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).
Engine vibration tests concerning friction torque, damping, and the effect of piston weight and position.
| Identifier | WestWitteringFiles\P\2July1926-September1926\ Scan180 | |
| Date | 20th September 1926 guessed | |
| contd :- -5- resulted in the vibrations being evident at both the higher and lower speed, but the higher one was not so violent as with the standard amount of friction. (4) Friction torque of approximately 1600 lbs.ins. resulted in the entire transference of the vibration to a speed of 2450 r.p.m. which vibration was then at a maximum but less severe than at 3300 r.p.m. (5) The damping friction used in case (3) (200 to 300 lbs.ins) seemed too high to effectively damp out the vibrations due to the explosion pressure harmonics at the lower speeds. As in the case of the Phantom the same applies to the 20 HP. with regard to the erratic torque experienced when the pressure on the friction wheel surface is high. The total inertia of the slipper wheels - apart from the spring drive parts - is .0163 units and a calculation shews us that with this effectively solid on the shaft would account for the critical speed being lowered to 2450 r.p.m. EFFECT OF POSITION AND WEIGHT OF PISTONS ON AMPLITUDE OF VIBRATION. --------------------------------- A test was made to compare the effect on the amplitude of the vibration of the whole six pistons and the three rear pistons - 4. 5. and 6 - only. The engine was motored for this test and after taking a diagram the three front pistons were removed. In the latter case the vibration was practically non-existant as will be seen from the appended print. The maximum total amplitude recorded with all six pistons was contd :- | ||