GB2246811A

GB2246811A - Pivot assemblies for windows

Info

Publication number: GB2246811A
Application number: GB9114178A
Authority: GB
Inventors: Robert Friederick Hoellrigl; Maja Elizabeth Hoellrigl
Original assignee: Smith W H & Sons
Current assignee: Smith W H & Sons
Priority date: 1990-07-12
Filing date: 1991-07-01
Publication date: 1992-02-12
Anticipated expiration: 2011-07-01
Also published as: GB9114178D0; GB2246811B

Abstract

A window 11 is mounted in an opening in a frame 10 by a pair of pivot assemblies 12 having a common axis 20 extending transversely across a central portion of the window. The pivot assemblies are arranged so that in the closed position of the window the pivot assemblies are wholly concealed between the frame and the openable member. The pivot assemblies may be arranged so that rotation of the window about said axis moves the window along said axis. The pivot assemblies may comprise threaded axle and socket components and a friction member. A method of installation is also described. <IMAGE>

Description

PIVOT ASSEMBLIES FOR WINDOWS This invention concerns apparatus such as pivotally openable windows; pivot assemblies, for pivotally openable members such as windows; and methods of installing openable members such as windows, utilising such pivot assemblies.

Apparatus is known in which an openable member such as a window is mounted in a fixed frame by means of a pair of pivot assemblies located so that they are aligned on a common axis which extends transversely, either vertically or horizontally, across a central portion of the openable member. Windows supported by such pivot assemblies are commonly known as centre pivoted windows, and have the advantage that they can be swung through about 1000 to 1800, i.e. almost reversed in the fixed frame, so that the outside surfaces thereof can be cleaned from inside a building.

However, known pivot assemblies have inherent, or give rise to, problems such as: (a) they are visually intrusive; (b) they require precise dimensioning of, and fixing to, the frame and window during manufacture thereof; (c) they do not permit or provide for adjustment of the position of the window in the frame; (d) they can be affected by wear or other factors so as to provide poor location for the window under some circumstances; and (e) some thereof are expensIve to manufacture.

For example, the pivot or bearing assembly disclosed in GB 1393671 comprises a first component which provides a stub axle, a second component which provides a bearing socket for the stub axle, and a friction member which is co-axial with the axle and socket and a radially expandable in the socket to vary the frictional resistance to turning of the axle in the socket.The components are fixed to the exposed faces of the window and frame; the peripheral gap at the junction between the axle and socket formations is occupied by a washer which may be ineffective in excluding dirt from the bearing if the gap is or becomes excessive due to excessive manufacturing tolerances or wear, or due to relative axial movement or displacement between the window and the frame; and the components do not provide for adjustment of the position of the window in the frame, or for removal of the window without detaching one of the components.

Another pivot or bearing assembly, sold by Grorud Industries AS of Norway, is similar to that disclosed in GB 1393671 in that it comprises a first component having a stub axle, a second component providing a bearing socket, and an exposed friction member to vary the resistance to relative rotation between the components which are exposed at one face of the window assembly. However, in this "Grorud" assembly, the socket has a radial opening which is closed by the friction member; and the latter is radially movable to vary said resistance, and is removable from one side of the window to permit the axle to be radially out of the socket in a direction perpendicular to the plane of the window, for removal of the window for repair.

A primary object of the invention is to enable the first of the aforementioned problems to be avoided, and accordingly, the present invention provides apparatus comprising an openable movable member mounted in an opening in a frame by a pair of pivot assemblies having a common axis extending transversely across a central portion of the movable member, wherein the pivot assemblies are arranged so that in the closed position, in which the movable member closes said opening, the pivot assemblies are wholly accommodated between the frame and the openable member, so as to be concealed.

To enable further ones of said problems to be reduced the pivot assemblies preferably each comprise a first component releasably secured to the movable member and having a stub axle, and a second component releasably secured to the frame and having a socket for the axle; and the arrangement thereof is preferably such that in one of the pivot assemblies the stub axle threadably engages in the socket whereas in the other of the pivot assemblies the stub axle is axially slidable in the socket, so that rotation of the movable member about said axis moves the movable member along said axis.

