Patent ID: 8327562

Claim:
A trencher comprising: a chassis supported on a pair of tracks, the tracks configured to move the trencher; a boom pivotally mounted to the chassis, the boom configured to support a tool; an engine mounted to the chassis; a plurality of hydraulic pumps configured to be driven by the engine; a hydraulic reservoir connected to the plurality of hydraulic pumps; a track drive hydraulic circuit having a hydraulic motor for driving the tracks, wherein the track drive hydraulic motor is connected to at least one of the plurality of hydraulic pumps; a tool drive hydraulic circuit having a hydraulic motor for driving the tool, wherein the tool drive hydraulic motor is connected to at least one of the hydraulic pumps; a control system that includes a thermal shock avoidance function; wherein, the control system determines a first and second value where the first value is representative of a temperature of hydraulic fluid in the reservoir, and the second value is representative of a temperature of a first hydraulic circuit desired to be activated, the first hydraulic circuit being one of the track drive hydraulic circuit and the tool drive hydraulic circuit; and wherein, the control system compares the first and second values and activates the thermal shock avoidance function if the comparison indicates that the temperature of the hydraulic fluid in the reservoir is a predetermined amount warmer than hydraulic fluid in the first hydraulic circuit.