Graph comparing the performance ratings of a Woodhead's Special Spring and a 1st Standard Spring under varying loads.
| Identifier | ExFiles\Box 67a\1\ scan0221 | |
| Date | 27th May 1925 guessed | |
| (13) SPRING RATING TESTS. (η & α) COMPARISON OF SPRINGS Wide Pads, 21" Shackles Mean Curve Y-Axis: SPRING RATING LBS/INS. X-Axis: TOTAL SPRING LOAD LBS. Legend: η = WOODHEAD'S SPECIAL SPRING α = 1ST STANDARD SPRING | ||
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).