Abstract: The stump grinder has a rotating cutting wheel that is mounted onto an arm for raising and lowering movement and is driven by a hydraulic motor. The arm is capable of being moved about a generally upright axis to control the rate of laterally feed of the cutting wheel. The actuator movement is controlled as a function of the pressure to the hydraulic motor driving the cutting wheel so that as the pressure increases, the rate of feeding movement laterally of the cutting wheel is reduced. The rate of movement is controlled in both directions of swinging of the post about an upright axis, by utilizing variable opening or proportional flow pilot operated valves on the lines to the actuator for controlling the swing. As pressure to the motor increases the variable outlet or proportional pilot operated valve connected to the pressurized end of the swing actuator opens a greater amount diverts a portion of the hydraulic fluid flow to drain to slow movement of the swing actuator.

Abstract: An attachment for a power machine includes a first mounting plate and a housing mounted to the mounting plate. The housing has a front end and a rear end and generally oppositely disposed first and second sides. The first side of the housing is removable. A rotor is rotatably mounted to the second side of the housing and has a surface and first and second longitudinal ends. A portion of the surface and the first longitudinal end are exposed by removal of the first side of the housing. A motor is coupled to the rotor to rotatably drive the rotor.