GB2249343A

GB2249343A - Friction stays

Info

Publication number: GB2249343A
Application number: GB9120689A
Authority: GB
Inventors: Terry J Dolman; Kenneth Gordon Griffin
Original assignee: Euromond Ltd
Current assignee: Euromond Ltd
Priority date: 1990-09-28
Filing date: 1991-09-27
Publication date: 1992-05-06
Anticipated expiration: 2011-09-27
Also published as: GB2249343B; FR2667347A1; GB9120689D0; CA2052388A1

Abstract

A stay for a window has a channel section (10) for connection to the frame and an arm (12) for connection to the opening window leaf. A linkage (14, 16,17) extends between the arm and the channel and includes a slider (20) on which is mounted at least one of the links and which slides along the channel during opening and closing movement of the arm. The slider carries an elongate member which is biased into a position in which the member engages a stop (23) on the channel to restrict the opening movement of the arm. A member can be depressed to disengage it from the slot and allow full opening movement of the window. A device may be provided between the slider and the base channel for selective operation to limit the opening movement of the leaf. This device may be an elongate removable intermediate stop that prevents the arm opening to the maximum extent and limits the opening to a point at which, for example, ventilation is provided but access through the window is not possible. As a second possibility a screw may be provided on an elongate restrictor bar attached to the slider so that when the screw is in an operative position it contacts the stop before the leaf is fully open. A third possibility is to provide a screw on the slider which, when moved to an operative position, engages the slider. <IMAGE>

Description

STAYS The invention relates to stays for connecting a closure to an associated frame to allow opening and closing movement of the closure out of and into the frame. Examples of such closures are windows and doors.

One commonly used stay comprises a channel for connection to one of the parts, an arm for connection to the other part and a linkage connecting the channel to the arm to allow the opening and closing movement. At least one link of the linkage is pivotally connected at one end to a slider which slides in the channel to guide the movement.

In general, the geometry of the linkage is such that substantial opening movement is possible, for example to allow the exterior of a window to be cleaned from the interior by movement of the inner vertical edge of the closure laterally relative to the frame. It is not, however, always desirable to allow such full opening movement without restriction, since it might be dangerous if a child were able to open a closure to its fullest possible extent.

According to the invention, there is provided a stay for connecting a closure to an associated frame comprising a channel for connection to one of the parts, an arm for connection to the other of the parts and a linkage connecting the channel to the arm to allow opening and closing movement of the closure out of and into the frame, the linkage including at least one link pivotally connected to a slider received for sliding movement in the channel, being provided a stop member being provided which acts on the slider for limiting the opening movement of the closure relative to the frame, the stop member being manually disengageable for allowing additional opening movement of the closure relative to the frame.

The following is a more detailed description of five embodiments of the invention, by way of example, reference being made to the accompanying drawings in which: Figure 1 is a side elevation of a first friction stay with an arm of the friction stay in an open position and showing a slider and a second stop member, Figure 2 shows a side elevation a plan view and an end elevation of the second stop member of the first friction stay of Figure 1, Figure 3 is a side elevation of a second friction stay with an arm of the friction stay in an open position showing a slider and a restrictor bar carried by the slider, Figure 4 is a side elevation, a plan view and a section of the restrictor bar of the second friction stay of Figure 3, Figure 5 is a side elevation of a third friction stay with an arm of a friction stay in an open position and showing a slot and a screw which act to limit the opening movement of the stay, Figure 6 is a side elevation of the third friction stay of Figure 4 showing the screw in the slot Figure 7 is a section on the line VII-VII of Figure 6, Figure 8 is a plan view bf a fourth window stay including an arm shown in a partly open position and a stop member engaged with a channel of the stay, Figure 9 is a similar view to Figure 8 but showing the arm in a second partly open position with the stop member engaged with the channel in a second position, Figure 10 is a similar view to Figures 8 and 9 but showing the arm in a fully open position, Figure 11 is a plan view of a fifth form of window stay similar to the stay shown in Figures 8 to 10 but with a second form of stop member attached to a slider of the stay and engaged with a stop on the channel to hold the arm in a partially open position, Figure 12 is a similar view to Figure 11 but with the arm in a fully open position, Figure 13A is a plan view of a push button of the stay of Figures 11 and 12, Figure 13B is a section on the line X-X of Figure 13A, Figure 13C is a section on the line Y-Y of Figure 13A but showing the push button in the channel of the stay of Figures 11 and 12, Figure 14A is an elevation of a stop bar of the stay of Figures 11 and 12, Figure 14B is a cross-section of the stop bar of Figure 14A, Figure 14C is a view on the arrow A of Figure 14A, Figure 15A is a plan view of an end part of the slider of the stay of Figures 11 and 12, Figure 15B is a side elevation of the end of the slider shown in Figure 15A, Figure 16 is a cross-sectional view of the spacer of the stay of Figures 11 and 12, Figure 17 is a schematic view of an end of the channel of the stay of Figures 11 and 12 showing the spacer of Figure 16 located in the channel, and Figure 18 is a scrap view of a channel of the stay of Figures 11 and 12 showing an ear pressed out of a flange of the channel.

