GB2093904A - Reversible latch bolt assembly for a closure - Google Patents

Abstract

A latch bolt 13 is mounted in a casing 10 for movement between relatively extended and retracted positions, in both of which a tongue 14 of rectangular cross-section extends through a corresponding rectangular aperture 12 in the casing front wall. A tail portion of the latch bolt 13 is rotatably received in a collar 32 and is normally keyed for movement therewith, but can be released for limited axial movement relative to the collar 32 by depressing an operating plate 36. Such limited axial movement relative to the collar 32 causes the tongue 14 of the latch bolt 13 to extend right out of the aperture 12, enabling the bolt 13 to be rotated through 180 DEG whereupon its tongue 14 can be returned into the aperture 12. The hand of the latch bolt assembly can thus be changed with the minimum of effort and inconvenience. <IMAGE>

Description

SPECIFICATION Reversible latch bolt assembly for a closure This invention relates to a reversible latch bolt assembly for use with a closure, such as a door.

It is well known that latch bolt assemblies can be of two distinct types according to whether the closure for which it is intended is hinged on its left side or its right side, and also according to whether the closure opens inwardly or outwardly.

Such latch bolt assemblies are commonly referred to as being of "left-hand" and "right-hand" construction, the hand of the assembly being determined by the need for the tongue of the latch bolt to have its chamfered surface facing in the direction in which the closure is closed.

Conventionally, it has been necessary either to provide two completely different constructions of latch bolt assembly to cater for left- and righthand operation respectively, or to produce a single construction of a given hand which can be converted to the opposite hand where necessary, often with the incorporation of additional components. It would be highly advantageous to provide a latch bolt assembly which could readily be interchanged between left-and right-hand operation, but to date no such assembly has been proposed.

It is an object of the present invention to remedy this deficiency.

According to the present invention a reversible latch bolt assembly comprises a casing, a latch bolt movable relative to the casing between relatively extended and retracted positions, means holding the latch bolt for rotation relative to the casing about an axis parallel to the direction of its extension and retraction, and retaining means operable to retain the latch bolt against such rotation in each of two positions which are 1800 opposed.

In this way, the hand of the assembly can easily be changed by releasing the latch bolt and rotating it through 1800 so that a chamfered tongue thereof faces in the opposite direction.

In a preferred construction, the latch bolt has a part which is non-circular in transverse crosssection and which normally locates in a corresponding non-circular aperture in the casing, and the retaining means when released allows the latch bolt to be moved axially to disengage said part thereof from the aperture and thereby permit the latch bolt to be rotated. The non-circular part may be formed by a tongue of the latch bolt, while the non-circular aperture may be provided in a front plate of the casing. Biassing means can be provided to urge the latch bolt into an axial position wherein its non-circular part is disengaged from the non-circular aperture, and the retaining means is operative to hold the latch bolt axially against the action of the biassing means.

Conveniently, the means holding the latch bolt comprises a collar which is mounted in the casing for movement relative thereto in the direction of extension and retraction of the latch bolt, the latch, bolt being rotatably received in the interior of the collar for movement therewith but being releasable for limited axial movement relative to the collar.

Desirably, the retaining means includes an operating member which is received in the collar for movement relative thereto in a direction transverse to the rotation axis of the latch bolt, the operating member being movable between a first position wherein it holds the latch bolt against axial movement relative to the collar and a second position wherein it releases the latch bolt for limited axial movement with respect to the collar.

The operating member is preferably biassed into its first position, and the latch bolt after said limited axial movement with respect to the collar may hold the operating member in its second position. In addition, arrangement can be made for the operating member when in its second position to engage a fixed abutment on the casing and thereby hold the collar against movement relative to the latter.

Advantageously, the part of the latch bolt received in the collar has two axially adjacent portions having transverse cross-sections of different sizes, and the operating member has an opening therein through which the latch bolt passes, the opening being configured to permit the portion of the latch bolt of larger cross-section to pass therethrough only when the operating member is in its second position.

The latch bolt assembly may also comprise a manually operable handle and a rotatable cam operatively coupled to the handle for movement therewith, the cam being engaged with said collar.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of a latch bolt assembly according to the present invention; Figure 2 is a sectional plan view of the latch bolt assembly; Figure 3 is a similar view to Figure 2 but showing a latch bolt of the assembly in a position wherein it can be reversed; Figure 4 is a section taken along the line IV--IV in Figure 2; Figure 5 is an underneath plan view of a component of a collar which forms part of the latch bolt assembly; and Figure 6 is a section taken along the line VI--VI in Figure 5.

