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).
Comparison of motor characteristics, focusing on noise and armature engagement issues between a Peregrine and a Bosch motor.
| Identifier | ExFiles\Box 62\1\ scan0106 | |
| Date | 3rd January 1933 guessed | |
| -2- (a) It is noisy. (b) The complete engagement is uncertain. (c) The armature does not disengage itself quickly enough when the engine fires. We consider (a) and (b) can be explained by the characteristics of the armature motion endwise on the slow motion teazer circuit. To illustrate this we also attach curves showing armature pull plotted against armature movement for various values of teazer current and main current. These have been taken on the Bosch motor and the R.R. Peregrine, and show the remarkable difference in the characteristics of armature engagement between the two motors. The Bosch motor moves into gear at an ever increasing rate, whereas our own motors move very rapidly at first, and then the force tails off to an almost constant value. This, as E.{Mr Elliott - Chief Engineer} has suggested, rather explains why our motors are noisy on initial engagement, but are uncertain in their final engagement. We have put an experiment in hand to ascertain whether the stepped armature used by Bosch is better than our taper armature scheme. With regard to (c) we consider a stronger armature spring will cure the trouble, but we do not recommend any increase in the spring pressure until this end pull has been improved. The weight of the Bosch motor is 12 lbs. 3 ozs. as against 12 lbs. 12 ozs. for the R.R. Peregrine motor. Hs{Lord Ernest Hives - Chair}/Wst. | ||