Referring first to Figure 1, the first friction stay comprises an elongate base member 10 of channel section with parallel guides 11 extending along respective side edges. A linkage, indicated generally at 12, is carried by the base channel 10 and includes an arm 13, a longer link 14, and an intermediate link 15 and two shorter links 16,17.

As seen in Figure 1, the longer link 14 has one end connected to the base channel 10 by a fixed pivot 18 located adjacent one end of the base member 10. The other end of the longer link 14 is connected to the arm 13 by a pivot 19 located intermediate the ends of the arm 13.

The intermediate link 15 and one shorter link 16 both have one end connected to a slider 20 for pivotal movement about respective spaced parallel pivot axes 21,22. The other end of the intermediate link 15 is connected intermediate the ends of the longer link 14 for pivotal movement and the other end of the first shorter link 16 is connected adjacent an end of the arm 13, also for pivotal movement. The second shorter link 17 extends between the intermediate link 15 and the arm 13 and is parallel to the longer link 14. The intermediate link 15 is parallel to the arm 13.

The slider 20 comprises a block of generally rectangular cross-section whose sides locate in, and are guided by, the guides 11 of the base channel 10. Thus the slider 20 is constrained for rectilinear reciprocating sliding movement along the base channel 10.

The base channel 10 also includes a stop 23 which projects into the path of the slider 20. The position of this stop 23 will be considered below.

A second stop member 24 (see Figure 2) is in the form of an elongate bar of rectangular cross-section having a hole 25 at one end and a notch 26 adjacent the hole. In use, as seen in Figure 1, the bar is fixed by a quick release screw to the base member 10 and the notch 26 covers the stop 23.

In use of the friction stay, the opening window sash (not shown) is mounted in a fixed window frame (not shown) by two friction stays of the kind described above with reference to Figures 1 and 2. The base channel 10 of each stay is mounted on a respective opposite member of the fixed frame and side members of the sash are connected to the arms 13. The linkage 12 allows the window sash to be moved between an open position, in which the linkage is positioned as shown in Figure 1 and a closed position. In the closed position, the arm 13 and the links 14,15,16 and 17 are all in register with the base channel 10. A pointed end 27 of the arm 13 projects into a groove 28 provided by an end cap 29 mounted at one end of the base channel 10.

In the closed position, the slider 20 is located adjacent the end cap 29. As the arm 13 moves to the open position, the slider 20 slides along the base channel 10, constrained by the guides 11, until it contacts the end of the stop member 24. This provides a stop which prevents further opening movement of the arm 13. As will be seen in Figure 1, the position of this stop is such that only limited opening movement is possible - sufficient to provide ventilation but insufficient to allow a person access through the window.

