what going on here

used my lathe yesterday morning just to run a small piece of brass down for a meccano project, went back to it in the afternoon, push the start button and its starts up running backwards, it hasn't got the reverse option. any ideas

Gone on strike maybe.

Either the start coil or capacitor has gone short circuit. Or if it has a centrifugal switch it may be faulty. Please give more information and a picture of the motor would help.

David

Hi there David, it hasn't got a capacitor coil that i can see, its an old motor one with the wick string packed around the bearings i'll go and take a few photos

here are a few pictures of the offending object the old motor theres more in the folder

What about the other end of the motor ?

There's a type of older motor that uses brushes to start which can be reversed by rotating the brush carrier, no cap involved. So if they come loose........

there is some more pictures in the folder

You could phone the manufacturer and chat to the people who made it

LOL, back then i bet they would just have replaced it and said good day to you sir.

Terry

Your picture album shows the label telling you how to reverse the motor by swapping leads about. The rectangular box attached to the motor could well contain a starting capacitor, they don't have to be in cylindrical form. How that can switch to reverse on it's own I don't know unless the motor has ingested swarf into the internal wiring and that is providing the new starting "wiring"

It might be appropriate to change the motor anyway for a more modern one.

Brian

Hi Terry, does it always go the wrong way when you start it now? You could try removing the belt from the motor and spin the motor in the right direction and keeping fingers and thumbs out of the way and then start it before it stops turning, if it then runs the right way, it is probable that the start circuit has failed in the winding, a loose wire or a faulty centrifugal switch or brushes that Dave Halford has mentioned, not making contact anymore. If when you do start it without turning before hand and sometimes it goes one way and sometimes it goes the other way, that would also indicate a fault in the starting circuit.

Regards Nick.

Edited By Nicholas Farr on 25/08/2022 11:38:02

My guess is that it would not have a capacitor. You can achieve the same result with windings of different inductance, so one winding will be lots of turns of thin wire, the other fewer turns of thick wire. It is probably the thin one that has failed.

Martin

I agree. There's no sign of a capacitor so my guess is it's a split-phase motor. Probably the start winding has failed, but that type also has a centrifugal switch that might be stuck, dirty, or the contacts are badly worn. Worth having a look. The switch will be under the cover with the motor plate at the red-taped box end. Undo the 4 nuts and ease the cover off to see what state the switch is in. With luck some tender loving care will put it right.

Otherwise time for a new one because the motor is ancient beyond repair. The other brass plate says the bearings have to be manually re-lubricated every 3 months, and avoiding the need to pay men to do that was a major reason for replacing old motors in the distant past.

Dave

H&S look away.

Slip the belt off, wrap around the shaft a length of soft cord, note the direction you did the wrapping, give the cord a firm pull and switch on. Note motor direction of rotation, switch off. Do the same with the cord, but in the other alternative direction, switch back on and again note DOR. You have just tested the run winding for continuity. So your fault is in the start circuit and most likely the centrifugal switch..

That terminal box doesn't look like the original one and no signs of a capacitor, so as Dave says, a spilt phase. Before you take it apart to hopefully locate the fault, with a scriber mark both bell ends. Two marks on the drive end and single on the non drive end straight across, these are to help you when reassembling the motor. When withdrawing the rotor be very care full not to scratch the windings and break a wire, as it can be very difficult to locate the other broken end and carry out a repair, also don't let the rotor fall on the workshop floor and bend the shaft. Do not oil the centrifugal switch mechanism, you might need to clean up the contacts. Once you have the motor reassembled, and for your own personal safety you ought to get your friendly electrician, to give it an insulation test, before connecting to the supply once again Let us know how you get on and don't forget the most important wire the EARTH. John

Hi, I thought about the cord idea that John Fletcher 1 suggests, after my edit window expired in my previous post. this will give you more time to switch on after spinning up the motor, but do make sure the cord is completely off and out of the way of the pulley/shaft before you press the start button.

Regards Nick.

Edited By Nicholas Farr on 25/08/2022 15:10:58

i have taken the box off the side of the motor and found the wires have cooked the isolating outer cover on the wires has fallen off leaving bare wires all the way into the windings..... bugger.

Thank you everyone

As a last ditch it might be worth putting shrink sleeve on the wires, replacing any that have burnt away and try it ! If it still runs backwards or takes the trip out - your right, your buggered ! Noel

Bad news indeed. Likely cause is an insulation failure inside the windings. It's unlikely to be worth fixing.

Deserves an honourable retirement. I don't suppose English Electric expected it to last until 2022!

On the plus side, the photos show it shouldn't be difficult to fit a replacement. Is it worth going 3-phase with a VFD to get smoother turning and speed control?

Dave

Hi Terry, $#it happens, but I would investigate Noel's idea, although you will probably have to take the back end off to get all of the bare wires covered, shouldn't be too difficult to do, just take photos of each stage so you can put all back together correctly.

Regards Nick.