GB2255798A

GB2255798A - Latch furniture assembly

Info

Publication number: GB2255798A
Application number: GB9208333A
Authority: GB
Inventors: Roy Carter
Original assignee: Marston & Co Ltd Albert
Current assignee: Marston & Co Ltd Albert
Priority date: 1991-05-16
Filing date: 1992-04-15
Publication date: 1992-11-18
Also published as: GB9208333D0

Abstract

A latch furniture assembly has opposite handles 5, 6 connected through a spindle 3 to a morticed latch bolt unit 1. The latch bolt follower 2 has the usual square-sectioned bore 4 for turning the follower to withdraw the bolt. The assembly of handles and spindle is axially displaceable relative to the latch bolt unit and is biased by a spring 21 to a rest position. In the rest position a central circular portion 26 of the spindle 3 lies within the follower bore 4 so that turning either handle is ineffective to turn the follower and retract the bolt. By pushing or pulling the respective handle 5 or 6 against the spring bias, however, a square-sectioned end portion 24 of the spindle can be engaged in the follower to turn the same. This action will cause little impediment or inconvenience to the average person but may suffice to prevent opening of a door by the confused or infirm and is therefore useful to provide a degree of control over the unsupervised egress of such persons e.g. in a residential institution. A screw device 37 is employed to adjust the position of the handle relative to the spindle. <IMAGE>

Description

Latch Furniture Assembly The present invention relates to a latch furniture assembly for a door or other closure member where a latch bolt is to be withdrawn by turning a handle and where it is required that some additional manipulative action is performed before the bolt can be withdrawn, but without requiring the possession of a key or any other such separate implement or even the manipulation of an associated device (such as a locking snib) additional to the handle. An assembly of this kind may in particular be of use on doors in a residential institution for the elderly or mentally deficient where a degree of control is required regarding the ability of vulnerable residents to leave a room or building on their own but without causing any significant impediment to the opening of the doors by their attendants.

Accordingly the present invention resides in a latch furniture assembly for use in conjunction with a latch bolt unit adapted to be mounted to a door or other closure member, comprising: a turnable handle adapted to be linked to a latch bolt unit for withdrawing the bolt; a spindle extending from the handle such as to pass into the non-circular bore of a bolt-withdrawing follower in the latch bolt unit; a first axial portion of said spindle being of non-circular cross-section so as to transmit turning movement of the handle to the follower when said portion is received in said bore while a second axial portion of said spindle is configured to be rotatable within said bore without transmitting turning movement to the follower; the handle and spindle being borne for limited axial movement relative to the latch bolt unit and being biased to a first position in which said second axial portion of the spindle is received within said bore but being manually displaceable against said bias to a second position in which said first axial portion of the spindle is received within said bore.

In this way, the handle is normally biased axially to a position in which it is rotatably uncoupled from the latch bolt unit, by virtue of the non-transmitting second spindle portion being received within the follower bore, but this can be overcome to withdraw the bolt by first pushing the handle in or pulling it out as the case may be, so that the first spindle portion is then received in the follower bore and the handle thus becomes coupled to transmit its turning movement. This is a simple action for the average person to perform but may be sufficient to prevent opening of a door or the like by those who may be confused or infirm.

The invention will now be more particularly described, by way of example with reference to the accompanying drawings, in which: Figure 1 is a section through a preferred embodiment of a latch furniture assembly in accordance with the invention, shown mounted to a door and in its normal (uncoupled) condition; Figure 2 is a side view of part of one of the handles of the assembly of Figure 1; Figure 3 is a view similar to Figure 1 showing the assembly in its coupled condition; Figure 4 is a view similar to Figure 1 showing the furniture assembly in the course of fitting to the door; Figure 5A is a side view of the spindle assembly used in this furniture assembly; Figure 5B is a side view of one of the adjustable fixing screws used in the spindle assembly; and Figure 5C is a section through one end of the spindle prior to its assembly with the respective adjustable fixing screw.

