GB843477A - Improvements in and relating to microtomes - Google Patents

Abstract

843,477. Microtomes. CAMBRIDGE INSTRUMENT CO. Ltd. March 13, 1958 [March 25, 1957], No. 9709/57. Class 97(1) In a microtome having a fixed cutting knife, the specimen is carried by an arm, which is pivoted about a knife edge to a second arm, which is also pivoted about the knife edge in such a manner that any movement of the second arm in one direction moves the specimen-carrying arm forwards to feed the specimen relatively to the knife. As shown in Fig. 1, the microtome comprises a base 2, having fixed thereto a knife edge member 48, 481 defining an axis 3 (Fig. 6) for one end of a knife edge 49 supported by an arm 4, the other end of the knife edge 49 supporting on an axis 18 a knife-edged member 51 carried by an arm 17. The arm 4 is engaged by a nut 8, Fig. 2, on a fine-pitched screw 9, rotatable by handle 44, this screw carrying a ratchet disc 10, and having loosely mounted thereon a lever 12, bearing a spring-urged pawl 13 for engaging the ratchet 10, and a quadrant member 11 linked at 33, 34 to a pointer on a shaft 35, which pointer rides over a setting scale. The lever 12 is connected at 14 to a crankpin 15 on a shaft 16, rotatable by handwheel 26, so as to reciprocate the lever 12. Another crankpin 25 on the shaft 16 is connected at 24 to the arm 17, which has a clamp 20 for accommodating a specimen, this clamp being adjacent to a cutting knife 38, mounted in a slidable carriage 27. The angle of the cutting knife 38 can be varied by screws 37. In operation, rotation of handwheel 26 moves the arm 17 downwardly, so that the specimen is cut by the knife 38, and then upwardly to its initial position, and during such upward movement the pawl 13, reciprocating lever 12, engages ratchet disc 10, so as to rotate screw 9 to an extent determined by the setting of the shaft 35. This rotation of screw 9 causes nut 8 to move downwardly, and thus pivots the arm 4 so that the specimen arm 17 is fed forward towards the cutting knife 38. For re-setting the arms 17 and 4, the nut 8 is moved upwardly by rotating a handle 44.