Accordingly, the present invention furthe; provides an improved form of apparatus comprising an openable movable member mounted in an opening in a frame by a pair of pivot assemblies having a common axis extending transversely across a central portion of the movable member, wherein the pivot assemblies each comprise a first component releasably secured to the movable member and having a stub axle, and a second component releasably secured to the frame and having a socket for the axle; and characterised in that in one of the pivot assemblies the stub axle threadably engages in the socket whereas in the other of the pivot assemblies the stub axle is axially slidable in the socket, so that rotation of the movable member about said axis moves the movable member along said axis.

The frame and=or movable member is or are preferably provided with removable stop means to restrict rotation of the movable member in the frame.

To facilitate installation and adjustment each first component is preferably secured releasably to the movable member by a mounting which comprises a body part of the first component, on which the axle is provided, and a channel which is securable to or provided by the movable member and in which the body part is slidable and releasably securable.

To further improve the function of the apparatus at least one of the pivot assemblies preferably comprises a friction member movable to vary the frictional resistance to rotation of the axle in the socket; and to keep the pivot assembly concealed in the apparatus, the friction member preferably extends longitudinally of said channel.

An object of the invention is to provide an improved pivot assembly to enable said problems to be obviated, reduced or further reduced.

According to the present invention there is provided a pivot assembly, for securing a movable member to a frame, comprising a first component, for securing to the movable member, having a stub axle; a second component for securing to the frame, having a socket for the axle; and a friction member movable to vary the frictional resistance to rotation of the axle in the socket, characterised in that the axle is externally screw threaded and the socket is internally screw threaded.

The first component is preferably provided with a mounting which preferably comprises a body part of the first component, on which the axle is provided, and a mounting member releasably securable to the body part and securable to the movable member.

The body part is preferably in the form of an elongate slider, and the mounting member is preferably in the form of an elongate channel in which the slider is longitudinally slidable. The mounting member preferably provides sockets in which fasteners can be secured to clamp the body part to the mounting member.

The present invention also provides a pivot assembly, for securing a movable member to a frame, comprising a first component having a first mounting, for securing together the first component and the movable member, and a stub axle; a second component having a second mounting, for securing to the frame, and a socket for the axle; and a friction member movable to vary the frictional resistance to rotation of the axle in the socket, characterised in that the first mounting comprises a body part of the first component, on which the axle is provided, and a channel which is securable to the movable member and in which the body part is slidable and releasably securable.

The friction member preferably extends within said second mounting.

The present invention also provides a pivot assembly, for securing a movable member to a frame, comprising a first component, for securing to the movable member, having a stub axle; a second component, for securing to the frame, having a socket for the axle; and a friction member movable to vary the frictional resistance to rotation of the axle in the socket, characterised in that the friction member and axle are arranged so that an arcuately toothed portion of the periphery of the axle is abutted by the friction member so as to engage in recesses between the teeth on said portion. The pitch of the teeth is preferably about lmm. The teeth may be provided by screw threads.

The external and internal screw threads on the axle and socket preferably have a pitch of about lmm and not more than 2mm.

The pivot assemblies of the invention are preferably employed in said apparatus.

The threads of the axle and socket of one assembly of said pair may be of the same hand as those of the other assembly, but alternatively may be oppositely handed.

However, in an improved form, the present invention provides a pair of pivot assemblies, wherein the pivot assemblies each comprise a first component having a stuble axle, and a second component having a socket for the axle; and characterised in that in one of the pivot assemblies the stub axle threadably engages in the socket whereas in the other of the pivot assemblies the stub axle is axially slidable in the socket.

The frame and/or movable member is or are preferably provided with removable stop means to restrict rotation of the movable member in the frame.

The invention also provides a method of installing an openable movable member, having or provided with a reception channel at each end, in an opening in a frame by means of a pair of said pivot assemblies comprising the steps of: (a) securing the second components to the frame so that the sockets extend into the frame, either before or after the axles are inserted into the sockets; and and (b) moving the movable member into the opening to engage the first components in the reception channels and clamping the first components to the movable member.

The reception channels are preferably provided by the movable member but may be provided by securing mounting members to the movable member.

For adjustment of the position of the movable member longitudinally of said common axis, in embodiments wherein the axles are both threaded, the first components may detached from the movable member or mounting members to allow removal of the movable member, and the positions of the first components are adjusted to vary the insertion depth of the axles or either thereof in the sockets or socket, before step (b) is repeated.

