Telephone Rentals Master Clock

Nice oak case with oak framed door.
Size: Approximately 52 inches high. 10 inches wide, 6 inches deep.

The whole movement looks as if someone was instructed to make a clock based on the synchronome design, but at a reduced cost and with sufficient style changes to avoid legal action ! The movement is smaller and lighter, it has what appear to be much smaller contacts and to use ready made parts where possible. The restoring electromagnet could well have been a modified bell, and the electromagnet in the slave or pilot dial has a strong family resemblance to a GPO type 600 relay coil.
The principle of operation is the same as a synchronome, with a "gravity arm" of rather weird shape released by a pin on the escape wheel arbor and restored by an electromagnet after it has dropped and impulsed the pendulum via a pallet on the pendulum rod.
I am told, by somebody who worked for the company, that they were a very successful and accurate master clock and were widely used in the midlands.

The clock requires a low voltage DC supply sufficient to provide the required operating current. (Like most English master clocks, this clock is current operated and the voltage of the supply should be adjusted to provide the required current. At the moment I do not know the recommended current, but in practice it is sufficient to adjust the voltage by a rheostat until the electromagnet reliably restores the gravity arm (but keeping the current as low as possible to avoid damage to the contacts)

---