An improved brush cutter having an upper feed control member with stop, forward, neutral, and reverse positions also has a lower feed stop member with selectable sensitivity. Another aspect of the invention is to predict the feed roller shutoff point according to the rate of engine deceleration. According to another aspect, when the feed rollers stop feeding material into the cutters, to overcome drag on the cutters, a controller stops the feed rollers and then reverses them for a short time, and then reverses the rollers again if the problem is still present. To prevent jamming, a pressure switch senses when oil in a hydraulic motor system for rotating the feed rollers is too high and the controller momentarily reverses the feed rollers and then causes them to go forward, a cycle which can occur several times until the feed rollers are no longer stalled. By another aspect of the invention, the controller senses characteristics of the brush cutter and chooses an operating system based on the characteristics sensed. The controller can also sense if the brush chipper has not been used for a predetermined period of time and automatically reduce the idle speed of the engine until the brush chipper is used again, and then automatically return the engine to a normal idle speed before the feed rollers will pull brush into the brush chipper.