Pulley flanges are the small rings attached to the pulley, sitting on either side of the teeth. The pulley belt rides between each flange, keeping the belt securely in place. The flange is important because of the tendency of belts to track one side or another side-or another known as angular misalignment.
Pulley flanges are the appropriate method for belt tracking for most timing belt drive and conveying systems. Flanges retain the belt on pulley by resisting lateral forces that pull the belt to one side or the other. Flanges are attached to pulleys by rolling process or fastened with screws depending on tooth profile and pulley diameter. Small and medium pitch pulleys up to approximately 250 mm in diameter are usually supplied with rolled-on flanges. Large pitch pulleys such as T20, AT20 and XH are commonly supplied with screws on flanges.
Pulley tracking with Flanges:
- Flanges can be used on one pulley only for systems with close center to center distances
- Flanges on back side idlers can be used to track belts when flanges on the tooth pulleys are not an option. Always locate the idler on the slack side of the belt towards the return pulley.
- For reversing applications, locate the idler between the pulleys.