Torsion axle having a selectively replaceable insert assembly

A torsion axle comprising:

• an axle tube having an interior chamber;
• and
• an insert assembly positioned in said interior chamber, wherein said insert assembly comprises,
• a substantially rigid shaft having a front tip and a rear tip,
• a relatively flexible cartridge having an interior passageway receiving said shaft, and
• means positioned on said shaft between said front tip and said cartridge and between said rear tip and said cartridge for substantially absorbing a vertical load on said insert assembly to the exclusion of said cartridge.

A torsion axle comprising:

• an axle tube having an interior chamber;
• and
• an insert assembly positioned within said interior chamber, wherein said insert assembly comprises,
• a substantially rigid shaft having a front tip and a rear tip,
• a relatively flexible cartridge having an interior passageway receiving said shaft, and
• means positioned around said shaft for limiting rotation of said shaft relative to said axle tube.

A torsion axle comprising:

• an axle tube having an interior chamber;
• an insert assembly positioned within said interior chamber, wherein said insert assembly comprises,
• a substantially rigid shaft having a front tip and a rear tip, and
• a relatively flexible cartridge having an interior passageway receiving said shaft;
• and
• a cap positioned over said interior chamber, wherein said cap has a selectively removable retention means to enable selective removal of said cap from over said interior chamber and selective removal of said insert assembly from within said interior chamber.

A method for selectively adjusting the torsion load rating of a torsion axle, wherein said torsion axle has an axle tube with an interior chamber, said method comprising:

• removing a first insert assembly from said interior chamber, wherein said first insert assembly comprises,
• a substantially rigid first shaft having a fixed length and having a front tip and a rear tip;
• a relatively flexible first cartridge having a first length and having an interior passageway receiving said first shaft,
• a relatively inflexible first front bushing having an aperture receiving said first shaft, wherein said first front bushing is positioned on said first shaft between said front tip and said first cartridge, and
• a relatively inflexible first rear bushing having an aperture receiving said first shaft, wherein said first rear bushing is positioned on said first shaft between said rear tip and said first cartridge;
• and
• positioning a second insert assembly in said interior chamber, wherein said second insert assembly comprises,
• a substantially rigid second shaft having said fixed length and having a front tip and a rear tip;
• a relatively flexible second cartridge having a second length different than said first length and having an interior passageway receiving said second shaft,
• a relatively inflexible second front bushing having an aperture receiving said second shaft, wherein said second front bushing is positioned on said second shaft between said front tip and said second cartridge, and
• a relatively inflexible second rear bushing having an aperture receiving said second shaft, wherein said second rear bushing is positioned on said second shaft between said rear tip and said second cartridge.