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).
Specifications for inner and outer valve springs, total spring load, and turning circles.
| Identifier | ExFiles\Box 124\3\ scan0138 | |
| Date | 1st March 1928 guessed | |
| contd :- -2- Inner springs. Outside dia. .8750 Inside dia. .625". Dia. of wire .125". Free length 1.850". Length : valve closed = 1.675" Length : valve open = 1.365". Load : valve closed = 17 lbs. Load : valve open = 55 lbs. 8 working coils and 2 half coils ground square, one at each end. Outer springs. Outside dia. = 1.360" Inside dia. = 1.030". Dia. of wire .168" Free length 2.340" Length : valve closed = 1.950 Length : valve open = 1.640 Load : valve closed = 40 lbs. Load : valve open = 85 lbs. 8 working coils and 2 half coils ground square, one at each end. Total spring load for the valve lift of .310 Valve closed = 57 lbs. Valve open = 140 lbs. Both the inner and the outer springs are made with the bottom two coils wound closer together than the remaining coils. The Stutz valve springs were made similarly; it was claimed that valve spring surging was eliminated by this means. The angle of attack of the valve rocker on the valve stem is zero; thus the thrust is always in one direction. Turning circles. Left lock 32.34 ft. in dia. Right lock 31.68 ft. in dia. measured between the tyre track centres. contd :- | ||