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).
Modifications and testing of generator components such as brushes, armature plates, and cutouts.
| Identifier | ExFiles\Box 43\1\ Scan026 | |
| Date | 26th October 1927 guessed | |
| 2 This was done and is being continued so that on all Springfield cars from the very first, the positive is grounded as on the post-war Silver Ghost built at Derby. I should be glad to know whether there is any practical or theoretical disadvantage in this as to spark-plug polarity, because if so we should probably change to Derby standard at a convenient car. With the Rolls Royce generator this only means reversing the battery in the box and changing the mark on the inspection lamp plug of the control switch, the generator terminal etc. CONTROL BRUSH The range is increased now to be seven degrees (115° to 122° in order to give a greater range of adjustment on the high side. This is because the banding of the armature reduced the output somewhat. We are also running at .010" air gap for the same reason and to get the cut-in speed as early as possible. This air gap is used on Westinghouse and other generators and appears almost standard practice in the U.S. All generators are run on the bench on the high output setting for 4 hours to verify that they do not overheat. The temperature of the outside of the case reaches approx. 75° C during this run. ARMATURE PLATES The end plates are bakelized paper 1/16" thick and are used to give a soft edge to prevent cutting the windings where they bend sideways on leaving the slot. The iron length of the armature with 47-48 plates actually comes 3.250 - 25. The arrangement drawing is being altered to show this correctly. Mica insulation between the plates was used on the first generators, but (for easier machining) was abandoned for ordinary enamelled iron plates. These are nominally .064 thick but actually average .069 with the enamel. BRUSHES Mr. Bailey has sent us particulars of the narrow brush generator. We span now Main brush - 1.4 commutator bars. 3 Control brush - 1 commutator bar. 2 Our current density in the main brushes at 22 amps. output (which we hope to reach on the high setting) is 58.6 amps /sq. in., as against 37 amps sq. in. on the Westinghouse and 43 amps/sq.in. on the original Phantom generator. It does not appear that we should run this up any higher. What do you CUTOUT Flat contact between silver points with fairly rigid mountings for the points is rather standard practice on cut_outs made in the U.S. and | ||