Updated 4 April 2013.
Production of synchronous clocks started in the 1930s with the availability of alternating current mains electricity with accurately controlled frequency, and continued until the 1980s when they were increasingly superseded by quartz clocks. Some houses of that era have electrical sockets intended for synchronous clocks.
Their popularity was due to the fact that, providing the electricity supply was not interrupted, they kept good time, and did not need regular attention. Some models were self starting and were therefore ‘plug and run’. Others had to be started using a simple procedure. A synchronous movement runs continuously, so inertia is not a problem, and wheels are usually not crossed out. They were also relatively cheap, and when they stopped working were usually discarded. They are widely available on eBay and elsewhere. Although prices have increased in the last few years they are still cheap when compared with other types of clock.
Provided that the coil is intact, cleaning and lubrication is usually all that is needed to get a synchronous clock running, although the depredations of unskilled ‘repairers’ sometimes make this impossible. It is quite common to find that screws are missing. BA threads are normally used in British made clocks so replacement is straightforward. Wear sometimes makes starting unreliable.
As an example of the problems that can be encountered when servicing synchronous clocks, the Timlec synchronous mantel clock, described on the Timlec page, had six distinct faults, all of which had to be rectified in order to put the clock into good condition. Five of the faults were only accessible by dismantling the clock so were probably introduced by an unskilled ‘repairer’. A fixing screw for the back cover was missing. The tell tale that should have been visible through an aperture in the dial was missing. was missing. The clock is not self starting, and the starter did not work because a spacer was missing. The original terminal block had been replaced by a modern one, which was not attached to the movement. This is now attached to the movement by a suitable bracket. The dial was attached to the dial plate by four glued on pieces of corrugated cardboard, apparently in an attempt to simplify re-assembly. The extra thickness meant that the movement did not sit neatly in the case. The clock has a double worm reduction gear and the worms had been ‘lubricated’ with what appeared to be graphite grease so the movement did not run freely.
Unfortunately, ‘Nanny State’ regulations mean that servicing of synchronous clocks is not financially viable for professional clockmakers. Replacement synchronous movements are available, but installation of these makes clocks of less interest to collectors. Unfortunately, many synchronous clocks with good cases have had the synchronous movements replaced with quartz movements.
A selection of clocks by the makers listed in the sub pages is described briefly. These were mostly made for the UK market and, unless noted otherwise, are for a 230 V 50 cycles mains supply. Most British made synchronous clocks have motors which rotate at 200 rpm. One exception is Ferranti which rotate at 166⅔ rpm.
To view descriptions click a sub page, and follow a link in the sub page.
BIRD C. Metamec. The clockmaker. Dereham. Ticehurst, Sussex: Antiquarian Horological Society, 2003.
LINES M A. Ferranti synchronous electric clocks. Milton Keynes: Zazzo Media, 2012.
LINZ J. Westclox electric. Atglen, PA: Schiffer Publishing Co., 2004.
MILES R H A. Synchronome. Masters of electrical time keeping. Ticehurst, Sussex: The Antiquarian Horological Society, 2011.
RAWLINGS A L. The science of clocks and watches. Third Edition. Upton: British Horological Institute Ltd, 1993.
ROBINSON T R. Modern Clocks. Their repair and maintenance. Second edition. London: N A G Press Ltd, 1942.
SMITH B. Smiths domestic clocks. Second Edition. Herne Bay: Pierhead Publications Limited, 2008.
TRAN DUY LI. New Haven clocks and watches. Fairfax, VA: Arlington Book Co Inc, 1997.
WISE S J. Electric clocks. Second edition. London: Heywood & Company Ltd, 1951