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).
Dunlop's production difficulties with out-of-balance limits for 20 HP tyres and proposing solutions.
| Identifier | ExFiles\Box 45\2\ Scan198 | |
| Date | 19th December 1929 | |
| To By.{R.W. Bailey - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} X 4050 Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson}1/MJ.19.12.29. 20 HP. TYRES. X. 4050 X. 5820 Messrs. Dunlop are in trouble because they find the limit of out of balance which we specified on the 6" tyre for 19" rim is beyond them as a production proposition. The present limit is 57 ins. ozs. This is equivalent to 3.85 ins. ozs. at the tyre periphery. Dunlops' have of course increased their own troubles by increase in tyre size and decrease in wheel size, for the former has increased the value of percentage of out of balance, and the latter dcreased the effectiveness of our balance weights. We consider, that, in view of these factors we ought to help them out of their difficulties to a certain extent, by increasing the out of balance allowance to 67 ins. ozs. To deal with this increase the weight of balancing washers will have to be increased. On the existing 19" wheels it is possible to increase the number of balancing washers from seven to nine, which would more than cover the desired amount. Alternatively, the number of balancing washers could be kept as at presentand the diameter increased from 1.25" to 1.35". This latter would certainly be the neater method but makes the question of interchangeability awkward. Will you please let us have your views on the problem. Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} | ||