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 dimensions and weights for various starter motors for the 40/50 HP size engine.
| Identifier | ExFiles\Box 61b\3\ scan0199 | |
| Date | 10th November 1927 guessed | |
| X.543. STARTER MOTOR TABLES. 40/50 H.P. size. GROUP B | MOTOR | X.2642. RR.45a. cl c. | X.3082. RR.45a. (cl c) | X.1058 Bijur I.A.D. | X.4007 U.S.A. Bosch. | X.1086 Westinghouse. | X.4341 C.A.V. S.B. | |---|---|---|---|---|---|---| | **DIMENSIONS.** | | | | | | | | Carcase diameter. | Not circular | 6.000 | 5.500 | 4.850 | 4.940 | 5.000 | | Carcase length. | 5.175 | 7.250 | 5.920 | 5.600 | 4.740 | | Carcase thickness. | .325 | .270 | .240 | .300 | .300 | | Armature diameter. | 3.600 | 3.600 | 3.875 | 3.250 | 3.250 | 3.000 | | Armature active length. | 2.550 | 2.250 | 2.670 | 3.800 | 3.300 | 3.050 | | Driving end arm: overhang.(") | 1.3 | 1.1 | 1.05 | .8 | 1.0 | .75 | | Length of comm. conns. excluding comm. spokes.(") | 1.15 | 1.15 | 1.0 | 1.0 | .9 | 1.15 | | Ditto, including comm. spokes.(") | 1.4 | 1.4 | 1.2 | 1.2 | 1.1 | 1.4 | | Ratio armature dia. to carcase dia. | - | .60 | .70 | .67 | .66 | .60 | | **WEIGHTS (lbs)** | | | | | | | | Complete machine but without pinion sprocket or suspension. | 35.5 | 29.5 | 31.1 | 25.6 | 26.6 | 23.75 | | Armature without pinion or sprocket | 11.56 | 10.0 | 12.75 | 10.3 | 9.4 | 8.5 | | Carcase & pole pieces bare‡ | 13.69 | 12.0 | - | - | - | - | | Armature stampings | - | 4.5 | - | - | - | - | Contd. -1- | ||