A hydraulic cutter device incorporates a rotatable base including a plurality of spaced cutter teeth. A protective shield covers at least a portion of the base. A fluid cooler is located adjacent the protective shield, and defines a window for movement of ambient air from a relatively high-pressure area upstream of the fluid cooler to a relatively low-pressure area downstream of the fluid cooler. A hydraulic motor is adapted for rotating the base, and includes a plurality of hydraulic lines communicating with the fluid cooler. Rotation of the base creates a pressure reduction downstream of the fluid cooler causing ambient air flow into and through the fluid cooler to cool fluid moving into and from the hydraulic motor.