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back end motors- a.o. smith


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  • back end motors- a.o. smith

    i have two a.o. smith be motors that are virtually brand new that will run on the bench, but not under load. they were on machines for about three weeks then quit. this was about two years ago and i just havent cared to look into this simply because my owner has that mantality of "if you need it just order it" i dont get asked any questions... yes i know im lucky. any ideas of what this could be? thanks all
    Don't mind me, what you read is invisible.

  • #2
    Re: back end motors- a.o. smith

    Short to ground somewhere or bad CM or CS.
    So it goes.


    • #3
      Re: back end motors- a.o. smith

      They may have had a manufacturing flaw... I'm just guessing, but some years back, we ordered in some new shur-pik motors that were AO Smith units... 3 out of 5 of them blew up about a month or two after they were put in. I probably shouldn't say 'blew up'... at least that would have been easy to find. They just quit... no reason, nothing. I took them apart, couldn't find anything wrong visually with the wiring or components, but they had no continuity through the windings.

      Just speculation, but I was thinking something like they had bad thermal switches in them... some motor manufacturers bury one or more self-reset thermal switches in the windings that will shut off the motor if the windings overheat, then allow it to come back on after it has cooled. I'm thinking that the switches failed, or the actuial windings failed internally... nothing visible on the outside.

      We started buying Westinghouse motors locally, and didn't have a problem after that.
      <span style="font-style: italic">Educatio est omnium efficacissima forma rebellionis</span>


      • #4
        Re: back end motors- a.o. smith

        Bent Wrench, check out the wiring on them to see if they are wired to your 110 volts, maybe they have been set to 220 volts. You should be able to tell as they have a diagram of the wiring with a color code for where to change the voltage on the motor near the end cap.

        always doing my best.


        • #5
          Re: back end motors- a.o. smith

          Bent W.--You need to read the resistdence between your wires (4 of them) 2 will read 1.3 to 1.8--2 will read between 2.5 and 3.8 The lower numbers are your run windings. It sounds like you are running on the start windings. PSC motors will start with the motor wired either way. Double check the amp draw without load should read 6.3 to 7.3 amps. A fluke 322 about $50.00 is a great tool.
          For Sale- Pickled Eggs--10 cents each, 2 for a quarter, I'll have a quarters worth please.


          • #6
            Re: back end motors- a.o. smith

            Possible the wrong HZ motor.
            They say that the **** rolls down hill but the smell always starts at the top.


            • #7
              Re: back end motors- a.o. smith

              Are these complete motors or just stators? What kind of gearboxes are you turning with them? There can sometimes be problems with the 785 501 014 worm shaft bushing &amp;/or alignment of the field and gearbox adaptor on a certain nameless manufacturer's adaptations of AOS motors.


              • #8
                Re: back end motors- a.o. smith

                astro, they are stators. you know the winding, switch, and klixon. turning westinghouse boxes thanks all.
                Don't mind me, what you read is invisible.


                • #9
                  Re: back end motors- a.o. smith

                  Well, there are a few things in play here. Lets start with the simplest. Sorry if some of these seem obtuse, but sometimes the simplest things get ya.

                  ~Klixon is closed
                  ~Belleville washer is in place
                  ~Capacitor is good
                  ~Wiring has not been pinched and terminals on switch and plug are tight
                  ~Type of cent mech matches type of switch in end bell (there are currently two combinations that AOS puts in BE motors)
                  ~End bell does not have any hairline fractures that would expand when seated to a rotor bearing
                  ~Stator, end bell, and adaptor mate nicely to eachother (some AOS frames are out-of-round or otherwise do not fit well and don't run)
                  ~Winding assy is at the proper depth in the frame to correspond to the rotor (I have seen some that were not assembled properly). You can check this by measuring the distance from the end of the frame to the end of the winding assy and comparing it to the windings in a good stator.

                  I guess I'd have to ask if they hum or try to go at all, or if they're just kaput.

                  Good luck, keep us posted!


                  • #10
                    Re: back end motors- a.o. smith

                    all our back end motors are AO smith and they are a nightmare!!!!. they run stinking hot all the time and we had TWO new ones go onto machines that we knew were good and one lasted 2 days, the other 6 hours, these werent re-wound, they were BRAND NEW and set for 230v 50hz!, if we get them wound to 260v and put a 10MFD run capacitor on them, they behave!!

                    lost three damn combi motors in the space of an hour today, the machines know exactly when you use your last cent mech!!!
                    Want your old pins collecting anywhere in the UK? email me on


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