Letter from Dunlop Rubber Co. discussing tyre power transmission efficiency, testing parameters, and offering to supply different tyre constructions.
| Identifier | ExFiles\Box 157\1\ scan0094 | |
| Date | 11th July 1933 | |
| X 4050. DUNLOP RUBBER CO.,LTD. TELEGRAPHIC ADDRESS: "DUNLOPS, PHONE, BIRMINGHAM" TELEPHONE: BIRMINGHAM CENTRAL 4108 (P.B.E) EXTENSION No. 302. YOUR REF: OUR REF: AH. FORT DUNLOP ERDINGTON BIRMINGHAM 11th July 1933. W. A. {Mr Adams} Robotham, Esq., Messrs Rolls-Royce Ltd., DERBY. Dear Robotham, In reply to yours of the 8th instant. We are still without any definite figures on the efficiency of power transmission of tyres. Other investigators have published figures which do not seem to us very reliable. Their tests however, were made by comparatively low speeds and low power transmissions. The loss of 12 BHP in transmitting over 100 H.P. seems to me reasonable in view of the nature of the materials employed in tyre construction. In order to check this, a test with higher and lower inflation pressures would be useful. With a higher inflation pressure, we should expect a marked reduction in loss of power. For the purpose of a test it would be safe to run at 80 lbs/sq.in. I am presuming that your tests are made on a curved drum. Have you measured the power loss by the air churning of the wire wheels? We found this to be quite considerable in the wheels for Sir Malcolm Campbell's car, while reference is made to the same subject in the report on the IndiaProduction 20 HP. with 4-speed box and Front Wheel Brakesnapolis 500 mile race in the current issue of the S.A.E. Journal. We are certainly very interested in this subject, and would like to submit some tyres of different constructions for you to test if this is agreeable to you. Will you please let me know if you would like this to be done, in which case we will put these special tyres in hand at once. Yours faithfully, For the DUNLOP RUBBER COMPANY LTD., A Healey Works Director. | ||
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).