Drive tumbler and track drive for mobile vehicles, including lift cranes

A method of transmitting force between a drive tumbler and a track wherein the track is made from a plurality of connected track shoes each having a ground engaging surface, an inside surface opposite the ground engaging surface and a driven surface, the track being wrapped around the drive tumbler so that a plurality of the shoes are in contact with the drive tumbler;

• and wherein the drive tumbler has an axis of rotation, a plurality of drive surfaces, at least one of which engages the driven surface on one of the track shoes that are in contact with the tumbler, and a circumferential rim surface that includes a plurality of shoe contact surfaces that each contact the inside surface of one of the track shoes that are in contact with the tumbler, the shoe contact surfaces each having a shape such that a line normal to the tangent of the shoe contact surface does not pass through the axis of rotation of the drive tumbler;
• the method comprising applying torque through the drive tumbler to the track through both i) the drive surface of the tumbler contacting the driven surface on the track shoes, and ii) the shoe contact surfaces on the rim contacting the inside surfaces of the shoes;
• the torque applied by the drive tumbler shoe contact surfaces on the rim of the tumbler having a moment arm about which to generate force on the track from the contact of the shoe contact surfaces on the rim.

A drive tumbler for a track vehicle comprising:

• a) a center hub having an axis of rotation;
• and
• b) a plurality of tooth members individually connected to the center hub by welds;
• c) at least two web plates welded to the center hub, wherein each respective tooth member of the plurality of tooth members span between the at least two web plates and are connected to the center hub by being welded to the at least two web plates;
• and
• d) support plates welded to the center hub and to and between the at least two web plates.

A method of making a drive tumbler for a track vehicle comprising:

• a) providing a center hub, at least two web plates, a plurality of support plates and a plurality of individual tooth members;
• b) welding the at least two web plates to the center hub;
• c) welding the support plates to the center hub and to and between the at least two web plates;
• and
• d) connecting the tooth members individually to the center hub by welds to produce said drive tumbler, wherein each respective tooth member of the plurality of tooth members span between the at least two web plates and are connected to the center hub by being welded to the at least two web plates with the tooth members extending radially outward around the perimeter of the drive tumbler.