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).
Page of procedures for testing and bedding the brushes of a dynamo.
| Identifier | ExFiles\Box 68\4\ scan0060 | |
| Date | 10th April 1929 guessed | |
| -2- Contd (e) The connections of the pigtail conductors are not in any way damaged. (f) The initial bedding of the brush shows partial contact reasonably well distributed over the working surface. (Preliminary bedding of brushes). (2) The insulation resistance of the machine should be taken and should not be less than 1 megohm. N.B. (1) For the running tests of the dynamo there must be no armature end play. It may be necessary to insert washers between the temporary driving pulley and bearing so as to keep the armature up towards this bearing, i.e. in the position which it will have when fitted on the chassis. N.B. (2) For S.S. type machines, the direction of rotation is left-hand, looking on the commutator end; also the main terminals are of reversed polarity. (3) Main bedding of brushes. The dynamo shall now, starting cold, be run on load at about 1300 r.p.m. charging a 12-volt battery of ample capacity and the condition of the brush bedding observed and improved from time to time, if necessary. This should continue until the working surface of each brush shews evidence of making contact across the whole thickness of the brush (i.e. in the direction of the commutator circumference at some place for an axial distance not less than .050".) Particular notice should be taken of any undue brush noise which may develop on this test. On any brush which is noisy, it should be again checked that the clearances between the brush and its holder both axially and Contd. | ||