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).
Comparative analysis of a Bosch motor's electrical and mechanical characteristics against an existing design, page 4.
| Identifier | ExFiles\Box 64\2\ scan0055 | |
| Date | 10th May 1927 | |
| EFC1/T10.5.27. -4- Contd. occupied by the teazer winding on each of the two poles being larger than the space occupied by the main winding on the other two poles. Further, the electrical connections are such that the teazer current does not pass through the main winding, but the negative ends of both windings come to the positive brush. It does not appear to be a highly efficient arrangement from the point of view of brake tests, and we should doubt whether the Bosch motor would give a large efficiency on our usual supply characteristic, but it appears that it may be a better arrangement from the engagement point of view. The Bosch motor has no helix on the pinion, and as in our case, the pinion can move axially along the spindle. The Bosch has an outward engagement whereas ours has an inward. The Bosch is arranged for running operating equally well either way by a simple alteration of the armature connections, both sets of brushes being insulated until earthed on the set desired. There is a large diameter end bearing on the Bosch which seems to exert a liquid frictional retarding torque and prevent the Bosch motor from turning rapidly. Although the resistances of the teazer and armature windings on our own and the R.Bosch motors are roughly the same, the R.{Sir Henry Royce} Bosch armature rotates very much more slowly, as if it were rotating against a viscous resistance, though it appears to require approximately the same torque to force it backwards against the armature torque. The Bosch motor very definitely moves right out and right in to the end of its Contd. | ||