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).
Causes of and solutions for engine vibrations, focusing on crank chamber stiffness and crankshaft bending.
| Identifier | ExFiles\Box 74\3\ scan0259 | |
| Date | 18th February 1922 | |
| Contd. -2- RL/M18.2.22. would reduce the cause but lower the period and so we should be perhaps worse off. As far as I know the only thing to do is to make the crank chamber stiffer sideways and help it all we can by the lower half. Our usual way is with broad horizontal flanges and big radii corners inside to stop parallelograming of the sides; the E.{Mr Elliott - Chief Engineer} is low in aluminium but we must not add weight unless we increase the stiffness considerably. You will easily be able to prove if the crankchamber is bending sideways, and whether it is a period from this cause. It will build up to a maximum amount at one speed, and you can put some fixing near toit so as to test if the crank-chamber bends sideways. I cannot imagine the end of the crankshaft bending, but I can imagine the centre bending sideways, but not vertically or the end crank web. Mr. Elliott will tell us the forces on the centre bearing, and we know the period is one per rev. If one struck the crankchamber in the centre sideways, with a tup, would it shiver at this speed? The period may be due to the slipper flywheel on the end of the shaft weakened by the crank webs inside - if this is the period it should be controlled by the weight of the slipper flywheels. E.{Mr Elliott - Chief Engineer} calculates that inertia of piston causes very large torque variation per crank at a very high period is 2 per rev. both + and -. R.{Sir Henry Royce} | ||