Abstract: A heavy duty, portable power shear device adapted to be driven by rotating a motor shaft. The shear includes two spaced stationary blades and a movable blade having two spaced arms in engagement with a circular cam ring. The cam ring surrounds an eccentric bushing connected to the motor drive shaft. The two arms of the movable blade diverge from the axis of the drive shaft and engage the periphery of the cam ring on the portion of the ring disposed toward the movable shear blade pivot. The movable blade pivot is displaced from the axis of the drive shaft on the side of the axis remote from the cutting blades.