RAF issue Aircraft Clock, 6A/433
General
4. This clock is for general use of a crew in a cabin on a flying-boat. It has an 8-day movement and is key wound from the front.
Description
5. The bezel is hinged to the case, and on the case is pivoted a screw with nut for locking the bezel. To ensure the case being water-tight, compressed rubber rings form seals between the glass and the bezel, and the bezel and the case.
6. The numerals forming the hour markings on the dial are supplemented to suit the 24-hour system, the additional numerals being finished in red. The lever for regulating the escapement is located in a slot at the top of the dial. It does not project above the dial. This is to avoid accidental disturbance when the hands require setting.
7. The specification requires that when tested, (a) at any temperature between -20 deg. C and + 50 deg. C, and with the dial either vertical or horizontal, the clock shall not accumulate an error of more than one minute during any period of 24 hours between winding; (b) while subjected to such vibration as may be experienced on aircraft, the errors shall not exceed twice the limits in (a).
Installation
8. The nominal diameter of the flange of the case is 6 in. The diameter of the body of the case is 4.3 in., and the depth of the case behind the flange is 1.75 in. Three equally spaced holes in the flange beneath the bezel are used for securing the clock to the supporting system, and when installed there should be sufficient clearance to allow the bezel to be opened for winding the clock.
9. The best position of the clock in the
flying-boat is one which is not only convenient for reading but also free from
excessive vibration. Where necessary, an anti-vibration mounting may be used
for supporting the clock.
Service Mk. I Type clock
This clock is a portable model and is for the use of a crew in a cabin of a flying boat. It has an 8 day movement and is key wound from the front.
Description
The Bezel is hinged to the case, and on the case is pivot a screw with a nut for locking the bezel. Compressed rubber rings form seals between the glass and the bezel, and between the bezel and the case. The numerals forming the hour markings on the dial are supplemented to suit the 24 hour system, the additional numerals being marked in red. The lever for regulating the escapement is located in a slot at the top of the dial. It does not project above the dial. This is to avoid accidental disturbance when the hands require setting. The specification requires that when tested:-
(a) At any temperature between -20°C. and + 50°C., and with the dial either vertical or horizontal, the clock shall not accumulate an error of more than one minute during any period of 24 hours between winding.
(b) While subjected to such vibration as may be experienced on aircraft, the errors shall not exceed twice the limits in (a).