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).
Instruction manual for the STROBORET type R speed measuring instrument.
| Identifier | ExFiles\Box 155\3\ scan0145 | |
| Date | 31th December 1936 guessed | |
| STROBORET type R In order to set the slits the disc is turned in such a way, as to bring the white point marked on its face into a position, in which it is visible through the centre of the visor. On pressing at the same time with a finger nail of the other hand on the lateral pushpin one or five slits can be obtained at will by turning to left or right the knob C and regulating the width depending on the light or the sharpness desired. To measure a speed or take an observation 1. Make (especially when measuring speed) a single reference mark with white chalk on the machine to be observed, as near as possible to the centre of rotation. 2. Wind up the movement by means of the lever B then turn the lateral milled knob A in the direction in which the finger slips on the milling to raise the pointer to the maximum graduation. 3. Watch the reference mark on the machine under observation through the rotating disc and bring down the pointer by turning the milled knob A in the direction in which the finger grips the milling, until for the first time a single image of the stationary reference mark is seen. 4. Read the speed indicated by the pointers; the machine is running at this speed or at some multiple of this speed. If, for instance, the indicated speed is 6,000, the machine is running at 6,000 or 12,000 or 18,000 etc. revs. per minute. Normally there is no hesitation in deciding on the speeds. (Consult us in special cases). Remarks It is essential, when measuring speeds, to make observation on a single reference mark in order to be certain to have one single stationary image of the reference mark. Multiple reference marks such as screws, nuts or pulley arms, should be carefully avoided. The best thing to do is to make a single reference mark with white chalk as near the centre of rotation as possible in order to reduce the lineal speed. In case of doubt as to whether the number of movements indicated by the pointer is the right one or a multiple, have the following examination : Turn the knob till for the first time immobilisation is seen ; say the pointer indicates : 600. Turn the knob further back till for the second time immobilisation is found ; suppose the pointer then indicates 400; the real number of movements is then : (600 x 400) / (600 - 400) = 1200 The instrument requires neither upkeep nor lubrication. When the disc is revolving, do not stop it either with the central knob or with the lateral pushpin. Do not move the pointer by means of the milled knob until the disc is revolving. | ||