Abstract: A latch including inner and outer cylindrical housings, the inner housing having a guide slot thereon for receiving a guide piece and fixing the slide path of the outer housing with respect to the inner housing. The inner housing has a protuberance which is engageable with a minimum or a maximum backset hole. A retainer plate having two retainer posts fits into the inner housing. The retainer post receives springs for loading a main bolt and an auxiliary bolt. A link and a slide bar can be used according to whether minimum or maximum backset is required. A stabilizer also prevents the auxiliary bolt from being forced open from the outside.

Abstract: A length-adjustable latch having an outer housing and an inner housing. The length of the latch is adjusted by engaging an extension block of the inner housing with either of two positioned holes of the outer housing. A drive linkage connnects to a backset plate by engaging an extension element of the former with a sliding space of the latter. The combination of the drive linkage and the backset plate is encompassed by a spring but with either a trail end of the backset plate or both the rear portions of the backset plate and the drive linkage passing through each longitudinal opening of a slidable plate, the inner housing, an installation seat and the outer housing. Due to the manner of engagement between the inner housing and the outer housing and the corresponding position of the drive linkage and the backset plate, the length of the latch is adjustable, as desired, for a 60 mm (23/8") backset length or a 700 mm (23/4") backset length .

Abstract: A heavy-duty panic proof lock unit comprising a latch bolt mechanism, a dead bolt mechanism, and a cartridge mechanism. The latch bolt mechanism cooperates with a primary spindle. The dead bolt mechanism cooperates with a secondary cylinder. The cartridge mechanism comprises a first cartridge plate, a second cartridge plate, a rocker lever, a collar, an H-shaped slide, a rotary lever, and a spring-loaded catch. The collar is a ring-shaped plate having approximately a same size with the opening of the drive ring of the rocker lever and comprises two outwardly projecting teeth at opposite locations respectively to cooperate with notches of the rocker lever. The collar also has an inwardly projecting tooth designed to fit in slide along the spindle slot and to transmit rotary force between the primary spindle and the rocker lever. The collar is entrapped in the opening of the drive ring, with the two outwardly projecting teeth thereof retained within the notches of the rocker lever.

Abstract: A lever type lockset with a rolling housing within a main housing. The roller housing normally only touches the main housing at the rollers and also connects to the latch portion of a lockset. The side plates of the roller are constructed separately from the roller housing so that they can be made thicker and more durable. The inner and outer spindle each have a curved elbow on it which is shaped somewhat like two boomerangs joined together on adjacent distal ends for minimizing local stress concentrations. The side plate also has a curved surface which is designed to offer minimal resistance to the elbows so that the handle can be turned with very little resistance.

Abstract: A tubular lockset which includes a backset plate and a drive linkage, both of which are integrated within the rear portion of a latch case. The surface of the backset plate and drive linkage are set with slots and openings for the mounting of drive unit at the fore or rear position within the slots. Two protrusions are provided on one end of the drive linkage, such that the foot of the drive unit engages with the protrusion of the drive linkage and drives the latch case forward and backward. An opening is provided on the drive linkage and slot is provided on each backset plate for the fixation of the drive unit, i.e. the drive unit is fixed within the slot of the backset plate and the opening of drive linkage. The backset length of the amphi-latch can be adjusted to either 60 mm (23/8") or 70 mm (23/4").

Abstract: A latchbolt slide extension for a cylindrical lockset which comprises a spring-loaded latch and a cylindrical body. The slide extension is connected to the spring-loaded latch and the cylindrical body so as to make such cylindrical lockset with a shorter backset latch to be installed to a door with a larger backset.