(ET) Lift motors from cars

[Chris Zach <czach computer org>]

Ok. In an effort to fix my real lift, I went out on Ebay and got a deal: 
4 window motors from a 1971 Buick. All were in pretty close to perfect 
shape. All for $20.00+15.00 shipping.

What a deal. I'm sure everyone thought these would be great cheap 
substitutes for the stock elec-trak lift motors:

Forget it.

I put one together last night. Hummed perfectly at 12 volts on the 
bench. Took off the gear system, changed the brushes to support a third 
wire instead of ground, drilled a hole in the side of the unit, and ran 
the wire. Packed it up, and tested it again.

Perfect.

So I filed down the case protrusion so it would work in the rear lift. 
Simple job. Once done I mounted it to the rear lift, hooked it up to the 
tractor and tested it no load.

Quick. Very nice, very strong. So I hooked it up to the tractor. Mind 
you it has an internal breaker, and I had it on a 30 amp fuse to 18 
volts of the rear batteries.

BOY does this thing lift the tiller. No problem, hauls it right up. That 
should have been my clue; nothing works that well.

So I did a row or two, lift died. Drove back to the shed, took the motor 
off, ran it on 12 volts. Very slow, very high current. Opened it up.

The armature wires are badly burned. Commutator (which was clean when I 
put it in) was black from carbon arcing. The resistance of the field was 
half what it should have been and most of the windings looked burned. 
This was from a few minutes.

My guess is that GE wired the motors to handle 18 volts by rewinding the 
armatures and stator coils. Or maybe just the armatures. Whatever they 
did, the stock 12 volt motors can't be run at 18 volts. They will be 
carbonized as sure as 18 volt lift motors are at 24 volts.

I'm going to try and build another motor and run it on a 12 volt tap. 
Might work better, but my guess is the lift power will be less, the amp 
draw will be more, etc.

The right solution is to pay $$$ for a new GE lift motor :-) Anyone else 
have a running Buick window motor?

Chris