The breaking wheel (originally, the whele) was a torture and capital punishment device of the Middle Ages and early modern times.
The wheel itself was similar to a large wooden wagon wheel, with many radial spokes. The victim's arms and legs were placed one by one over two sturdy wooden beams. A large hammer was then applied to the limb over the gap between the beams, breaking the bone. This process was repeated several times per limb.
Afterwards, the victim's shattered limbs were woven through the spokes of the wheel. The wheel was then hoisted onto a tall pole, so that birds could eat the still-living victim.
Legend has it that Saint Catherine of Alexandria was to be executed on one of these devices, which thereafter became known as Catherine wheels.