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).
Investigation into the failures experienced with the 20 HP starter motor.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 204 | |
| Date | 1st May 1927 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to BJ.W Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} OY. c. to Mx.{John H Maddocks - Chief Proving Officer} EP.{G. Eric Platford - Chief Quality Engineer} c. to Hm.{Capt. W. Hallam - Head Repairs} ORIGINAL Hs{Lord Ernest Hives - Chair}2/LG24. 5.27. X5620 20 HP. STARTER MOTOR FAILURES. We have been investigating the various troubles which are experienced in the Test Dept. and Repair Dept. with the 20 HP. starter motor. These can be placed in the following order :- 1. Sticking of pinion in disengaged position. 2. Pinion crashing on teeth of flywheel and not engaging. (3. Clutch slipping when engaged. In investigating the first condition, we find that the failures are due to three causes - namely - cross-binding effect of the nut, climbing effect of the stop, and a slipping clutch. The cross binding of the pinion unit is due to the slackness of the nut on the thread, which has been found necessary for the free movement of the unit. It appears to happen when the two stop faces are not exactly square, which throws the whole unit cross-wise. The binding is not severe but is sufficient to prevent the unit from engaging at the first attempt. The climbing effect appears to be the worst feature. In this case the slackness of the thread allows the unit, upon being returned, to climb up on the face of the stops causing a binding effect of the unit on the thread and faces of the stops, which requires several attempts when starting before contd .. | ||