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).
Specifications and analysis of a machine's electrical components and construction.
| Identifier | WestWitteringFiles\K\June1923\ Scan47 | |
| Date | 12th June 1923 | |
| Contd. -2- EFC1/T12.6.23. Field Circuit. Number of wound poles ---- 4 Arrgt. of coils ---- all in series. Resistance of field circuit at 18°C ---- 4.6 ohms. Armature Circuit. No. of slots ---- 15 No. of coils per slot ---- 3 No. of coils or comm. bars.-- 45 Armature resistance at 18°C-- .327 ohms. Commutator & Brushes. Commutator diameter ---- 1.93" Useful comm. length ---- .975" No.of brushes per holder ---- 2, each .392 x .392 Total brush cross section per holder ---- .308 sq.in. Grade & hardness of brushes - Morganite Link 5. Very soft graphitic. Operating voltage ---- 12 Thickness of armature stampings, inclusive of insulation ---- .0218" Thickness of end stampings (Two each end) ---- .066" The machine presents a well finished appearance and the workmanship is good. It is fitted with cone ball bearings. The commutator micas are under-cut. One noticeable feature about the design is the brush spring mechanism. Pressure on the brushes is maintained by helical springs attached to arms in toggle fashion so that the arms can easily be moved back and will stay in this position while the brushes are removed. The armature is hand wound with tunnelled slots, similar to the Bosch. The machine was at first investigated as a plain shunt machine, the following curves being taken:- Contd. | ||