US Patent 7201361 Gate valve having reduced friction

Valve having a valve housing, a valve member slidable in the valve housing between open and closed positions, and a friction reducer to reduce friction between the valve member and the valve housing. The friction reducer comprises at least one guide shoe made of low friction material, to provide a low friction sliding surface, the guide shoe being removably insertable into a slot in the valve member. The guide shoe is arranged to cooperate with the slot such that the ends of the slot prevent the guide shoe from being extracted from the valve member in the direction of movement of the valve member, when the valve member is in position with the valve housing.