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).
Competitor automotive engineering developments, including crankshafts, pistons, and valve gear.
| Identifier | ExFiles\Box 173\3\ img090 | |
| Date | 4th April 1934 | |
| -5- General Motors lab. are at present conducting tests on improving volumetric efficiency which is in parallel with our own project. They have also carried out a research on the deflection in valve gear and its effect on silence. This is something we do not know a deal about. The latest tendency is to step up crankshaft journal bearings towards the flywheel, presumably to improve their torsional characteristics. As far as we know, Ford is the only manufacturer using a cast semi-steel crankshaft. The rubber type of crankshaft damper is universally employed on eights and twelves and crankshaft periods seem to be conspicuous by their absence. For some reason a nine bearing eight seems rather more difficult to deal with than a five bearing eight. Facards have therefore supplemented the rubber with a little dry friction. The latest development, sponsored by Longa working with Cadillacs, is to substitute micarta for the rubber, and this development should be followed up as it gives a damper that is much less susceptible to small variations in tuning. Cadillacs adopted aluminium pistons for the first time this year. In consequence they have been doing some intensive development work on them running over a third of a million miles in four months. Some of the information they have obtained is interesting. The invar-strut piston is being superceded by the all aluminium type similar to our own but with much less skirt flexibility, the type is known as the T slot due to the method of splitting. Several examples of this piston in quantity production appeared to be appreciably lighter than our own, and we have therefore obtained some made from the Chrysler die for test. These will fit the Bentley. Alumiliting, an electrolytic process to surface the finished piston and so reduce the tendency to partially seize when starting from cold, is found to improve this feature some hundreds percent, and has already been adopted by Cadillacs, Lincolns, etc, and others. | ||