From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Test report on two Smith motor-type electrical clocks proposed for standardisation.
| Identifier | ExFiles\Box 164\1\ img187 | |
| Date | 7th April 1938 | |
| To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/RC.{R. Childs} c. to By/RD. Rm{William Robotham - Chief Engineer}/RC.{R. Childs}9/JH.7.4.38. SMITH MOTOR-TYPE ELECTRICAL CLOCK. Two Smith clocks of the impulse motor type have been submitted for test by the makers as samples of a cheaper type of clock proposed for standardisation. This is an electric motor driven instrument and is intended to take the place of the present type which is a mechanical clock electrically wound. Preliminary tests have now been made. It was first ascertained - (a) That the clocks would not start in operation by merely connecting to a battery; it was necessary to move the hands or shake them. (b) That when disconnected from the battery they stopped immediately. The current taken by these instruments was then measured and found to be very small, .9 milli-ampere at 12.1 volts. A test for accuracy was next carried out. This consisted of running the clocks for a period of three weeks at various voltages and observing the extent to which they gained or lost as compared with the Works master clocks. Results of this test were as follows :- First Week. Voltage constant between 12.1 and 12.0 volts. Time variation - No.1 clock gained 2.0 minutes. No.2 lost 4.0 minutes. Second Week. Voltage constant at 10.0 volts. Time variation No.1 clock lost 3.0 minutes. No.2 clock lost 9.0 minutes. | ||