WO2002070845A1

WO2002070845A1 - Improvements in mortice latches

Info

Publication number: WO2002070845A1
Application number: PCT/GB2002/000917
Authority: WO
Inventors: Colin Sidney Middleton
Original assignee: Carlisle Brass Limited
Priority date: 2001-03-06
Filing date: 2002-03-05
Publication date: 2002-09-12
Also published as: EP1366257A1; NZ527816A; DE60203601D1; HK1062468A1; GB0105521D0; DE60203601T2; ZA200306788B; PT1366257E; EP1366257B1; AU2002236047B2; ATE292726T1; ES2240692T3

Abstract

A latch having a casing (1, 2) in which is linearly movable a latch bolt head (5) mounted on a spindle (6) with first and second coil springs (18, 15) thereon to urge the latch bolt head (5) to project at least partially form one end (4) of the casing (1). The casing includes a pair of aligned slots (2a, 20) through which may pass a tool (41) which engages the spindle (6) and moves it linearly to move the bolt head (5) out of the casing sufficiently to enable it to be reversed by rotating it through 180 degrees.

Description

IMPROVEMENTS IN MORTICE LATCHES

This invention relates to mortice latches and is particularly concerned with improvements in the latch bolt heads of mortice latches.

A problem with existing mortice latches is that the bolt head which is usually tapered can only be fitted to a door which is either left hand or right hand hung but not to both. The conventional way of overcoming this problem is to provide mixed hands of locks in each box. This is not very satisfactory because a prospective purchaser often does not know which hand is needed.

It is possible to solve the problem by opening the latch casing and changing the latch bolt head over. This operation is not, however, easy, especially on site, entailing disengagement of the latch bolt lathe from the follower spring before the latch bolt head can be reversed. This is not only difficult to achieve, there is also the risk of components falling out of the open latch casing with possible loss of these components. At best, re-assembly is intricate and time-consuming.

The present invention aims to solve the problem by providing a mortice latch in which the bolt head can be reversed without the necessity to open the latch casing. According to the invention, there is provided a latch having a casing and a latch bolt head which is linearly movable in the casing and which is urged by a spring to project at least partially from an end wall of

the casing, wherein the latch bolt head is mounted on a spindle which is axially movably mounted in the casing; characterised in that the casing includes an aperture to permit a tool to be inserted into the casing; in that the aperture is so disposed in the casing that the tool, when inserted into the aperture, engages with the spindle; and in that engagement of the spindle by the tool is effective to move the bolt head out of the casing so as to be free therefrom and so that the bolt head can be reversed by rotating it through 180 degrees.

Preferably, the casing comprises a main body and a cover plate extending substantially parallel to the main body, the cover plate being provided with an aperture aligned with said aperture in the casing to permit said tool to be inserted into one of the apertures, passing through the casing and out through the other aperture.

Preferably, the spring is mounted on the spindle, the spring taking the form of a coil spring bearing at one end against the bolt head and, at the other end, against a guide mounted in the casing and through which the spindle extends. According to a preferred embodiment of the invention, a second spring is mounted on the spindle and is arranged to bear at one end against a collar provided on the spindle adjacent the end which is remote from the bolt head and, at the other end, against a link to a follower which is mounted in the casing.

The second spring should be heavier than the first- mentioned spring and normally urges the follower link against the guide.

The tool preferably takes the form of a wedging tool having an inclined surface which is engageable with the end of the spindle remote from the latch bolt head and which progressively moves the bolt head out of the casing as said wedging tool is passed through the casing and the aligned apertures.

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 part of a mortice latch according to the invention with the casing cover plate removed to show the internal components;

Fig. 2 is a section taken on the line II-II in Fig. 1; Fig. 3 is an exploded perspective view of components of the mortice latch shown in Figs. 1 and 2;

Fig. 4 is a section, similar to Fig. 2, but showing a wedging tool partially inserted into the casing; and

Fig. 5 is a section, similar to Fig. 4, but showing the wedging tool fully inserted into the casing.

In the drawings, like parts are denoted by like reference numerals.

