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).
The specifications for Myth rear springs, including a design for a flat section spring and shot blasting requirements.
| Identifier | ExFiles\Box 110\3\ scan0073 | |
| Date | 15th May 1941 | |
| 746. To Rm{William Robotham - Chief Engineer}/HH. from Rm{William Robotham - Chief Engineer}/GB. Copy to Rm.{William Robotham - Chief Engineer} Ev.{Ivan Evernden - coachwork} Ev{Ivan Evernden - coachwork}/ID. Rm{William Robotham - Chief Engineer}/Ulm. Rm{William Robotham - Chief Engineer}/GB.5/GT.15.5.41. MYTH REAR SPRINGS. ------------------ Myth rear springs. As we cannot get grooved section springs elsewhere, a flat section spring has been designed. Details of it are given here. Leaf No Thickness. Maximum Stress Leaf length when flat Free radii ======================================================================== 1 .203 112,700 44 54 2 " 137,700 42 1/4 39 3 " " 37 13/16 " 4 " " 32 1/2 " 5 " " 27 1/4 " 6 " " 22 11/16 " 7 " " 17 11/16 " 8 " " 12 1/4 " 9 " " 7 9/16 " The leaves should be tapered in thickness for 2.5" at the ends. The shot blasting on the Toledo Woodhead springs was particularly bad. Shot blasting is desirable if it can be done properly. The percentage of broken shot must be kept low. We want a 3/8" dia. nozzle and 25 lb/sq.in. air pressure, or the equivalent. The tension surface only should be treated and it should be done at the rate of 15-30 sq.ins/minute. Will Rm{William Robotham - Chief Engineer}/HH. please make a drawing of this. Rm{William Robotham - Chief Engineer}/GB. G.B | ||