Drive wheel

A drive wheel 10 is shown to include a support member 12 and, a wheel member 11 having a surface contacting portion 18 extending about a periphery of the wheel member 11. A drive shaft 24 includes a drive device 25 arranged to engage a drive surface 26 on the wheel member 11 such that the wheel member 11 can be rotatably driven relative to the support member 12. When the drive device 25 is engaged with the drive surface 26, a line of engagement 27 is defined along portions of the drive device 25 and the drive surface 26 that engage with one another. This line of engagement 27 forms an acute angle with the longitudinal axis 24a of the drive shaft 24 such that when the drive wheel 10 is traveling over a traveling surface 19, the line of engagement 27 intersects a part of the surface contacting portion 18 that contacts the traveling surface (this intersection is shown at 28), whereby the part of the surface contacting portion 18 that contacts the traveling surface is spaced from an intersection of the steering axis and the traveling surface 19.