Abstract: A horizontal support frame having an upstanding lever pivoted to the frame adjacent one end thereof with the toggle comprising a pair of arms having adjacent ends pivoted together, the opposite end of one of the arms being pivotly connected adjacent the end of the frame opposite the upstanding lever. The opposite end of the other arm is pivotly connected to the upstanding lever intermediate the ends thereof. A hydraulic actuator for the upstanding lever comprises a cylinder having one end closed and the opposite end open, the closed end being pivotly connected to the pivotly connected ends of the toggle arms. A piston is reciprocally mounted in the cylinder and has a piston rod extending outwardly of the open end of the cylinder, the free end of the piston rod being pivotly connected to the frame on the same pivot pin pivotly connecting the lower end of the lever to the frame.