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).
Design modifications for the 20HP side wheel carrier, including a sketch with dimensions.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan196 | |
| Date | 29th August 1929 | |
| HS.{Lord Ernest Hives - Chair} } FROM DA.{Bernard Day - Chassis Design} DA{Bernard Day - Chassis Design}1/M29.8.29. x5600 x7600 20HP. SIDE WHEEL CARRIER. We thank you for HS{Lord Ernest Hives - Chair}/RM{William Robotham - Chief Engineer}3/MJ26829. Our impression that the SS.{S. Smith} carrier was perfectly rigid and strong was obtained partly from actual trial, and partly from the fact that no complaints have been received. We investigated the lengths of the tubes and found that there was nothing in it. In view of your remarks we wish to make the best possible job, and suggest that the following should be done: (1) Use the SS.{S. Smith} tubes, shape of plate, tube fittings, etc. The tube centres will be the same as now on the 20HP. (2) Increase the plate thickness on both SS.{S. Smith} and 20HP. from .160" to .187". (3) We suggest that the rapid failure of the specimen plate you have sent us was probably due to one of the bolts never having been tight. We agree that our scheme is slightly defective in this respect, in that it does not shew a countersunk on the tube fitting to make sure that the countersunk head was on its seat. We think however that we are justified in making an alteration, and we suggest that a washer should be used as indicated in sketch below. The aluminium wheel centre requires slight modification to clear this on both cars. The bolt in both cases should be .375" dia. [SKETCH TEXT] .187 .375o 1.500 MODIFIED SHAPE TO CLEAR WASHER. (4) We agree to increase the length of the bolthead to provide more surface, and suggest from 1" to 1.5". This has the additional advantage of bringing the load opposite the inclined sides of the slot. This should be done on both SS.{S. Smith} and 20HP. If you could fix up a 20HP. carrier quickly on these lines, it would enable us to decide whether any stiffening to the frame is needed. This latter point does not seem to have been as yet investigated. DA.{Bernard Day - Chassis Design} | ||