Referring to Figure 1, the illustrated furniture assembly is shown together with a latch bolt unit 1 of conventional form morticed into a door D. The unit 1 comprises a spring-biased latch bolt 8 (Figure 2) which normally extends into a keeper in the door frame when the door is closed, and a rotatable follower 2 for withdrawing the same. A specially configured spindle 3 passes through the square-sectioned bore 4 of follower 2 with freedom to slide axially therein, and is received at opposite sides of the door in square-sectioned drive sockets of respective lever handles 5 and 6, the drive socket 7 of handle 5 only being seen in the Figure.The spindle is secured relative to each handle by a respective co-axial screw 37,38 so that the assembly of handles and spindle will turn and slide as one, the screws 37,38 being adjustable in such manner as to accommodate variations in door thickness and position of lock relative to door centreline as will be more fully described hereinafter.

Each handle 5,6 has a spigot 9,10 which passes through an aperture 11,12 in respective channel-section furniture plates 13,14 attached to the opposite sides of the door.

Beneath each furniture plate 13,14 the respective handle spigot 9,10 carries a respective stop plate 15,16 as a sliding fit, but constrained to turn therewith and retained by a circlip 17,18. Return springs 19,20 trapped beneath the furniture plates 13,14 act on the stop plates 15,16 to bias the two handles to their horizontal position corresponding to extension of the latch bolt 8.

Furthermore, a coil spring 21 trapped between the latch bolt unit 1 and the distal end of the handle spigot 9 biases the handle/spindle assembly 3/5/6 to the left in the sense as viewed in Figure 1, to the limit permitted by the abutment of a washer 22 held slidably on the spigot 9 with the inside face of the furniture plate 13 and of a washer 23 on the handle 6 with the outside face of the furniture plate 14.

As will be seen also in Figure 5A, the spindle 3 is formed from a length of square-sectioned bar, with respective end portions 24,25 to be received partially in the respective drive sockets of handles 5,6 and which are of a complementary section to the bore 4 of the latch bolt follower 2. A central portion 26 of the spindle is however machined down to a circular section and has an axial length slightly greater than that of the follower bore 4. In the condition of Figure 1, to which the spindle 3 is biased by the spring 21, it will be seen that the central circular portion 26 of the spindle lies through the whole length of the follower bore 4, and is rotatable therein without transmitting any drive to the follower. If either handle 5 or 6 is turned in this condition, therefore, it will be ineffecctive to withdraw the latch bolt.In order to couple the spindle 3 to the follower 2 for turning the same, the handle 5 first must be pushed in or the handle 6 pulled out, as the case may be, which is permitted by the clearance between a washer 27 on the handle 5 and the outside face of the furniture plate 13 and between the circlip 18 and stop plate 16 of the handle 6. As will be seen from Figure 3, this action is effective to engage the square-sectioned spindle portion 24 partially into the complementary follower bore 4 so that turning of either handle 5 or 6 will now turn the follower 2 and the latch bolt can accordingly be withdrawn. After the door has been opened and the handles return to their horizontal position under the action of springs 19 and 20, the assembly will automatically return to the uncoupled condition of Figure 1 under the action of the spring 21.

It will be appreciated that a definite push or pull action is required the handle 5 or 6 before it can be rendered effective to unlatch the door. Preferably the assembly is mounted such that this initial action is in the opposite sense to that which is required to open the door once unlatched, i.e. so that handle 5 is on the inside in the case of an inwardly opening door and so that handle 6 is on the inside in the case of an outwardly opening door.

Whilst causing little impediment or inconvenience to operation by the average person, this may suffice to prevent the unsupervised egress of the confused or infirm.

Returning to the method of fixing the spindle 3 to the handles 5,6, the respective screw 37,38 is held captive in each end portion 24,25 of the spindle and received in tapped bores 39,40 (Figure 1) formed in the shanks of the handles coaxial with their spigots 9,10. The spindle assembly is itself constructed by drilling each end portion of the spindle, as at 41 in Figure 5C, to receive a screw 37 or 38 as a sliding and rotating fit, and crimping those end portions into the necks 42 of the screws, as at 43 and 44 in Figures 1 and 5A, to retain the screws axially but freely rotatable with respect to the spindle.