Referring first to Figure 1, the illustrated assembly comprises a casing 10 which in use is mortised into an edge of a closure, such as a door, the casing having a front or facia plate 11 in which is formed a rectangular aperture 12. A latch bolt 13 is slidably mounted in the casing 10 for movement relative thereto between an extended position (as shown) wherein a chamfered tongue 14 thereof extends outwardly from the facia plate 11, and a retracted position wherein a tip of the tongue 14 lies substantially flush with the plate 11. In the extended position of the latch bolt 13, a base portion 1 5 of the chamfered tongue 1 4 (which is of rectangular transverse cross-section) locates within the aperture 12.

The latch bolt 13 is guided in its sliding movement by means of a circular shank 1 6 thereof which slidably passed through an opening in a fixed bridge plate 1 7 housed within the casing 10, by means of a lug 1 8 (shown in broken line) which slides along an elongate slot 1 9 in one side wall of the casing, and by means of a tab 20 which slides along a further eiongate slot 21 (shown in chain-dotted line) in the opposite side wall of the casing. A compression spring 22 engaged between the tongue base portion 1 5 and the fixed bridge plate 1 7 urges the latch bolt 13 into its extended position.The latch bolt is extended and retracted by suitable manual operation of a handle (now shown) provided on the closure, a rotatable cam 23 being keyed to the handle for movement therewith and having a lobe 24 which engages the latch bolt. A tension spring 25 connected between a pin 26 on the cam 23 and a fixed pin 27 on the casing 10 biasses the cam in an anticlockwise direction into the position shown, wherein a lug 28 thereon abuts against the fixed pin 27.

Referring now also to Figures 2, 3 and 4, at an end thereof remote from the tongue 14, the latch bolt shank 1 6 has a portion 29 of comparatively small diameter and a portion 30 of comparatively large diameter which define therebetween a forwardly-facing annular shoulder 31. A collar 32 is mounted around the portions 29, 30 and has a stepped internal bore 33 along which the portion 30 can slide, the stepped bore defining an annular shoulder 34 which confronts the shoulder 31. A slot 35 extends through the collar 32 perpendicularly to the bore 33 and slidably accommodates an operating or retaining plate 36, one end of the plate 36 forming the abovementioned tab 20.The plate 36 has a circular opening 37 therein through which the latch bolt shank passes, and is movable between a first position (shown in Figures 2 and 4) wherein the opening 37 is disposed eccentrically with respect to the bolt shank, and a second position (shown in Figure 3) wherein it is disposed generally coaxially therewith. A pair of springs 38 (see Figure 4) housed within the collar 32 act on respective laterally extending arms 39 of the plate 36 and thereby urge the latter into its aforementioned first position. From Figure 2 it will be seen that the tab 20 stands proud of the casing exterior when the plate 36 is in its first position, while from Figure 3 it will be seen that a chamfered tab 40 at the opposite end of the plate 36 extends into a slot 41 in the casing side wall when the plate is in its second position.

The collar 32 is constructed from two identical halves which rotatably embrace the shank of the latch bolt, one of the halves being shown in detail in Figures 5 and 6. Each half has a transverse bore 42 extending therethrough at a position offset from the bore 33, and an upstanding pin 43 at a symmetrically opposite position with respect to the bore 42. The two halves are secured together by inserting the pin 43 on each half through the bore 42 in the other and then peening over its end.

Shown at 44 are blind bores which, in one of the halves only, accommodate the aforementioned springs 38.

During normal operation of the assembly, the latch bolt 13 is keyed to the collar 32 for movement therewith on the one hand by abutment of the plate 36 with the shoulder 31 and on the other hand by abutment of a shoulder 45 on the bolt shank with a front surface of the collar 32, as shown in Figure 2. At this time, although the bolt shank is capable of rotation, relative to the collar 32, such rotation is prevented by engagement of the tongue base portion 1 5 with the rectangular aperture 1 2 in the casing facia plate 11. The above-described engagements can however be released in order to enable the latch bolt to be reversed as follows.

