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).
Testing of stiffer springs to prevent top plate failures on cars with front wheel brakes.
| Identifier | ExFiles\Box 72\3\ scan0108 | |
| Date | 1st September 1924 | |
| To Wor.{Arthur Wormald - General Works Manager} from CJ. CJ3/E4/9/24 - 2 - a certain number of springs of 12½% (or whatever weight may be decided upon) fitted with the Woodhead clip so that we may try them on two cars in parallel in France for 10,000 miles, one set made by Firth's, one set made by Woodhead. Now we come to a more serious matter. BY.{R.W. Bailey - Chief Engineer} says that he does not agree that the issue is really determined by the clip 'as the vital factor was a top plate failure which had no 'relation to the type of clip and moreover I (BY) am satisfied 'that the springs now being prepared will also fail, the real 'issue being that a spring 12½% stiffer than standard is not a 'sufficient increase to prevent top plate failures on our 40/50 'HP cars using front wheel brakes driven at high speeds over 'rough roads. 'The suggested inadequacy of a 12½% stiffer spring will be 'questioned. I therefore am forced to draw attention to the 'fact that failures of Woodhead springs on standard cars 'without front brakes compelled me to urge on CJ and R the 'necessity for a 20% increase for use under high speed and 'rough road conditions apart altogether from the front brake 'issue. 'It is noteworthy that the Firths' springs fitted with Firths' 'clip we have run on the 'Bumper test' have in each case not 'failed at clip plates but on the top plate which is the vital 'point, as then, and only then, control of the axle fails.' Before arranging for cars to be run in France with 12½% stiffer springs, it would be wise to ascertain whether R.{Sir Henry Royce} agrees with BY that springs now being prepared will also fail. If R.{Sir Henry Royce} is of this opinion, then he will doubtless state what percentage of stiffness of spring should be used for the forthcoming further 10,000 miles trial in France. Would it not be wiser to test springs of a stiffness which it is thought will be sufficient in any case but of course something less than 25%, and then later to test with lighter springs until we arrive at what is a safe and what is an unsafe percentage. CJ | ||