If wider opening movement is required, either in emergency or for cleaning and decorating purposes, the screw is removed from the hole 25 in the stop member 24 and the stop member 24 detached from the base channel 10. The slider 20 is thus no longer limited in its opening movement by the stop member 24 and can continue to slide as the arm 13 is opened until the slider 20 contacts the stop 23. In this position, the window is open to an extent that allows access to the exterior surface for cleaning and decorating and also to an extent that allows egress through the window.

It will be appreciated that the stop member need not be in the form of a bar. It could be in the form of a block or any other member which limits the movement of the slider 20 but which is removable from engagement with the base member.

Referring now to Figure 3, the second friction stay comprises an elongate base member 30 of channel section with parallel guides 31 extending along respective side edges. A linkage, indicated generally at 32, is carried by the base member 30 and includes an arm 33, a longer link 34, an intermediate link 35 and three shorter links 36,37,38. As seen in Figure 1, the longer link 34 has one end connected to the base channel 30 by a fixed pivot 39 located adjacent one end of the base member 30. The other end of the longer link 34 is connected to the arm 33 by a pivot 40 located intermediate the ends of the arm 33.

The intermediate link 35 and one shorter link 36 both have one end connected to a slider 41 for pivotal movement about respective spaced parallel axes 42,43. The other end of the intermediate link 35 is connected intermediate the ends of the longer link 34 for pivotal movement and the other end of the first shorter link 36 is connected adjacent an end of the arm 33, also for pivotal movement. The second and third shorter links 37,38 extend between the intermediate link 35 and the arm 33 and are parallel to one another and generally parallel to the longer link 34. The intermediate link 35 is parallel to the arm 33.

The slider 41 comprises a block of generally rectangular cross-section whose sides locate in, and are guided by, the guides 31 of the base member 30. Thus the slider 41 is constrained for rectilinear reciprocating sliding movement along the base channel 30.

The base channel 30 also includes a stop 44 which projects into the path of the slider. The function of this stop 44 will be considered below.

An elongate restrictor bar 45 is connected at one end to the slider 41 for movement with the slider 41 and is guided in such movement by the guides 11. For this purpose, as best seen in Figure 4, the restrictor bar 45 has a channel shaped cross section with parallel shoulders 46 that engage the guides 31. A grub or slot screw 47 is carried by the restrictor bar 45 at an end opposite its connection to the slider 41. The purpose of this screw 47 will be described below.

In use of the friction stay, an opening window sash (not shown) is mounted in a fixed window frame (not shown) by two friction stays of the kind described above with reference to Figures 3 and 4. The base channel 30 of each stay is mounted on a respective opposite member of the fixed frame and side members of the sash are connected to the arms 33. The linkage 32 allows the window leaf to be moved to an open position in which the linkage is positioned as shown in Figure 3 and to a closed position.

In the closed position, the arm 33 and the links 34,35,36,37 and 38 are all in register with the base member 30. A pointed end 48 of the arm 33 projects into a groove 49 provided by an end cap 50 mounted at one end of the base channel 30.

In the closed position, the slider 41 is located adjacent the end cap 50. As the arm 33 moves to the open position, the slider 41 slides along the base channel 30, constrained by the guides 11, until it contacts the stop member 45. This provides a stop which prevents further opening movement of the arm 33. This stop defines the maximum opening movement of the arm 33. If, however, only limited opening movement is required, the grub or slot screw 47 on the restrictor bar 45 is moved downwardly from the retracted position shown in Figure 4 to an extended position. When the grub or slot screw 47 is so positioned, it will engage the stop 44 well before the slider 41 engages the stop 44 and so will restrict severely the available degree of opening movement.The length of the restrictor bar 45 and the position of the grub or slot screw 47 can be chosen so that the limited opening movement of the arm 33 is such as to allow adequate ventilation while providing too small a gap for a person to pass through the window, so increasing security. If wider opening is required, either for more ventilation or an emergency, the grub or slot screw 47 can be quickly and easily retracted to allow full opening movement.

