A roller cutter includes a hub having crushing members mounted on an outer periphery thereof, and a shaft on which the hub is mounted for rotation. Opposite ends of the shaft include respective spigots. Seals are disposed adjacent respective ends of the shaft and are arranged radially between the shaft and the hub for preventing leakage of lubricant. Covers are disposed axially outwardly of respective seals for covering the respective seals. Each cover includes a generally radially inwardly directed projection received in an indentation formed in an outer surface of the shaft to lock the cover axially and rotationally with respect to the shaft.
