Baler plunger drive system

In a baler for forming parallelepiped bales of crop material including an elongate baling chamber having a rectangular cross section and a central longitudinal axis, a plunger mounted in said baling chamber for reciprocating along said axis in a first end region of said chamber for compressing crop material towards a second end region of said chamber, a drive assembly coupled to said plunger for causing reciprocation of said plunger and including an output shaft extending crosswise to said longitudinal axis and being spaced from said first end region of said baling chamber, said drive assembly further including a gear drive arrangement including an input shaft adapted for being coupled to a tractor power take-off, an output gear arrangement coupled to said output shaft, a crank arm assembly fixed for rotation with said output shaft and a connecting rod assembly coupled between said crank arm assembly and said plunger for effecting reciprocation of said plunger when said output shaft is rotated, the improvement comprising:

• said drive assembly including an overrunning clutch coupled between said output gear arrangement and said output shaft and being operable for operating in a driving mode, when said crank arm assembly is moving within a range of positions causing a compression stroke of said plunger through the action of said connecting rod assembly resulting in said plunger being advanced toward said second end region of said chamber, and being operable for operating in an overrunning mode, when said crank arm assembly is moving within a range of positions causing a reverse stroke of said plunger and wherein crop material compressed during said compression stroke is rebounding and imposing a force on said plunger in a direction away from said second end region of the chamber.