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).
Examination and test report on the first Spectre Switchbox, providing suggestions for improvement.
| Identifier | ExFiles\Box 166\3\ img024 | |
| Date | 31th July 1934 | |
| Y6090. E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Wst.3/MA.31.7.34. EXAMINATION AND TEST OF THE FIRST SPECTRECodename for Phantom III SWITCHBOX. We have now preliminarily tested the first model of the new R.R. Switchbox pre-eminently designed for the SpectreCodename for Phantom III Chassis with the master switch incorporated, etc. As a result of our examination and test of this switchbox, the following suggestions for its improvement are put forward for your consideration :- (1) There is too much play in the main and ignition switch levers. This appears to be due to the spring loaded ball being slack in its guide and not having sufficient bearing surface. It is also considered that excessive friction and wear may result from the levers bearing direct on to the aluminium of the casing. Phosphor bronze bushes inserted at points like this might be a refinement. We believe that you already have these points under consideration. (2) The action of both main and ignition switches is rough and rather indefinite. An improvement might be obtained with the use of a plunger instead of a ball, a stronger spring and a reduced lobe terminating in a rather sharp crest. (3) With a current of 50 amperes passing through the main contacts, which current is representative of extreme conditions, the volt drop across the two contacts in series was .3 volts. We would like to reduce this not only from the point of view of the switch itself but also from the point of view of the dynamo voltage regulator. With this current maintained for 30 seconds, parts of the two contacts became excessively warm the hottest and therefore the weakest part was the copper connecting link on the main finger contact connecting the copper rubbing block to the terminal post. The cross section of this link only has a current carrying capacity of 4.5 amperes based on the 1,000 amperes per sq.in. law. The section of this link should therefore be increased as much as possible. | ||