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).
Vehicle weight reduction through material substitution and redesign, comparing a Bentley to a Pontiac.
| Identifier | ExFiles\Box 88\3\ scan0103 | |
| Date | 1st February 1935 | |
| -2- MATERIAL The use of Magnesium is one obvious move and on the next 15,000 miles car we shall have most of the pieces that can be made in magnesium without re-design on the car. The total of these save only 33 lbs. weight because the top half of the crankcase, axle centre etc. require redesign before we can change from aluminium, silence does not permit of rocker covers and timing cases being changed, and weakness at high temperatures prohibits brake shoes in this material. With regard to the other parts of the chassis, as far as we know there are few if any places where weight can be gained by improving material specification. DESIGN However, if we take various sections of the chassis and compare them with those of another chassis of similar dimensions, we get some rather surprising results which indicate that we can save weight by design and development work. The attached list shews that, tabulating sections of the Pontiac which is about a 30 HP. car, on ten sections this chassis is a total of 257 lbs. lighter than the Bentley, and on the remaining five sections the Bentley is 209 lbs. lighter than the Pontiac. This is taking existing standard weights. Briefly running over the sections - (1) Brake Linkage We have always considered that we are extravagant with our brake gear, particularly as we have recently shewn that in addition to being complicated it is inefficient. The fact that it is inefficient reacts upon the servo which has to be unnecessarily large. We might expect to be twice as heavy as the Pontiac because their brakes are not much good, but not five times as heavy. One definite saving would be to use steel shoes with copper rivets in contact with the drum, which would mean that the hand and foot brake linkage could be common without the chance of the car running away when the shoes cool down. The Girling people are getting out a linkage for us, the weight of which will be interesting. We attach an analysis of the weight of our brake linkage. | ||