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 technical specifications for four different starter motors for small cars.
| Identifier | ExFiles\Box 61b\3\ scan0194 | |
| Date | 21th June 1927 guessed | |
| X 543. STARTER MOTOR TABLES II. Motors for small car MOTOR x4342x C.A.V. S.C. x4342x SMITH S.S. x4384 R.R. GOSHAWK x434PL Lucas 4880 WEIGHTS IN LBS COMPLETE MACHINE WITHOUT PINION SPROCKET OR SUSPENSION: 20.0, 16.4, 17.1, 17.5 ARMATURE COMPLETE WITHOUT PINION OR SPROCKET.: 8.6 WITH END-PLATE, 6.3 WITH END-PLATE, 8.1 WITH END-PLATE, 8.5 WITH END-PLATE BARE WEIGHT OF CARCASE AND POLE PIECES.: —, —, —, — WEIGHT OF ARMATURE STAMPINGS.: —, —, —, — WEIGHT OF ARMATURE COPPER [EXCLUSIVE OF COMMUTATOR]: —, —, —, — WEIGHT OF FIELD COPPER: —, —, —, — AIR GAP Mm.: .69, .95, .38, .38 INCHES: .027, .035, .015, .015 FIELD CIRCUIT NUMBER OF WOUND POLES.: 4, 4, 4, 4 CONDUCTOR DIMENSIONS [INCHES]: —, —, 4 wires per strip .15" x .05" bare, — NUMBER OF TURNS PER COIL.: —, —, 5.5, — ARRANGEMENT OF COILS.: 2 SERIES 2 PARALLEL, ALL IN SERIES, ALL IN SERIES, ALL IN SERIES RESISTANCE OF FIELD CIRCUIT. OHMS [COLD 18°C]: .0070, .0213, .0064 20°C, .0088 ARMATURE CIRCUIT TYPE OF WINDING.: RET. WAVE, RET. WAVE, RET. WAVE, PROG LAP NO OF SLOTS.: 25, 13, 29, 29 NO OF CONDUCTORS.: —, —, 116, — CONDUCTORS PER SLOT.: —, —, 4, — COILS PER SLOT.: 1, 1, 1, 1 NO OF COILS OR COMMUTATOR BARS.: 25, 13, 29, 29 TURNS PER COIL.: —, —, 2, — VIRTUAL CONDUCTORS.: 50, 26, 58, 58 WINDING PITCH IN VIRTUAL CONDUCTORS: 13 & 11, 7 & 5, 15 & 13, FOR. 13 BACK. 11 STEP OR WINDING PITCH IN SLOTS.: (1 & 7), (1 & 4), (1 & 8), (1 & 7) ARMATURE RESISTANCE OHMS [COLD 18°C]: .0125, .0180 23°C, .0205 20°C, .0098 CONDUCTOR DIMENSIONS [INCHES].: —, —, .080" 14 S.W.G., — COMMUTATOR and BRUSHES COMMUTATOR DIAMETER.: 1.62, 1.50", 1.825, 1.375 COMMUTATOR LENGTH.: 1.13, .90", .95, .70 BRUSH CONTACT AREA.: 2x .875" x .28" .490□", 2x .75" x .375" = .281□", 2x .75" x .31" = .465□", 2x .50 x .30 = .300□" GRADE AND HARDNESS OF BRUSHES: MORGANITE C.M.3., MORGANITE C.M.3., MORGANITE C.M.3, MORGANITE C.M.3 ARRANGEMENT OF BRUSHES.: 4 AT. 90°, 2 AT 90°, 4 AT. 90°, 4 AT 90° RATIO OF FIELD RESISTANCE TO ARMATURE RESISTANCE: .560, 1.180, .312, .898 | ||