The elevating scraper concept and the Cat J621.

The article discusses the history and features of the Caterpillar J621 elevating scraper. It mentions that there was debate over who came up with the elevating scraper concept, but it is generally accepted that Hancock produced the first practical elevating scraper. The J621 was a logical development of Caterpillar's previous model J619 and was powered by a 300-horsepower diesel engine. The article also mentions some technical details and features of the J621, such as its hydraulic operation, cutting edge, and tyre equipment. The J621 was a popular machine for Caterpillar and remained in production until 1972. The article concludes by noting that there are currently no models of the J621 available, but it is hoped that a model manufacturer will produce one in the future. [Extracted from the article]