In the improved form, the removal of the stop means enables the longitudinal position to be adjusted without removal of the movable members from the frame, and the method of the invention preferably includes the step of adjusting the position of the movable member longitudinally of the pivot axis by rotating the movable member about said axis prior to removable stop means being fitted to restrict the movement of the movable member to a predetermined arc.

For adjustment of the movable member transverse to said axis, the clamping is released to an extent sufficient to allow the or each first component to be shifted longitudinally of the channel, before the clamping is restored.

When the movable member is correctly positioned in the frame, the first component is preferably further secured by fasteners engaged in the movable member.

The method preferably includes the making of such adjustments as required, and the further securing of the first component to the movable member.

The invention will be described further by way of example, with reference to the accompanying diagrammatic drawings, wherein:- FIGURE 1 shows a median vertical cross-section through a central portion of one end part of apparatus of the invention, in the form of a window assembly, which portion includes one of a pair of pivot assemblies of a first embodiment of the invention, FIGURE 2 shows a transverse cross section through said portion on the line II-II in FIGURE 1; FIGURES 3 to 7 show parts of the pivot assembly of the invention, FIGURES 6 and 7 being to a smaller scale than the other figures; FIGURES 8, 9 and 10 show parts of the apparatus including a second embodiment of pivot assembly of the invention;; FIGURE 11 is a cross-section through part of a window assembly of the invention in a plane including the pivot axis and transverse to the mid-plane of the window assembly, showing one of two pivot assemblies; and FIGURES 12 and 13 are part sectional exploded views of the two pivot assemblies.

The window assembly comprises a fixed frame 10 defining an opening in which a centre pivot window frame 11 is located by a pair of pivot assemblies 12 aligned on a common axis 20 which extends transversely, horizontally across the mid-part of the window frame from one end thereof to the other, so that the upper portion of the window frame moves arcuately in the opposite direction to the lower portion of the window frame 11 as the latter is swung about said axis 20. The window frame is glazed in known manner, and the glazing is not shown.

The fixed frame 10 includes a vertical hollow plastics extrusion 14 which is internally reinforced by a a metal upright 15, and in use is fixed to a building structure in known manner.

The window frame 11 comprises a hollow plastics end extrusion 16 which is internally reinforced by a metal stiffener 17 in known manner.

In the first two embodiments, each pivot assembly 12 comprises a first and second component 21 and 30. The first component comprises a stub axle 23 which is fixed to or integral with the centre of a flat elongate body part 25. The body part 25 is provided with two arrays of holes 26 to receive fasteners 27, for securing the component to the frame 11 and two sets of slots 22 to receive clamping fasteners 28 or 28A.

The component 30 is a casting or fabrication providing a central spigot 36 in which socket 33 is formed to receive the axle 23, two diametrically opposed passages 31 which extend radially from the socket in a body of the component. The body 32 serves as a mounting and has cross-passages 34 to receive fasteners 35 for securing the component to the fixed frame 10.

The fasteners 27 and 35 are omitted from FIGURE 8.

The proximal portions of the passages 31 serve as guides and sockets for friction members 36, and the distal portions of the passages are internally screw threaded to receive bolts 37 to force the friction members radially towards (and slightly into) the socket 33.

In the first, but not the second, embodiment, a third component (FIGURE 7) in the form of a mounting member 40 is provided, firstly to serve as a guide channel for the body part 25 so that the latter is slidable in the guide channel, and, secondly, to serve together with the body part 25 as an adjustable mounting for the first component.

The member 40 is provided with a pair (or set) of spigots 41 which are internally threaded to receive the clamping fasteners 28; an array of holes 42 to receive fasteners 43 for securing the member 40 directly to the frame 11; two lateral flanges 44 providing walls for the guide channel; and a transverse stop flange 45 at one end only of the guide channel; and a further array 46 of slots to admit the fasteners 27.

Instead of employing a third component, in the second embodiment the body part 25 is wider so as to fit slidably in a median channel 55 in the extrusion 16, and two pairs of internally threaded apertures 47 to receive stepped bolts 48 having plain cylindrical extensions 49.

