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).
Analysis of clutch plate cracking and failure on the 20 HP model, chassis 48-G-2, due to slipping.
| Identifier | ExFiles\Box 74\2\ scan0373 | |
| Date | 9th May 1924 | |
| X.4244 H.S. BY25/H.{Arthur M. Hanbury - Head Complaints} 9. 5. 24. 20 HP. CLUTCH. CHASSIS 48-G-2. HYDE. In my opinion the sole cause of the clutch cracking and failing from the point of view of the driving disc having this fault, is the result of slipping in the first place. The slipping of the plate heats the outer edge very quickly. The outer diameter of the plate therefore expands, but since the inner diameter is not heated at anything like the same rate, the outer plate takes a permanent set during the heating operation, with the result that when it cools, a very high stress effect is thrown across the outer edge of the plate at the bottom of the slots. Originally small holes were drilled at the bottom of the slots and this procedure is being returned to, but the absence of the holes is not the cause of the cracking as I have seen another plate which had holes, which has a similar trouble. The remedy for the trouble is to fit clutch springs sufficiently strong to prevent slipping. Generally speaking, I think we are fairly well on the stiff side, although if the fit of the keys on the sliding member of the clutch is on the tight side, this will of course detract from the effectiveness of the spring in its function as a friction producer and would make it appear that the springs were not sufficiently strong. I think we are doing all we know on this matter from a design point of view. BY.{R.W. Bailey - Chief Engineer} | ||