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).
Comparing the performance of Firths' road springs against American springs and discussing spring failures on car 14-EX.
| Identifier | ExFiles\Box 43\2\ Scan249 | |
| Date | 1st May 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/an. c. to SJ. Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} CY. +3900 Hs{Lord Ernest Hives - Chair}/RM{William Robotham - Chief Engineer}/LG2. 5. 28. √4429 √3900 √7+10 ROAD SPRINGS. We have been testing on the bumping rig some front road springs made by Firths which are an exact copy of the American springs, which recently gave such excellent life on the bumper test. We ran three sets of these springs and their average life was only ten hrs. In every case the top leaf broke. The average life of a pair of American springs we ran in parallel was 23 1/4 hrs. We have previously had similar American springs average 39 1/4 hrs. so that 23 1/4 hrs. may be said to be below the average. We therefore draw the inference that Firths cannot make such good top leaves as America, and they are investigating the differences in manufacture. The spring question is somewhat emphasised by the fact that no less than eight leaves were broken in the front springs of 14-EX, on its return to the Works, including a top leaf. Though the buffer clearance was small it was due to alteration in initial camber, not to over-stressing the spring by deflection as the buffer should have prevented this occurring. The rear springs on this car give 4" buffer clearance with four passengers, thereby confirming our previous experience that this is about the minimum for a normal customers Continental work. On the return journey with the back full of luggage, we did not hit the buffers with undue frequency, though we believe the effectiveness of the shock absorbers during large contd :- | ||