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).
High-speed wobble and road shock tests for the 12 EX - EAC VIII, detailing axle and tyre performance.
| Identifier | ExFiles\Box 17\3\ Scan025 | |
| Date | 14th August 1926 | |
| To "H.S." From "R.M." Hotel de France, Chateauroux, Indre, France. August, 14th 1926. 12 EX - EAC VIII. We have now almost completed our test on high speed wobbles on 12 EX-EAC VIII. Incidentally, we have also got some road shock impressions, but we are trying to keep the two items separate as far as possible. Today and tomorrow, we are investigating the best compromise for road shocks. As a summary of results so far, we think we can say that: (i) - The new axle can be made satisfactory for use with high pressure tyres (S.S. CORD.) (ii) - It is very improbable that this axle can be used with the Dunlop 33x6 "TRIPLE STUD" well base tyre, unless some further radical improvement can be introduced to check high speed wobble. (iii). - It is quite possible that the axle will be able to be used with Dunlop traction or Michelin tread 33x6.75 well base rim tyres inflated to 35 Lbs per Sq.Inch or over. Our main difficulty at the moment is that the only 33x6" well based tyres that we have are the triple stud pattern Dunlop. The Michelins that we have hoped to use turned out to be 6.75" tyres. We cannot recollect a test in England, where an average 6" tyre was worse than a 6.75" tyre. There is always the point that the 6.75", being larger tyres on the same rim, have more peripheral weight. We have proved that peripheral weight definately opposes wabbles. (Brass band on rim aginst lead band on drum tests.) We consider it of the first importance to get some 6" traction tread Dunlop out here to prove this point. Briefly our tests up to date are as follows: standard S.S.Tube, 3500 springs; solid cross steering tube; parallel wheels; shocks dampers 75Lbs and 35 Lbs. Tyre pressure 35 Lbs per Sq.Inch All wheels balanced. | ||