Help with Cowells 90 Lathe wiring diagram

Could any of you experts out there help me please?

I have a Cowells 90 Lathe. It is on a blue cast base with the single forward and reverse switch. It has a GEC electric motor.

The problem is the motor is getting extremely hot in a short period of time although it does go in forward and reverse. The motor was examined by a specialist and they found that the starter windings were burnt out and they re-wound it for me. I have just re-fitted the motor but it is doing the same thing again and getting very hot in a short period of time.

Has anyone got any ideas what the problem could be? And also, has anyone got a wiring diagram or perhaps a replacement electric motor?

I'd be very grateful for your assistance. Chris.

sounds like the centrifugal switch is not opening (if it has one), if it gets too hot to bear your hand on, stop using itbecause there IS a problem

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Dear Phil. Thanks very much for your information. Yes I did it off straight away - as they say there's no smoke without fire. I will check and see if the motor has a centrifugal switch. Best wishes, Chris.

Dear Bill. I did speak to Cowells but they said they haven't got the wiring diagram for the older models. They did tell me that the GEC motor does get hot but not so quickly as mine does. Hopefully someone out there has got the wiring diagram or if they have got a similar Cowells me as mine they would be kind enough to send me a picture of the wiring under the plate. The trouble is that on the older lathes you don't know in the past if someone has reconnected the wires incorrectly. Thanks again, Chris.

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Hi, I just wanted to thank all the replies I had regarding the overheating of the motor on my Cowells 90 lathe. I tracked it down with a problem with the relay, now its running fine. Also I would like to personally thank Malcolm at Penny Farthinng Tools.. Although I never purchased the lathe from them he was of great assistance and couldn't of been any more helpful. Also thanks to brothers EMR Swindon who sorted the motor for me.There are some great companies out there. Thanks again to you all you were a great help, Chris.

Chris

I have a Cowells of, by the sound of it, similar age, certainly the GEC motor. My problem is that whilst it will start and run, the motor sounds very lumpy until the start relay lethargically operates, after which it is fine. I spoke to Cowells who identified the relay as the problem but they didn't have any replacements. Am I correct in thinking that you have sourced a replacement relay? I did look at putting a new motor in but other things got in the way. I have got the Cowells book which has a wiring diagram, I'll post it in my album.

Regards

Martin

Edited By Martin Shaw 1 on 13/01/2019 16:57:12

Dear Martin, I was lucky I have a secondhand relay, why my motor was overheating is because the relay contact was dancing up and down rather than making a clean contact. Personally I don't think you'll have any luck sorting a relay or a moor. You can get a replacement motor from Cowells but you will have to do a lot of modifications as the motor is bigger you would would have to raise the base and change pulleys and it would probably outweigh the value of the lather. I am not an electrician I am a motor mechanic but what you could try (totally at your own risk) with the lathe completely disconnected from the mains, if your lathe has the large cream belt cover loosen the two screws at the back of the lathe and carefully remove the cover turn the lathe upside down, there is a plate with four screws, remove the screws, you will see the black relay with three wires connected to it, near the single red wire from the motor there is a small screw and a plate, remove the screw you will be able then to lift the relay off it will leave the T section in the base, lift the relay and carefully lift the black box you will the contacts near the coil, as long as the coil is alright its a possibility the points can be dirty, if you get some very fine 800 wet and dry paper fold it in half so both sides are abbrassive slide it between the points carefully push the top point down gently so it has slight pressure on the paper and gently move it forward and back, but don't damage the metal section. After you have done this get some clean paper with the same method rub it between the points to remove any residue, similar to what you would do on an old cars distributor.then FULLY assemble and then try it again. If this doesn't work it would pay to un-solder the motor and get a competent electric motor repairer to test it. Hope this helps, best wishes, Chris.

I always found cowells to be a bit evasive about giving out info, I asked what colour blue were the base castings painted on the present lathes? they are not hammerite by the way. sorry don't know, could you send me a sample pot, no sorry, thanks for your help.

Hi Allen, YES, I can see with your picture you're a biker as well so you already probably know this, most car spray paint suppler can usually match and mix the paint. I did want some once for an Emco and they did a perfect match for me. Best Wishes, Chris.

Hello again Allen I am sure some time ago I did get some paint mixed for a cowells you first have to spray a clear texture finish then the blue finish as it is not a smooth finish Chris

Chris

Many thanks for your notes, I'll have another look at it and see where it might go.

Regards

Martin

Hello all, I am an electrician based in Melbourne, Australia. I had my neighbour come to me with a Cowells 90 ME lathe, saying that it was getting exceptionally hot. The problem is with the little black box that I have seen referred to as “a relay”. In a way, it is, but it is actually a temperature or thermally operates switch. The motor starts and generates heat in the windings as it speeds up. The switch in question then is supposed to change over to switch from the start winding to the run winding. If this thermal switch does not change over, the motor will run hot and potentially burn out. I hope that this helps.
Regards Mark.🇦🇺

Hi all you experts.

I have an old Cowells 90 lathe that has been disconnected from its motor, relay and 2-way switch. I would like to reconnect but can't find a wiring diagram. Before I blow myself up, please can anyone help?

I saw Phil some years ago promised to post one in his album but can't see it there?

Many thanks

Rod

Rod

This may help.

JA

I believe the figure 9 circuit shows a circuit where the starting relay has a normally closed contact which connects the starting winding (A2, A1) to the supply and after short time period it operates and disconnects the starter winding allowing the motor to continue running on the main winding Z1, Z2. If the relay fails to operate the starter winding remains powered and the motor rapidly overheats.

The relay is probably an AC type and the delay achieved by a dashpot. If of this type they can become sticky or corroded causing a longer than needed delay or failure to operate.

The delay may also be achieved electronically but I'm not familiar with Cowells electrics. A picture of the relay with thee cover off may resolve this.

CS

The time delay "relay" is probably a thermal bi-metallic type. A common application for these is fridge compressors. See https://refrigeratorsreviewed.com/refrigerator-compressor-relay-issues-solutions/

Note that the modern PTC type is not suitable for frequent stopping and starting. This is because they take more time to cool down and "reset".

Robert.

I failed to read an ealier post regarding the relay being a thermal delay device. These are similar to early flashers units for car direction indicators. A heating element is wound around a bimetal strip which forms the contact circuit.

These can fail because the heater goes open circuit as it is on all the time the motor is running or the snap action, if it has one, fails.

CS

There is also a type of start relay with a coil in series with the main winding (in fact only a few turns) that pulls in a contact supplying the start winding. This is activated by the initial surge, then drops out at the run current level. There is adjustment for the transition point that has been set up during manufacture.

Obviously a loss of calibration or sticking can give rise to the start winding remaining energised.

Many thanks JA. I can now connect it up with confidence.

Rod