Caster wheel with constant force mechanism

A wheel assembly, comprising:

• a wheel having a hub and an axle;
• a support;
• and
• a constant force mechanism coupled to the wheel and to the support, the constant force mechanism comprising:
• a first support;
• a first carriage associated with the first support;
• a first resistance device that is coaxial with the first support;
• a second support;
• a second carriage associated with the second support;
• a second resistance device that is coaxial with the second support;
• and
• a rigid arm that is pivotally coupled with the first carriage, the second carriage, and the axle,
• wherein the first carriage is capable of being urged along the first support, and
• wherein the second carriage is capable of being urged along the second support.

A material handling vehicle, comprising:

• a vehicle chassis;
• a fork carriage coupled to the vehicle chassis;
• at least one lifting fork coupled to the fork carriage and displaceable in at least one dimension;
• a drive wheel coupled to the vehicle chassis;
• and
• at least one wheel assembly coupled to the vehicle chassis, the wheel assembly comprising:
• a wheel having an axle;
• and
• a constant force mechanism coupled to the wheel, the constant force mechanism comprising:
• a horizontal support;
• a horizontal carriage associated with the horizontal support;
• a vertical support oriented perpendicular with respect to the horizontal support;
• a vertical carriage associated with the vertical support;
• and
• a rigid arm that is pivotally coupled with the horizontal carriage, the vertical carriage, and the axle,
• wherein the horizontal carriage is capable of being urged along the horizontal support, and
• wherein the vertical carriage is capable of being urged along the vertical support.