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Motor Replacement on 1940 Sundstrand Drive


Sep 28, 2002
Salinas, CA USA
The GE TriClad 3HP 1720 RPM single phase motor in my 1940 10EE failed a couple weeks ago. It started smoking and ran with a loud buzz, even though it seemed to have full power. There are some overheated windings, but I think the problem is related to the run or start capacitors, so the motor may be repairable.


I needed to get the lathe running so in the mean time I am installing another motor. There are a few details about making the swap that may be of interest to others, so that is the reason for this thread.

The other 3HP single phase motor I had on hand is a Rockwell 1720 RPM motor, originally from a 20” bandsaw. It is not a simple drop in, however. The length and diameter of the motor were perfect. The pulley from the GE Motor fits the shaft on the Rockwell. However, there are some problems. The peckerhead and the dual capacitors were both on the sides of the motor, so they needed to be moved to the top. The mounting holes have a different spacing, so an adapter plate needed to be fabricated.



I tried moving the peckerhead to the top of the motor, but the capacitors were in the way, so I ended up adding a jbox to the top of the motor.


The sight glass for the hydraulic unit was leaking, so it needed to be removed and a new cork gasket was installed.



Also, the way the Sundstrand drive is mounted in the base casting may be of interest. First, there is a base plate that is attached to the bottom of the base casting with rubber mounts. It is attached in three places, using typical Monarch fasteners with two pin holes.
Second, the Sundstrand drive attaches to the base plate using four SHCS. There are shims between the Sundstrand drive and the base plate. The pair at the outer end of the drive were thinner than the pair at the inner end, so my guess is that they were intended to level the drive. One of the shims is shown on the adapter plate photo above. Here are some photos of the inside, but they are dark and it may be hard to make out the details.

There are also some rubber discs on the sides that fit between the Sundstrand drive and the base casting.



That motor is repairable by being rewound. The coil with the cooked insulation is not usable, no mater what the original cause.
The operator's manual says the oil capacity of the Sundstrand drive is "3 to 5 gallons". That really narrows it down, doesn't it? I have no idea why there is such a large range. The pump might retain a pint of oil, but a 2 gal. range makes no sense. It actually took 3.25 gal, and that was after tilting the base of the lathe so all the oil would drain out. Next time I drain the oil I will make a fitting with a tube to direct the oil. But based on how long it took for me to change the oil this time, it will likely be someone else's problem.

BTW, I think the spacers under the drive are actually to provide a bit of a slope to drain the sump. The outer spacers are ⅛" and the inners are ⅜" thick.
Russ, that is the replacement motor that I just installed. The motor it replaced had a 215 frame. The original three phase motor was yet another frame, but close enough to 215 that I was able to re-drill the feet of the 215 to fit.