[0001] This invention relates to improvements in doors and more particularly to improvements
in sliding doors.
[0002] Sliding doors are used for many purposes from small cupboards, to wardrobes, to external
doors, to doors spanning wide distances, such as in garages and doors which can occupy
the whole side of a building, as in a produce store or a bond store. Normally the
arrangement of sliding doors has been in one of several ways. Where there are only
two doors they are conventionally on different tracks so that either door can be slid
across or behind, the face of the other door. Where there are three doors, such as
in a common type of wardrobe, there are normally two tracks and the centre -door is
on the front track and the other two doors are on the rear track. In this arrangement
the central portion of the wardrobe can be moved to either side enabling access to
the centre of the wardrobe and either of the outer doors can be slid inwardly to a
position behind the centre door.
[0003] Where wide spans are required.and particularly where the whole of the area, or any
part of the area, may need to be exposed, it is conventional to provide as many tracks
as there are door components so any individual door member can be moved, at least
in one direction, to expose the area occupied by the door. In such arrangements the
track lengths normally vary and the doors can slide to the inner ends of their tracks
to reach their closed condition and each of the tracks terminate at the same position
at their outer ends so that when the area is fully exposed the door panels are located
one behind the other.
[0004] All such arrangements have difficulties. Firstly, in every arrangement the door panels,
when the door is closed, terminate at different levels and this, asthetically, is
not pleasing.
[0005] Secondly, it is difficult to make a permanent seal between panels as there must be
some form of rubbing seal, at least close to the end of the movement of the door.
In indoor and furniture applications such seals are undesirable as they tend to mar
the surface of the piece of furniture.
[0006] Thirdly, where multiple door panels are being used, there is the expense of having
a large number of tracks and the effective further expense caused by the encroachment
of the tracks into the area to which the door is fitted.
[0007] It is an object of the present invention to provide a sliding door in which these
disadvantages are obviated or minimised.
[0008] It is a further object to provide sliding door assemblies which are relatively cheap
to manufacture, which can readily be fitted and which can operate satisfactorily for
substantial periods of time.
[0009] The invention includes a sliding door having at least two panels and a pair of parallel
track assemblies at both the top and the bottom of the opening into which the panels
are to be located, low friction means associated with, at least, the lower edge of
each door panel, which means are adapted to be received in the track assemblies and
which extend below the lower extremity of each panel, and means whereby the panel
can be moved transversely across the track assemblies.
[0010] Thus, panels can be located in the same track and be flush, while on forward or rearward
pressure one panel can enter another portion of the track assembly and can be moved
longitudinally relative to the other panel or panels.
[0011] The movement between tracks can be effected in one of several ways.
[0012] Firstly, there may be cutouts between two tracks in the assembly and when the low
friction means are in alignment with the cutouts the-panel can be moved forwardly
or rearwardly. In such an arrangement the panels may be spring biased in one direction
so that on the panel reaching a position where the cutouts are aligned with the low
friction means the panel will be moved to a predetermined track.
[0013] In a second form, the track may be of such a section that on pressure the panel will
move up the ramp and enter the second track. In such an arrangement the low friction
means are sprung or are otherwise moveable to permit the effective overall height
of the door to vary.
[0014] In a third form each track assembly is in the form of an inclined plane and each
portion has on its rear surface a plurality of spacers which enables panels to move,
one past the other without the necessity of defined tracks. More specifically, in
this aspect we provide a sliding door having at least two panels and a pair of parallel
track assemblies in the top and the bottom of the opening into which the panels are
to be located wherein the tracks are each in the form of an inclined plane having
means whereby it can be fixed to the opening, the planes being inclined to form an
opening of maximum height at the front of the door and with the height being restricted
at the rear of the door opening, low friction means at the lower edges of the panels,
springloaded low friction means at the upper edges of the panels and spacers on the
rear of each panel and being so arranged as to ensure that contact between panels
is restricted to contact between the spacers and the face of the adjacent panel.
[0015] In a fourth form the track assembly may be separated into two tracks by a spring
loaded stem which extends through a longitudinal slot and which may be moved into
its slot on transverse movement of a panel and which will re-extend .after the panel
has passed thereover.
[0016] The low friction means or guides may be castors or multiple castor assemblies, may
be ball bearings or may simply be blocks of a low friction material such as polytetra-
fluorethylene (P.T.F.E. sold under the Registered Trade Mark TEFLON).
