Patent ID: 7485996

Claim:
A position retention device comprising: a pivot member having a mounting axle; a cylindrical seat mounted co-axially on said mounting axle of said pivot member, and having pluralities of circumferentially formed north and south pole sectors, each of said north pole sectors being disposed between adjacent two of said south pole sectors; a cylindrical housing mounted co-axially and rotatably on said mounting axle of said pivot member; and an annular member disposed in said cylindrical housing for simultaneous rotation with said cylindrical housing, and having pluralities of circumferentially formed north and south pole sectors, each of said north pole sectors being disposed adjacent two of said south pole sectors; wherein, position of said cylindrical housing is retained stationarily with respect to said cylindrical seat by virtue of attraction between one of said north pole sectors of said cylindrical seat and one of said south pole sectors of said annular member.