Anti-backlash tractor assembly

Claim 1

A transport assembly device for being mounted upon a printer for transporting an endless form image receptor to and from a printing mechanism, said printer including a pair of side walls, a platen mounted upon a support shaft journalled for rotation in said side walls, transport assembly positioning pins extending from each of said side walls and drive gear means supported by one of said side walls, said transport assembly being characterized by comprising: a pair of side plates supported in opposed, spaced relationship to one another, a drive shaft supported by said side plates for rotation relative thereto, driven gear means supported upon one of said side plates and coupled to said drive shaft, image receptor driving means supported between said side plates and driven by said drive shaft, means for mounting said side plates upon said support shaft, said means for mounting being adjustable so as to move said driving means toward and away from said platen, adjustment means for varying the location of said means for mounting relative to said side plates, means for locating said transport assembly in an operative position on said printer, and means for biasing said transport assembly against said printer, so as to urge said driven gear means against said drive gear means when said transport assembly is in its operative position for eliminating substantially all backlash therebetween, and so as to urge said means for mounting against said support shaft and wherein said means for biasing comprises a pivotable lever mounted to said side plate supporting said driven gear, and a spring secured to said pivotable lever for urging a biasing surface on said lever against one of said transport assembly positioning pins, said biasing surface being disposed at an angle for both urging said driven gear means against said drive gears means and urging said means for mounting against said support shaft.