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 specifications and performance characteristics for Bosch and R.R. machines.
| Identifier | WestWitteringFiles\J\January1923\ Scan34 | |
| Date | 23th November 1923 guessed | |
| EFC2/T23.1.23. -3- Contd. Bosch. R.R. Air gap. .020" .015" No. of poles 4 4 Field wire 21 SWG. 19 SWG. Field circuit resis. S.D 5.D 3.6 No. of slots. 17 29 Coils per slot. 2 1 No. of coils of comm. bars. 23 29 Armature resistance. .42 .37 Commutator dia. 1.0 2.1 Length. 1.0 .925 Brush contact area. .26 sq." .23 sq." Brush material. Soft graph- hard graph- itic E.6. itic. Z Le Carbone. One of the principal differences is the fact that the Bosch machine has a hand-wound armature. The temperature shown on the output curves(at which the curves were taken) are the maximum temperatures which can be obtained on the rig with the given control brush setting. On the rig it would be safe to increase the outputs by retarding the control brushes so as to run up to say 85°C with a much bigger output, but it considered that for a safe temperature on the engine this should not exceed 75° on this rig. EFC. | ||