Closure fasteners – Bolts – Sliding
Patent
1985-06-10
1987-07-28
Moore, Richard E.
Closure fasteners
Bolts
Sliding
292DIG27, 70149, E05C 2100
Patent
active
046827994
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a latch lock mechanism. The invention will herein be described with particular reference to locks of the type provided for security either by mounting to or mortising into a door but it will be understood that the invention is not limited to use in door locks.
BACKGROUND ART
Latch locks of the type herein discussed are usually operated by rotation of a spindle extending from the lock case, and in the case of a mortise lock, extending through at least one side of the door. A lever, knob, handle or like door furniture is mounted on the spindle to facilitate operation of the latch. Rotation of the spindle operates a system of cams or levers which withdraws a latch bolt from latching engagement with a latch keeper or slot in the door jamb and permits the door to open. The mechanism is provided with a lock operable for example by rotation of a separate cylinder, which drives a wedge or block into a position which prevents rotation of the spindle and thus prevents retraction of the bolt until the door is unlocked thus removing the wedge or block.
A disadvantage of such mechanisms is that if excessive torque or entry effort is applied to the handle or knob while the mechanism is locked then damage to the mechanism results. To avoid such damage it is commonly practiced to groove the spindle in such a way as to ensure that the spindle shears prior to other parts of the mechanism becoming damaged. While that avoids the need to replace the whole lock it remains necessary for the spindle to be replaced before the mechanism can be operated again. Often the services of a tradesman are required to replace the spindle before access can be given through the doorway.
DISCLOSURE OF INVENTION
An object of the present invention is to avoid the above discussed disadvantages of latch lock mechanisms.
According to the present invention there is disclosed a latch lock comprising:
a latch bolt adapted for movement between a latching and a retracted position,
a first part adapted in use to be rotated by a door handle,
a second part adapted in use to drive the latch bolt between one of the positions and the other, and
clutch means which when engaged transmit drive from the first part to the second and when disengaged allow free rotation of the first part by the door handle.
Preferably, the latch lock further comprises a locking means which when in a locked configuration disengage the clutch means and prevent movement of the latch bolt.
An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows schematically an embodiment according to the invention in a latched unlocked configuration, and
FIG. 2 shows the embodiment of FIG. 1 in a latched locked configuration, and
FIG. 3 shows a schematc exploded view of part of a 3000 series door lock fitted with an embodiment of the present invention.
BEST MODE OF CARRYING OUT THE INVENTION
The mechanism will first be described in a latched unlocked configuration. With reference to FIG. 1 there is shown a latch lock mechanism comprising a latch bolt 10 having a tongue portion 11, a shaft 12 and a bracket 13 and supported for translational movement by guide means not shown in the drawing. Bolt 10 is spring loaded to a latching position in which bolt 10 extends from a lock case so that tongue 11 may engage a bolt keeper 14.
A square cross-section spindle 20 extends at right angles to the direction of movement of latch bolt 10 and is mounted for axial rotation by, for example, extending through bearings in a lock case. Spindle 20 extends through a square cross section aperture of a boss 30 which is thereby keyed to the spindle and which is thus mounted for rotation by the spindle. A cam 40 is mounted coaxially with spindle 20 for axial rotation about boss 30.
The circumference of boss 30 is provided with a recess 32 adapted to receive a detente or spur 33 provided on a clutch lever 34 pivotally mounted to cam 40 by means of a pin 35 adjacent
REFERENCES:
patent: 323918 (1885-08-01), Crockett et al.
patent: 509194 (1893-11-01), Carty
patent: 1330650 (1920-02-01), Pehel
patent: 2529230 (1950-11-01), Smith et al.
patent: 2593573 (1952-04-01), Kulbersh
patent: 4255953 (1981-03-01), Dietrich et al.
patent: 4429556 (1984-02-01), Kambic
Efco Manufacturing Company Pty, Limited
Moore Richard E.
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