Ron Weiss and his daughter, Kristen (center), place asparagus spears on a conveyor belt to be washed at the Weiss Asparagus Farm processing facility in Red Lake Falls, Minn. on Sunday, May 20, 2018.

And conveyor-belt manufacturers assume some method of roller crowning will be used, so they make belts that accept a modest level of crown without increasing wear. Crown rollers can be used with ...