A rotary snowplow (American English) or rotary snowplough is a piece of railroad snow removal equipment with a large circular set of blades on its front end that rotate to cut through the snow on the track ahead of it. The precursor to the rotary snowplow was the wedge snowplow. History The rotary was invented in Toronto, Canada, by dentist J.W. Elliot in 1869. He never built a working model or prototype. Orange Jull of Orangeville, Ontario, expanded on Elliot's design, building working models he tested with sand. During the winter of 1883–84, Jull contracted with the Leslie Brothers of Toronto to build a full-size prototype that proved successful. Jull later sold his design rights to Leslie Brothers, who formed the Rotary Steam Shovel Manufacturing Company in Paterson, New Jersey. Leslie Brothers contracted with Cooke Locomotive & Machine Works in Paterson to do the actual construction. Another inventor is said to be Colonel Lewis P. Campbell. He is listed in US patent 1848554 (filed in 1929). Operation Wedge snowplows were the traditional mechanized method of clearing snow from railroad tracks. These pushed snow off the tracks, deflecting it to the side. Deeper drifts cannot easily be cleared by this method; there is simply too much snow to be moved. For this purpose, the rotary snowplow was devised. Rotary plows are often deployed when snow is too deep or hard-packed for traditional plows. The ability to operate slowly, as there is no requirement for train momentum to break up the snow, is often an advantage in mountainous regions, where a high speed derailment could be disastrous. Many rotary plows are not self-propelled, so one or more locomotives are coupled behind it to push the plow along the line. An engine within the plow's carbody rotates the large circular assembly at the front of the plow. The blades on this wheel cut through the snow and force it through a channel just behind the disk to an output chute above the blade assembly. The chute can be adjusted to throw the snow to either the left or the right side of the tracks. An operator sits in a cab above and behind the blade assembly to control the speed of the blades and the direction of output from the chute. With the increasing prevalence of diesel locomotives, multiple-unit train controls have been added to the cabs, so that the pushing locomotives can