Abstract: A material handling vehicle, especially a log skidder, having articulated front and rear sections and a boom mounted on the rear section which pivotally supports a material handling member such as a grapple adapted to seize the ends of logs to be moved by the skidder. The grapple hangs from the end of the boom on a self-centering mechanism which includes a plurality of first circular discs, a plurality of second circular discs interleaved therewith with the uppermost disc being fixed and interacting between discs, a plurality of spring elements which resist rotation of the grapple in either direction about the grapple turning axis tending to return it to a normally centered position relative to the centerline of the vehicle without operator assistance.

Abstract: A material handling vehicle, especially a log skidder, having articulated front and rear sections and a boom mounted on the rear section which pivotally supports a material handling member such as a grapple adapted to seize the ends of logs to be moved by the skidder. The grapple hangs from the end of the boom on a selfcentering mechanism which includes a plurality of first circular discs, a plurality of second circular discs interleaved therewith with the uppermost disc being fixed and interacting between discs, a plurality of spring elements which resist rotation of the grapple in either direction about the grapple turning axis tending to return it to a normally centered position relative to the centerline of the vehicle without operator assistance.

Abstract: A track suspension for a track laying vehicle having a pair of endless tracks, one on each side of the vehicle body, independently driven by drive sprockets at the front. Each track suspension unit has an elongated suspension beam pivoted at one end behind the drive sprocket and sprung at the opposite end to the vehicle body providing a major suspension primarily responding to major changes in ground reaction forces. Inside each track and supported on the beam are trucks, each having a walking beam pivotally mounted on the suspension beam and providing a minor oscillatory suspension motion responding to minor changes on ground reaction forces.