Thread: Motor swap advice please

The original motor of my 1948 10ee has expired. I was thinking of going with an A/C type motor when I came across an original style 1954 DC motor for $200. As I am a novice guy that does not use the machine a great deal I thought to put an original style back in and save a little money. The rate I use the machine it will be goods for another 50 ot 60 years this way.
The problem arises when I see a couple of differences, hence my questions.
1 The old motor has a keyway style shaft as the "new" motor has the splined version. Other than the gear is there any thing else I must change?
2 will my gear box bolt directly up to the new one?
3 did they wire these motor differently as the years went by?
I remember the machinist I bought mine from telling me it was wired in "series" and the new one is advertised as being "shunt" wound. Can anyone explain the differnece if there's any at all?
My machine is wired to 220 single phase input and has what I remember to be a solid state syle unit about the sixe of a small shoe box in the far end.
I'm sorry I cannot give more detailed information more than this as I am in Afghanistan at this time.
Any advice or suggestions are greatly appreciated and I thank you in advance.

"The problem arises when I see a couple of differences, hence my questions.
"1 The old motor has a keyway style shaft as the "new" motor has the splined version. Other than the gear is there any thing else I must change?"

That's probably all. It would be a one-gear change.

The interesting part of a splined backgear unit is the splined input gear may be bored to 1-1/8 and then a keyway may be broached, for a VFD conversion.


"2 will my gear box bolt directly up to the new one?"

Should be able to be bolted together, in concept.

However, after the final assembly, Monarch usually placed some dowel pins, and these are probably in different locations on different machines.


"3 did they wire these motor differently as the years went by?"

The 3 HP motors on the M-G machines were purely shunt wound.

The 3 HP motors on the early WiaD machines could be purely shunt wound, or these could be compound wound.

The 5 HP motors on the late WiaD machines, and the Modular machines were compound wound.


"I remember the machinist I bought mine from telling me it was wired in 'series' and the new one is advertised as being 'shunt' wound. Can anyone explain the differnece if there's any at all?"

The shunt wound motors have terminals identified as A1 and A2 for the armature and F1 and F2 for the field.

The compound wound motors have terminals identified as A1 and A2 for the armature, F1 and F2 for the field and S1 and S2 for the series field.

The armature is always reversed. The field never is.

However, the series field, which is in series with the armature, is also never reversed.

Therefore, the DC Panel is designed to reverse the armature, but the series field is not. Therefore, it always has the same polarity as the shunt field.

Peter,
Thank you for the explantion and questions answered. I appreciate it.
One last question if you wouldn't mind though.
Is it safe for me to "assume" that it will not be an issue wiring the shunt wound unit to the solid state convert as the series wound unit after a review of the owner's manual of the solid state controller that is?
I know what a difficult question to answer this is not having more information.
I'm sure it will be a differnet schematic diagram to follow from the controller's manual.