reference for terminology - motor "front end" and "back end"

[electricpete]

In the motor business, the terminology is well established:
Front end = non-drive end = opposite-shaft end = outboard end.

Back end = drive end = shaft end = inboard end.

What I need is some kind of authoratative reference to prove to others the above standard definition of the terms "front end" and "back end". I'm really looking for a standard, but even a website might be helpful.


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[jraef]

Hmmm, I have always considered it to be exactly opposite of what you posted: Front = drive end, Back = non-drive end. But then again, I never had anyone tell me one way or the other so I could be totally wrong.

Check this out. You appear to be correct according to Reliance's motor glossary. Click "B" to look up "back end" and "F" for "front end".

http://www.reliance.com/prodserv/motgen/b9652new/b9652.htm

Of course double ended motors now have me confused. Thanks a lot, just another useless conundrum to have rattling around in my brain!

"Venditori de oleum-vipera non vigere excordis populi"

 

[dpc]

I'm not a motor expert, but my first impression was the same as jraef - the opposite of what you said.

I've not heard the terminology used much at all, to be honest.

 

[electricpete]

OK, probably well established was not a good way to say it, but this front/back terminology is sometimes used among OEM's.

1 - Here is an excerpt from Reliance's motor terminology:

http://www.reliance.com/mtr/cmna.htm

"BACK END OF A MOTOR
The back end of a normal motor is the end that carries the coupling or driving pulley (NEMA). This is sometimes called the drive end (D.E.), pulley end (P.E.) etc"

"FRONT END OF A MOTOR
The front end of a normal motor is the end opposite the coupling or driving pulley (NEMA). This is sometimes called the opposite pulley end (O.P.E.) or commutator end (C.E.) "

2 - Here is an excerpt from the EASA (Electrical Apparatus Service Association) Technical Manual

http://reliability-magazine.com/pub/easa_allis.jpg

It is a table of bearings for Allis Chalmers motors manufactured at a specific plant. The two right columns use the terms front end and rear end (rear=back is hopefully not in question). From examination of the chart we see that presence of a belt affects the selection of the rear bearing. It is easy to conclude from this that the intended meaning that front=outboard, rear=inboard. The EASA manual includes a similar chart with similar terms for every motor manufacturer, although nowhere in the manual are the terms specifically defined.

This front/back terminology is also used on a drawing for one of our motors purchased 17 years ago. I know the correct bearing (from the nameplate), but for reasons that are difficult to explain I am tasked to unravel a series of parts paperwork errors made 10 years ago and a reversal of front/back terminology is one piece of many errors in my proposed explanation. I was challenged to prove my assertion on the terminology and as of yet I have no definitive reference. If anyone knows a standard or industry (vs vendor) publication, I would be interested to hear it.

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[jraef]

I assume you already searched in NEMA MG-1?

"Venditori de oleum-vipera non vigere excordis populi"

 

[electricpete]

There is no definitino in 2003. I did find use of the words in the following section:

"Section II MG 1-2003
DEFINITE PURPOSE MACHINES Part 18, Page 51
SMALL MOTORS FOR COOLANT PUMPS
MANUFACTURING
18.144 GENERAL MECHANICAL FEATURES
Coolant-pump motors shall be constructed with the following mechanical features:
(see 18.131)
a. Totally enclosed
b. Grease-lubricated ball bearings suitable for horizontal or vertical mounting which shall have suitable provision for taking axial thrust away from the front end.
c. Back end shield shall be machined in accordance with Figure 18-16, except that the 5/8”-18
tapped hole in the bearing hub shall be omitted.
d. The straight shaft extension shall be in accordance with 4.4.1 and 4.5 or, alternatively, in accordance with Figure 18-17.
e. Terminals or leads shall be located in the front end shield or on the frame adjacent to the front end
shield.
f. The capacitor unit, when mounted externally on capacitor motors, shall be attached to the motor
frame 90 degrees counterclockwise from the terminal location while facing the front end of the
motors."

item b - not sure what they mean.
item c - the only 5/8”-18 tapped hole I see on the figure is on ODE which would imply back=ode - opposite of what I have assumed.
item e - the only terminals I have ever seen in an endshield of small motor are on the ODE. implies front=ode - consistent with what I have assumed.
item f - can't draw any conclusions from the figure. Although in similar section 18.130 for jet pump motors there is a requirement "g. The capacitor unit, when mounted externally on capacitor motors, shall be attached to the motor frame 90 degrees counterclockwise from the terminal location facing the end opposite the drive end as shown by the dotted lines in Figure 18-16." IF the requirements are intended to be the same, THEN we conclude front = ODE, which is the same as I have orginally assumed.

All in all, NEMA doesn't seem very definitive on this issue. It is annoying that NEMA MG-1, like the EASA Technical manual, uses the terms front and back without ever defining those terms.

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[electricpete]

I should clarify that my last post applies to NEMA MG-1, in response to jraef's comment.

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