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).
Experimental comparison report on three magnetos: Watford ZC6, R. Bosch ZR.6, and B.T.H. CE.6.
| Identifier | ExFiles\Box 4\5\ 05-page317 | |
| Date | 3rd November 1924 | |
| X430 To R.{Sir Henry Royce} & E.{Mr Elliott - Chief Engineer} from EFC. c. CJ. & BJ. c. EY. EP.{G. Eric Platford - Chief Quality Engineer} Wor.{Arthur Wormald - General Works Manager} c. Da.{Bernard Day - Chassis Design} Hs.{Lord Ernest Hives - Chair} EPCI/T3.11.24. X.430. MAGNETOS - AND IN PARTICULAR PRESENT STD. WATFORD ZC6, R.{Sir Henry Royce} BOSCH ZR.6., AND B.T.H. CE.6. As referred to in our previous general report EFCI/T20.10.24, the following is an experimental comparison of these three machines, taken item by item on our Schedule of experimental test. (1) Weight of the Standard Watford magneto. 12.5 lbs. 73957 " " R.{Sir Henry Royce} Bosch ZR.6. " 18.5 lbs. 2571555 " " B.T.H. CE.6. " 14.5 lbs. 406821 (2) As regards the mechanical and electrical details of design of the B.T.H. CE.6 magneto, the following is an extract from my assistant's report WA.{Mr Wallis}82 :- "The general appearance of the machine is good, the body and base being made of die-cast aluminium, whilst the distributor (of the jump spark type incorporating the safety gap) is moulded of a special synthetic compound. The armature windings and the condenser are neatly housed on the top of the rotating inductors, this magneto being of the polar inductor type. The permanent magnetic field is supplied by two short bar magnets of Cobalt steel, and the contact breaker is operated by a two-lobed cam, although the magneto would be capable of being operated with a four-lobed cam to give four sparks per revolution. An interesting feature of this machine is the distributor gear pinion which is made of a fibrous compound, this being for the purpose of obviating gear noise. Although this special feature reduces gear noise, the noise emanating from the other mechanical parts is considered rather excessive." (3) The lengths of the respective H.T. safety gaps of the three magnetos are :- Watford 8.5 mm. R.{Sir Henry Royce} Bosch 10.2 mm. B.T.H. 8.6 mm. Contd. | ||