CLOCK No. 110

BATTERY OPERATED CLOCKS

1. GENERAL
Battery operated wall mounted clocks, designated Clock No. 110, have been introduced into the Vocabulary of Post Office Engineering Stores to replace mechanical clocks.

This instruction describes the clocks and gives guidance on their installation and maintenance.

2. DESCRIPTION
The clock has a matt white 12 in diameter dial with black minute and hour hands and a red sweep second hand.  The chapters (five minute intervals), minute markings and the words POST OFFICE are also in black with numerals 13 to 24 inscribed in red at the chapters.

The circular case is made of plastic or spun aluminium and is usually grey.

3. INSTALLATION
The clocks should only be used in temporary accommodation or where the use of pulse operated or synchronous clocks is impractical.

4. MOVEMENT
The movement operates on the tuning fork principle with an accuracy better than '2 seconds per day under normal conditions and is powered by an SP11 type battery (1.5v) obtained by local purchase.  Regulation is by means of a screw calibrated to a change in time of approximately 7 seconds per division per week.

The movement is started by pulling the minute/hour adjustment knob away from the case.

5. MAINTENANCE
The four principal aspects of maintenance should be dealt with as follows:-

1. The battery should be replaced annually,
2. Regulation may be necessary after installation and it is advisable to allow a minimum period of seven days before adjustment,
3. Broken face glass should be replaced locally,
4. If the clock should stop and an exchange of battery and cleaning of terminals does not effect a re-start, the clock should be scrapped.

Last revised: January 03, 2022