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).
Analysis of 'thump' caused by backlash in actuator gearing and a comparison of different design schemes.
| Identifier | WestWitteringFiles\Q\2-July1927-September1927\ 65 | |
| Date | 26th August 1927 | |
| Contd. -3- EFC2/T26.8.27. slowly and no click is produced, the force of the actuator box meanwhile maintaining the teeth in contact on their non- diving side. Since the main motor power comes on near the completion of the actuator travel and finds the main teeth in contact on the non-driving side, a comparatively big thump is produced in taking up the backlash in the teeth. This appears to be the explanation, that the thump still exists in this case though to a lesser degree then in the 34° 52' case. It is not due to the pinion travelling along the thread as before, but due to the sudden take up of the backlash in the teeth when the main power comes on. If we artificially delay the action of the main switch until the motor has taken up the backlash of the teeth, after completion of the actuator box travel, by utilising an additional switch in series with the actuator box operated switch, we can make a start on this present arrangement on 9-EX without any initial thump. The follow up thump still exists apparently for the same reason of backlash in the teeth. This will be avoided in the newer schemes by the altered gear ratio. Thinking of these matters generally, there appears to us to be no fundamental difference between, on the one hand, parallel teeth on the pinion and wheel with a spiral longitudinal motion of the motor pinion in relation to the motor armature, as in the No.1 scheme; and on the other hand, helical teeth on the pinion and wheel, with a parallel longitudinal motion of the motor pinion in relation to the motor armature, as in the No.2A and 2B schemes. In any case it appears possible for a jam to exist, however unlikely it may be to occur in actual service, if the | ||