Flat-Flex harnesses are designed for positive drive to eliminate the tracking and slipping problems common with other harness types. Whenever possible, the drive should be placed so that the loaded portion of the belt is being pulled (rather than pushed). For best results, the drive shaft should be as close to the trailing end of the belt as possible. The driving gears, which are in contact with the shafting, should engage in the belt at 120° to 180°.
Gears are usually placed in every other stitch across the width of the belt. It is absolutely critical that the sprockets are aligned across the width of the belt. If a cog is positioned a little too far forward, all traction will be concentrated at that point. The result is that the belt breaks prematurely at this point. You can make it easier for yourself to align correctly by making yourself a keyed drive shaft. This enables an even pull over the belt, as the teeth of the gears always pull the same strand.
In most applications only one driven drive shaft should be used per belt run, thus avoiding problems caused by the normal changes in stitches. Sometimes, however, a double drive or another form of drive may be the practical solution. Please contact our technical service to discuss the application-specific exceptions.