Phil has been busy. I like his stuff and he’s one of those tenacious people who have what ot takes to do it right. Over to Phil..
Blog attached! Took me hardly any time at all…!
It’s been a while since I offered you anything in the way of a ‘blog’ for your excellent website. The truth is, most of my recent activities as Volunteer Horologist at the Black Country Living Museum have been relatively routine, involving repairs to conventional clocks which you cover in far more detail than I ever can.
However over the past few months – one day per week – I’ve slowly been restoring a large and unusual three-dial electric turret clock dating from the very early 1930s. The clock once hung at the entrance to the Victoria Square tram and trolleybus terminus in Wolverhampton, where it acquired the nickname of “the three-faced liar” due to its tendency to indicate different times on all three dials. The clock was relocated to the Museum in the 1970s and apparently worked – sporadically – till around ten years ago.
I’d been keen to get my hands on this turret clock for some time, as it’s quite an imposing showpiece and the only public clock on the site, but it was only earlier in 2025 that I persuaded the Museum to hoist me aloft in their ‘cherry picker’ to gain safe access to the clock and see if I could do anything with it.
Behind each of the three two-feet-diameter backlit dials is a high-torque mains synchronous movement, which my research identified as the manually-started Gents C272 from around 1932. I picked the south-facing movement to service first as this is not in view to the majority of visitors, so I removed the hands, unbolted the movement and took it down to the workshop.
Mechanically, the movement is a fine, strongly-built design with thick plates (and, incidentally, involute profile wheel and pinion teeth rather than cycloidal) which responded well to conventional dismantling and clock cleaning techniques. However, once reassembled, the 200 RPM synchronous motor proved difficult to start and tended to stop at the slightest provocation. I suspected that the magnetic field wasn’t strong enough. Measuring the DC resistance of the motor’s single coil showed a ominously low value of around 400 ohms, which suggested the coil may have had shorted turns. A second trip up in the ‘cherry picker’ was then necessary to measure the other two motor coils in-situ. Both measured 850 ohms, which at least confirmed my suspicions, and indicated that the remaining two motors were electrically okay at least.
The faulty coil was sent away to be re-wound by a specialist, who reported back that the coil had been repaired previously, and that the inner half of the winding showed signs of burning. Sure enough, the re-wound coil measured around 750 ohms and, when fitted, the motor ran perfectly. A new earth wire was fitted and the motor was successfully PAT tested.
At my third visit in the ‘cherry picker’ I removed the north-facing movement and replaced it with the one I’d just finished. The hands were re-sprayed in satin black to match the existing, refitted to the movement and the clock re-started. That was back in June, and it’s still going two months later…!
The second movement was now on the bench. As well as being filthy dirty, the rotor shaft was very loose in its ball bearings – it appeared that the shaft had been spinning inside the inner races, and its diameter had worn down – and rattled about so badly that apart from the loud buzzing noise, the drive end (where the rotor laminations spin between the pole pieces) was jumping about, causing greatly reduced torque. I obtained some new ball bearings (tiny, Imperial measurements 1/8” ID by 9/16” OD by 1/4” deep) which thankfully are still available from UK bearing suppliers, but was then faced with obtaining a tight sliding fit between the rotor shaft and the bearing. I was reluctant to use Loctite or similar, as the shaft has to be pushed through the bearing during assembly and I feared the locking compound would contaminate the ball race itself. In the end, I very carefully centre-punched the shaft at 90 degree intervals, forming tiny craters with raised edges which gripped the bearing perfectly. On reassembly, the motor ran smoothly and quietly and generated plenty of torque. It again passed a PAT test.
Last week was my fourth trip up in the ‘cherry picker’ to reinstall the second overhauled movement, refit its newly-painted hands, and bring down the third and final movement for attention. The work involved should be a repeat of what I did to the second. We now have two of the three dials, both the ones visible to visitors, working and telling the correct time for the first time in over a decade!
Power cuts are mercifully rare, but despite these motors having resiliently-coupled flywheels which keep the rotors spinning at synchronous speed during very short outages, any power loss of more than about half a second will stop the clocks. Being hand-started, a journey up in the ‘cherry picker’ would then be needed to re-start the motors. Experiments with an inexpensive 650VA UPS of the type used with computers showed that this will keep the rotors turning at the correct speed, even during a longer power cut, so once the third motor is overhauled and refitted, I’ll do the work of rearranging the wiring within the turret to incorporate the UPS. This should reduce the need for site visits to twice per year for the GMT/BST time changes, as well as keeping the three dials in synchronism. The clock’s days of being a “three-faced liar” will hopefully be over!
Thanks Phil.
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