Full definition
A flat belt pulley with a slight convex curvature (crown) across its face width that automatically centers the belt and prevents lateral drift during operation. The crown works because the belt naturally migrates toward the highest point of the pulley surface. Standard crown height: approximately 0.5-1.0 mm per 100 mm of face width (e.g., a 200 mm wide pulley has a 1-2 mm crown). Per DIN 111 and ISO 22 for flat belt pulleys. Only one pulley in a two-pulley drive should be crowned; the other should be cylindrical. For conveyor systems, the head (drive) drum is typically crowned while the tail drum is flat. Excessive crown causes belt center stress concentration; insufficient crown allows tracking problems. Also used on non-driven return pulleys in conveyor systems. Material: machined steel or cast iron. Crowning can be trapezoidal (easier to machine) or true arc (better tracking).