On fitting of the furniture to the door D, in which the latch bolt unit 1 has already been mounted, the spindle assembly is first assembled with handle 5, together with its furniture plate 13 and associated return spring 19 and stop plate 15. For this purpose, the slotted end of the screw 37 is offered through the spigot 9 to the inner end of the handle bore 39, and a thin-bladed screwdriver is passed through the handle bore to turn the screw 37 anticlockwise, thus drawing it into the bore 39 and bringing the end portion 24 of the spindle into the drive socket 7 of the handle. When the spindle is approximately in the correct position the bias spring 21 is added and the furniture and spindle assembly is positioned onto the door as in Figure 4.The furniture plate 13 is fixed to the door surface in conventional fashion and the screwdirver used to adjust the screw 37 in the handle 5 to finally set the position of the spindle with its central machined-down portion 26 in register with the latch bolt follower bore 4, (that is with the handle 5 biased away from the latch bolt unit by the spring 21). The other handle 6, together with its furniture plate 14 and associated return spring 20 and stop plate 16, can now be added. For this purpose, the inner end of the handle bore 40 is offered to the slotted end of the screw 38 and the screwdriver blade (seen at 45 in Figure 4) is passed through the handle bore and turns the screw 38 anti-clockwise to draw the handle onto the end portion 25 of the sprindle. This is continued until the furniture plate 14 comes up against the door surface, (that is with the handle washer 23 up against the furniture plate), and the latter is fixed to the door to complete the assembly. By virtue of the variable-depth engagement of the spindle ends 24,25 into the respective handle drive sockets which the screws 37,38 allow, the same furniture assembly can be fitted to a range of doors of different thicknesses and also compensate for variations in the position of the bolt unit 1 from the centreline of a door.

Claims

1. A latch furniture assembly for use in conjunction with a latch bolt unit adapted to be mounted to a door or other closure member, comprising: a turnable handle adapted to be linked to a latch bolt unit for withdrawing the bolt; a spindle extending from the handle such as to pass into the non-circular bore of a bolt-withdrawing follower in the latch bolt unit; a first axial portion of said spindle being of non-circular cross-section so as to transmit turning movement of the handle to the follower when said portion is received in said bore while a second axial portion of said spindle is configured to be rotatable within said bore without transmitting turning movement to the follower; the handle and spindle being borne for limited axial movement relative to the latch bolt unit and being biased to a first position in which said second axial portion of the spindle is received within said bore but being manually displaceable against said bias to a second position in which said first axial portion of the spindle is received within said bore.

2. An assembly according to claim 1 wherein said first axial portion of the spindle is of square cross-section while said second axial portion of the spindle is of circular cross-section with a diameter not greater than the length of one side of said square.

3. An assembly according to claim 1 or claim 2 wherein said handle has a shank portion borne by a furniture plate beneath which is housed a spring for biasing the handle to a predetermined rotary position, stop means being borne upon said shank beneath the furniture plate for defining the limits of turning movement of the handle by abutment with said plate, said stop means being borne upon said shank to turn therewith but such as to permit axial movement of the shank relative thereto.

4. An assembly according to any preceding claim wherein the handle and spindle are biased axially to said first position by means of a compression spring surrounding the spindle and compressed between the handle and latch bolt unit.

5. An assembly according to any preceding claim wherein said spindle has an end portion of non-circular crosssection which is received within a socket of said handle of complementary cross-section whereby to transmit turning movement of the handle to the spindle but such as to permit limited axial movement of said end portion therein; a screw extending coaxially from said end portion of the spindle with freedom to rotate relative to the spindle but being retained axially thereto; said screw being received in a threaded bore of said handle extending coaxially from said socket and the head of the screw being accessible through the end of said bore which is remote from the socket, whereby to adjust the axial position of said end portion of the spindle within said socket by turning said screw within said bore.

6. An assembly according to any preceding claim further comprising a second turnable handle adapted to be mounted to the closure on the opposite side thereof to the firstmentioned handle, said spindle extending through the follower of the latch bolt unit to be connected to said second handle whereby the assembly of said two handles and spindle turn and displace axially in unison.

7. A latch furniture assembly substantially as hereinbefore described with reference to the accompanying drawings.