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).
Analysis of spring performance and manufacturing tolerances related to the side steering tube.
| Identifier | WestWitteringFiles\P\2July1926-September1926\ Scan007 | |
| Date | 7th July 1926 guessed | |
| contd :- -3- Then the ball load with the stronger springs is only 280 lbs. and with the weaker springs 350 lbs. As a matter of fact the errors need not be so great as those indicated above because in a spring of this type the manufacturing limits are such that the rating of the springs cannot be guaranteed within 10% which with small variation due to slight permanent set and varying ball end and plunger friction, are sufficient to produce the discrepancy quoted with half the stated fitting errors. With reference to the assembly of the side steering tube, it is not implied that as a production job the necessary accuracy could not be attained by means of gauges, but that in the hap-hazard changing over of springs for test, without knowledge of the necessary difference in set up, the results obtained are liable to be mis-leading. One of the reasons why we wish to make a large step from 3500 lbs. to 2000 or 1500 lbs. springs, is because we realise the cumulative errors which can creep in, and wish to be certain that when the customer complains of shocks he will definitely appreciate the difference caused by fitting the weaker springs. He will be in a position then to decide which of the two compromises he prefers. What we want to emphasize is that the side steering tube is not a portion of the car where it is possible to obtain results to fine limits. The springs are difficult to make and cannot be produced without variations in performance. Owing contd :- | ||