Caster

A caster having a fixed bracket (3) secured to an object (101) to be moved by said caster, a rotary bracket (4) supported for rotation around a fixedly installed vertical shaft (5) vertically extending from said fixed bracket (3), and a wheel (11) rotatably supported with respect to said rotary bracket (4) on an axle (10) horizontally spaced from the axis of said vertical shaft (5), said caster comprising a wheel attaching member (12) which supports the axle (10) of said wheel (11) is turnably attached to said rotary bracket (4) by a horizontally directed pivot shaft (13) positioned between said vertical shaft (5) and said axle (10);

• said rotary bracket (14) comprising a stopper (19) which when said wheel attaching member (12) is turned around the axis of said pivot shaft (13), defines the terminal end of the upward movement of said wheel (11);
• a key member (20) movable toward said vertical shaft (5) installed in said wheel attaching member (12) at a position above said pivot shaft (13);
• the outer surface of said vertical shaft (5) including at least one fitting recess (29a, 29b) into which said key member fits as it is moved with at least one predetermined angle obtained by the rotation of said rotary bracket (4) around said vertical shaft (5);
• wherein the arrangement is such that when said key member (20) fits in said fitting recess (29a, 29b), the rotation of said rotary bracket (4) around said vertical shaft (5) is inhibited and, wherein in this inhibited state when a force greater than a predetermined value is applied to said wheel attaching member (12) in a direction to move said wheel (11) downwardly, said wheel attaching member (12) is turned in this direction, with the key member (20) escaping from said fitting recess (29a, 29b), thereby allowing the rotation of said rotary bracket (4) around said vertical shaft (5).