Subject:
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RE: 8475 Motor Tests
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 8 Jan 2003 19:16:54 GMT
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Original-From:
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Tony Burton <TONY.BURTON@CRYSTALROCK.nomorespamCO.NZ>
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Viewed:
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661 times
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I don't have a 5292 motor or I would do this test myself, but it would be
possible to get a more direct comparison with the 71427 gear motor. The
1700-RPM output could be geared down to 340 RPM at a gear ratio of 1:5 with
8- and 40-tooth gears.
Tony
-----Original Message-----
From: news-gateway@lugnet.com [mailto:news-gateway@lugnet.com]On Behalf
Of TJ Avery
Sent: Thursday, 9 January 2003 4:21 a.m.
To: lego-robotics@crynwr.com
Subject: 8475 Motor Tests
Last night I performed a few quick tests on the 5292 motors (the new motors
from the 8475 Race Buggy set:
http://www.bricklink.com/catalogItem.asp?P=5292) to compare them to the
standard geared 9V motor
(http://guide.lugnet.com/partsref/search.cgi?q=71427c01).
In summary, the 5292 motor (when geared down to match RPM of 71427) has
about 2.33 times more torque (when stalled). I powered the motors with a 9V
train controller, the dial being rotated to maximum output.
The test set up was simple. I tested the 5292 in several arrangements, and
also tested the 71427 motor for comparison. The test involved powering a
winch that lifted a variable weight. I increased weight until the motor
could just barely lift it. This test and winch set up may not provide the
most precise answers, but will hopefully give us a fair comparison of the
motors (which was my goal).
The test set-up and maximum torque results are presented below:
• 5292 motor, 1:1 ratio[1], 1200 rpm output[2], TORQUE = 0.40 lb·in (4.6
N·cm)
• 5292 motor, 1:3 ratio[1, 3], 1200 rpm output[2], TORQUE = 1.09 lb·in (12.4
N·cm)
• 5292 motor, 1:1 ratio[1], 1700 rpm output[2], TORQUE = 0.34 lb·in (3.8
N·cm)
• 71427 motor, 1:1 ratio[1], TORQUE = 0.48 lb·in (5.5 N·cm)
Looking at the 2nd and 4th test set ups, the winch has a no load rpm of 400
and 360, respectively. To make an equal comparison of torque output, the 2nd
test should have had a no load rpm of 360, but I could not gear it that way
easily.
Taking the first two test set ups and fitting a line to the data (Torque vs.
RPM), you can extrapolate to get the torque at a no load rpm of 360. The
result is 12.8 N·cm, which is 2.33 times the torque of test 4 (the 71427
motor).
-TJ
notes:
1. Ratio means the additional gear reduction I built onto the motor. 1:1
means direct drive- no gears.
2. The 5292 motors have two output holes. No load RPM are different for
each: 1200 and 1700 (Ref. http://news.lugnet.com/technic/?n=7701 &
http://news.lugnet.com/org/ca/rtltoronto/?n=6087).
3. 1:3 ratio: A set of 8t and 24t gears were added between the motor and
winch.
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