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).
Comparative table of specifications for various starter motors.
| Identifier | ExFiles\Box 61b\3\ scan0193 | |
| Date | 24th May 1927 guessed | |
| X5482 X.543 STARTER MOTOR TABLES. X.3174 | | X.3283 C.A.V. E.C. | X.3161 LUCAS A.510. | X.1055 BIJUR A.21. | X.1242 BOSCH S.A.2. | X.2642 R.R.17. C.I.C. | X.2632 R.R.24. C.I.C. | X.3052 R.R.45a. C.T.C. | X.3740 R.R.45b. R.C. | R.R.45c. C.C. Motor | X.1058 BIJUR I.A.D. | X.4007 U.S.A BOSCH | X.1056 WESTINGHOUSE | X.4341 C.A.V. S.B. | R.R.44 S.B. | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | MOTOR | | | | | | | | | | | | | | | | WEIGHTS IN LBS. | | | | | | | | | | | | | | | | COMPLETE MACHINE WITHOUT PINION SPROCKET OR SUSPENSION. | 19.0 | 21.4 | 30.5 | 39.15 | 35.0 | 34.5 | 35.5 | 29.5 | -- | 31.1 | 25.6 | 26.6 | 23.75 | -- | | ARMATURE COMPLETE WITHOUT PINION OR SPROCKET. | 6.94 | 7.86 | 11.25 | 11.0 | 11.06 | 10.62 | 11.56 | 10.0 | -- | 12.75 | 10.3 | 9.4 | 8.5 | -- | | BARE WEIGHTS OF CARCASE AND POLE PIECES. | -- | -- | -- | -- | 13.69 | 13.69 | 13.69 | 12.0 | -- | -- | -- | -- | -- | -- | | WEIGHT OF ARMATURE STAMPINGS. | -- | -- | -- | -- | -- | -- | -- | 4.5 | -- | -- | -- | -- | -- | -- | | WEIGHT OF ARMATURE COPPER. (EXCLUSIVE OF COMMUTATOR) | 1.25 | 1.66 | -- | 1.41 | 1.60 | 1.01 | 1.60 | 1.50 | -- | -- | -- | -- | -- | -- | | WEIGHT OF FIELD COPPER. | 2.50 | 1.75 | -- | 3.20 | 3.80 | 3.80 | 3.80 | 3.25 | -- | -- | -- | -- | -- | -- | | AIR GAP. | | | | | | | | | | | | | | | | Mm. | .79 | .58 | .63 | .43 | .63 | .63 | .63 | .63 | -- | .56 | .48 | .89 | 1.27 | -- | | INCHES | .031 | .015 | .025 | .017 | .025 | .025 | .025 | .025 | -- | .022 | .019 | .035 | .050 | -- | | FIELD CIRCUIT | | | | | | | | | | | | | | | | NUMBER OF WOUND POLES. | 4 | 4 | -- | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 2 | | SIZE OF CONDUCTOR. | -- | -- | -- | -- | .070"x.056" | .310"x.055" | .370"x.055" | .250"x.116" | .250"x.116" | -- | -- | -- | -- | -- | | NUMBER OF TURNS PER COIL. | 6 | 18 | -- | -- | 13.5 | 13.5 | 13.5 | 8.75 | 8.75 | -- | -- | -- | -- | -- | | ARRANGEMENT OF COILS. | 2 SERIES 2 PARALLEL | 4 IN PARALLEL | 1 IN PARALLEL | 4 IN SERIES | 4 IN SERIES | 4 IN SERIES | 4 IN SERIES | 4 IN SERIES | 4 IN SERIES | ALL IN PARALLEL | ALL IN SERIES | 2 SERIES 2 PARALLEL | 2 SERIES 2 PARALLEL | 2 IN SERIES | | RESISTANCE OF FIELD CIRCUIT. OHMS [COLD 18°C] | .0039 | .0023 | .0012 | .0030 | .0204 | .0204 | .0204 | .0085 | .00745 | .0023 | .0044 | .0061 | .0019 | -- | | ARMATURE CIRCUIT. | | | | | | | | | | | | | | | | TYPE OF WINDING. | RETROG WAVE 2 CIRCUIT | RETROG WAVE 2 CIRCUIT | RETROG WAVE 2 CIRCUIT | PROG WAVE 2 CIRCUIT | RETROG WAVE 4 CIRCUIT | PROG. LAP 4 CIRCUIT | RETROG WAVE 2 CIRCUIT | PROG