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).
Issues and modifications related to crankshaft dampers.
| Identifier | ExFiles\Box 123\5\ scan0287 | |
| Date | 1st February 1939 | |
| -9- CRANKSHAFT DAMPER. We have experienced a considerable amount of trouble with the crankshaft damper, so much so that the oscillation comparisons taken with various loadings in trying to tune the damper to the crank are not too reliable. Tabulated, the troubles have been as follows:- (1) S/M damper flywheel siezing up on the hub, also S/M and which from previous experience know they are not suitable materials together. A graphited bronze bush (Vandervell product) so far as we have run is satisfactory. (2) Similar to No.1 trouble, the flywheel face also siezed on the hub face and a bronze thrust washer keeping the two faces apart is proving satisfactory. (3) The leaf damper springs are continually breaking; at the best setting of 195 lbs.ft/degree, the .027 thick springs have a stress of 185,000 lbs/sq.in. the .018 springs 250,000 lbs/sq.in. the .015 springs 350,000 lbs/sq.in. but they all break with the same regularity. There are various alternatives that are to be tried such as limiting the movement by rubber wedges. The springs also appear to start rusting after short time. (5) After running several hours, the springs begin to dig into the S/M hub face. In order to prevent this we are trying hardened steel thrust washers for the springs to thrust on. As seen from the attached curve (RM{William Robotham - Chief Engineer} 582) the inclusion of the damper reduces the half period crank oscillation (2700 r.p.m.) from 1 degree to approx .5 degree, whilst at 4250 r.p.m. the reduction is from 1.5 to .5 degrees. Under this condition after 7 hrs. endurance (max. r.p.m. 4250) thus limiting the oscillation to approx .5 degree, the Fibre camwheel failed, the teeth being torn off. Several of the leaf damper springs were broken and digging is so that it was thought that the oscillation may have been much higher than recorded thus causing the teeth to fail. A new camwheel was fitted in conjunction with the studebaker damper, rubber blocks being used as the medium and not springs as standard studebaker practice. Incidentally, this damper included the 75% extra inertia flywheel and the endurance was run at speeds never exceeding 4000 r.p.m. et | ||