Synchronous high-torque clock motor question

[Phil G4SPZ]

The second restored motor is back in position. We now have two dials working and telling the correct time for the first time in over a decade!

Dial no. 3 faces south and cannot normally be seen by visitors, so its motor was selected as the last to be done as my work will be delayed by the summer holidays. I’m guessing October for this one. Same problems as No. 2, filthy dirty and worn-out rotor bearings, plus the flywheel is slipping on the shaft.

Phil

[Nickthedentist]

Beautiful! Not many like that still in existence, let alone telling the right time on their original movements. Well done.

[Phil G4SPZ]

Thanks Nick! An interesting project and a bit of a learning curve along the way. Your help in identifying the Gents C272 movement was also much appreciated.

Incidentally I have also tested one of these movements running off an inexpensive 650VA ‘line interactive simulated sine wave’ inverter, and the motor continues to run in nine cases out of ten after a power interruption. The inverter’s output frequency is 50.25Hz, according to my optical tachometer, meaning the motors would run 0.5% fast whilst on inverter power, so the clocks will gain around 18 seconds per hour. I can live with that, especially as lengthy power outages on site are rare.

Once the third movement is overhauled and back in place, some work by the Museum’s electricians will be necessary to rationalise the wiring within the tower, but that’s a job for the winter closed period.

[Ed_Dinning]

Hi Phil, keep an eye on the motor temp when running on a simulated sine wave.

Depending on the type of simulation it may have fast rising edges/ not be a 240V RMS wave and cause overheating

Ed

[Phil G4SPZ]

Thanks for the warning, Ed. I ran a motor on test from the UPS for over two hours, and could discern no increased temperature rise compared with when running on the mains.

The RMS value of the simulated sine wave may be 230 volts, but the average value as measured by a conventional moving-coil rectifier multimeter reads 165 volts. I was actually pleasantly surprised that synchronous motors run from it as well as they do.

[Phil G4SPZ]

Originally Posted by Phil G4SPZ

...plus the flywheel is slipping on the shaft.

Motor No 3 is now under restoration. I was amazed that it was still capable of running. The boss at the centre of the flywheel was completely worn away, and the rotor itself was loose on the shaft. I turned a new boss from brass bushing rod on the lathe, and will get it all reassembled in the next couple of weeks.

[Nickthedentist]

Please do post some before and after pics.

[McMurdo]

Here's a pic of the clock in its original position posted on the wolves facebook page.
The locals apparently called the clock 'the three-faced-liar'. How on earth they ever kept the movements in sync during power cuts or brown outs is anyone's guess..obviously they didn't!
I once set up a Gents 2-faced post office clock in my dad's big shed and that also had 2 seperate mains movements, and they were always at odds.

[Phil G4SPZ]

Kevin, that’s fantastic! Thank you very much. I’ve been looking for a picture like that for years.

Keeping the three movements in sync is still a problem. A local power interruption has already stopped the clock. As I mentioned in an earlier post, I plan to install a UPS to keep them running during power cuts.

[high_vacuum_house]

That’s an interesting and complicated looking street light with the clock. I wonder what the street light technology was. Looks like some kind of fluorescent fixture.

Christopher Capener

[Phil G4SPZ]

Agreed. Judging by the size of the clock, the lamp appears to contain four 2-foot fluorescent tubes. Sadly the lamp and its post were not preserved alongside the clock.

I reckon the photo dates from the mid-sixties; the Ford Cortina and Mk III Zephyr were both introduced in 1962.

[Phil G4SPZ]

Originally Posted by Nickthedentist

Please do post some before and after pics.

Apologies for the delay, Nick, I’ve been down with Covid-19 for a fortnight.

Here are a couple of ‘before’ and ‘after’ pictures. I didn’t take a picture of the flywheel with its worn-away centre boss, the two remnants of which can be seen adjacent to the rebuilt rotor/flywheel assembly.

Running beautifully now. Still peripheral mechanical components to add, a new earth wire and a PAT test, and it’s scheduled to go back into service on 4th December.

Phil

[VT FUSE]

So sorry to learn that you have been infected with Covid again Phil.
I admire your work on this clock, I wonder if you will be writing any notes for inclusion when it is all back together? One can only guess as to who might be treading in your footsteps in many decades to come, folders etc are easily lost or mislaid.
I would go as far as to say, the mechanisms will be back to new ex works performance.
Best regards.
Mike.

[Phil G4SPZ]

Hi Mike, and thank you for your kind comments! Being at a Museum, the clock is part of the permanent inventory of artefacts and, as such, is documented electronically and the records are maintained and updated by the Collections Care team.

I will indeed be documenting this restoration for posterity!

Having lost a tiny 2mm screw from a bearing cap yesterday, I can quite imagine some future clock repairer wondering “Which clumsy idiot lost this screw…?” and the records will identify me as the guilty party!

[Phil G4SPZ]

The third clock motor reassembled and running on test from UPS with simulated mains failure.

Phil