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).
Leaf spring hardness, interleaving, grooved sections, and load grading.
| Identifier | ExFiles\Box 154a\2\ scan0349 | |
| Date | 25th June 1941 | |
| -cont'd- - 4 - Rm{William Robotham - Chief Engineer}/GB.5/SW.25.6.41. Regarding leaf hardness Fox's like to keep to 350-400 Brinell. Vauxhall now specify 375-425 Brinell, presumably on information received from America. Interleaving. It is fairly certain that one of the main reasons for the short life of interleaving, has been faulty leaf bedding resulting in excessive pressures on the interleaving and gaps which allow mud etc., to enter. It would appear that the clamping together of all the leaves during the tempering operation, must produce good leaf bedding and give interleaving its greatest chance of success. We suggest that we obtain for trial one pair of Myth rear springs and one pair of Senior Range springs from Fox's for trial with interleaving. Grooved Section Springs. It is well known that fatigue failures on leaf springs always start at the tension surface. For this reason, Toledo Woodheads' make grooved section springs. The Toledo groove is not big enough and these springs also start to break on the tension surface. It was for this reason that the T.W. Myth rear springs were shot blasted on the tension side only. Fox's have taken grooving further and have taken out patents covering the removal of metal on the compression side amounting to half the leaf width and two thirds of its thickness. They claim to have balanced the tensile, compressive and shear stresses and to have effected a weight saving of 23½%. See attached Patent Specification No. 532698. They have not yet a complete set of rolling equipment for these grooved springs. They are quite prepared to supply samples using leaf sections for which they have rolls. Spring Load Grading. On the Senior Range, the normal spring load for the 50" spring rises in seven stages of 50 lbs. from 900 lbs to 1200 lbs. The 56" spring loads rise in nine stages of 50 lbs. from 1000 lbs to 1400 lbs. Spring costs could be reduced and storekeeping and the spares position -continued- | ||