RE: (ET) E20 motor stud getting extremely hot.

["Hazen, Dwight L" <hazen indiana edu>]

Don, 

 The stud, connector or wiring may have been damaged by the heat from
the loose connection. You are right some or all of the above parts may
now be a resistor. Try replacing parts. Also be sure the field to the
motor is working ok, no field voltage or low field voltage will cause
the motor to draw lots of current heating up connections and parts. 

  Dwight

Dwight L. Hazen, Indiana University, UITS 
Bloomington, In. 47408-7378
812-855-5367 IP phone 317-278-4014    
hazen indiana edu http://php.ucs.indiana.edu/~hazen/
Ham Radio wb9tlh arrl net http://wb9tlh.ampr.us
 

-----Original Message-----
From: Don Cohen [mailto:bond007d netsync net] 
Sent: Tuesday, June 03, 2003 12:47 PM
To: elec-trak cosmos phy tufts edu
Cc: ThompsonG DFO-MPO GC CA
Subject: (ET) E20 motor stud getting extremely hot.



Model #26AE20ED

Hello all,

I have been following this group since 1999.  Since I haven't had many
problems, I haven't posted in a while.  I have a problem now, and need
some advice.  For about a year or so, now, I have noticed a loss of
power from the ET.  It can't go near as fast as it used to in D2, and
the power use gauge tends to move up into the red area much faster than
it should when tractor is under load and pedal is down too far.  The
batteries were new from Sams Club in the summer of 1999.  They charge up
just fine and have no trouble holding the about the same charge.  A few
days ago, I was poking around trying to find some answers and noticed
that the A1 stud (red #8 wire) on the traction motor was too hot too
touch after only driving the tractor a few hundred feet in D1, which
included going up one approximately, very short 35 degree incline.  The
stud felt loose at the motor (wire itself seemed tight), so I went to
the trouble of removing the motor and inspecting the brush area where
the stud is mounted.  Everything looked OK inside.  No evidence of
scoring or overheating at all.  The brushes and bearing were just
replaced last year.  The bottom of the stud where the brush connector
screws to was a little less than shiny, so I cleaned that up - but it
really didn't look that bad.  Screw that holds the spade connector
against the bottom of bolt was fairly tight.  The insulator on the stud
was intact as far as I could tell.  The bottom nut that rests on the
square black insulating pad seemed to be rusted on, as I couldn't remove
it.  I put everything back together and replaced the ring terminal on
the red wire which was heat fatigued back about an inch.  Tried the
tractor again, and the same problem is there, although it seems to get
SLIGHTLY less hot as compared to the same use time before. The heat
buildup is only at the stud and ring terminal.  The wire itself and the
terminal at the 2A contactor only seems to be very slightly warm, if at
all.  I did notice that the 2 terminals at the bottom of the R-contactor
get quite hot also.
 
Has anyone seen this kind of behavior?  Can someone take their E20 for a
short run of a minute or so, with light to moderate load in say D1 or D2
and then check the red power wire on the motor stud to see how hot it
gets?  Also, check the bottom studs at the R-contactor to see if they
heat up as well, and how much.

I am suspecting that the motor stud itself may be bad, possibly at the
place where that bottom nut is stuck on, and acting like a resistor.  At
any rate, there seems to be a lot of voltage dropped at that point for
it to be heating up so.  I  wonder if between that, and the apparent
abnormal heating at the 2A contactor, that those are causing my poor
performance?  

Any ideas that anyone has as to what may be causing this will be greatly
appreciated.

Thanks, 
Don C.
Shinglehouse, PA