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).
Calculation of the effect of Dural connecting rods on the crankshaft critical speed for a Bentley.
| Identifier | ExFiles\Box 138\1\ scan0076 | |
| Date | 25th October 1933 | |
| x634 To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. Wor.{Arthur Wormald - General Works Manager} By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}1/KT. 25.10.33. DURAL CONNECTING RODS FOR BENTLEY. vrie We have calculated the effect on the crankshaft critical speed of the Dural rods, and also of whitemetalling direct the existing steel rods, thereby dispensing with the bearing shells. Type of Big End. Weight. Inertia. Std. Steel Rod. 1.285 lbs. 7.76 lbs.in2. R.W.56.rod. .800 lbs. 4.83 lbs.in2. Steel Rods less shells. .925 lbs. 5.60 lbs.in2. Using the Dural rods we expect a gain of 4.6% or 230 r.p.m. in critical speed. When whitemetalling the steel rods direct, we can either increase the crankpin diameter to 2.100, save no inertia but increase slightly the crankshaft stiffness raising the speed approx. 3%; or keep to a 2" pin when we should gain 125 r.p.m. since we can decrease the overall dimensions of the big end. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||