In the removal of trash and waste from beneath a carding machine the trash and waste is collected on support means positioned beneath the carding elements of the machine and a flow of air is created in a direction to transport the trash and waste on the support means to a waste collection zone by supplying pressurized air to a plurality of spaced nozzles arranged above the support means in such a manner that each of a plurality of preselected groups of rows of said nozzles is supplied with the pressurized air in turn and cyclically.