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).
Crankshaft balancing methods and vibration experiments on a 20 HP engine.
| Identifier | ExFiles\Box 25\3\ Scan365 | |
| Date | 13th November 1928 guessed | |
| contd :- -9- The Packard, in which the crankshaft appears to be not a forging, but machined all over, is indication of the lengths to which they are prepared to go. The Packard and the Chrysler use the method of only balancing the resultant load on each bearing, i.e. the weights are set to bisect the angle between the cranks, when they can be made much lighter. In a new car called the De Soto (made by Chrysler) the balance weights are all set in one plane instead of directly opposite the webs they are balancing. Since 6 and 8 cyl. shafts are in static balance already, it is necessary to arrange for the added weights to be in balance among themselves. Many firms use bolted-on counter weights but we think against this is the fact that sooner or later the engine will be run on its main period, when the stresses in the counter bolts weights will be incalculable. VIBRATION EXPERIMENTS. With the previous reasoning in mind we did some experiments to try and separate the contributory causes in high speed vibrations. We fixed steel blocks on the crank-pins of a 20 HP. engine and motored it over by towing or with the rear wheels on drums. The steel blocks weighed 2 lbs. 13 ozs. ± 1/4 oz. They eliminated the first two of the possible causes of engine vibration. The total centrifugal force at each crank was 4100 lbs. of which 1/2 was due to the steel block. We removed the valve gear, and this made little difference below the floating speed. The spring drive and contd :- | ||