As a result of agreeing to restore this system, I became involved in tracing the history and purpose of its installation in what had been a Shadow Factory for the war time (WW2) production of aero engine components by The Standard Motor Company Ltd.
This got me into conversation with an 78 year old gentleman who had worked at the factory as an apprentice electrician in 1942. He could not remeber the clock system, but he produced a photograph of the canteen with a save dial badged CRONOMATIC. So now we know what we are looking for in that department.
A few details:
On the top of the backboard of the Time Transmitter (Master Clock) is the (?) Serial Number S 19038, and there are two case makers numbers 91 and 64. The inclined plane of the impulsing pallet is formed from a single piece of brass strip which wraps around the pendulum rod. The gravity lever restoring coils have a resistance of 5.2 Ohms and bear a serial number S10573.
On the underside of the Time Transmitter movement is engraved :
1
26.5.36
I am making an assumption that this is a manufacturing date of 26 May
1936.
What the 1 signifies I do not know, perhaps the first unit to be made in
that month.
The Pilot Dial movement has stamped on it Pat. No. 227499/23
It has a twin bobbin electromagnet wound with enamel coated wire.
The dial has a matt silvered finish with Arabic numerals, and the only
other
inscription is
BRITISH MADE which appears below the numeral 6.
The hands are matt black, the minute hand having a counter balance, but it
is not lead weighted as per Synchronome or GENT. The minute hand is fixed
to
the arbor by a threaded nut.
Connecting the pilot dial to the time transmitter circuit and internal rheostat is a fine cotton covered and braided flexible cord which has looped and bound terminations at both ends, a practice common to telephonic work. The Telephone Rentals log book describes the Time Transmitter as L.M. (low movement)
The Central Equipment, mounted on the green cabinet comprises: (topmost) GENT C68 Programmer and an interfacing relay for operating the mains voltage Sound Signals. This latter device incorporates a thermal relay to limit the duration of the signal to approximately 10 seconds. ((below left) Mains Transformer & Rectifier. (below right) Impulse converter, now missing. (below right) Sound Signal Control comprising a tumbler switch and mains voltage bell push. (below centre) Prime Time and Sub Circuit Relay unit GENT (?) C63 complete with impulse delaying resistance and spark quench circuit. In the cupboard beneath is accommodation for the batteries, in this unit there are 18 x 2 volt lead acid accumulators manufactured by EXIDE.
The complete assembly was wired together with 3/029 tinned copper conductors, vucanised rubber insulation and lead sheathed cable.
Pictures and description copyright Hugh Burrows
