Abstract: A castor includes a body, a wall of a rotary bearing, a wheel including an orifice, a rotary shaft, elements for mounting the shaft to co-operate with the bearing wall, the latter having a first bearing wall portion of tuning-fork-shape defining a slot between two limbs and another bearing wall portion having a base and a tenon secured to the base, the tenon may be engaged in the slot. The elements include two oblong holes formed in the limbs and a third oblong hole formed in the tenon. The holes are arranged in the limbs, and in the tenon in such a manner that all three of them are centered on a first axis when the tenon is engaged in the slot. The shaft passes through the bearing wall so that its axis is substantially parallel to the first axis and can be engaged in the orifice in the wheel.