[0017] The section of the track may be modified as desired. Preferably it.is of a section
to closely correspond with the low friction means. For example, if the low friction
means are ball bearings the tracks should be part circular, if blocks of P.T.F.E.
square or rectangular, assuming the blocks are this shape and if castors, normally
rectangular.
[0018] In order that the invention may be more readily understood and put into practice
we shall describe several embodiments of the invention as applied to door tracks and
various possible modifications of these. Reference will be made to the accompanying
drawings in which:-
Fig. 1 is a partly sectional, partly broken perspective showing one particular form
of door and track assembly made in accordance with the invention;
Fig. 2 is a section of the assembly showing the arrangement of low friction means;
Fig. 3 is a perspective of a lower track assembly of a type similar to that shown
in Fig. 1 but of different construction;
Figs. 4, 5, 6, and 7 are sections through various profiles of tracks which can be
used with this or other embodiments of the invention;
Figs 8, 9, 10 and 11 are partial sections of a further embodiment of the invention
showing diagramatically the manner of operation of the door of the invention;
Fig. 12 is a section along line 12-12 of Fig. 8 showing the arrangement where the
door panels are in their forward, closed orientation;
Fig. 13 is a section along line 13-13 of Fig. 10 showing two doors when located one
behind the other;
Fig. 14 is a view along line 14-14 of Fig. 13 showing the arrangement of the upper
low friction means;
Fig. 15 is a perspective view of a low friction roller used as a spacer between adjacent
door panels;
Fig. 16 is-a broken view of a roller similar to that of the type illustrated in Fig.
15 but which is one of a group of rollers located along the length of a strip;
Fig. 17 is an alternative form of track adapted to permit the face of the door to
terminate flush with the outer flange of the track;
Fig. 18 is a sectional end elevation showing a still further embodiment of the device;
Fig. 19 is a front elevation partly broken away showing a door having the arrangement
of Fig. 18;
Fig..20 shows an alternate form of track which can be useful in some applications;
and
Fig. 21 shows an arrangement where at least one of the panels can be rotatable to
permit, selectively, the faces of the panel to be outwardly directed.
[0019] The track assembly of the invention is applicable to many applications from small
sliding door cupboards, such as medicine chests and kitchen cupboards, through a wide
range of articles such as domestic wardrobes and domestic and industrial cupboards
and can also be applicable for application to sliding doors from relatively small
doors, such as would be used domestically to large indistrial doors which may have
to be motorised. It can also be used, for-example, for chalk boards and room dividers.
[0020] Turning now to Fig. 1, we shall, for simplicity, refer to the area being enclosed
by the doors, area 10, as a cupboard, which cupboard may be provided with a floor
11 and a top member 12. Connected to the floor 11 and the top member 12 there are
track assemblies 13 which can be identical and which, as illustrated in this figure,
would be made of extruded plastics material or an extruded metal such as aluminium,
but could be fabricated in any other way. Each of these track assemblies have two
tracks 14,15 which run the length of the assembly and which are so spaced as to permit,
as will be described hereinafter, a door panel to be located in each assembly with
the panels being able to pass. Between the tracks 14,15 there are a number of cutouts
16 which are at a predetermined spacing, as will be described hereinafter. Each panel
17,17' has a height slightly less than the spacing between the tracks or, more specifically,
between the flanges 18, 18', 18", being the flanges on each side and centrally of
the tracks.
[0021] The door panels are provided with low friction means 19 at their lower edges which
low friction means are complimentary to the track formation. As illustrated, these
low friction means can be considered to be simply more or less spherical plastic members
which extend below the lower surface of the panel or, alternatively, they could be
single balls rotatably mounted in carriers or they could be ball bearings or any other
required form of low friction device. The spacing of these along the width of the
underside of the panel is the same as the spacing between the cutouts 16 in the track
assembly. In their upper surface, as illustrated, the panels have spring loaded low
friction means 20 which have low friction heads 21 which are connected to a shaft
22 which passes through a socket 23 and into a bore 24 in the door panel. Mounted
about the shaft 22 and abutting the underside of the and the floor of the socket 23
there. is an helical compression spring 25 which maintains pressure on the head 21
against the tracks 14,15. In order to maintain the low friction means 18 when the
door is removed we provide & lock nut 26 which controls the available outward movement
of the low friction member.
[0022] This arrangement, as with the low friction member 19, is purely exemplary as it would
be possible to provide many alternative forms of upper connection which would operate
satisfactorily.
