A ride-on mower having an air directing pulley is disclosed. The mower includes a cutter deck having an upper wall and a vertical drive shaft passing through the upper wall for driving one or more cutters. A drive pulley (22) is mounted on the drive shaft above the cutter deck to transferring drive to the shaft. The drive pulley including air forcing means in the form of vanes (41) that force air (42) across the upper wall to prevent or inhibit the build-up of debris.