The first and second embodiments of pivot assembly incorporate positioning means for adjustment of and determination of the axial position of the axle in the socket. In the embodiments shown in the drawings, the positioning means comprises a fine pitch, e.g. 1 m pitch, male screw thread on the axle which is about, or slightly less than, 2 cm in diameter, and a complementary internal female thread in the socket, so that the axle has the same effective diameter as, and threadably engages in, the socket.

In order to reduce manufacturing costs, the female thread could be omitted, the function of that thread being transferred to those end surfaces of the friction members which abut the axle.

Such an alternative positioning means could be further modified by providing a series of annular teeth on the periphery of the axle at close spacings or at a fine pitch, instead of a male thread, but instead of the axle being screwed into or out of the socket to vary its axial position therein, the or some of the pressure on the friction members would probably have to be released to allow the axle to be shifted, e.g. driven, bodily in the axial direction. To facilitate initial adjustment or positioning of the axle, the end surfaces could be left plain, so that teeth are formed thereon only by wear and/or pressure applied by the bolts 37 to shape those end surfaces to engage in the recesses between the annular teeth on the axle, and thereby determine the axial position of the axle.

Each embodiment of pivot assembly may be fitted in the window assembly, either during installation or, preferably, during manufacture of the window assembly, in the following manner.

A hole is drilled mid-way along the length of each extrusion 14 through a main web 50 of the extrusion 14 and through one wall 51 of the upright 15 therebehind, to receive the spigot 36 so that the component 20 is located in a median channel 52 provided by the extrusion 14; and further holes are drilled in the extrusion 14 and upright 15 to receive the fasteners 35 to secure the components 30 to the frame at opposite ends of the opening in the fixed frame 10.

Each first component is fitted to the second component by screwing the stub axle 23 (or, in the case of the modified forms in which the socket is not threaded, pushing the stub axle 22) into the socket 33, and rotating the bolts 37 to cause the friction members 36 to bear gently upon the axle 23.

The procedures for the embodiments differs thereafter.

For the first embodiment, two holes are drilled in slightly above mid-way along the length of each end extrusion 16 through a main web 53 of the extrusion and one wall 54 of the stiffener 17 therebehind, to receive the spigots 41 at positions such that the third component 40 is located in the median channel 55 of the extrusion 16 so that the axis 20 of the axle 23 will pass through or close to a point at the centre of the guide channel; and the component is secured to the window frame 11 by the fasteners 43 which are inserted into the further holes drilled into the window frame.

Thereafter, the first components are turned so that the body parts 25 are generally transverse to the plane of the aperture; the window frame is inserted, bottom end first, through the aperture so that the ends of said parts 25 enter the open ends of the guide channels; the window frame is thrust further through the aperture to cause said parts 25 to slide along the guide channels until the ends approach or abut the stop flanges 45; and the clamping fasteners 28 are inserted into the spigots 41 via the slots 22 to clamp the first component to the third component.

For the second embodiment, two holes are drilled further above mid-way along the length of each extrusion 16 through the main web 55 and the wall 54, to receive clamping fasteners 28A, at positions such that the axis 20 of the axle 23 will be close to the axis of the socket when the slots 22 overlie said holes.

Thereafter the first components are turned so that, as the window frame is inserted end first into the aperture, the ends of the parts 25 enter the median channels 55 so that the latter serve as guide channels as they are traversed by the parts 25 until the slots 22 reach said holes in the extrusion 16; and the fasteners 28A are inserted to clamp the parts 25 directly to the window frame and the window is turned to the closed position so that its alignment in the aperture in the fixed frame can be checked. If the alignment is correct, further holes are drilled to the window frame to receive the screws 27 and the extensions 49 for securing the parts 25 in position.

During final installation of the window assembly in a building, after the frame 11 has been secured to the structure of the building and the window frame inserted in the fixed frame, the position of the window frame can be adjusted so that it is central in the aperture, in the closed condition, and is not excessively stressed by being tensioned or compressed between the pivot assemblies, before the fasteners 27 are inserted through one of the two arrays of holes 26 and holes drilled in the window frame in alignment with the holes 26 (and, in the first embodiment, via the slots 46)..

