Generated using the following Eukleides script, followed by judicious tweaking in en:Inkscape and manually editing the XML.

box(-2, -2, 10, 10)
cc = point(4,4)
Ci = circle(cc, 3)
Co = circle(cc, 4)
base = line(point(0,0), point(2,0))
vert = segment(point(4, 0), point(4,40))
ang = line(cc, 60:)
draw(Co)
draw(Ci)
mark(point(Ci, 60:), cc, point(4,6), backarrow, 3)
color(lightgray)
draw(base)
draw(vert)
mark(point(0,0), point(4,0), cc, right)
color(red)
draw(ang, dashed)
draw(segment(point(ang, -2), point(ang, 2)))
color(black)
draw(cc)

draw(point(ang, 2), box)
draw(point(ang, -2), box)
draw(point(vert, 2), cross)
draw(point(vert, 6), cross)

This work has been released into the public domain by its author, Ktims at ingilis Vikipediya. This applies worldwide. In some countries this may not be legally possible; if so: Ktims grants anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.Public domainPublic domainfalsefalse

• 2006-03-14 15:35 Ktims 600×600×0 (12061 bytes) Diagram indicating caster angle. The solid red segment indicates the steering axle, with the dashed red line indicating the pivot line. The gray shaded section would be the vehicle's tire.