| 摘要 |
An adjustable-backset latch system for a lockset includes three main subsystems: a bolt retraction system, a backset-adjustment system and a deadlatching system. By virtue of the simplicity of the design of the backset-adjustment subsystem, the user can change the backset from 2⅜'' to 2¾'', and vice-versa with one hand. A pin is simply moved through a "U"-shaped slot formed in a housing and housing and bolt actuation components are extended simultaneously by the desired backset increment. The bolt retraction system of the present invention uses a cam in which the distance from a point about which the cam rotates and the end of the cam, and the distance to a smaller cam pin, are selected to multiply the relatively small angular distance transversed during a half-round rotation of the knob or handle into the desired retraction distance of a main bolt. The deadlatching system uses two springs, one of which not only biases an auxiliary bolt to its extended position, but also biases a deadlocking dog so as to pivot into a blocking position preventing the main bolt from being retracted completely, in the event an intruder attempts to move the bolt.
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