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T&N Master Clock
(Kick Rewind)

Early T&N Master clock
This early example of a T&N (Telefonbau und Normalzeit) style electric master clock was probably manufactured in the 1930s in Germany. It has a veneered wooden case with small circular windows each side to view the movement. Although there are no manufacturer's marks on the clock, the mechanical style is certainly by T&N or its fore-runners. The clock has a extremely well made dead-beat escapement and will drive a number of alternating polarity, one minute slave dials.

Early T&N

The 3/4 second pendulum rod is of wood with  a spun brass bob. Note that there is no seconds dial as there is on later T&N master clocks.

Early T&N back plane

The electric rewind mechanism consists of a large flywheel and a small weight in common with the later clocks and is mounted on a wooden back plane (later clocks were mounted on a rigid plastic, possibly Bakelite, back plane). The rewind impulse arrangement consists of a pair of coils mounted vertically from the back plane, with a rotating armature between them. The rotary switching mechanism for deriving alternate polarity pulses to drive the slave dials is to the left and is similar to later clocks. 
Early T&N movement

Alternate polarity slave dial pulses are triggered by means of a two armed 'wheel'  being released by a pinion every minute (circled and enlarged in the picture). Later versions of the clock, which have a seconds dial, have a cam on the seconds arbor behind the dial, and extra wheel work between the front plate and a small third plate which triggers this function. The steel rod, shown near the circled area in the picture projecting towards the camera, can be moved downwards to push the two armed 'wheel' out of mesh with the pinion so that the slave dials may be advanced.
Voltage: 6v
Battery type: Non-specific; may need to supply around 200mA 
Slave Type: 30 seconds: Alternating polarity pulses
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Copyright  Text & Pictures - Martin Ridout.   Last updated Jan 2005.