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).
Test methods, wear, and noise issues related to leaf springs.
| Identifier | ExFiles\Box 178\2\ img041 | |
| Date | 30th March 1940 guessed | |
| A cranking rig is excellent for life testing of springs, both wet and dry, clean and dirty. Geoff. has used them all ways. Also good for getting static and dynamic friction loops, as described above. It is not a representative test for liner life because the wear on these is largely due to lateral motion due to "sculling" of the axle. This "sculling" action has been restrained by Vauxhall in various ways by intensive work on the part of Serjeantson and Mackenzie on the bump rig. However, when it is present, you will find that to prevent wear of the linings it is essential to make the spring plates by circular-arc bending methods, with the ends relieved, or actually made tangent to the curve 4" back from the tips. Eaton do this. This prevents concentrated pressure on the linings close to the ends. Creaking Geoff. can tell you we ran into this with Spauldite linings when we tapered the leaf ends. The grunting was due to lateral motion of the leaf ends. We ran into it with a type of rubberized liner years ago when we used "knife blade" tapers (Spring Perch). Leaf ends of the Eaton type (taper diamond) seem fairly free from it. Summarizing 1) Best place to test the friction coefficient is on the spring. Ordinary friction tests mean little because of low rubbing speed in springs, and unknown bearing pressures. 2) Wear cannot be measured very well on cranking rig because of lack of lateral motion. We cannot produce fast enough lateral motion on the rig. Bastow will tell you of attempts. Wear is best checked on road, or on bumping rig under sculling conditions, preferably with moisture and dirt. 3) In case of Spauldite, I should say 1/16" was plenty thick. The weight of clamps and U-bolts and difficulty with center bolt increases with thickness of spring at the butt. Also, fear fatigue breaks in thick material proposed. 4) Spauldite considered best material. Original "Jackson board" not waterproof. 5) Creaking. Watch the shape of leaf ends and leaf bedding. Also note rebound clips must have specified side clearance. Say 1/16" a side. 6) Cranking rig useful for life testing and for indicator diagrams. OY. | ||