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).
Performance test report on a modified PH.III starter motor comparing its efficiency and engagement to a standard model.
| Identifier | ExFiles\Box 142\3\ scan0338 | |
| Date | 9th September 1937 | |
| To Mr, from Rm{William Robotham - Chief Engineer}/RC.{R. Childs} O: B/RD. C: [crossed out] c. Rm.{William Robotham - Chief Engineer} Rm{William Robotham - Chief Engineer}/RC.{R. Childs}S/H.9.9.37. 1204 Re PH.III Starter Motor Modified by Production Electrical Department. We have now tested the above motor and find the performance of same a definite improvement to that of a standard machine, in respect to the following. (1) The efficiency of the Teazer Torque is increased. (2) Engagement of the motor both hot and cold is improved. We are carrying out a further test by fitting the motor to an experimental chassis to ascertain that the extra Teazer Torque will not cause crashing of the pinion or the gear ring teeth. This improvement has been achieved by a modification to the main winding which allows the Teazer winding to be inside the main winding instead of at the side; thereby providing a more efficient form of coil for the teazer. This motor was tested on the production rig to the production specification, with the following results. Light Test. Current at the end of test 24 amperes at 6 volts. This is equal to standard performance. Armature Damping Test. During this test it was noticed that the armature thumped on travelling outwards, but there was no thump on return. This did not occur on the hot or cold engagement tests, and we do not think it will occur under normal working conditions. This point will be ascertained by further tests on a chassis. Longitudinal Motion Test (Cold). The engagement during this test was satisfactory down to 7.5 volts. This shows an improvement, the specification calling for 9 volts. | ||