Horizontal adjustment for overall position or stress avoidance can be effected by unclamping the first components from the third components or the window frame, removing the window frame from the fixed frame, and rotating the second component or components to screw the stub axle or stub axles further into or out of the socket or sockets (or in the modified form, releasing the pressure on the friction members and thrusting, e.g.

prising or tapping, the stub axles further out of or into the sockets); and replacing the window frame in the fixed frame. The 1 mm pitch affords adjustment in 0.5mm increments by rotation of the first component through 1800, and the second array of holes 26 and second set of slots 22 permit either end portion of the body part 25 to be used for securing the first component to the third component.

Vertical adjustment can be effected by releasing the clamping pressure of the fasteners 28 or 28A and shifting the first component along the third component, before retightening the fasteners 28 or 28A and drilling the holes for and inserting the fasteners 27.

As can be seen from FIGURE 2, when the window is in the closed condition, the pivot assemblies including the friction adjusting screws are totally concealed inbetween the two median channels, by the flanges of the extrusions and the seals 58 thereon, and are substantially unobtrusive when the window is opened by being pivoted about the common axis of the axles. To improve the appearance of the installation, a thin cover strip 59 may be fitted to the exposed face of each body part 25. The friction adjusting screws are only accessible within the main channel when the window is open (or the window frame is removed). The window frame is easily removed, from inside the building, for repair, especially for replacement of broken glazing. For the manufacturer, the pivot assemblies offer the major advantage that the permissible dimensional tolerances on manufacture of the frames can be increased to reduce scrap wastage. For example, the assemblies can be adjusted to accept window frames which are several millimetres narrower and a millimetre or two wider than the nominal width limits which are acceptable or permissible with other forms of pivot assembly.

In the third embodiment, the general forms of the fixed frame 10 and window frame 11 of the third embodiment of window assembly are as described hereinbefore and the parts thereof shown in FIGURE 11 are indicated by the same reference numbers as those employed in FIGURES 1 to 10 and are not described again.

As previously described, the frames 10 and 11 are connected by a pair of pivot assemblies 12, but in this embodiment the pivot assemblies differ and the reference numbers relating to the first pivot assembly 12A are distinguished by the addition of the suffix letter A from those relating to the second pivot assembly 12B denoted by the suffix letter B.

Each pivot assembly 12A or B comprises a first and second component 21A or 21B and 30A or 30B. The first component comprises a hollow stub axle 23A or 23B which is fixed by a support screw 59 to the centre of the flat elongate body part 25A or 25B. The body part 25A is provided with two arrays of holes 26 to receive fasteners 27, for securing the component to the frame 11 and two sets of slots 22 to receive clamping fasteners 28 or 28A; whereas the body part 25B has one array of holes 26 and one slot 22.

The component 30A or 30B is a casting or fabrication providing a central portion 36A or 36B in which a socket 33A or 33B is formed to receive the axle 23A or 23B. Both components 30 have two diametrically opposed passages 31 which extend radially from the socket in a body 32 of the component. The body 32 serves as a mounting and has cross-passages 34 to receive fasteners 35 for securing the component to the fixed frame 10.

The fasteners 27 and 35 are omitted from FIGURES 11 to 13.

The body part 25A or 25B fits slidably in a median channel 55 of the extrusion 16.

The first pivot assembly 12A incorporates positioning means for adjustment of and determination of the axial position of the axle in the socket. In the embodiments shown in the drawings, the positioning means comprises a fine pitch, e.g. lm pitch, male screw thread 60 on the axle which is about, or slightly less than, 2cm in diameter, and a complementary internal female thread 61 in the socket, so that the axle has the same effective diameter as, and threadably engages in, the socket.

In the second pivot assembly 12B the male and female threads are omitted, so that the axle and socket have plain cylindrical bearing surfaces 62 and 63 which permit axial sliding of the axle in the socket.

Set pins 64 are secured in the component 20 and stub axle flanges 65 for location and support.

The position of the window frame 11 in the fixed frame can be adjusted in this embodiment by rotating the window frame about the pivot axis, without removing the window frame in most instances, but removal may be beneficial to allow the first component 21A to be rotated through 1800 before being re-secured to the window frame.

