Patent GB-191411527-A (GB)
Title: Improvements relating to Dividing Engines.
Inventor: ABRAHAM ROBERT MORRISON
IPC: G01D13/12
Filed: 1914-05-09
Granted: 1915-04-22
Abstract: 11,527. Abraham, R. M. May 9. Dividing-engines.-In a dividing - engine for graduating clinical thermometers &c. in which it is required to divide an arbitrary length into a given number of equal parts, a continuouslyrotated handle or wheel imparts intermittent feed movements to a leading-screw through a variable - throw crank mechanism and a oneway driving-mechanism, and also operates the marking - device. As shown in plan in Fig. 1 and in side elevation in Figs. 2 and 3, the toothed wheel 3 operated by the handle 4 gears with a pinion 5 carrying a disk or block 48 having a transverse slot 49 in which a crankpin 50 is adjustable. A connecting-rod 47 connects the pin 50 with a pin 46 fixed on a disk 45 carrying a pawl, or two or more pawls 52, Fig. 5, arranged to minimize back - lash, which reciprocate over and drive a finely toothed ratchet - wheel 42, which is secured to the leading screw 38, and is surrounded by a fixed casing 43. The marking needle 26 is carried by a frame 13, which is pivoted at 15 to a link member 14 mounted on fixed pivots 16. The backward stroke of the needle 26 marks the thermometer &c. 37 and is effected by a spring 18, its forward stroke being effected by a crank 10 provided on the end of the spindle of the pinion 5 and engaging in a slot 11 in a member 12 forming part of the frame 13. The needlecarrying portion 19 of the frame 13 is pivoted at 20 and has a tailpiece 21 held between a spring 22 and a setscrew 23 so that the circular motion of the crank 10 causes the needle 26 to be pressed down during the marking-stroke and raises it during the. return stroke. The length of the marking-stroke is limited and regularly varied by one of an assortment of replaceable notched disks 55, Fig. 1, which is positively driven from the shaft carrying the crank 10, and is engaged on its edge by a set-screw 58 carried at one end of an horizontally moving spring-controlled lever 57 which is operated by a pin 59 on the frame 13. The disk 55 is driven by worm or other gear and may be cut to give any desired sequence of strokes. Means for irregularly varying the length of the stroke may be provided, the disk 55 in this case having an upper or lower cylindrical extension of one or more diameters, and the relative levels of the disk and lever 57 being variable by a hand-operated key. The thermometer or the like 37 is mounted on a T-shaped carrier 30, of which the head travels on a bar 29, and the tail, having a part nut 40, travels on the leading screw 38. A weight 39 on the carrier 30 ensures engagement of the part nut 40 and the screw 38 and facilitates lifting of the carrier for adjustment of its position. A lens or glass 68 with a transverse mark may also be mounted on the carrier 30 so as normally to rest just above a scale 64 adjustably clamped to a fixed bar 62 above the leading-screw 38. The reading on the scale 64 corresponding to the distance between the calibration marks on the thermometer &c. may be taken by adjusting the carrier 30 so that the marking-needle is first over one calibration mark and then over the other. The reading obtained indicates the setting of the adjustable crank-pin 50 necessary to obtain the required number of graduations between the calibration marks, a different scale 64 being used for each particular number of such graduations required. The crank-pin 50 is set so that the reading of a second scale associated with it is in agreement with that of the scale 64. The second scale may be on the edge of the disk 45, its reading being facilitated by a vernier scale on the casing 43, or may be along the slot 49 or on a micrometer screw which may be provided to move the crank-pin 50. During adjustment of the crank-pin 50, a pin or the like in a rearward extension 70 of the connecting-rod 47 temporarily engages the slot 49. When using the engine, the appropriate scale 64 and disk 55 are first placed in position, the reading on the scale 64 is taken, and the crank 50 is then set. Graduation by marks of regularly varying length then proceeds automatically on turning the handle 4, marks of irregular length being inserted as desired with the aid of the hand operated key. As an alternative to the adjustable crank-pin 50 or as a fine adjustment, the leading screw 38 may be connected to the ratchet-wheel 42 by a universal joint and be angularly adjustable so as to vary the feed-movements imparted to the carrier 30. The positions of the thermometer &c. and marking-needle may be reversed.