US Patent 7287403 Hook latch

A hook latch for fastening and unfastening a closure member to a keeper in a latched position. The hook latch is moveable between the latched position and an open position. The hook latch comprises a rotation means which preferably comprises a knob connected to a cam shaped protuberance which acts upon an actuator plate and a locking plate. Upon rotation of either the knob or the key which is inserted in a lock cylinder which has a locking ring having a cam-shaped protuberance, the cam-shaped protuberances displace both the actuator plate and the locking plate.