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).
Design and friction challenges of a slipper flywheel.
| Identifier | ExFiles\Box 74\2\ scan0234 | |
| Date | 8th July 1929 | |
| Sg.{Arthur F. Sidgreaves - MD} c. Hs.{Lord Ernest Hives - Chair} X H194 BY9/G.8.7.29. RRAI. SLIPPER FLYWHEEL. SECTION 5020. ------------------------------------ Referring to Sg{Arthur F. Sidgreaves - MD}22/E28.6.29. and OY2 of June 19th on the same subject, there is no doubt but that in his original design R.{Sir Henry Royce} intended to use dry friction faces for the damping of the crankshaft by means of a slipper flywheel. The necessity, however, to lubricate the spigots upon which the wheels slip, and also to lubricate the surface upon which the crankshaft pinion oscillates made it practically impossible to ensure dry surfaces on the friction faces, whilst on the other hand any attempt to eliminate the lubrication for the spigots referred to would certainly land us in greater trouble than the one R.{Sir Henry Royce} was trying to avoid. We realise, of course, that the difference between static dry friction and moving dry friction is very small compared with the difference between similar faces for lubricated surfaces, but we have tried to reduce this to a minimum by using large surfaces and finally resorting to materials which would carry oil enmesh in the surfaces, whereby it was hoped to obtain a condition which did not represent a broken down oil film when the surfaces were stationary relative to one another. One other point is worthy of attention viz. that it has only been comparatively recently that is during the last couple of years, that the effect of the slipper in producing what has been known as 'a bus knock' has been appreciated, and of course conditions were then faced with an existing design which rather accentuated this defect, and which it was very difficult to depart from. In facing the new position thus developed Mr. Royce has produced a design of slipper which gives a very light friction couple indeed in the initial stages of the running of the engine, but which provides for the building up to a very heavy friction factor, in order to meet the demands of crankshaft damping at higher speeds. We are not at all satisfied ourselves that any dry friction device can be produced which will not involve greater difficulties than those we are handicapped with at the moment, as obviously parts must be spigotted, and if this is the case wear of the spigots must be avoided, and therefore absence of lubrication which is the only adequate method one sees in producing and maintaining really dry surfaces, is certain to be the source of even greater difficulties. BM BY.{R.W. Bailey - Chief Engineer} | ||