Can we really get 225 in-lbs from the drills?
 

Posted by Jason Rukes at 1/12/2001 1:53 PM EST


Engineer on team #109, Arial Systems & Libertyville HS, from Libertyville High School and Arial Systems Corp & SEC Design.



One of Woody's slides during the Kick-Off showed that a current-limited motor will have the same max speed, but less torque than a "current-unlimited" motor. That got me thinking about the drill motors and the effect of the 30A circuit breaker.

The datasheet states the drill motor will stall at 225 in-lbs(low speed). The torque constant is 5.836mN-m/Amp which means the motor can only generate 62in-lbs of torque at 30 amps before tripping the breaker.

Does this sound correct?

Re: Can we really get 225 in-lbs from the drills?
 

Posted by Raul at 1/12/2001 1:58 PM EST


Engineer on team #111, Wildstang, from Rolling Meadows & Wheeling HS and Motorola.


In Reply to: Can we really get 225 in-lbs from the drills?
Posted by Jason Rukes on 1/12/2001 1:53 PM EST:



The breaker does not really trip at 30A. I do not know the specs but it will typically allow quite a bit more current for a certain amount of time.

Raul

: One of Woody's slides during the Kick-Off showed that a current-limited motor will have the same max speed, but less torque than a "current-unlimited" motor. That got me thinking about the drill motors and the effect of the 30A circuit breaker.

: The datasheet states the drill motor will stall at 225 in-lbs(low speed). The torque constant is 5.836mN-m/Amp which means the motor can only generate 62in-lbs of torque at 30 amps before tripping the breaker.

: Does this sound correct?

you get all that and more
 

Posted by Joe Johnson at 1/12/2001 3:14 PM EST


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.


In Reply to: Re: Can we really get 225 in-lbs from the drills?
Posted by Raul on 1/12/2001 1:58 PM EST:



My experience is that you get all that and more.

The motor is a .6N-m motor. In low, you have a 64:1 ratio. .85-.90 per stage and 3 stages, the effective stall torque is between (low est) .6*64*.85*.85*.85 = 23 N-m or 210 in-lbs and (high est) .6*64*.9*.9*.9 = 28 N-m or 250 in-lbs.

From playing with the transmissions over the years, I estimate that it is closer to the second than the first.

Joe J.

P.S. The breaker does trip but not for a while.