[0023] It is preferred that means be provided whereby total overall height of the door can
vary to enable the door to be located after the track assemblies are positioned and
affixed to the cupboard opening, although it'would be possible to locate the assembly
as a whole and then affix the track assemblies at one end, move the panels to a position
over the fixing and affix the track assemblies at the other end. This would, however,
not be completely satisfactory.
[0024] As we have previously indicated, the low friction members 19 are spaced at distances
equal to the spacing of the cutouts 16 and, similarly, the spacing of the low friction
means 20 is such that these are also equal to the spacing between the the cutouts
on the upper track assembly.
[0025] The operation of the door of the present invention will be described more fully in
relation to Figs.'8 to 11 which relate-to an alternative embodiment of the door but,
briefly, we provide a minimum of two panels, but normally three or more panels. The
total number and width of the panel= are such that all of the panels can be located
in one of the tracks, in this case track 14, and when so located are closely abutting
and are flush surfaced. This differs from previous conventional sliding doors where
if, say, three doors were used, two would lie in one track, normally the rear track,
and one in the other track and the panels can then be moved so that the single panel
in one track can overlie or lie behind either of the other two panels whilst either
of the other two panels can be brought in behind or in front of the single panel to
thereby permit, at any time, accessibility to approximately one-third of the area
of the opening of the cupboard.
[0026] In the arrangement of our invention, where three panels are used, each panel can
be moved from its flush position to assume a position behind its adjacent or
.one of its adjacent panels. This is achieved as follows. The low friction means 19,20
are, when the panels are in alignment, directly in line with the cutouts 16 and thus
rearward pressure on any one panel will cause it to pass rearwardly through the cutout
16 until it is received in the other track, in this case track 15. As there is sufficient
spacing between the tracks 14,15 to permit movement of the doors, the door can then
be slid along the track 15 to a position behind the, or one, adjacent, panel. When
it is required to close the door it is only necessary to move the panel to its original
position when the low friction means are again in alignment with the cutout portions
16 so the panel can move forward and present a fully flush surface. We do prefer,
although this is not illustrated .in the particular embodiment, to spring load the
panels forwardly so that when they reach their required position they are automatically
drawn into the forward track 14.
[0027] It will be seen that this arrangement permits any number of panels to be located
in one of two tracks and as the number of panels increases so access to approximately
one-half the opening can be obtained at any time.
[0028] . The embodiment shown in Fig. 3 is simply a modification of that of Figs. 1 and
2 in that there are still a pair of tracks 27,28 which are spaced by upstanding members
29, thereby leaving recesses 30 which are effectively identical to the cutouts 16.
This particular embodiment, which may be extruded or which can be formed by placing
wooden laths on a flat surface, is particularly suitable for use with, say, roller
bearings. In this embodiment, together with each of the other embodiments if so required
both the upper and the lower low friction means can be spring loaded.
[0029] In each of these embodiments, if it is required to lock the panels, it is only necessary
to ensure' that. the track assembly extends slightly further than is necessary in
one direction and by simply causing the panels to move slightly in this direction,
after they have passed through the cutouts 16 or the recesses 30 and are flush to
then locate the panels. In this case the low friction members will no longer be in
alignment with the cutouts or recesses, transverse movement cannot be obtained and
the opening is locked.
[0030] It is preferable to provide a spring bias against which to move the panels as this
will ensure that they are returned to. their required position when the locking is
released and the lock may be either in the form of a member which occupies the space
opened at the end away from which the panels have been moved or, say, a locking pin
which enters the track behind the panel and prevents movement there along. Again,
these are only exemplary and many different forms of lock could readily be achieved
once the panels have moved away from alignment with the cutouts and recesses.
[0031] The tracks of Figs. 4 to 6 have a great deal in common with those of.Figs. 1 and
2 but, in this case, instead of providing the cutouts 16 or the recesses 30 we work
on the compressability of the springs 25 to enable the panels to be moved from one
track to the other.
[0032] Each of these extrusions has tracks 31 and 32 which are so formed that the total
height of the doorway above these tracks is greater than it is in the intermediate
position, and such that when the door is moved transversely the springs 25 are compressed
and when they go over the minimum height portion they tend to be released and relieve
their tension, thus providing energy to push the panel towards the other track.
[0033] In this embodiment it will be appreciated chat the panels can move from track to
track in any position, provided this is not obstructed by part of another panel so,
we prefer, as will be described hereinafter, to provide low friction spacer means
to ensure that panels do not scrape one along the other when they are being moved
from track to track.
[0034] The extrusion of Fiq. 5 is effectively identical to that of Fig. 4 but the extrusion
is modified in having rectangular recesses which are adapted to receive roller bearings
rather than being part cylindrical to receive balls or plastic low friction means.
