Abstract: Axles projecting oppositely from opposite ends of a ribbed limb-breaking roller are carried by bearings mounted on plates projecting downward from the opposite ends of a transverse beam extending across the front of a crawler tractor. Arms projecting rearwardly from opposite ends of the beam alongside opposite sides of the tractor are pivotally connected to the tractor for elevational swinging of the beam about the arm pivots to alter the elevation of the ribbed roller. The roller has six equally spaced straight cleats, each projecting radially from the roller a distance approximately equal to one-third of the roller radius and extending along substantially the full length of the roller.