It will, of course, be appreciated that the engagement between the restrictor bar 45 and the stop 44 need not be by way of a grub or slot screw. It could be by any other form of releasable detent.

Referring next to Figure 5, the third friction stay comprises an elongate base member 60 of channel section with parallel guides 61 extending along respective side edges. A linkage, indicated generally at 62, is carried by the base channel 60 and includes an arm 63, a longer link 64, an intermediate link 65 and a shorter link 66.

As seen in Figure 5, the longer link 64 has one end connected to a base member 60 by a fixed pivot 67 located adjacent one end of the base channel 60. The other end of the longer link 64 is connected to the arm 63 by a pivot 68 located intermediate the ends of the arm 63.

The intermediate link 65 and the shorter link 66 both have one end connected to a slider 69 for pivotal movement above respective spaced parallel pivot axes 70,71. The other end of the intermediate link 65 is connected intermediate the ends of the longer link 64 for pivotal movement and the other end of the shorter link 66 is connected adjacent an end of the arm 63, also for pivotal movement. The intermediate link 65 is parallel to the arm 63.

The slider 69 comprises a block of generally rectangular cross-section whose sides locate in, and are guided by, the guides 61 of the base channel 60. Thus the slider 69 is constrained for rectilinear reciprocating sliding movement along the base channel 60.

The base channel 60 also includes a stop 72 which projects into the path of the slider 69. As seen in Figure 5, this limits the maximum opening movement of the arm 63. The base channel 60 is provided with an aperture 73 between the stop 72 and an adjacent end of the base channel 60 in the path of the slider 69.

The slider 69 carries a screw 74 which is best seen in Figure 7. The screw 74 has an enlarged head 75 which, by rotation of the screw 74, can be moved between the extended position shown in Figure 7 and a retracted position in which the head 75 is spaced upwardly from the position shown in Figure 7.

The purpose of the screw is to provide limited opening of the arm 13. As seen in Figure 6, if the head 75 of the screw 74 is moved to the extended position when the screw 74 is in register with the aperture 73, opening and closing movement of the arm is prevented by engagement of the head 75 in the aperture 73. Movement of the head 75 to the retracted position, however, allows the slider 69 a full range of movement limited only by the stop 72.

In use of the friction stay, the opening window sash (not shown) is mounted in a fixed window frame (not shown) by two friction stays of the kind described above with reference to Figures 5, 6 and 7. The base channel 60 of each stay is mounted on a respective opposite member of the fixed frame and side members of the sash are connected to the arm 63. The linkage 62 allows the window sash to be moved to an open position, in which the linkage is positioned as shown in Figure 5, and a closed position.

In the closed position, the arm 63 and the links 64,65 and 66 are all in register with the base channel 60. A pointed end 76 of the arm 63 projects into a groove 77 provided by an end cap 78 mounted at one end of the base channel 60.

In the closed position, the slider 69 is located adjacent the end cap 78. As the arm 63 moves to the open position, the slider 69 slides along the base channel 60, constrained by the guides 61, until it contacts the stop 72. This provides a stop which prevents further opening movement of the arm 63 and, as described above, the position of this stop 72 is such that it provides maximum opening of the window.

When the screw 74 is aligned with the aperture 73 the arm 63 is in only a partially open position, which may be a position which allows adequate ventilation but prevents ingress or egress through the window. When in this position, the screw 74 can be moved to the extended position in which it engages in the aperture 73 to prevent either opening or closing movement of the window leaf.

It will be appreciated, of course, that this locking of the arm 63 in a limited opening position need not be achieved by engagement of a screw head 75 with an aperture 73. It could be achieved by any other latching means, for example a rotatable or slidable detent may be provided on the slider which engages with the guides at some other part of the base.

The length of the aperture could be increased to extend the aperture towards the end cap so that the arm may be moved between the closed and the limited opening positions with the screw head 75 in the extended position.

Two further forms of stay will now be described with reference to Figures 8 to 18. The basic construction of the two stays is the same in both Figures 8 to 10 (the fourth stay) and in Figures 11 and 12 (the fifth stay).

