Adjustable tension control means for microscopes

Claim 1

In a microscope, a base, an upstanding arm extending upwardly therefrom and overhanging the base, microscope lens assemblies fixedly mounted to the upstanding arm and a vertically-extending rack gear mounted upon the front face thereof, a main block connected to the front face of the upstanding arm and over the rack for vertical slide adjustment with respect thereto, said main block having an opening extending laterally through the opposite side of the block, pinion gear case means extending laterally through the block opening and meshing with the arm rack and turnable to raise and lower the main block for coarse adjustment relative thereto, bearing support plates secured to the opposite sides of the main block over the laterally-extending opening and having the pinion gear case means journaled therein, a specimen slide supporting platform carried upon the front of the main block to be adjustable therewith to bring the specimen under the focus of a microscope lens assembly, a hand knob secured to the pinion gear case to turn the same, and tension control means extending between the hand knob and the gear case to regulate by friction the force required to turn the hand knob relative to the block and the lifting and lowering of the specimen slide supporting platform, said tension control means including the provision of a threaded sleeve portion extending laterally outwardly from one of the bearing support plates on the main block through which the pinion gear case extends, said one bearing support having a plurality of small holes extending through plate and parallel to the axial axis thereof and circumferentially spaced from one another thereabout, said pinion gear case being provided with an annular radially-extending shoulder extending thereabout, friction ring means mounted on the gear case for axial adjustment thereover between the holes in the support plate and the shoulder for frictional and locking engagement therewith, short work rods respectively axially slidably adjustable in the respective small holes in the bearing support plate, and a tension control wheel threaded upon the support plate threaded sleeve portion and engageable with the short pins to apply pressure upon the ring means and the gear case shoulder when axially adjusted upon the sleeve portion toward the ring means to provide frictional or locking engagement with the gear case shoulder to thereby regulate the friction between the block and the gear case.