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).
Experiment report on the effect of a sticking negative brush on a Goshawk dynamo.
| Identifier | ExFiles\Box 51\1\ Scan271 | |
| Date | 4th October 1923 | |
| EFC. {E. Fowler Clarke - Electrical Engineer} AB.88. X. 4383 - GOSHAWK DYNAMO - EFFECT OF STICKING NEGATIVE BRUSH. An experiment has been made on machine E to reproduce overheating due to a sticking negative brush, whilst operating on a normal battery circuit. The machine was first run ordinarily at maximum output whilst heat insulated on the bench rig, until the temperature became steady. This was at 77°C. The operating particulars were :- Dynamo speed 1550 r.p.m. Amperes delivery 9.3 Main volts 14.75 Field volts 6.3 The negative brush was next made tight in its holder by being packed with a piece of paper, and a very light spring was fitted, so that fairly bad sparking took place. In this way the machine rose to a temperature of about 90°C, and the operating particulars, though not very steady were approximately :- Dynamo speed 1550 r.p.m. Amperes delivery 10.0 Main volts 14.8 Field volts 8.5 The negative brush surface became a little rougher than usual, and the commutator surface was slightly pitted, although the solder was not thrown. RJA. | ||