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).
Instructions and use cases for the Ashdown Rotoscope, a speed-determining instrument.
| Identifier | ExFiles\Box 143\3\ scan0182 | |
| Date | 15th April 1940 guessed | |
| [Page Four] The value of this form of visual examination cannot be overestimated, and is best proved by a reference to the extensive use of the Ashdown Rotoscope in Government and research centres, technical institutes, and almost every department of industry. A more important service even than this can be foreshadowed by the increasing use of the Ashdown Rotoscope as a speed-determining instrument, in which regard it is already to be found in the testing equipment of various Government departments and industrial factories in all parts of the world; also in hundreds of applications where it is found impracticable, or inadvisable, to use speed-counters and tachometers which have to be pressed into the ends of moving shafts—with all the danger attending such operation. [Image Caption] Examining the link-and-tooth action of Morse high-speed chain drive at 2,200 f.p.m. in “slow-motion,” also checking the speed variations under different load conditions. (Note the extreme safety of taking speed by the Ashdown Rotoscope as compared with the old method of pushing a speed counter into the end of the revolving shaft) The Ashdown Rotoscope will give the speed of all shafts, high-speed grinding wheels, tools, bobbins, friction saws, silk spinners, Page Four [Page Nine] DIRECTIONS FOR USING THE ASHDOWN ROTOSCOPE THE operation of the Ashdown Rotoscope is perfectly simple, requiring no special technical knowledge for its successful use. It is sufficiently rugged for workshop use, and has no parts which can easily get out of order, and practically no maintenance costs. First, the machine must be fully wound with the handle—which is inserted in the base of the handpost. Then the instrument should be started up by the little lever which projects through the back cover, after which it can be set approximately to the speed of the object to be observed, if this is known, by turning the engraved wheel at the side. The instrument has a total speed range of 160 to 6,000 glimpses per minute. This maximum can still further be increased up to 12,000 per minute if desired by a spare shutter—known as the “displaced type” shutter—which can be supplied with the instrument as an extra when required. To fit this shutter, the main casing and plain side should be carefully removed: jewel screws brought back to release the standard shutter, and the “displaced” type shutter put in its place. It must be seen that this turns very freely after the jewel screws are reset, before the cover is refixed. The gear change knob is at the side of the instrument for setting the range as indicated: “high” or “low”; when it is at “high,” an inclusive range of 800 to 6,000 is permitted; at “low” —one-fifth of this, i.e. 160 to 1,200. By this division there is a useful overlap between 800 and 1,200, but it is recommended to use the “low” position of gear between these figures for the reason that it gives a better driving radius on the friction plate. On the top range (800 to 6,000) the speed is indicated in “hundreds of r.p.m.” by the rack scale on top of the cover, and the “unit division” on the controller wheel at side, so that complete readings of the speed can be taken without charts of any kind, reference to stop watches, or separately attached tachometers. These scales are shown in the illustration. If the speed of the object it is desired to inspect is not even approximately known (presuming that it is within the range of the instrument itself), the controller should be set primarily at the topmost speed; then, during observation of the moving object, it should be slowly worked back until the first clear stationary view is seen. At this point the speed can be noted accurately from the scales, if desired, should the instrument setting be on “high”; or if on “low,” obtained by dividing the scale reading by five. Page Nine | ||