This construction will now be described.

The stay comprises a channel 110, an arm 111, a longer link 112, a shorter link 113 and an intermediate link 114. The channel is of metal and has a base 115 and parallel upstanding side walls 116. Flanges 117 project inwardly from the edges of the side walls 116 to define a slot 118.

The channel 110 contains a slider 119 whose edges extend into the two opposed grooves defined between the base 115, the side walls 116 and the flange 117, to constrain the slider 119 to sliding movement back and forth along the channel 110. The outer face of the slider 120 projects through the slot 118 and the shorter link 113 and the intermediate link 114 are connected to the slider at spaced points therealong for pivotal movement about parallel axes normal to the base 115. The shorter link 113 is pivotally connected at its other end to one end of the arm 111.

The longer link 112 is connected to the channel 110 for pivotal movement about an axis normal to the base 115 which is fixed relative to the channel 110. The other end of the longer link 112 is pivotally connected to the arm 111 at a point between the ends of the arm. The end of the intermediate link 114 remote from the slider 119 is pivotally connected to the longer link 112 intermediate its ends.

This configuration allows the arm 111 to be moved with pivotal and translational movement relative to the channel, as shown in Figures 8 to 11. During this movement, the arm 11 is guided by the links 112,113,114, and the slider 119 moves from a position adjacent one end of the channel 110 to a position adjacent the other end of the channel 110 where the longer link 112 is connected to the channel 110.

In use, the channel is connected to, for example, a uindow frame and the arm 111 is connected to an associated window leaf. The stay controls the opening and closing of the window leaf into and out of the frame.

The stay shown in the drawings is only one of a large number of stay arrangements which feature a channel and an arm connected by one or more links. It will be appreciated that the invention can be applied to any such arrangement and is not limited to that shown in the drawings. In addition, such stays can be used with other closures such as doors.

Referring now to Figures 8 to 10, in the fourth stay, the slider includes a generally rectangular elongate plate 120 which lies in a plane generally parallel to the plane of the base 115 and is received in the channel, projecting along the channel in the direction of opening movement of the slider 119. The plate is made of a flexible material, such as spring steel, and is bowed upwardly so that its free end engages the under surfaces of the flanges 117.

The end of the plate 121 is provided with two upward projections 121.

The flanges 117 are formed with two cut-outs 122,123.

In use, starting with the arm 111 in a position in which it overlies the channel 110, opening movement of the arF.

11 causes the slider 119 to slide along the channel 110.

The projections 121 on the plate 120 are urged into engagement with the inner surfaces of the flanges 117 and slide along the flanges 117. When the projections 121 reach the first cut-outs 122, the projections extend into the cut-outs 122 and prevent further opening movement of the arm 111. This is the position shown in Figure 8. In this position, further opening movement of the arm 111 is not possible.

If, however, the end of the plate 120 is depressed, for example with a finger, the projections 121 are disengaged from the first cut-outs 122 and opening movement of the arm can continue. However, when the projections 121 reach the second cut-outs 123, the projections once again engage in the cut-outs 123 preventing further opening movement of the arm. This is the position shown in Figure 9.

Again, however, the projections 121 can be pressed out of the cut-outs 123 to allow opening movement of the arm 111 to continue until the plate 120 engages the end of the channel 110. This is the fully open position of the arm illustrated in Figure 10.

Closing movement of the arm 111 causes the projections to ratchet back over the cut-outs 122,123, so not interfering with this closing movement.

Referring next to Figures 11 to 18, as mentioned above, the fifth stay shown in these Figures is identical to that shown in Figures 8 to 10 (except that it is of the other hand). Its construction will not therefore be described in detail.

In this embodiment, the slider 110 is formed with two elongate stop bars 125 best seen in Figures 14A, 14B and 14C. Each stop bar 125 is elongate with flat upper and lower surfaces 126,127 (see Figure 14B) and a V-shaped groove 128 formed along one edge. Adjacent one end, each stop bar 125 is formed with an aperture 129 and ajacent the other end one wall of the V-shaped groove 128 is deformed to provide a projection 130 which effectively closes the groove 128.

