Evaluating DC Motors

1
Evaluating DC Motors
Determining Motor Stall Torque and No Load RPM
2
The Test Bench Set Up
Requirements
Securely fasten motor to the Test Bench. Use 10
AWG or larger, Multi Stranded Wire. Battery or
Batteries similar to those intended for use in
the BattleBot. HD Automotive Starter Switch
Caution Testing motor torque creates strong
electrical and mechanical forces. Wear Eye
Protection. Work with Adult supervision.
3
Special Equipment
Build a motor torque arm
Use 1x1x1/16 steel angle 3/8 Shaft Collar
4
Create the Stall Condition
Wear Eye Protection
3 People should perform the test. Set up and hold
the scale Mark the scale Energize/de-energize the
system.
5
Set Up and Hold the Scale
Wear Eye Protection
Scale with Taped Marking
Torque Arm Retainer
Motor Torque Arm
6
Create the Stall Condition
Wear Eye Protection
Procedure
Assume the stations Energizer Scale holder Scale
marker Energize the System Raise the Torque Arm
with the Scale Mark the Scale Deflection De-Energi
ze.
ALWAYS Record, Describe and Date the Data
7
Determining the Torque Value
F Force (lbs.) 3 lbs D Length (ft.) .5 ft Q
Torque (ft.lbs.)
F
D
Q
D x F
1.5 ft.lbs. .5 ft. x 3 lbs.
ALWAYS Record, Describe and Date the Data
8
Measure No Load RPM
Wear Eye Protection
Procedure
Mark Armature Shaft with Reflective
Tape. Energize the System Read the No Load
RPM De-Energize.
ALWAYS Record, Describe and Date the Data
9
Directly Measuring Motor Stall Torque is a
Learning Experience.
Voltmeter
12V Battery
Sample Motor
Ammeter
NC MO Switch