Tracked vehicle suspension systems

In a tracked vehicle comprising:

• a chassis supporting a power unit;
• two track assemblies disposed at respectively opposite sides of said chassis and each including an endless track, means for guiding the track in a closed path including a lower portion along which the track runs in contact with the ground;
• means drivably coupling the power unit and the track for driving the track in said path to propel the vehicle in use, and a plurality of ground wheels rotatable about an axis normal to the direction of vehicle movement and arranged in rolling contact with the track along said ground-contacting portion of its path;
• and, a suspension system for said ground wheels;
• the improvement wherein said suspension system comprises:
• in association with each of said track assemblies, a plurality of suspension arms, each rotatably supporting one of said ground wheels;
• and
• a corresponding plurality of torsion cells, each coupling one of said arms to said chassis;
• each torsion cells comprising:
• an inner member having an outer surface which is of non-circular shape and which extends about a longitudinal axis of the member;
• an outer tubular member having an inner surface which is of non-circular shape and which extends about said longitudinal axis, said outer member extending around said inner member to define a space between said members;
• a resilient elastomeric material disposed in said space and torsionally coupling said members;
• and a plurality of elongate elements extending longitudinally of and spaced equally about said outer surface of the inner member of the cell to mechanically key the inner member to said elastomeric material and provide, on said inner member, spaced stress-distribution surfaces tending to equalize throughout the elastomeric material, stresses produced in said material in response to relative turning movement between said inner and outer members when the cell is in use;
• each said torsion cell being coupled to the chassis of the vehicle by one of its said inner and outer members so that the longitudinal axis of the cell extends parallel to the axis of rotation of the associated wheel and the other member of each cell being coupled to the relevant wheel suspension arm so that said arm defines an obtuse angle with respect to the direction of vehicle movement, whereby vertical displacement of a ground wheel as the vehicle travels over obstructions in use causes relative turning movement between said inner and outer members of the associated torsion cells and torsionally stresses the elastomeric material of the cell.

A torsion cell comprising:

• an inner member having an outer surface which is of non-circular shape and which extends about a longitudinal axis of the member;
• an outer tubular member having an inner surface which is of non-circular shape and which extends about said longitudinal axis, said outer member extending around said inner member to define a space between said members;
• a resilient elastomeric material disposed in said space and torsionally coupling said members;
• and, a plurality of elongate elements extending longitudinally of and spaced equally about said outer surface of the inner member of the cell to mechanically key the inner member to said elastomeric material and provide, on said inner member, spaced stress-distribution surfaces tending to equalize throughout the elastomeric material, stresses produced in said material in response to relative turning movement between said inner and outer members when the cell is in use.