The end of the slider is modified as shown in Figures 15A and 15B to provide two lugs 131 projecting from opposite sides of an end of the slider 119. Each lug 131 fits into an aperture 129 on a respective one of the stop bars 125 so that the stop bars 125 are connected to the slider 119.

Thus, each stop bar extends along a respective groove formed between the base 115, a side wall 116 and an associated flange 117. The thickness of each stop bar 125 (i.e. the distance between the upper and lower surfaces 126,127) is less than the width of the associated groove.

In this position, the two V-shaped grooves 128 face each other across the channel 110.

The stop bars 125 carry a push button 132 that is best seen in Figures 13A, 13B and 13C. The push button 132 comprises a plastics body of generally rectangular shape in plan provided with parallel V-section guides 134 extending along respective edges of the body 133. An upper surface of the body 133 is provided with ribs 135.

As best seen in Figure 13C, the guides 134 project into the V-shaped grooves 138 in stop bars 125, so that the push button 132 is carried for sliding movement along the stop bars 125 - united by the projections 130. As seen in Figure 13C, the under-surface of the push button 132 is hollow and receives a U-shaped leaf spring 136 whose ends engage the button 132 and whose base engages the base 115 of the channel 110 under bending tension to force the push button 132, and thus the stop bars 125, out of the channel 110 so that the body 133 of the push button 132 is located in the slot 118 between the channel flanges 117 and so that the stop bars 125 engage the flanges 117.

The flanges 117 of the channel 110 are deformed at a point intermediate their ends to form a pair of downwardly projecting ears 137, as best seen in Figure 18.

The end of the longer link 112 is mounted on the channel 110 via a spacer 138 shown in Figure 16. The spacer 138 is a rectangular block having the same width as the slot 118 provided with a central hole 139 to receive a pivot for the longer link 112. The sides of the spacer 138 are provided with respective ribs 140.

The spacer 138 is mounted towards the end of the channel 110 as shown in Figure 17. The ribs 140 project into the channel grooves for a purpose to be described below.

In use, the stay is mounted in a closure as described above with reference to the drawings. When the arm is in the fully closed position, it overlies the channel 110.

As the arm 111 moves to an open position, the associated stop bars 125 move along the sides of the channel 110 beneath the flanges 117. This opening movement continues until the ends of the stop bars 125 engage the ears 137.

At this point, no further opening movement of the arm 111 is possible. This is the position shown in Figure 11.

If the push button 132 is depressed against the force of the spring 136, the ends of the stop bars 125 move out of engagement with the ears 137 towards the base 115 of the channels 110, so allowing the stop bars 125 to pass beneath the ears 137. In this way, opening movement of the arm 111 can be continued until the arm 111 reaches the fully open position. This position is shown in Figure 12.

Towards the end of the opening movement, the V-shaped grooves 128 in the stop bars 125 engage the ribs 140 on the spacer 128 so allowing the stop bars 125 to pass the spacer 128.

As with the embodiment of Figures 8 to 10, there may be two or more sets of ears to define a number of different restricted opening positions.

It will be appreciated, of course, that the push button 132 need not be formed separately from the stop bars 125.

It could be formed integrally with the stop bars.

Further, the stop bars 125 could be formed integrally with the remainder of the slider 119.

Claims

1. A stay for connecting a closure to an associated frame comprising a channel for connection to one of the parts, an arm for connection to the other of the parts and a linkage connecting the channel to the arm to allow opening and closing movement of the closure out of and into the frame, the linkage including at least one link pivotally connected to a slider received for sliding movement in the channel, a stop member being provided which acts on the slider for limiting the opening movement of the closure relative to the frame, the stop member being manually disengageable for allowing additional opening movement of the closure relative to the frame.

