weight on the beam (either side) sufficient to apply close to 100% of full-scale rated
torque. If the reading is stable, switch the weight to the other side of the beam.
4. Steady the weight and the beam to be sure they are motionless.
Note:
8.1.2.1
Steady Torque Reading
If the torque reading is active and steady, you will need to reestablish the zero load cell balance.
1. Adjust the zero control on the rear panel for an approximate mechanical center. This is a
20 turn control, so rotate it clockwise more than 20 turns and then counterclockwise for 10
turns.
2. Disconnect the dynamometer line cord from the line power source.
3. Turn off the digital readout device or dynamometer controller.
4. Lower the rear panel.
Note:
5. Remove resistor R20 from the torque amplification circuit board.
6. Turn on the digital readout instrument.
7. While observing (or recording) the torque reading, start with a 100 K to 200 K resistor and
temporarily connect it in the R20 position on the circuit board.
8. Temporarily jumper solder link SL14. If the reading becomes larger, remove the jumper
and bridge solder link SL 17. If the reading becomes smaller, remove the jumper and bridge
solder link SL 14.
8. Troubleshooting
The torque reading may show activity, but hold steady within three
or four dynamometer torque digits.
It is a good idea to clamp the rear panel to the dynamometer base
plate. This will decrease the possibility of pulling on the fragile
interconnection lead wires.
60
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