Abstract: A method and apparatus for preventing underdigging of a work machine, which may occur if the implement digs under or too close to the work machine, is disclosed. An underdigging boundary or a space of allowable implement movement is established relative to the work machine. The position of the implement is sensed, and the movement of the implement is controllably prevented from underdigging the work machine.

Abstract: A method and apparatus for controllably preventing an implement from damaging a work machine or itself, which may occur if the implement strikes the work machine, by restricting the movement of the implement. A boundary is established a predetermined distance from the work machine. By controllably restricting the movement of the implement when it approaches the boundary, the implement is prevented from making contact with the work machine.

Abstract: A cold fluid protection circuit is provided for controlling the rate of fluid flow in a hydraulic system in response to the temperature of the oil in a reservoir. The subject invention includes a temperature sensor operative to sense the temperature of the fluid in the reservoir and deliver an electrical signal representative thereof to a controller. The controller processes the sensed temperature with respect to the rate of flow in the hydraulic system that is returning to the reservoir from an actuator through a fluid conditioning mechanism and proportionally reduces the rate of flow therethrough by controllably reducing the displacement of a directional valve mechanism in response to the sensed temperature.