Specification document for a revolution counter, detailing performance and testing criteria.
| Identifier | ExFiles\Box 165\2\ img150 | |
| Date | 7th January 1938 | |
| 7.1.38. SPECIFICATION FOR REV-COUNTER. EL.16/2. 1) The outside dimensions, arrangement of scale and general appearance shall be in accordance with that as specified on the detail drawing. 2) The torque required to turn the flexible drive through one revolution, when coiled to form a loop of 6" radius and held in this position, shall not exceed 6 ozs/ins. and shall not take longer than 3 3/4 secs. at a temperature of 20°C. 3) The instrument shall be capable of running with its flexible drive, looped as above in test (2) for a period of 500 hrs. at a speed corresponding to 4,500 engine revs. per minute without showing any signs of failure. Throughout this test the behaviour of the instrument shall be consistently good, and operation of the drive shall be noiseless. 4) At the end of the test (3) the speed of the instrument shall be increased from zero to full scale reading in a period of 5 secs. allowing the oscillations of the pointer to die down, the operation shall be reversed. The instrument shall be capable of withstanding this oscillation test for 1,000 operations without showing any signs of failure. 5) The speed of the instrument shall be steadily increased from zero to full scale in a period of 5 secs, when there shall be no appreciable over-swinging of the pointer. 6) At the conclusion of the above test, the indicated reading shall not be more than 5% fast and shall not read slow at any point of the scale. 7) The calibration of the instrument shall not vary more than ±1% between 15°C and 30°C. A certain percentage of all instruments supplied, will be tested as above, to ensure that the quality of the instruments is being maintained. 8) The rev.counter to be fitted with an indicator which will permanently record that the needle has exceeded the 4,500 mark, a drag equal to 60-80 revs, is allowed to operate the indicator. -contd- | ||
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).