Accumulating conveyor system

In a conveyor system of the type having a first conveyor drive driving a plurality of trucks along a conveyor track to a drop off point and a second conveyor drive spaced at a distance from the first conveyor drive for picking up the trucks at a pick up point and driving the trucks further along the conveyor track, an accumulating conveyor system for shuttling conveyor trucks from the first conveyor drive to the second conveyor drive to insulate the conveyor drives from a stoppage of the other conveyor drive, comprising:

• a drive track extending parallel along the conveyor track;
• a plurality of tractors adapted to selectively couple with a truck at the drop off point, tow the truck along the conveyor track to the pickup point of the second conveyor drive, and uncouple from the truck each of the tractors being individually controllable to stop, start, and travel independent of the other tractors;
• a return track extending parallel along the drive track for returning the tractors from the pick up point to the drop off point;
• and
• a first tractor switch device for transferring the trucks from the drive track to the return track after uncoupling from the truck and a second tractor switch device for transferring the trucks from the return track to the drive track to await coupling with a truck.

In a conveyor system of the type having a first conveyor drive driving a plurality of trucks along a conveyor track to a drop off point and a second conveyor drive spaced at a distance from the first conveyor drive for picking up the trucks at a pick up point and driving the trucks further along the conveyor track, an accumulating conveyor system for shuttling conveyor trucks from the first conveyor drive to the second conveyor drive to insulate each conveyor drive from a stoppage of the other conveyor drive, comprising:

• a drive track extending parallel along the conveyor track;
• each truck having a coupling;
• a plurality of tractors, each tractor having a coupler adapted to selectively couple with the coupling of a truck at the drop off point, tow the truck along the conveyor track to the pickup point of the second conveyor drive, and uncouple from the truck;
• a return track extending parallel along the drive track for returning the tractors from the pick up point to the drop off point to await the next truck delivered to the drop off point by the first conveyor drive.