The medieval spiked breaking wheel used as an instrument of torture and execution. It is the symbol of the virgin-martyr St. Catherine of Alexandria, who legend says was condemned to die on the wheel only to have it shatter when she touched it. Then she was beheaded. The Katherine-wheel (or Katherine wheel) is found on the arms and crests of numerous European towns, guilds, and families, and adorns the college shields of St. Catherine's College, Oxford and St; Catherine's College, Cambridge.
Spellings of the Saint's name vary in heraldry. For example:
"Azure, two bars or, in chief a Katherine-wheel between as many buglehorns argent--MERTINS, Lord Mayor of London."
"D'azur, à trois roues de Sainte Catherine d'or--CATHERINE, Bourgoyne."
I have a couple of friends who went to the College of Saint Catherine (now known as St. Catherine University) in Saint Paul, Minnesota. The school is sometimes referred to as St. Kate's (and my friends often refer to themselves as Katies).