Gleaner Manufacturing Company was the name of a company which made the first self-propelled combine harvesters. They are best known for their production while part of Allis Chalmers Manufacturing Company Manufacturing Company. Gleaners were silver in colour, unlike the Allis Chalmers field tractors, which were unique for their bright orange paint. Gleaners were notable for being the first to use galvanized sheet metal. Gleaning itself is the act of collecting leftover crops from farmers' fields after they have been commercially harvested or on fields where it is not economically profitable to harvest.