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).
Tests comparing standard and low inertia spring drive balance weights for a 25 HP engine.
| Identifier | WestWitteringFiles\W\September1931-November1931\ Scan076 | |
| Date | 7th November 1931 | |
| R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. to SG.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} De. c. to Ey. ORIGINAL Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}5/KT. 7.11.31. BALANCE WEIGHTS 25 HP. X.634. X.5010. We have carried out tests on the relative merits of the standard and low inertia type of spring drive on the 25 HP. The tests were done on C.I. unit fitted with a 2" dia crankshaft capable of taking either of two noses to accomodate the two types of slipper wheel. Balance weights were fitted to this shaft to Lec.2963. (K.57287/8) balancing the crankshaft and .3 of the big end. With the low inertia slipper wheel there was no sign of the top period at the valve bounce at 4100 r.p.m. With the standard spring drive one ran well into the master period at 3700 r.p.m. With the low inertia spring drive and synchromesh gearbox, therefore, one should be able to attain 82 m.p.h. top and 60 in 3rd. before running into the top period. The damping on the low inertia wheel was 17 lbs. at 17+" radius., this being necessary to eliminate the period. The other tests we have done on the low inertia spring drive have been on crankshafts fitted with Chrysler balance weights to Lec.3936 and R's scheme to Hs.{Lord Ernest Hives - Chair}359 and 439. In both cases the master period has been at 4100 r.p.m. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||