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 report on a Phantom engine investigating whether piston friction causes overrun vibrations.
| Identifier | ExFiles\Box 66\1\ scan0148 | |
| Date | 10th October 1927 | |
| X8040 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG10.10.27. X7040 We have carried out a test on the Phantom in which the piston clearance was arranged to be .008" cold and holes were drilled in the skirt to reduce viscous oil friction. The object of the test was to ascertain whether reducing the piston friction would eliminate engine vibrations on the overrun. We found that a reduction in piston friction did not appreciably affect any overrun vibrations above 1500 r.p.m. Below this figure we produced a free running engine which pleasant to drive, with this clearance the noises from the piston were quite unbearable. The nett results of the test show that piston friction is NOT directly responsible for overrun vibrations and that we must look to some other feature to cure this trouble. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||