[0035] The embodiment in Fig. 6 varies in that the movement in one direction is gradual
because of the location of the ramp 34 and thus there is a self closing tendancy when
moving from track 32,to track 31 once the high peak has been passed. Again, in this
particular form we illustrate recesses 33 but the particular configuration can be
used with any other form of low friction means.
[0036] Fig. 7 is, to all intents, practically identical to Fig. 4 but whereas the extrusion
of Fig.'4 could well be of a plastics material that of Fig. 7 is more suitable for
a metal having a higher strength and thus can have narrower wall thickness.
[0037] Figs. 8 to 11 illustrate the operation of a different embodiment of the invention
which is similar to the operation of an embodiment using profiles of any one of Figs.
4 to 7. Generally, in this case, we have a cupboard 40 which has three panels 41,
41', 41". In this case, as will be described hereinafter, the low friction means 42
are mounted on the rear of the door panels and also mounted on the rear of the door
panels are low friction spacer means 43 which permit the face of one panel to run
behind the rear of an adjacent panel with no damage to the panel face.
[0038] The particular embodiment uses a sloping profile track, as will be described hereinafter,
but the operation would be the same for any one of the profiles of Figs. 4 to 7. If
a panel is to be moved it is wholly or partially moved transversely rearwardly and
then slid in the required direction. Thus, it will be seen that the panel 41' of Fig.
8 can be moved rearwardly and then can be moved along behind panel 41 with the contact
between the two panels being restricted to the low friction spacer means. This movement
can continue until the centre third of the cupboard is completely exposed and then,
if required, the panel 41' can simply be moved in the opposite direction until it
clears the spacer means 43 at which time it tends to move forwardly and finally to
assume the condition illustrated in Fig. 8. To demonstrate the invention, however,
we illustrate, in Fig. 10 the simplicity of simply moving panel 41 to the position
originally occupied by panel 41' and when panel 41 reaches this position panel 41'
will simply move forwardly to provide the original flush surface but with the panels
in different orientations.
[0039] In order to more fully describe the arrangement of this particular embodiment reference
will be made to Figs. 12 to 16.
[0040] Fig. 12 is a section along line 12-12 of Fig. 8 and shows the cupboard 40 to which
there is connected the tracks 44,45 which, as can be seen, are mirror images and each
of which has a continuous track surface 46,47 respectively, which. surfaces are so
arranged that they slope upwardly and downwardly respectively as they approach the
opening to the cupboard. Thus, the total width of the opening increases from the rear
of the track to the front of the track.
[0041] Connected to the lower edges of the doors there are low friction means 48 which comprises
a compartment 49 which is open at the front 50 and in which there is located a low
friction member 51 which comprised a leg 52 having on its lower end a ball' receiving
member 53 and a ball 54. The outer face 55 of the leg member is provided with serrations
as is the adjacent inner face 56 of the compartment 49, the arrangement being such
that when the container is screwed to the rear of the panel, as by screws 57, the
leg 52 is locked into a position by the co-operating serrations. The upper low friction
means 60 also comprises an open fronted compartment 61 in which 'there is, again,
provided a low friction assembly 62 comprising an upwardly directed arm 63, a ball
receiving member 64 and a ball 65. In this case the arm 63 is constrained to move
in an inner compartment bounded by side walls 66 and in which there is located an
helical compression spring 67. Again, when the compartment 61 is fitted to the rear
of the panel, as by a screw through apertures 68, the arm and its associated spring
are retained. Thus, depending upon the height of the door, so the effective length
of the leg 52 can be altered and the compression in the spring 67 can be varied for
most effective operation. Also located on the back of the door panels there are spacers
70 which may take one of two forms. In the first of these, illustrated in Fig. 15,
the spacer comprises a roller 71 of a low friction material which is carried by a
pair of arms 72 which are located on a body 73, the assembly being provided with a
spike 74 by means of which it can be fitted to the door panel.
[0042] In an alternative form, illustrated in Fig. 16, a similar roller 75 is rotatably
mounted in similar arms 76 which themselves are connected to a strip 77.which may
extend the width of the panel and which may be provided with the required number of
spacers. This strip may have apertures 78 which permit fixing.