In a finished condition the window assembly is provided with stop means, which limits arcuate movement of the window frame. The seals 58 shown in FIGURES 2 and 8 may serve as a form of the stop means. However, lengths of a clip in extrusion 67 are preferably employed as the stop means, one length being clipped into one of the channels in the fixed frame which extends along an upper transverse member of the frame, and another length being clipped into one of the channels in the window frame which extends along a lower transverse member of the frame, so that the flange 66 on each length depends at the outside of the window assembly. The manner of interengagement of the extrusion 67 in the frame channels is indicated diagrammatically in broken lines in FIGURE 11.

The invention includes and provides apparatus, a pivot assembly or a window assembly incorporating any novel part, feature or concept disclosed herein or in the accompanying drawings, and any novel combination of parts, features or concepts so disclosed. The invention is not confined to details of the foregoing examples, and many variations and modifications are possible within the scope of the invention.

Claims

1. Apparatus comprising an openable movable member mounted in an opening in a frame by a pair of pivot assemblies having a common axis extending transversely across a central portion of the movable member, wherein the pivot assemblies are arranged so that in the closed position, in which the movable member closes said opening, the pivot assemblies are wholly concealed between the frame and the openable member.

2. Apparatus as claimed in Claim 1 wherein the pivot assemblies each comprise a first component releasably secured to the movable member and having a stub axle, and a second component releasably secured to the frame and having a socket for the axle.

3. Apparatus as claimed in Claim 2 wherein the or each axle is arcuately toothed.

4. Apparatus as claimed in Claim 3 wherein the teeth are provided by a male screw thread on the axle or each axle.

5. Apparatus as claimed in Claim 2 wherein in one of the pivot assemblies the stub axle threadably engages in the socket, whereas in the other of the pivot assemblies the stub axle is axially slidable in the socket, so that rotation of the movable member about said axis moves the movable member along said axis.

6. Apparatus as claimed in Claim 2 wherein both axles and sockets are threaded and the threads of the axle and socket of one assembly of said pair of the same hand as those of the axle and socket of the other assembly.

7. Apparatus as claimed in any one of Claims 3 to 6 wherein the teeth or threads have a pitch of about 1 millimetre and less than 2 millimetres.

8. Apparatus as claimed in any one of Claims 2 to 7 wherein at least one of the pivot assemblies comprises a friction member movable to vary the frictional resistance to rotation of the axle in the socket.

9. Apparatus as claimed in Claim 8 was appended to Claim 7 wherein the friction member and axle are arranged so that an arcuately toothed portion of the periphery of the axle is abutted by the friction member so as to engage in recesses between the teeth on said portion.

10. Apparatus comprising an openable movable member mounted in an opening in a frame by a pair of pivot assemblies having a common axis extending transversely across a central portion of the movable member, wherein the pivot assemblies each comprise a first component releasably secured to the movable member and having a stub axle, and a second component releasably secured to the frame and having a socket for the axle; and characterised in that in one of the pivot assemblies the stub axle threadably engages in the socket whereas in the other of the pivot assemblies the stub axle is axially slidable in the socket, so that rotation of the movable member about said axis moves the movable member along said axis.

11. Apparatus as claimed in any one of Claims 2 to 10 wherein each first component is secured releasably to the movable member by a mounting which comprises a body part of the first component, on which the axle is provided, and a channel which is securable to or provided by the movable member and in which the body part is slidable and releasably securable.

12. Apparatus as claimed in Claim 11 as appended to Claim 8 or 10 wherein the friction member extends longitudinally of said channel.

13. Apparatus substantially as hereinbefore described with reference to FIGURES 1 to 7 of the accompanying drawings.

14. Apparatus substantially as hereinbefore described with reference to FIGURES 8 to 10 of the accompanying drawings.

15. Apparatus- substantially as hereinbefore described with reference to FIGURES 11 to 13 of the accompanying drawings.

16. A method of installing an openable movable member, having or provided with a reception channel at each end, in an opening in a frame by means of a pair of pivot assemblies as claimed in any one of Claims 2 to 15 comprising the steps of: (a) securing the second components to the frame so that the sockets extend into the frame, either before or after the axles are inserted into the sockets; and (b) moving the movable member into the opening to engage the first components in the reception channels and clamping the first components to the movable member.