When it is desired to change the hand of the latch bolt assembly, the tab 20 is depressed so as to move the plate 36 into its aforementioned second position, wherein the opening 37 therein becomes aligned with the large diameter portion 30 of the bolt shank. The force of the compression spring 22 then causes the portion 30 to pass through the opening 37 and thereby bring the shoulder 31 into abutment with the shoulder 34 on the collar 32, as shown in Figure 3. Since the opening 37 is substantially the same size as the external cross-section of the portion 30, this action serves to maintain the plate 36 in its second position against the action of the springs 38.The resultant axial extension of the latch bolt causes the base portion 1 5 of the tongue 14 to disengage from the rectangular aperture 12, so that the bolt may now be twisted through 1 80O to turn the tongue 14 so that its chamfered surface faces in the opposite direction.

Once the base portion 1 5 has been re-aligned with the rectangular aperture 12, the tongue 14 can be pressed to return the latch bolt to its original axial position. As the shoulder 31 on the bolt shank clears the opening 37 in the plate 36, the springs 38urge the latter back into its first position, whereupon the latch bolt is once again keyed against movement relative to the collar 32.

It will be appreciated that when the tongue 14 is pressed during the above operation, the latch bolt will not retract into the casing 10 because of the interengagement between the tab 40 and the slot 41. However, when the plate 36 returns to its first position as aforesaid, the tab 40 disengages from the slot 41 and thus releases the latch bolt for retraction into the casing when required.

The construction described above thus allows the hand of the latch bolt assembly to be set as desired according to requirements, and obviates the need to provide separate and distinct constructions from left- and right-hand operation.

Moreover, the hand of the assembly can be reversed by means of a simple sequence of operations, namely by depressing the tab 20, twisting the tongue 14 and then pressing the tongue back into the opening in the casing facia plate. It will be noted that the tongue is automatically extended from the opening 1 2 when the tab 20 is depressed, and that the tab 20 is automatically re-set when the tongue is pressed back into the opening.

Claims (11)

1. A reversible latch bolt assembly comprising a casing, a latch bolt movable relative to the casing between relatively extended and retracted positions, means holding the latch bolt for rotation relative to the casing about an axis parallel to the direction of its extension and retraction, and retaining means operable to retain the latch bolt against such rotation in each of two positions which are 1800 opposed.

2. An assembly as claimed in Claim 1, wherein the latch bolt has a part which is non-circular in transverse cross-section and which normally locates in a corresponding non-circular aperture in the casing, and the retaining means when released allows the latch bolt to be moved axially to disengage said part thereof from the aperture and thereby permit the latch bolt to be rotated.

3. An assembly as claimed in Claim 2, wherein the non-circular part is a tongue of the latch bolt, and the non-circular aperture is provided in a front plate of the casing.

4. An assembly as claimed in Claim 2 or 3, wherein biassing means urges the latch bolt into an axial position wherein its non-circular part is disengaged from the non-circular aperture, and the retaining means is operative to hold the latch bolt axially against the action of the biassing means.

5. An assembly as claimed in any preceding Claim, wherein the means holding the latch bolt comprises a collar which is mounted in the casing for movement relative thereto in the direction of extension and retraction of the latch bolt, the latch bolt being rotatably received in the interior of the collar for movement therewith but being releasable for limited axial movement relative to the collar.

6. An assembly as claimed in Claim 5, wherein the retaining means includes an operating member which is received in the collarfor movement relative thereto in a direction transverse to the rotation axis of the latch bolt, the operating member being movable between a first position wherein it holds the latch bolt against axial movement relative to the collar and a second position wherein it releases the latch bolt for limited axial movement with respect to the collar.

7. An assembly as claimed in Claim 6, wherein the operating member is biassed into its first position.

8. An assembly as claimed in Claim 6 or 7, wherein the latch bolt after said limited axial movement with respect to the collar holds, the operating member in its second position.

9. An assembly as claimed in Claim 6, 7 or 8, wherein the operating member when in its second position engages a fixed abutment on the casing to hold the collar against movement relative thereto.

10. An assembly as claimed in any one of Ciaims 6 to 9, wherein a part of the latch bolt received in the collar has two axially adjacent portions having transverse cross-sections of different sizes, and the operating member has an opening therein through which the latch bolt passes, the opening being configured to permit the portion of the latch bolt of larger cross-section to pass therethrough only when the operating member is in its second position.

11. An assembly as claimed in any one of claims 5 to 10, further comprising a manually operable handle and a rotatable cam operatively coupled to the handle for movement therewith, the cam being engaged with said collar.

1 2. A reversible latch bolt assembly substantially as hereinbefore described with reference to the accompanying drawings.