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).
Durability, slow running, and mechanical reliability of centrifugal superchargers.
| Identifier | ExFiles\Box 140\1\ scan0089 | |
| Date | 18th December 1934 | |
| To Messrs. From HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to OF. c. to W. c. to By.{R.W. Bailey - Chief Engineer} c. to Lr.{Mr Ellor} c. to Hn.{F. C. Honeyman - Retail orders} c. to Hn{F. C. Honeyman - Retail orders}/Wd.{Mr Wood/Mr Whitehead} +209 Centrifugal Supercharging. We have now accumulated a considerable amount of information on the centrifugal supercharger as fitted to the Graham-Paige. We have been running a second supercharger on a Bentley unit on the test bed. (1) Durability and Silence of Supercharger Drive. The Graham car has completed 10,000 miles and the strip of the blower shows it to be in exceedingly good condition. The drive too has worn well. The American worm gears are so far better than anything we have been able to get in England. We think that if we were rather more generous with the proportions of the worm drive it could be made a completely reliable proposition. The drive was not of course perfectly silent at the beginning of the test, but was not obtrusively noisy, and the noise did not increase very much during the test. We anticipate that the drive will have already been improved in the U.S.A. (2) Slow Running. We find that the Graham Car can be made to pull at slow speeds better than any of our existing cars. It will pull evenly at 5 m.p.h. Idling it is not so good, being about the same as the present Bentley. On the test bed on a Bentley unit, however, we have been able to demonstrate that with the correct quantity of heat to the blower we can get good idling. We think that with the correct induction system and an exhaust heated hot spot it would be as easy to obtain idling with a supercharger as with a normal induction system. We are trying several induction systems on the test bed with a view to finding out the best arrangement. (3) Mechanical Reliability of Engine fitted with a Supercharger. The test in England has not of course been a very severe one for the Graham engine. Our only mechanical trouble has been the failure of the cylinder head gasket. Three of these failed in quick succession, and we then found that the cylinder head joint face was not flat. Since correcting this by machining we have had no further trouble. | ||