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).
Instruction sheet detailing specifications and tolerances for brushes, comparing S.M.M.+T and R.R. standards.
| Identifier | ExFiles\Box 60\1\ Scan123 | |
| Date | 8th December 1924 | |
| RR 238 (150 BKS.) (DB{Donald Bastow - Suspensions} 461-8-12 24) MP 306975 ROLLS-ROYCE, LTD. INSTRUCTIONS. To_____________________________________19___ Order No. PD40 (2) Customer's No.__________________ | Detail. | S.M.M.+T Standard | R.R. Standard | |----------------------------------------------------------------------------------------|-------------------------|---------------------------| | Tolerances on brushes. | | | | Length | ± .030" | +0 / -.015" | | Width | ± .008" | +0 / -.005" | | Thickness | ± .004" | +0 / -.005" | | Brush tolerances, plus holder tolerances, giving clearances between brush and holder:- | | | | Width | .001" to .011" | .002" to .009" | | Thickness | .001" to .007" | .002" to .009" | | Flex. | | | | Position of flex. | On top of brush | At an angle of 45° to the top. | | Length. | 2.25" | 1.10" | | Diameter. | 1.0mm to 1.5mm | — | | Nº of strands. | 105 to 252 | 120 | | SWG of strand. | 45 SWG | 42 SWG | | Flex Terminal. | 2.B.A. Eyelet Tag. | 5.B.A. Lug. | Signed C.A.P. This Sheet must be filed on completion of the work. | ||