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 starter motor specifications for large cars.
| Identifier | ExFiles\Box 61b\3\ scan0129 | |
| Date | 1st June 1921 | |
| X543 X.543. STARTER MOTOR TABLES. X.3174. 1.6.21. (Additional Sheet I) (Motors of size suitable for large car). STARTER MOTOR. X.3247 C.A.V. ZC. X.3161 Lucas A.510. X.1058 Bijur A.21 X.1248 Bosch S.45 X.2642 R.R.17 (ClC) X.2642 R.R.24 (clc) X.2642 R.R.45a (clc) X.3082 RR.45b (sc) X.3740 RR.45c (U.S.A. motor). Also RR. S.motor for early cars. X.1058 Bijur A.1.D. X.4007 U.S.A. Bosch. X.1086 Westinghouse. X.4341 C.A.V. CARCASE Diameter: 4.500, 5.650, 5.500, 5.900, Not circular, Not circular, Not circular, 6.000, 6.000, 5.500, 4.850, 4.940, 5.000 Length: 5.375, 3.750, 7.600, 4.760, , , , 5.175, 4.475, 7.250, 5.920, 5.600, 4.740 Thickness: .280, .375, .275, .385, Not circular, Not circular, Not circular, .325, .325, .270, .240, .300, .300 ARMATURE Diameter: 2.870, 3.575, 3.560, 3.700, 3.600, 3.600, 3.600, 3.600, 3.600, 3.875, 3.250, 3.250, 3.000 Length (active): 2.800, 2.050, 3.000, 2.870, 2.550, 2.550, 2.550, 2.250, 1.575, 2.670, 3.800, 3.300, 3.050 END CONNECTIONS Length of overhang at driving end: .9", .85", 1.0", .9", 1.3", .95", 1.3", 1.1", 1.1", 1.05", .8", 1.0", .75" Length of Commutator connections Excluding com:spokes.: 1.45", 1.0", 1.05", .9", 1.25", 1.2", 1.15", 1.15", 1.15", 1.0", 1.0", .9", 1.15" Ditto Including com:spokes.: 1.7", 1.2", 1.3", 1.05", 1.5", 1.45", 1.4", 1.4", 1.4", 1.2", 1.2", 1.1", 1.4" Note:- All machines are 12 volt except Bijur A.21 which is 6 volt. | ||