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).
Article from 'Automotive Industries' on using a Stroborama to observe torsional crankshaft vibration.
| Identifier | ExFiles\Box 53\1\ Scan040 | |
| Date | 5th March 1927 | |
| 370 x. 4541 Oscilloscope File Automotive Industries March 5, 1927 Torsional Crankshaft Vibration Seen Through Stroborama Invention of French engineers allows degree of torsion to be read while engine is in motion. Device makes possible more accurate examination of all moving parts. By W. F. {Mr Friese} Bradley USE is being made in a certain number of Continental automotive works of the Stroborama invented by Laurent and Augustin Seguin, French engineers best known abroad by reason of their invention, in the early days of the flying movement, of the Gnome rotary air-cooled engine. The practical advantage of the Stroborama over earlier stroboscopic methods is that, instead of being a laboratory instrument, it is intended to be employed in the factory, without changing the normal daylight or artificial system of lighting, and it allows the moving parts under observation to be examined with a much greater degree of accuracy than has been possible hitherto. The automotive factories at present using the Seguin Stroborama comprise Citroen, Lorraine-Dietrich, Chenard-Walcker, Michelin Tire Co., R. {Sir Henry Royce} B. Magneto Co., the Hobson Co. of Brussels and also the French Government artillery and aviation departments. This method of direct observation of moving parts, by reducing them to apparent immobility, is particularly valuable in the case of automobile and aviation engines. Some of the most obvious applications of the Stroborama are the observation of the movement of cams and valves, the detection of the “floating” of valves, a study of the vibration of valve springs, etc. Torsional vibration of the crankshaft can be observed and the degree of torsion read while the engine is in motion by fitting two graduated plates to the ends of the crankshaft. This examination is carried out by the use of a crankcase with a glass window fitted in it. Flexions of the connecting rods can be examined and studied in the same convenient manner. Valuable results have been obtained by the examination of lubrication systems in this manner, for under the stroboscopic rays the atomized liquids appear to be divided into distinct drops, the movement of each being easily followed. The first practical results obtained with the Stroborama were in an examination of the formation of jets and emulsions in carburetors and in Diesel and in semi-Diesel engines. Merely by fitting windows in induction manifolds, the movement of the gases can be followed and deductions made with the greatest degree of accuracy. The Stroborama differs from the usual type of stroboscope by reason of the entire separation of the functions of synchronizer and illuminator. The normal type of stroboscope consists of a Ruhmkorff coil illuminating a rarefied vapor or gas tube and of a rotary or alternative interrupter which constitutes the synchronizer and determines the frequency of the flashes. With this system the moment of illumination is determined by the rupture produced in the synchronizer of the primary current of the coil. The power of the illuminator is, of course, a function of the power of the electric source from which it is fed. But as the illuminating current must pass through the synchronizer, this very rapidly limits the illuminating power of this type of apparatus. Above a certain intensity, the arc produced at the rupture of the primary very rapidly deteriorates the contacts and robs the flash of its precision. In addition, this arc lengthens the duration of the... Fig. 1. Seguin Stroborama as delivered for factories | ||