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US 4,679,420 AGranted
Force immune door latch
OwnerTai-Her Yanginventor
Life of this patent
Estimating the term…
Abstract
An improved force immune door knob/latch is provided which, by use of resiliently-biased ratcheting means, is rendered immune to force resulting from the application of excess torque to the door knob. These resiliently-biased ratcheting means are such that their biasing force is oriented in a direction perpendicular to the longitudinal axis of the door latch shaft.
Claims4
A force immune door latch, in combination, comprising:
- a handle, a sleeve extending rearwardly of the handle, said sleeve having a forward reduced end and a rearward enlarged end, said ends defining a shoulder therebetween, an inner annular collar having at least one aperture formed therein, said collar being positioned abutting the shoulder, nested within the rearward enlarged end of the sleeve on a substantially common longitudinal axis therewith, a cylinder having a locked position and an unlocked position and further having a plurality of depressions formed annularly therein, said cylinder being nested with respect to the sleeve, the collar and the handle such that the handle, sleeve, and the collar having a substantially common longitudinal axis, means cooperating between the collar and the rearward enlarged end to preclude substantial axial separation and rotational movement therebetween, means cooperating between the cylinder and the forward reduced end of the sleeve to preclude substantial axial separation therebetween, a spring-loaded ball detent being positioned within the aperture of the collar with its biasing force being oriented inwardly in a direction substantially perpendicular to the common longitudinal axis, wherein said detent is received within the depressions on the cylinder to accommodate rotation of the cylinder and the handle substantially in unison with each other in the unlocked position of the cylinder, but providing relative rotation therebetween in the locked position of the cylinder, whereby in the locked position of the cylinder excessive torque applied to the handle normally sufficient to break the latch will not result in breakage thereof, thereby precluding an undesired destruction of the lock by a burglar or others.
Dependencies are inferred from the claim text.