WAVE 2 CIRCUIT | PROG WAVE 2 CIRCUIT | PROG. WAVE | RETROG WAVE | RETROG WAVE | PROG WAVE | PROG WAVE | | No. OF SLOTS. | 21 | 43 | 21 | 41 | 17 | 24 | 45 | 45 | 45 | 33 | 27 | 25 | 15 | 15 | | No. CONDUCTORS. | 84 | 86 | 84 | 82 | 102 | 384 | 90 | 90 | 90 | 66 | 108 | 50 | 60 | 60 | | CONDUCTORS PER SLOT. | 4 | 2 | 4 | 2 | 6 | 16 | 2 | 2 | 2 | 2 | 4 | 2 | 4 | 4 | | COILS PER SLOT. | 1 | 1 | 1 | 1 | 3 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | No. OF COILS OR COMMUTATOR BARS. | 21 | 43 | 21 | 41 | 51 | 48 (series 4 parallel) | 45 | 45 | 45 | 33 | 27 | 25 | 15 | 15 | | TURNS PER COIL. | 2 | 1 | 2 | 1 | 1 | 4 (series 4 parallel) | 1 | 1 | 1 | 1 | 2 | 1 | 2 | 2 | | VIRTUAL CONDUCTORS. | 42 | 86 | 42 | 82 | 102 | 96 | 90 | 90 | 90 | 66 | 54 | 50 | 30 | 30 | | WINDING PITCH IN VIRTUAL CONDUCTORS. | 9 & 11 | 21 | 9 & 11 | 21 | 25 | 25 forward 23 backward | 21 & 23 | 23 | 23 | 15 & 17 | 13 | 11 & 13 | 7 & 9 | 7 & 9 | | STEP OR WINDING PITCH IN SLOTS. | 5 | 11 COIL 10 COM | 5 | 11 COIL 10 COM | 5 COIL 4.5 COM | 6 COIL 5.75 COM | 11 | 11 COIL 12 COM | 11 COIL 12 COM | 8 | 7 COIL 6 COM | 6 | 4 | 4 | | ARMATURE RESISTANCE. OHMS [COLD 18°C] | .0086 | .0054 | .0016 | .0095 | .015 | .0195 | .0114 | .0116 | .0116 | .0028 | .0162 | .0038 | .0060 | .0060 | | CONDUCTOR DIMENSIONS [INS] | -- | -- | -- | -- | .195x.040 | .140x.040 | .140x.064 | .140x.064 | .140x.064 | -- | -- | -- | -- | -- | | COMMUTATORS & BRUSHES. | | | | | | | | | | | | | | | | COMMUTATOR DIAMETER. | 1.770 | 1.940 | 2.00 | 2.125 | 2.438 | 2.438 | 2.438 | 2.400 | -- | 2.083 | 1.544 | 1.790 | 1.780 | 1.780 | | COMMUTATOR LENGTH. | 1.150 | .938 | 1.200 | .875 | 1.250 | 1.250 | 1.250 | 1.230 | -- | 1.187 | 1.150 | .969 | 1.125 | 1.125 | | BRUSH CONTACT AREA. | 1"x.60x.25=.15" sq | 1"x.36"=.18" sq | 1"x.625"=.25" sq | 2x.18 3/4"=.065" sq | 2x1.0"x.375"=.750" sq | 2x1.0"x.375"=.750" sq | 2x1.0"x.375"=.750" sq | 2x1.0"x.375"=.750" sq | 2x1.0"x.375"=.750" sq | 2x.347"x.996"=.492" sq | 2x.953"x.348"=.660" sq | 2x.314"x.732"=.549" sq | 2x.870"x.275"=.272" sq | 2x.870"x.275"=.272" sq | | GRADE AND HARDNESS OF BRUSHES. | C.M.1. MORGANITE | C.M.4. MORGANITE | CONTAINS C.U.C. HARDER THAN CM1 | CONTAINS C.U.C. HARDER THAN CM1 | C.M.1. MORGANITE | C.M.1. MORGANITE | C.M.1. MORGANITE | C.M.2. MORGANITE | C.M.2. MORGANITE | NETTE N MORE METALLIC THAN C.M.3. | C.M.4 MORGANITE | SPEER K.K.K. C.M.3. | C.M.O. MORGANITE | C.M.O. MORGANITE | | ARRANGEMENT OF BRUSHES. | 2 AT 90° | 2 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | 4 AT 90° | | RATIO OF FIELD TO ARMATURE RESISTANCE. | .453 | .333 | .750 | .316 | 1.36 | 1.046 | 1.79 | .732 | .64 | .822 | .272 | 1.60 | .317 | .317 | NOTE ALL MACHINES ARE OF THE 12 VOLT TYPE, EXCEPT THE BIJUR A.21. WHICH IS 6 VOLT. | ||