GB2439783A

GB2439783A - Reversible latch with slidable block

Info

Publication number: GB2439783A
Application number: GB0613375A
Authority: GB
Inventors: Colin Sidney Middleton
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-07-05
Filing date: 2006-07-05
Publication date: 2008-01-09
Also published as: GB0613375D0

Abstract

A latch comprises a casing (1), a latch bolt (2), a latch bolt lath (14) mounted in the casing (1), a follower (23) arranged to act on the latch bolt lath (14) and a spring (28) arranged to act on the follower (23). The latch bolt (21) is rotatably mounted on the latch bolt lath (14) and is normally urged by the spring (28) to a position in which it partially projects from the casing (1). A block (31) is slidably mounted in the casing (1) and is normally engaged by an arm (24) of the follower (23). The block (31) is movable to a position in which the follower (23) can be moved under the action of the spring (28) to a position in which it moves the latch bolt lath (14) to a position in which it allows the latch bolt (21) to be moved to a position in which it projects entirely from the casing (1) and can be rotated with respect to the casing (1) to reverse said latch bolt (21). The latch may also be provided with a dead bolt (35).

Description

Title: IMPROVEMENTS IN LATCHES AND LOCKS This invention relates to

latches and locks for doors or the like and is particularly concerned with a latch having a means for reversing the latch bolt without having to open the casing of the latch.

According to the invention, there is provided a latch comprising a casing, a latch bolt, a latch bolt lath mounted in the casing, a follower arranged to act on the latch bolt lath and a spring arranged to act on the follower, wherein the latch bolt is rotatably mounted on the latch bolt lath and is normally urged by the spring to a position in which it partially projects from the casing and wherein a block is slidably mounted in the casing and is normally engaged by an arm of the follower, said block being movable to a second position in which the follower can be moved under the spring action to a position in which the latch bolt lath allows the latch bolt to be moved to a position in which it projects entirely from the casing and can be rotated with respect to said casing to reverse said latch bolt.

Preferably, the spring is mounted in the casing and the spring may take the form of a coil spring.

According to a preferred embodiment of the invention, the spring is arranged to act on a toothed rack the teeth of which are engageable with a toothed portion of the follower.

The follower arm is desirably arranged to engage with an upstand projecting from the latch bolt lath.

The block is preferably mounted on a guide for sliding movement in the casing and the sliding movement of the block is desirably achieved by a captive screw which is engageable in a screw-thread in the block whereby turning the screw is effective to move the sliding block along the guide in the casing. The screw is desirably accessible from the front of the casing.

The invention will now be described in detail, by way of example, with reference to the drawings, in which:-Fig. 1 is a side elevation of one embodiment of a lath according to the invention showing the latch bolt in the withdrawn or retracted position; and Fig. 2 is a side elevation of the latch shown in Fig. I but showing the latch bolt in a position in which it can be reversed.

Referring to the drawings, the latch according to the invention comprises a casing 1 having an inner forend 2 to which an outer forend 4 can be secured by means of screws 5 which pass through bores in the outer forend 4 and engage in screw-threaded bores 3 in the inner forend 2. A pair of columns 6, 7 project from the base of the casing, each column. having a screw-threaded bore by means of which a cap can be secured to the casing by screws (not shown). A first hole 8 and a second elongated hole 9 are provided in the casing for bolt-through furniture which is likewise not shown. A block 11 is mounted on the column 6 and a post 13 also extends from the base of the casing 1. The inner forend 2 is secured to the casing and is provided with further screw-threaded bores 12 by means of which the inner forend, and hence the casing, can be secured in a door or the like.

A latch bolt lath 14 is slidably mounted in the casing 1, the sliding movement of the latch in the casing being guided by a slot 15 in the lath in which the post 13 is located. The post 13 also serves to limit the extent of sliding movement of the lath in the casing. The latch bolt lath 14 has an upstand 16 at the end which is closer to the inner forend 2 and a pin 17 having a head 18 is rotatably mounted on the upstand 16, the head 18 bearing against one side of the upstand 16. A latch bolt 21 is secured to the pin 17 by a cross-pin 19. The latch bolt lath has a second upstand 22 at its other end.

A follower 23 is pivotally mounted in the casing I and has an aim 24 one side of which is arranged to bear against the upstand 22. The follower 23 also has a square-sectioned bore 25 for the reception of a spindle (not shown) to one or both ends of which can be fitted a handle or knob (not shown). The follower 23 is also provided on its periphery with a toothed section 26 which is arranged to be engaged by the teeth of a toothed rack 27 which is slidably mounted in the casing 1. The toothed rack 27 is arranged to be acted on by a coil spring 28 which bears at one end against one end of the toothed rack 27 and at the other end against a stop plate 29 secured to the inner forend 2. The spring 28 urges the toothed rack 27 towards the rear of the casing 1 which causes the follower 23 to rotate in an anti-clockwise direction, or viewed in the drawings, and urges the other side of the follower arm 24 against a block 31. The block 31 has a screw-threaded bore in to which a captive screw 32 is engaged. The screw 32 is rotatably mounted in a boss 33 secured to the inner forend 2 and the end of the screw 32 is provided with means which are adapted to be engaged by a tool, such as a screwdriver and which are accessible through an aperture 34 in the inner forend 2. The block is guided for sliding movement in the casing and the guide holds the block against rotation.

