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).
Two-page document describing the features and operation of the Ashdown Rotoscope instrument.
| Identifier | ExFiles\Box 143\3\ scan0183 | |
| Date | 15th April 1940 guessed | |
| Page Eight [Image of the Ashdown Rotoscope instrument. A gauge on the instrument is labelled 'HUNDREDS OF R.P.M.'. Text running vertically on the side of the image reads 'Scales of Instrument.'] Page Five sewing machine needles and shuttles, silk-throwing mechanisms, cam shafts, springs, and hundreds of similar objects, without any form of contact with the moving object, thus cutting out accidents, saving considerable production time, and eliminating wasteful expenditure by disclosing those losses due to slippage, voltage variation, defective running of shafts and clutches, and the countless unsuspected factors taking toll of production speeds. The standard form of the Ashdown Rotoscope now offered for quick delivery is that shown in the first illustration, as covering the field of operations generally obtaining in industry. Other standard forms are, however, available for speed ranges outside that mentioned for this type. The chief feature of the Ashdown Rotoscope is the patent rotary shutter, or “sight gear,” which is capable of giving a thousand separate glimpses per second each less than one fifty-thousandth part of a second duration. This ultra-rapid succession of glimpses blends (by retentivity of vision) into a continuous sight impression or picture. The speed of this shutter is, in the standard type described, infinitely variable by means of a two-speed gear change for the range setting, and a fine adjustment from a friction disc controlled by a centrifugal governor at constant speed which can be regulated. The operation of the Ashdown Rotoscope is self-contained and purely mechanical, and thus avoids any outside contacts, or trailing wires which are always a great source of danger. The driving mechanism is by powerful clockwork governed by a master-key control to one definite standard of speed. This standard is set so that it can be checked by sound in a simple way, and its regulation cannot be interfered with by any but an authorised person who keeps the key by which the instrument is regulated. This he does by noting the time period of the clicks produced in the machine when it is being so tested—and adjusting with the little key provided. The operator has only to wind the instrument and, while sighting, to turn the controller wheel until the desired “static” view of the object is seen. At this point its speed can be read straight off from the instrument scales shown in the illustration on page 8. It will be seen there are two of these: the rack scale giving “hundreds of r.p.m.” and the dial giving the subdivisions to units. These figures represent the actual speeds when the instrument is set to the “high” range, and five times actual speed on the “low” range—when it is an easy matter to divide by five to obtain the actual speed of the object. By these scales the instrument can be set to the definite speed of the object if this is known: alternatively, to an approximate speed for adjustment when sighting for finding such speed: or | ||