Compensation for shaft twist in the drive system of modular conveyor belts

A drive system for a modular conveyor belt, the drive system comprising:

• a plurality of belt drive surfaces spaced across the width of the underside of each row of a modular conveyor belt;
• a drive shaft rotatably supported with an axis extending in the width direction of the belt;
• a plurality of sprockets mounted at spaced apart locations along the drive shaft and including sprocket drive surfaces circumferentially spaced around the periphery of each sprocket and arranged in rows of sprocket drive surfaces from sprocket to sprocket to drivingly engage corresponding belt drive surfaces of the belt rows;
• wherein the sprocket drive surfaces of each row define a curve in non-parallel relation to the axis of the drive shaft in an unloaded condition.

A drive system for driving a modular conveyor belt with a twisted shaft, the drive system comprising:

• a plurality of belt drive surfaces spaced across the width of the underside of each row of a modular conveyor belt;
• a drive shaft rotatably supported with an axis extending in the width direction of the belt;
• a plurality of sprockets mounted at spaced apart locations along the drive shaft and including sprocket drive surfaces circumferentially spaced around the periphery of each sprocket and arranged in rows of sprocket drive surfaces from sprocket to sprocket to drivingly engage corresponding belt drive surfaces of the belt rows;
• and
• means, associated with at least some of the drive surfaces, for varying the timing relationship among the drive surfaces so that the sprocket drive surfaces engage the belt drive surfaces across the entire width of the belt when the shaft is twisted.