If a handle or knob on the spindle is turned in a clockwise direction as viewed in the drawings, the follower 23 will be rotated in a clockwise direction until the follower arm 24 forces the upstand 22 against the block 11. In this position, the latch bolt lath 14 will be moved to the right, into the casing, and will move the latch bolt 21 to the withdrawn or retracted position in which the latch bolt is located substantially entirely within the casing 1 as shown in Fig. I of the drawings. At the same time, rotation of the follower 23 will cause its toothed sector 26 to move the rack 27 to the left as shown in the drawings to compress the coil spring 28. If the handle or knob is then released, the spring 28 is free to re-exert itself and to move the toothed rack 27 to the right. The engagement of the toothed sector 26 by the teeth of the rack 27 will cause the follower 23 to rotate in an anti-clockwise direction, as viewed in the drawings, until the other side of the follower arm 24 makes contact with the block 31. At the same time, a latch bolt spring (not shown) acting on the latch bolt lath 14 will ensure that the upstand 22 is held in contact with the follower arm 24 and will move the latch bolt lath 14 to the left, as viewed in the drawings, until the latch bolt 21 projects from the outer forend 4 while only its inner end is bounded by an aperture in the inner forend 2 through which the latch bolt projects. This position is not shown in the drawings.

If it is desired to reverse the latch bolt 21, for example to change it from a right-handed door to a left-handed door, it is merely necessary to undo the screws to remove the outer forend 4 from the inner forend 2. The captive screw 32 is then turned by means of a tool inserted through the aperture 34 in the inner forend s 2. Since the block 31 is held against rotation, rotation of the screw 32 will be effective to move the block towards the inner forend 2. This movement of the block 31 towards the inner forend 2 will allow the follower 23, to rotate in an anti-clockwise direction, under the action of the coil spring 28, which will, in turn, allow the latch bolt lath 14 to move to the left until the latch bolt 21 is clear of the inner forend 2 as shown in Fig. 2 of the drawings. The latch bolt 21 can then be rotated through 1800 to reverse it. The screw 32 is then turned in the opposite direction to move the block 31 away from the inner forend 2. Since the block 31 acts on the follower arm 24, the latch bolt lath 14 will be moved by the follower arm back to the position in which the inner end of the latch bolt 21 is bounded by the inner forend 2.

It will thus be seen that the latch bolt 21 can easily be reversed without even having to take the casing 1 out of a door in which the latch has been installed because the means for allowing latch bolt reversal are accessible from the inner forend 2.

The latch according to the invention may also be provided with a dead bolt which, in the drawings, is shown in the thrown position. The dead bolt 35 can be operated by means of a key (not shown) which can be inserted into a key hole 36 and, when turned, will act on spring-loaded detainers 37 to move the dead bolt from the thrown to the retracted or withdrawn position and vice versa.

The invention is not restricted to the above-described embodiment but modifications and variations may be made without departing from the scope of the invention. For example, the latch may be provided with a cylinder lock instead of a detainer lock.

Claims

CLAIMS

1. A latch comprising a casing, a latch bolt, a latch bolt lath mounted in the casing, a follower arranged to act on the latch bolt lath and a spring arranged to act on the follower, wherein the latch bolt is rotatably mounted on the latch bolt lath and is nonnally urged by the spring to a position in which it partially projects from the casing and wherein a block is slidably mounted in the casing and is normally engaged by an ann of the follower, said block being movable to a position in which the follower can be moved under the spring action to a position in which it moves the latch bolt lath to a position in which it allows the latch bolt to be moved to a position in which it projects entirely from the casing and can be rotated with respect to said casing to reverse said latch bolt.

2. A latch according to claim I, wherein the spring is mounted wholly within the casing.

3. A latch according to claim I or claim 2, wherein the spring takes the form of a coil spring.

I I..

4. A latch according to any one of the preceding claims, wherein the spring is arranged to act on a toothed rack the teeth of which are engageable with a toothed portion of the follower.

5. A latch according to any one of the preceding claims, wherein the latch bolt lath is provided with an upstand and wherein the follower arm is arranged to engage with the upstand.

6. A latch according to any one of the preceding claims, wherein the block is mounted on a guide for sliding movement in the casing and the sliding movement of the block is achieved by a captive screw which is engageable in a screw-thread in the block whereby turning the screw is effective to move the sliding block along the guide in the casing.

7 A latch according to claim 6, wherein the screw is accessible from the front of the casing.

8. A latch according to claim 7, wherein the latch is provided with an inner forend adapted to be secured to the front of the casing and having a bore through which the head of the screw for moving the sliding block is accessible.

9. A latch according to claim 8, wherein the latch is provided with an outer forend adapted to be secured to the inner forend to cover the said bore in the inner forend. S.,. * U *.

JO. A latch substantially as described herein with reference to the drawings.

U * *. * * S ** S S..