Referring now to the drawings, a latch according to the invention comprises a casing 1 to one side of which is mounted an inner fore-end 3 and an outer fore-end 4. The casing is arranged to be closed by a cover plate 2 having an elongated aperture 2a therein. A latch bolt assembly is reciprocally mounted in the casing and comprises a latch bolt head 5 secured to a latch bolt spindle 6 by a cross pin 7 which engages in aligned bores 5a and 6a in the latch bolt head 5 and latch bolt spindle 6 respectively. The latch bolt head 5 is urged by a spring 8 to project through apertures in the fore-ends 3, 4 under normal conditions, the spring bearing at one end on the latch bolt head 5 and at the other end against a latch bolt spindle guide 10, a washer 9 being interposed between the spring 8 and guide 10. The spring 8 takes the form of a coil spring which is mounted on the spindle 6. The guide 10 is fixedly mounted in the casing 1 and has a cut out region 10a through which the spindle 6 extends. A substantially U-shaped link 11 is slidably mounted in the casing, the link being guided for sliding movement by a guide pin 12 which is secured to one arm of the link 11 and extends into a slot 20 in the wall of the casing 1. The purpose of the slot is not only to guide sliding movement of the link 11 but also to limit the extent of movement of the link. The slot 20 in the casing 1 is aligned with the elongated aperture 2 a in the cover plate 2, when the cover place is fitted to the casing, for a

purpose to be hereinafter described.

The latch bolt spindle 6 extends through an aperture 13 in the web of the U-shaped link 11 and a coil spring 15 mounted on the spindle 6 bears at one end against the web of the U-shaped link 11 and at the other end against a collar 6b provided on the spindle 6 adjacent the end remote from the bore 6a.

A follower core 16 is pivotally mounted in the casing, said follower core having a square- sectioned bore for the reception of a square- sectioned spindle of a latch handle (not shown). The follower core 16 is located in the casing below the link 11 and is provided on one side with a shoulder projection 19. The follower core 16 further has a circular upstand 17 on each side surrounding the square- sectioned bore, said up stands bearing against raised flanges on the casing 1 and cover plate 2 to form a wide journal. An ear 18 extends radially outwards from each of the upstands 17. An inner follower arm 21 having a circular aperture 22 and a notch 23 extending radially therefrom is mounted on one of the upstands 17 with the ear 18 engaging in the notch 23 and a similar outer follower arm 24 having a circular aperture 25 and a notch 26 extending radially therefrom is mounted on the other upstand 17 this time with the ear 18 engaging in the notch 26. In the assembled condition of the latch, the arms 21 and 24 straddle the spindle 6 and press against both legs of the U-shaped link 11.

The link 11 is provided with a peg 14 for locating one end of a follower spring 27. The spring 27 takes the form of a coil spring which is mounted on a guide in the form of a rod 28 having a head 29 from which bayonet prongs 30 extend radially outwardly therefrom. The outer surface of the head 29 is provided with slots 31 for engagement by a screw-driver or like implement.

A spring retainer control plate 32 is mounted in the casing and has a circular aperture 33 from which slots 34 extend radially outwards. The guide 28 with the spring mounted thereon can be inserted into the casing, through an aperture in the wall of the casing which is aligned with the aperture 33 in the plate 32, and through said aperture 33 with the bayonet prongs 30 aligned with the slots 34 so that the prongs can pass through the plate 32. The end of the spring 27 is located on the peg 14 on the link 11 and the spring is then compressed by engaging the slotted head 29 of the guide 28 with a screw-driver or similar tool which

then turns the head 29 until the prongs 30 are no longer aligned with the slot 34. The screw-driver or similar tool can then be disengaged from the head 29 whereupon the spring 27 will re-exert itself and force the prongs

30 against the plate 32. At the same time, the spring 27 will force the arms of the link 11 against the follower arms 21 and 24 which in turn act on the follower core 16 to force the shoulder projection 19 on the follower core against a screw column 35 mounted in the casing 1.

In this manner handles (not shown) mounted on the ends of a square-sectioned spindle extending through the bore in the follower core 16 will be maintained in a substantially horizontal position by the spring 27. Turning of one of the handles is effective to cause the follower core 16 to pivot in a clockwise direction as viewed in Fig. 1 which causes the follower arms 21 and 24 to move the link 11 to the right as viewed in Fig. 1 compressing the spring 27. At the same time, the web of the link 11 acts on the spring 15 and is effective to move the spindle 6 to the right as viewed in Fig. 1. This has the effect of moving the latch bolt head 5 to the right and of compressing the latch bolt return spring 8. The latch bolt head 5 is thereby retracted into the casing and the door or other openable member in which the latch is installed can be opened. If the handle is now released, the springs 8, 15 and 27 re-exert themselves and force the latch bolt head 5 once more to project from the fore ends 3 and 4. The spring 8 can be a fairly light spring since it is merely needed to return the latch bolt head 5 to the position in which is projects from the fore ends 3 and 4. The spring 15 should be fairly heavy since it is required to transmit the movement of the link 11 to the spindle 6. The

force of the spring 27 can be chosen to match the handles. If light or sprung handles are used, the spring 27 can be quite light but, if heavy or unsprung handles are used, the spring 27 should be heavy.

