GB434289A - Improvements in gearing applicable to focussing movements or other adjustments of optical projection apparatus, philosophical instruments or the like - Google Patents

Abstract

434,289. Adjusting-gear for optical &c. instruments. BAKER, E. A., 17, Ladysmith Road, Edinburgh, and RENOUF, G. B., 52, Monktonhall Terrace, Musselburgh, Midlothian. May 22, 1934, No. 15164. [Class 97 (i)] [See also Group XXXVI] A gear applicable for focusing or other adjustments of optical or other scientific apparatus consists of a chain, flexible cord, or wire which is lapped round an axle mounted for rotation accompanied by axial movement on one of two relatively movable parts, the ends of the cord, &c. being attached to the other part to maintain the cord &c. in tension. In Fig. 1 the telescope &c. tube 11 tobeadjusted lies in recesses 12 of rests 13 projecting from a support 14. A threaded spindle 16 with its axis at right-angles to that of the tube 11 passes through threaded lugs 15 on the support 14 so that as the spindle is turned it also moves axially. The cord &c. 10 is lapped round the threads of the spindle and its ends are attached to the tube 11, a spring 18 being provided to maintain the cord &c. in tension. Owing to the axial movement of the spindle 16 the position of that part of the cord &c. which is lapped round the spindle remains constant and can be maintained in the plane containing the axis of the tube 11, and the centres of the recesses 12. To provide a fine adjustment, e.g. for a microscope tube, the bearing for the spindle 16 may be mounted so as to be rotatable about a pivot under the control of a fine-adjustment screw. The gear may be used to adjust a slider such as the movable contact of a rheostat. Fig. 6 shows an arrangement whereby a member A can be independently adjusted in two directions a, b at right-angles to each other. The cord 10, which is endless except for the spring 40, passes round a pulley 41 on the base B and round a groove 42 on the member A, and then over a pulley 43 coaxial with 42 to the threaded spindle 44 around which it is lapped. From this spindle the cord passes round a pulley 45 and a groove 46 on the member A to a pulley 47 coaxial with 45 and thence round the threaded spindle 48 to the spring 40. Rotation of the spindle 48 or 44 causes the member A to be displaced in the direction a or b respectively. The invention may also be applied for transmitting rotary motion from one element to another, e.g. for adjusting variable condensers &c., the ends of the cord, &c. being secured to a pulley, bellcrank &c., by which motion is transmitted to the rotary element to be adjusted.