[archiver]

Posted by Jerry Eckert.

Engineer from Looking for a team in Raleigh, NC sponsored by .

Posted on 4/2/2000 9:51 PM MST


In Reply to: Re: Eliminating a few other things... posted by Travis Covington on 4/2/2000 3:59 PM MST:



: : Is the motor on the bad side running significantly
: hotter than the opposite side?

:
: Not really. As soon as we install a new one it seems
: to be fine. The are equally warm (not hot). But after
: we have it out on the floor under some load the current
: draw just sky rockets, and the motor is shot. We are
: pretty sure that it is not a problem w/ side loads or
: too much friction.

Current in a circuit is a function of voltage and resistance. The higher the voltage
and/or the lower the resistance the higher the current flow. The voltage isn't a factor,
so the only way for the current to increase is for the load resistance to decrease.

Assuming your robot is wired according to the rules, there should be only three
components in the load side of the circuit: the circuit breaker, the wiring, and the
motor. The normal resistance of the breaker and wiring is negligible, leaving the
motor as the primary suspect.

Joe or one of the others can probably give you a much better idea of the factors which
might cause the motor resistance to suddenly decrease. If you really believe there are
no mechanical problems (abnormal loading, etc.), is it possible metal shaving are getting
inside the motor casing?

Another possibility is an electrical short. If the power connections at the motor are
properly insulated, check all the wiring from the speed controller for damaged
insulation. If you use staples to fasten the wiring to the chassis make sure none of
them have nicked the insulation.

Jerry