17. A method as claimed in Claim 16 wherein transverse adjustment of the movable member is effected by sliding said first components in said channels whilst the components are not clamped to the movable member.

18. A method as claimed in Claim 16 or 17 wherein the position of the movable member is adjusted longitudinally of the pivot axis by being rotated about said axis prior to removable stop means being fitted to restrict the movement of the movable member to a predetermined arc.

19. A pivot assembly, for securing a movable member to a frame, comprising a first component, for securing to the movable member, having a stub axle; a second component for securing to the frame, having a socket for the axle; and a friction member movable to vary the frictional resistance to rotation of the axle in the socket, characterised in that the axle is externally screw threaded and the socket is internally screw threaded.

20. A pivot assembly as claimed in Claim 19 wherein the first component is provided with a mounting which comprises a body part of the first component, on which the axle is provided, and a mounting member releasably securable to the body part and securable to the movable member.

21. A pivot assembly as claimed in Claim 20 wherein the body part is in the form of an elongate slider, and the mounting member is in the form of an elongate channel in which the slider is longitudinally slidable.

22. A pivot assembly, for securing a movable member to a frame, comprising a first component, for securing to the movable member, having a stub axle; a second component having a socket for the axle and a mounting for securing to the frame; and a friction member movable to vary the frictional resistance to rotation of the axle in the socket, characterised in that the friction member and axle are arranged so that an arcuately toothed portion of the periphery of the axle is abutted by the friction member so as to engage in recesses between the teeth on said portion.

23. A pivot assembly as claimed in Claim 22 wherein the friction member extends in the mounting of the second component.

24. A Pivot assembly as claimed din Claim 22 or 23 wherein the teeth are provided by a male screw thread and wherein the socket is internally screw threaded.

25. A pivot assembly as claimed in Claim 22 or 23 or 24 wherein the pitch of the threads is less than 2 millimetres.

26. A pivot assembly as claimed in Claim 25 wherein the pitch of the threads is less than 1 millimetre.

27. A pivot assembly substantially as hereinbefore described with reference to FIGURES 1 to 7 of the accompanying drawings.

28. A pivot assembly substantially as hereinbefore described with reference to FIGURES 8 to 10 of the accompanying drawings.

29. A pair of pivot assemblies substantially as hereinbefore described with reference to FIGURES 11 to 13 of the accompanying drawings.

29. A pair of pivot assemblies comprising a first pivot assembly as claimed in any one of Claims 19 to 28 and further pivot assembly in which a stub axle is slidably accommodated in a socket.

30. A pair of pivot assemblies substantially as hereinbefore described with reference to FIGURES 11 to 13 of the accompanying drawings.

Amendments to the claims have been filed as follows 1. Apparatus comprising an openable movable member mounted in an opening in a frame by a pair of pivot assemblies having a common axis extending transversely across a central portion of the movable member, wherein the pivot assemblies are secured to and disposed between the frame and the openable member; wherein the pivot assemblies each comprise a first component having a stub axle, and a second component having a socket for the axle; wherein in at least one of the pivot assemblies positioning means is provided by arcuate toothing on the stub axle being engaged in the socket so as to permit determine and adjustment of the axial position of the stub axle in the socket.

2. Apparatus as claimed in Claim 1 wherein the arcuate toothing is provided by a male screw thread on the stub axle.

3. Apparatus as claimed in Claim 2 wherein in one of the pivot assemblies the stub axle is threadably engaged in the socket, whereas in the other of the pivot assemblies the stub axle is axially slidable in the socket, so that rotation of the movable member about said axis moves the movable member along said axis.

4. Apparatus as claimed in Claim 2 wherein both axles are threadably engaged in the sockets, and the threads of the axle of one assembly of said pair are of the same hand as those of the axle of the other assembly.

5. Apparatus as claimed in Claim 1 wherein the arcuate toothing is provided by annular teeth.

6. Apparatus as claimed in any one of Claims 1 to 5 wherein the teeth or threads have a pitch of about 1 millimetre and less than 2 millimetres.

7. Apparatus as claimed in any one of Claims 1 to 7 wherein at least one of the pivot assemblies comprises a friction member movable to vary the frictional resistance to rotation of the axle in the socket.

