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).
The design and function of a motor's brushes, commutator, and engagement mechanism.
| Identifier | WestWitteringFiles\R\2December1927-February1928\ Scan061 | |
| Date | 1st December 1927 guessed | |
| -2- Contd. The third brush is adjustable for control of the major output. All brushes are of the same size and carried on radially pivoted arms. The brushes are very inaccessible. There are 28 commutator segments and the width of each brush is about 1-1/2 segment. Brushes appear to be of soft graphitic material. With the machine arranged in the way described, there is only one terminal excluding the earth or carcase. MOTOR. This is of the four-pole type with field coils two series two parallel and an ordinary wave armature winding. Of the four brushes on radial arms two are earthed and two are insulated. There is a main switch mounted on the motor which is operated by a lever which also slides the pinion along parallel keyways into engagement with the wheel when the lever is operated, the switch not making contact until nearly full engagement is secured. The teeth are parallel and when the engine starts there is a free-wheel which prevents the motor being raced if the lever is not released soon enough on starting. There appears also to be a limiting torque friction clutch in the long housing on the front of the motor, the body of this housing, as also the carcase of the machine, being of cast iron so that the whole motor unit is very heavy for its size. Contd. | ||