[0043] It will be seen that in this form of door the door panels are located in what is,
effectively, an inclined plane and will normally move forwardly so that the panel
occupies the open front of the cupboard. It can be shown that this forward position
is the position of least energy as the potential energy of the spring is at its lowest
level. If a panel is located partially or wholly behind a panel in the forward position,
as is the case of panel 41' in Fig. 9, then it will tend to assume the position illustrated
in Fig. 9 but a simple sidewise movement will readily cause it to assume the condition
shown in Fig. 10, that is with the panel open. Because the rollers 71 and 75 of the
spacers can be made of a relatively soft and low friction material, such as nylon,
there is little or no marking on the contacted panel face even after a large number
of operations.
[0044] We have also found that this arrangement is cheap and easy to produce and the doors
formed in this way are simple to operate.
[0045] The track assembly of Fig. 17 is very similar to that of Figs. 12 and 13 but differs
in that at the end of the inclined plane there is a turned up portion 81 which is
spaced from the forward flange 82. This turned up portion 81 acts as a stop.for the
ball, say 54, which means that the edge of the ball receiving member 83 no longer
contacts the forward flange 84 and thus the door panel can be arranged to finish flush
with the flange 82, thus removing the necessity for a plinth or the like at the lower
end of the cupboard. Otherwise the operation of this embodiment is identical to that
of the embodiment illustrated in Figs. 12 and 13.
[0046] The embodiment of Figs. 18 and 19 provides a very similar type of operation as does
the previous embodiment but instead of having balls which can rotate in any direction
we provide two sets of rollers which rotate about axes at right angles. The first
rollers 90 are connected to the . underside of the panels 91 and, effectively, extend
across the width of the panels. The transverse panels 92 lie across the track assembly
93 and are sufficiently closely spaced so that there is always a plurality of them
beneath each roller 90 so that the panel is at all times stable. In this case, when
the panel is being opened or closed the roller 90 is effectively stationary whilst
the rollers 92 rotate, whereas when the panel is being moved transversely, that is
into a position where it can be opened or closed then the roller 90 rotates.
[0047] Fig. 20 is a sectional elevation of a form of track which can be used with any of
the previous embodiments. In this case, as illustrated, the track comprises an inclined
plane 95 although it does not have to be inclined and passing therethrough longitudinally
is an upwardly directed stem 96 which is connected in the form of an inverted T to
the base 97 which, in turn, is acted upon by compression springs 98 located in a container
or recess 99. In this form of the invention, when the panel is moved rearwardly the
low friction device causes depression of the stem 96 and the panel passes into what
is effectively a second track and may be moved along this track.. The tension of the
spring 98 may be such as to provide little force against depression of the stem 96
but, nevertheless, when the panel is moving will tend to retain the panel in the area
of the track bounded by the stem at the forward side but, on the panel stopping or'being
slightly drawn forward, the stem will again be moved downwardly and the panel will
be able to move forwardly, largely under the frictional effect from the inclined plane
and the tension spring in the upper low friction member.
[0048] Fig. 21 shows an embodiment which is most suitable to the arrangement of Figs. 1
to 3 but is still applicable to the other embodiments. In this case we wish to provide
a panel 100 which can be rotated about a central axis to provide either a plain surface,
not illustrated, or, say, a mirrored surface 101. Assuming the arrangement is similar
to that of Fig. 1 we extend the cutouts 16 at 102 and 103 so they pass completely
across the width of the track assembly. The panel 100 can be provided with a central
pivot which can be engaged and the low friction means both top and bottom, although
only the top low friction means 104 have been illustrated, pass through the expanded
cutout portions to permit rotation about 180
0. At the termination of rotation the low friction means 104 can re-enter the opposite
extended cutout portion.102 and the panel becomes located in its original condition
but with its opposite face being outwardly directed.
[0049] Also, should we desire we can make the width of the total track assembly greater
than that which is necessary for receiving two door panels and in this way can stack
doors to provide greater percentage opening.
[0050] Should we desire to lock the door of this embodiment we can either lock each panel,
force the panels together and hold them in this orientation or form the edges of the
panels so they can interengage.
1. A sliding door having at least two panels (17,17') and a pair of parallel track
assemblies (13) at both the top and the bottom of the opening into which the panels
are to be located, low friction means (19) associated with, at least, the lower edge
of each door panel, which means are adapted to be received in the track assemblies
(13) and which extend below the lower extremity of each panel, and means (16) whereby
the panel can be moved transversely across the track assemblies.
2. A door as claimed in claim 1 wherein there are cutouts (16) between the two tracks
(14,15) in the track assemblies (13) which cutouts have a depth substantially equal
to the depth of the track which cutouts are spaced at distances equal to the spacing
of the low friction means (19).
