GB784959A - Microtomes - Google Patents

Abstract

784,959. Microtomes. TECHNICON INTERNATIONAL, Ltd. Aug. 22, 1955, No. 24162/55. Class 97(1) In a microtome having a stationary cutting knife, the specimen is rotated in a circular path past the knife and is fed continuously towards the knife at a uniform rate with a stepless movement. As shown in Fig. 1, the knife 18 is clamped at each end in two blocks 318 by means of screws 354 and may be adjusted by screws 340 in the sides of blocks 318. The blocks 318 pivot about the shaft 320 and may be locked thereto in any desired position. The specimen in a paraffin block 26 is held in holder B of the flywheel 32. The flywheel 32 is mounted on a hollow shaft 38, keyed to shaft 48 and rotated therewith by means of handle 54 or by a belt round pulley 46. The hollow shaft 38 may move longitudinally independently of shaft 48 to advance the specimen towards the knife, but is urged away from the knife by spring 242. A plate 212 and gear 88 are fixed to the hollow shaft 38 to rotate therewith, the gear 88 driving a pinion 92 and a plate 110. A second plate 124 is mounted on a shaft with pinion 128 but out of line with plate 110, and is driven by the latter through a variable speed drive 126. This variable drive comprises two balls 140 in a block 138 (see also Fig. 2) and each contacting one of the plates. The speed is increased from zero in the position shown in Fig. 2 with the balls on the axis of plate 110 to a maximum, by moving the block and balls to the left. This is accomplished by rotating knob 142 on shaft 144 which has a portion 146 threaded into the block. A coarse adjustment may be provided from a second knob (not shown) working through gears 184, 182, 180, 178. For rapidly advancing the flywheel towards the knife prior to cutting, the knob 142 may be pulled out to 142<SP>1</SP> when balls 140 work on the maximum diameter of plate 110. The drive from plate 124 and gear 128 is transmitted through gears 190, 192, 204 (Fig. 6) to shaft 202 which is threaded at 206 into the frame 198. The shaft 202 is thus advanced longitudinally as it is rotated, and the ball 210 on the end of shaft 202 bears against the plate 212 on shaft 38 and thus advances the shaft 38 and flywheel 32 towards the knife. An indication of the position of the flywheel relative to the knife is given at 266 by a pointer 286 connected to forks 270, 272 on either side of gear 88. Means are provided to lock the flywheel against rotation while inserting the specimen. A further embodiment is described whereby a handle 54 is not on a shaft co-axial with shaft 38 but drives the latter through suitable gearing.