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).
Detailed specification for a Magneto Speed Indicator and its D.C. generator component.
| Identifier | ExFiles\Box 34\2\ Scan054 | |
| Date | 17th October 1922 | |
| To Rg.{Mr Rowledge} from EFC. X 2238 EFC1/T17.10.22. X.2238 - MAGNETO SPEED INDICATOR. X1888 The R.R. magneto speed indicator consists of a magneto D.C. generator with drum wound armature; an adjustable resistance housed in the C of the magnet, together with a Weston moving coil instrument calibrated in revs. per minute. D.C. GENERATOR. This has aluminium end plates carrying ball bearings. The armature dia. is 1.39", active length 1.15", No. of slots 10. The winding is two-pole wave wound with a step of 5 (1 to 6). The armature resistance is 8.37 ohms and the weight of the armature 12.5 ozs. The slot dimensions are according to sketch herewith and the winding wire is of .010" (33 S.W.G.) with 59 turns per coil. Commutator. This is of dia. 1.043", length .323". No. of segments 10. Brushes. These are of rolled copper gauze and the magnet particulars are as follows :- Mean length 8.3" Mean span 2.1" Width 1.0" Thickness of bar. .35" Cross section. .35 sq.in. Internal dia. of C of magnet 1.75" Dia. of armature tunnel 1.4025" The magnetic circuit has a mean length of 8.8" Air gap each .00625" (total .0125") Weight of the complete machine 3 lbs.8 ozs. The machine may be mounted on a stand which, with bolts and nuts, adds 11.5 ozs. to this. The machine is intended to run at engine speed when used in conjunction with the Weston instrument as a speed indicator. Contd. | ||