Torsion spring vehicle suspension

A torsion spring cartridge is provided for torsionally absorbing loads on a trailer frame or the like. The torsion spring cartridge is insertable into an axle tube and includes a counter torque hub, a bearing block spaced therefrom, and a torque shaft mounted for oscillating rotational movement in the bearing block with torsion rods operably interconnected between the counter torque hub and the torque shaft. The bearing block and the torque shaft each include over-rotation stops that cooperate to prevent over-rotation of the torque shaft during use. The bearing block supports the inside of the axle tube to prevent distortion of the axle tube profile during over-torquing of the torque shaft during use, and a frame bracket supports the outside of the axle tube and transmits forces from the bearing block and axle tube directly to the trailer frame. The torsion rods have ends with substantially circular cross-sections, and are held in place by brazing. Oven brazing is utilized to equalize stress and minimize stress risers in the brazed joint so that the resulting brazing bonds resist stress fractures and failure from cyclical loading of the torsion spring cartridge.