8. Apparatus as claimed in Claim 7 was appended to Claim 5 wherein the friction member and axle are arranged so that an arcuately toothed portion of the periphery of the axle is abutted by the friction member so as to engage in recesses between the teeth on said portion.

9. Apparatus comprising an openable movable member mounted in an opening in a frame by a pair of pivot assemblies having a common axis extending transversely across a central portion of the movable member, wherein the pivot assemblies each comprise a first component releasably secured to the movable member and having a stub axle, and a second component releasably secured to the frame and having a socket for the axle; and characterised in that in one of the pivot assemblies the stub axle threadably engages in the socket whereas in the other of the pivot assemblies the stub axle is axially slidable in the socket, so that rotation of the movable member about said axis moves the movable member along said axis.

10. Apparatus as claimed in any one of Claims 1 to 9 wherein each first component is secured releasably to the movable member by a mounting which comprises a body part of the first component, on which the axle is provided, and a channel which is securable to or provided by the movable member and in which the body part is slidable and releasably securable.

11. Apparatus as claimed in Claim 10 as appended to Claim 7 or 8 wherein the friction member extends longitudinally of said channel.

12. Apparatus substantially as hereinbefore described with reference to FIGURES 1 to 7 of the accompanying drawings.

13. Apparatus substantially as hereinbefore described with reference to FIGURES 8 to 10 of the accompanying drawings.

14. Apparatus substantially as hereinbefore described with reference to FIGURES 11 to 13 of the accompanying drawings.

15. A method of installing an openable movable member, having or provided with a reception channel at each end, in an opening in a frame by means of a pair of pivot assemblies to form apparatus as claimed in any one of Claims 1 to 14 comprising the steps of: (a) securing the second components to the frame so that the sockets extend into the frame, either before or after the axles are inserted into the sockets; and (b) moving the movable member into the opening to engage the first components in the reception channels and clamping the first components to the movable member.

16. A method as claimed in Claim 15 wherein transverse adjustment of the movable member is effected by sliding said first components in said channels whilst the components are not clamped to the movable member.

17. A method as claimed in Claim 15 or 16 wherein the position of the movable member is adjusted longitudinally of the pivot axis by being rotated about said axis prior to removable stop means being fitted to restrict the movement of the movable member to a predetermined arc.

18. A pivot assembly, for securing a movable member to a frame, comprising a first component, for securing to the movable member, having a stub axle; a second component for securing to the frame, having a socket for the axle; and a friction member movable to vary the frictional resistance to rotation of the axle in the socket, characterised in that the axle is externally screw threaded and the socket is internally screw threaded.

19. A pivot assembly as claimed in Claim 18 wherein the first component is provided with a mounting which comprises a body part of the first component, on which the axle is provided, and a mounting member releasably securable to the body part and securable to the movable member.

20. A pivot assembly as claimed in Claim 19 wherein the body part is in the form of an elongate slider, and the mounting member is in the form of an elongate channel in which the slider is longitudinally slidable.

21. A pivot assembly, for securing a movable member to a frame, comprising a first component, for securing to the movable member, having a stub axle; a second component having a socket for the axle and a mounting for securing to the frame; and a friction member movable to vary the frictional resistance to rotation of the axle in the socket, characterised in that the friction member and axle are arranged so that an arcuately toothed portion of the periphery of the axle is abutted by the friction member so as to engage in recesses between the teeth on said portion.

22. A pivot assembly as claimed in Claim 21 wherein the friction member extends in the mounting of the second component.

23. A pivot assembly as claimed in Claim 21 or 22 wherein the teeth are provided by a male screw thread and wherein the socket is internally screw threaded.

24. A pivot assembly as claimed in Claim 21 or 22 or 23 wherein the pitch of the threads is less than 2 millimetres.

25. A pivot assembly as claimed in Claim 24 wherein the pitch of the threads is less than 1 millimetre.

26. A pivot assembly substantially as hereinbefore described with reference to FIGURES 1 to 7 of the accompanying drawings.

27. A pivot assembly substantially as hereinbefore described with reference to FIGURES 8 to 10 of the accompanying drawings.

28. A pair of pivot assemblies comprising a first pivot assembly as claimed in any one of Claims 18 to 27 and further pivot assembly in which a stub axle is slidably accommodated in a socket.