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).
Comparison table of motor brush particulars and weights for various motor types.
| Identifier | ExFiles\Box 35\1\ scan 012 | |
| Date | 8th September 1919 guessed | |
| MOTOR: Lucas A.510 | C.A.V. | R.R.45 | R.R.17. | R.E.24 | Bosch. | Bijur. BRUSH PARTICULARS. No. of brushes: 2 | 2 | 4 | 4 | 4 | 4 | 4 Contact area per brush(sq.ins): .360 | .160 | .40 | .40 | .40 | .180 | .25 (1" x 1/4") Amperes per sq. inch at start (approx): 1110 | 2500 | 312 | 282 | 312 | | Ditto at max. power: 589 | 1625 | 153 | 139 | 131 | | Grade and hardness of brush: - Lucas A.510: Link C.M.4 Morganite Soft. Fair %age of carbon. - C.A.V.: Link Morganite to all tests same as R.R. Standard. - R.R.45 / R.R.17. / R.E.24: C.M.I link morganite copper carbon brushes have now been standardised for R.R. motors. (large %age of copper) - Bosch.: Copper carbon softer & darker than RR standard probably with larger %age of carbon. - Bijur.: Copper carbon zinc apparently by colour Harder than R.R. standard. WEIGHT Weight of motor complete.(lbs). £: 21.375 | 19.25 | 35.5 | 35.0 | 34.5 | | 39.15 | ||