A swather is a farm implement that cuts hay or small grain crops and forms them into a windrow. A swather (also called a "windrower") may be self propelled via an internal combustion engine, or may be drawn by a tractor and powered through a power take-off shaft. A swather uses a sickle bar (see mower) to cut the stems of the crop. A reel helps the cut crop fall neatly onto a canvas or auger conveyor which moves it and deposits it into a windrow, with all stems oriented in the same direction. As combines replaced threshing machines, the swather was needed to replace the binder.