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).
Materials for leaf spring interleaving, their properties, and methods for testing.
| Identifier | ExFiles\Box 178\2\ img040 | |
| Date | 4th April 1940 | |
| Serial no 66 E.v. Rolls-Royce, Ltd. Derby, England Leaf Springs Interleaving Re Rm.{William Robotham - Chief Engineer}/C1m.4/ML 15.3.40 I consider the Jackson material, as originally offered to us, worthless. Will not resist moisture. Neither will the Cadillac waxed Monroe paper or material. Spauldite will do so. Spauldite is of two types; resinized fabric and resinized paper with fabric outer layers. Vauxhall used the latter, which is cheaper. We also used some Raybestos strips, but these are N.G. as they run up in friction with use. Also they are expensive. A Ferodo brake material would probably do the same. All brake lining materials used at Cadillac for the past 6 years had this fault. They indicated an ultimate break away friction coefficient of about .6 - .7, as I remember. Geoffrey Bastow has all this experience at his finger ends and really knows more about it than I do. The life of interleaving depends on several more things than those stated, moisture, dirt, quality of leaf bedding and presence or otherwise of axle-sculling, for example. How do you propose to measure the friction coefficient? The only really satisfactory way that I know is to find its effect on the spring by taking indicator diagrams on the cranking rig at various strokes and speeds. (See sketch). This will show for example that rubber or any rubberized lining will throw waves into the spring action that ruin the ride. Various linings will do the same. Others give just as smooth a loop at 450 r.p.m. 1" stroke as at hand-turning speed. These ride well. Cranking Rig It seems to me pretty pathetic if R.R. limited have to appeal to Woodhead to do their cranking for them. Surely R.R. can afford £150 for a home-made cranking rig like the sketch, even if the boys build it with the stuff they swipe from the millwright's shop. Again Geoffrey could rig up one for you in short order. | ||