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 of specifications for various magneto machines, including Bosch and Watford models.
| Identifier | WestWitteringFiles\F\February1921\ Scan78 | |
| Date | 3rd February 1921 | |
| THOS.D (03-21-01 SHT H.2) (T 001) A822 .Я.Я Contd. -2- EFC4/T3.2.21. cover is removed, and yet permits of this being taken off by hand. We understand that except for the distributor, many of the parts of these two machines are interchangeable. Mr. Hives also now reports, after seeing their factory, that the American Bosch Z.R.6 is very well made. As regards the details of the B.6, these were reported to you under cover of our EFC2/T20.11.20. As suggested therein, we find this machine to be quite quiet; what noise there is being due to the tapping of the contact breaker. (3) The radial air gap between armature and pole pieces we find to be .006" & .005" for the R.{Sir Henry Royce} Bosch and U.S.A. Bosch Z R.6 machines respectively. The gap for the B.6 is unobtainable. These figures are similar to those of the Watford. (4) The lengths of the H.T. safety gaps are 9.9 mm. for the R.{Sir Henry Royce} Bosch Z.R.6, 8.7 mm. for the U.S.A. Bosch Z.R.6. and unobtainable for the B.6 These gaps are larger than those of the Watford machines. (5) The distributor dimensions we found to be as in the following sketch and table :- Cont | ||