A proximal end region of a load beam is provided with a proximal-end widthwise
beam extending in the width direction and a pair of proximal-end lengthwise beams
respectively extending from the opposite ends of the proximal-end widthwise beam
towards a distal end of the load beam, while an intermediate region of the load
beam is provided with a pair of intermediate lengthwise beams extending from the
distal ends of the pair of proximal-end lengthwise beams towards the distal end
of the load beam. The proximal-end lengthwise beams have an angle of inclination
relative to the longitudinal center axis of the load beam greater than the angle
of inclination of the intermediate lengthwise beams relative to the longitudinal
center axis of the load beam.