Richards fixed lever lock

Richard's fixed lever ..Invented about 1827. The method of design consists in the shape of the part of the levers which comes in contact with the V-end of the detector. If the levers are overlifted in an attempt to open the lock ,the projecting arms of the levers are forced beyond the V-end of the detector, which keeps them in a FIXED position. The detector is release by turning the key in the direction of locking out the bolt. At this period box of wards were still being used in lever locks,hence, the elaborate key.