The latch as shown in Figs. 1 to 3 of the drawings is intended for a left hung door. If the latch is to be used for a right hung door, a wedging tool 41 is inserted through the aperture 2 a in the cover plate 2, passes through the casing 1 and emerges from the other side of the casing through the slot 20 as shown in Fig. 4. The wedging tool comprises first and second portions 43 and 44 of different but uniform widths interposed by a portion of increasing width thus to define an inclined surface 42 and, as the tool is moved further through the casing, the inclined surface 42 bears against the end of the spindle 6 to move the spindle to the left as shown in Fig. 5 of the drawings, against the force of the spring 25, until the latch bolt head 5 is moved clear of the outer fore end 4. The spindle 6 can be rotated through 180° to reverse the bolt head 5. The wedging tool 41 can be withdrawn from the casing and, as the inclined surface 42 moves out of the casing, the spring 15 will re-exert itself and, acting on the collar 6b on the spindle 6, will cause the bolt head 5 to move back into the apertures in the fore ends 3 and 4 to the position shown in Figs. 1, 2 and 4 of the drawings.

It will thus be seen that, by means of the wedging tool, the latch bolt head can readily be reversed without having to open the casing.

The wedging tool may be made of any described material but since it will normally not be required once the latch has been fitted, it should normally be made of a cheap material which is readily disposable. It is envisaged that the tool will take the form of a plastics moulding although other materials such as wood or metal may be used if desired. It may also be possible to make the wedging tool from thick, stiff cardboard materials.

The wedging tool preferably has substantially flat sides which may carry advertising material which may be applied directly, such as by printing or engraving, to the sides of the tool or the advertising material may take the form of labels which are adhered to the substantially flat sides of the tool.

The latch according to the invention may, if desired, also be provided with a dead bolt assembly. Dead bolt assemblies which could be used with the mortice latch according to the present invention are disclosed in European Patent Specifications Nos. 0 848 125 and 0 354 634.

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, instead of being substantially planar, the end of the wedging tool may be provided with a concave surface so that the tool could be used, for example, as a golf tee when no longer required for reversing the latch bolt head. According to another embodiment, it is necessary to remove the outer fore end 4 before the latch bolt head 5 can be reversed. Further, while the latch according to the invention is primarily intended for use in doors, it is not restricted to this use and can be used in conjunction with other openable members such as windows or hatch covers.

Claims

1. A latch having a casing and a latch bolt head which is linearly movable in the casing and which is urged by a spring to project at least partially from an end wall of the casing, wherein the latch bolt head is mounted on a spindle which is axially movably mounted in the casing; characterised in that the casing includes an aperture to permit a tool to be inserted into the casing; in that the aperture is so disposed in the casing that the tool, when inserted into the aperture, engages with the spindle; and in that engagement of the spindle by the tool is effective to move the bolt head out of the casing so as to be free therefrom and so that the bolt head can be reversed by rotating it through 180 degrees.

2. A latch according to Claim 1 , wherein the casing comprises a main body and a cover plate extending substantially parallel to the main body, the cover plate being provided with an aperture aligned with said aperture in the casing to permit said tool to be inserted into one of the apertures, passing through the casing and out through the other aperture.

3. A latch according to Claim 1 or Claim 2, wherein the spring is mounted on the spindle and takes the form of a coil spring bearing at one end against the bolt head and, at the other end, against a guide mounted in the casing and through which the spindle extends.

4. A latch according to any preceding claim, including a second spring mounted on the spindle and arranged to bear at one end against a collar provided on the spindle adjacent the end thereof which is remote from the bolt head and, at the other end, against a link to a follower which is mounted in the casing.

5. A latch according to Claims 3 and 4, wherein the second spring is heavier (stronger) than the first mentioned spring and urges the follower link against the guide.

6. A latch according to Claim 2, wherein the tool takes the form of a wedging tool having an inclined surface which is engageable with the end of the spindle remote from the latch bolt head and which progressively moves the bolt head out of the casing as the wedging tool is passed through the casing and the aligned apertures.

7. A latch according to Claim 6, wherein the wedging tool comprises first and second portions having different but uniform widths interposed by a portion of increasing width thus to define said inclined surface.

8. A latch according to Claim 6, wherein the wedging tool has substantially flat sides and said apertures are formed as elongate slots.

9. A latch according to any preceding claim, wherein said end wall of the casing comprises an inner fore end and an outer fore end, the latter being removably attached to the former and requiring removal to enable the bolt head and spindle to be rotated.