2. A stay according to claim 1 wherein the stop member is carried by the slider, is elongate and is urged by a spring into a position in which the stop member engages a stop on the channel, the stop member being movable against the force of the spring to disengage from said stop.

3. A stay according to claim 2 wherein the stop member comprises a spring strip having inherent flexibility to provide said spring and to urge the strip into said stop engaging position, the spring strip flexing to disengage from said stop.

4. A stay according to claim 3, wherein the channel includes a base, upstanding side walls and flanges projecting inwardly from said side walls to define an elongate slot therebetween the slider sliding in the channel and projecting through the slot to connect to said at least one link, the spring strip lying in a plane generally parallel to the base but flexing upwardly to engage inner surfaces of said flanges, the flanges including at least one stop for engagement with an end of the spring strip for limiting said opening movement, the spring strip being flexible to disengage from said at least one stop to allow said additional opening movement.

5. A stay according to claim 2, wherein a spring is provided between the stop member and the channel.

6. A stay according to claim 5, wherein the stop member includes a button at an end thereof remote from the slider, with the spring being arranged between a button and the channel so that depressing the button disengages the stop member from the stop to allow said additional opening movement.

7. A stay according to claim 6, wherein the channel includes a base, upstanding side walls and flanges projecting inwardly from said side walls to define an elongate slot therebetween, the slider including a body sliding in the channel and projecting through the slot to connect to said at least one link, the stop member comprising two parallel but spaced bars projecting from said body along respective grooves each defined by the base, one side wall and one flange of the channel, each stop bar being narrower than the associated groove and sliding in a path adjacent the associated flange, depression of the button depressing ends of the stop bars remote from the body out of said path towards the base to disengage the stop bar ends from the stop to allow said additional opening movement.

8. A stay according to claim 7, wherein the stop bars include respective elongate grooves which face each other, the button comprising parallel guides which engage said grooves to allow sliding movement of the button relative to the stop bars.

9. A stay according to claim 7 or claim 8, wherein the stop comprises a pair of ears pressed out of respective flanges to project into the associated grooves.

10. A stay according to any one of claims 5 to 9, wherein the spring comprises a U-shaped spring, the free ends of the U-shaped spring engaging the button and the base of said spring engaging the base of the channel.

11. A friction stay according to claim 1, wherein the stop member is releasably connected to the channel in the path of the slider, for engaging the slider to permit only limited opening movement of the arm.

12. A friction stay according to claim 11, wherein the stop member comprises an elongate bar releasably fixed to the channel and extending along the channel parallel to the length of the channel, movement of the slider being limited by engagement of the slider with an end of the bar.

13. A friction stay according to claim 1, wherein the stop member comprises an elongate restrictor bar connected to the slider for movement therewith, the restrictor bar carrying a detent which, then in an operative position, engages the channel to permit only limited opening movement of the arm.

14. A friction stay according to claim 13, wherein the detent is a screw which, when in a retracted position, permits maximum opening movement of the arm but which, when in an extended position, engages the channel to permit only limited opening movement of the arm.

15. A friction stay according to claim 1, wherein the stop member is a latching device carried by the slider which is operable to lock the slider to the channel to permit only limited opening movement of the arm.

16. A friction stay according to claim 15, wherein the stop member is a screw carried by the slider and movable between a retracted position in which maximum opening movement of the arm is permitted and an extended position in which a head of the screw engages the channel to permit only limited opening movement of the arm.

17. A friction stay according to claim 15 or claim 16, wherein the base member includes an aperture into which the head of the screw enters when in the extended position.

18. A friction stay according to any one of claims 1 to 14, wherein the stop member is elongate and extends along the channel between the slider and a stop on the channel to limit the opening movement of the slider, the elongate stop member being manually disengageable for allowing said additional opening movement.

19. A friction stay substantially as hereinbefore described with reference to Figures 1 and 2 or to Figures 3 and 4 or to Figures 5 to 7 or to Figures 8 to 10 or to Figures 11 to 18 of the accompanying drawings.