3. A door as claimed in claim 2 wherein there are low friction means (20) on the upper
edge of each panel (17).
4. A door as claimed in claim 2 wherein the cutouts (16) are so located that each
panel can be moved to one track and when so moved, they abut and close the opening.
5. A door as claimed in claim 1 wherein the low friction means (20) on at least one
edge of the door are sprung (25) and the portion of the track assembly between the
two tracks is so shaped as to permit the door to ride over this portion from one track
(31) to the other (32).
6. A door as claimed in claim 5 wherein the portion between the two tracks is arcuate
or of saw-tooth form.
7. A door as claimed in claim 1 wherein there is provided a longitudinal stem (96)
extending through a slot in the track assembly, (95) the stem being spring loaded
(98) so that, on contact by the low friction means it can be displaced downwardly
to permit a door panel to move thereover.
8. A door as claimed in claim 1 wherein the door panels can be displaced longitudinally
so the low friction means (19,20) are displaced from the cutouts (16) to thereby prevent
transverse movement of the panels.
9. A door as claimed in claim 8 wherein there is a moveable stop at one side of the
door and a lockable stop at the other.
10. A door as claimed in claim 1 wherein at least one door panel (100) has a central
extension at its top and bottom edges which enter a track and two low friction means
(104), one on either side, and wherein the cutouts (16) are extended (102,103) to
enable rotation of the panel about the central extension.
11. A door as claimed in claim 1 wherein the track assemblies (44) are each in the
form of an inclined plane having means whereby it can be fixed to the opening, the
planes being inclined to form an opening of maximum height at the front of the door
and with the height being restricted at the rear of the door opening, low friction
means (48) at the lower edges of the panels, spring loaded low friction means (60)
at the upper edges of the panels and spacers (70) on the rear of each panel and being
so arranged as to ensure that contact between panels is restricted to contact between
the spacers (70) and the face of the adjacent panel.
12. A door as claimed in claim 11 wherein the low friction means (48) at the lower
edges of the panels are connected to the rear of the panels and comprise a body, (49)
a leg (52) extending from the body which leg has a low friction means (54) on its
lower end, the leg and body having co-acting parts (55,56) whereby the extension of
the leg can be varied.
13. A door as claimed in claim 12 wherein the leg has serrations (55) on one surface
which can co-act with serrations (56) on the body, the arrangement being that when
the two members (49,52) interengage and the body is fitted to the panel the length
of the extension is fixed.
14. A door as claimed in claim 11 wherein the low friction means (60) at the upper
edges of the panels are connected to the rear of the panels and comprise a body (61),
an arm (.63) extending from the body, which arm has a low friction means (65) on its
lower end, the arm and body being interconnected by a compression spring (67) whereby
the arm is biased outwardly from the body.
15. A door as claimed in claim 11 wherein the spacers (70) are low friction means
extending rearwardly from the rear of the panels for a distance greater than the extension
of any other part of the door.
16. A door as claimed in claim 15 wherein the spacers are rollers (71) adapted to
be fitted to the panels.
17. A door as claimed in claim 16 wherein the rollers (75) are fitted along a strip'(77)
adapted to be fitted to the rear of a door panel.
18. A door as claimed in claim 11 wherein at least the lower track (80) has adjacent
its outer end a longitudinal upward return (81) .of such dimension as to retain the
low friction means and to provide them with a running surface whilst restraining them
from reaching the front of the track.
19. A door as claimed in claim 18 wherein there is an upward flange (82) at the front
of the track (80)and wherein the door, when in its forward position, terminates behind
this.
20. A sliding door as claimed in claim 1 wherein each panel has a roller (90) or rollers
extending longitudinally under its lower edge and the lower track (93) is in the form
of an outwardly and downwardly directed inclined plane having a plurality of rollers
(92) transverse to the longitudinal axis and extending across the width of the track,
the rollers (92) having a spacing such as to stably receive the roller(s) (90) of
each panel.
21. A sliding door as claimed in claim 11 wherein means are provided to lock the panels
when they lie in a single plane.
22. A sliding door as claimed in claim 21 wherein the means comprises moving the panels
together and preventing movement,of one end panel.
23. A sliding door as claimed in claim 11 wherein the side edges of the panels are
formed to interengage and each panel is provided with a locking means so if it should
be an end panel it can be retained in position to restrain movement by the other panels.
24. A sliding door as claimed in claim 1 wherein the width of the track is sufficient
to receive a plurality of door panels, one behind the other.