Counterbalanced Windows For Curtain Wall System

Abstract

A curtain wall system for buildings using a wooden frame in which fixed and movable panels are mounted, and provided with exterior coverings of extruded plastic applied to cover the exposed surfaces of the wooden frame. A counterbalanced double-glazed double-hung window forms a part of the system, and incorporates a novel counterbalanced supporting structure.

Description

The present invention relates to a curtain wall system for buildings and in particular to a curtain wall system including movable and fixed window sections and sections with opaque panels. The present invention also relates to components for use in curtain wall systems.

The curtain wall system of the present invention includes a wooden frame, for example of Canadian Red Cedar, in which movable and fixed windows and opaque panels may be inserted to provide the desired configuration of windows and wall. In accordance with an important aspect of the present invention, at least the outer surfaces of the wooden frame may be entirely clad in a plastics material such as vinyl (polyvinyl chloride), and preferably all exposed surfaces of the wooden frame are clad in such plastic extrusions. The advantages of such cladding on a wooden frame are immediately obvious to those skilled in the art. The plastics which are used for cladding the frame may be produced in a range of colors to satisfy the aesthetic demands of the building design, and such surfaces do not require painting or other maintenance throughout the life of the building. The finished appearance of the window structure is also considerably enhanced by such cladding, an element of building constructions which has not received its fair share of attention in the design of buildings up to the present.

The plastics extrusions applied to the window frame structure in accordance with the invention are coordinated so that a minimum number of different extrusions are required, and so that all possible variations of curtain wall construction may be accommodated with a minimum of different extrusions.

The present invention also encompasses novel window structures which may be used in curtain wall systems. In particular a novel form of double-hung window having improved hardware is provided. A simple and reliable counterbalanced double-hung window system is an important aspect of the present disclosure, as will appear hereinbelow.

In the accompanying drawings which illustrate a curtain wall system constructed in accordance with the present invention and details of such a system;

FIG. 1 is a perspective elevation of a building incorporating a curtain wall system of the present invention;

FIG. 2 is a cross section through a double-glazed double-hung window unit in a curtain wall system of the present invention;

FIG. 3 is a cross section through a double-glazed sliding-type window complete with insect screen as utilized in the system of the present invention;

FIG. 4 is a fragmentary cross section on the line IV--IV of FIG. 2;

FIG. 5 is a cross section on the line V--V of FIG. 3;

FIG. 6 is a cross section through the upper header of a double-glazed slider-type window with a fixed double-glazed window of the "Thermopane" or "Twindow" type mounted above the header;

FIG. 7 is a cross section through a portion of the window system constructed in accordance with the present invention showing at the top the sill of a double-glazed double-hung window beneath which a fixed wall panel is shown inserted in the frame;

FIG. 8 illustrates a cross section through a fixed double-glazed section of window of the so-called "Thermopane" type with all exposed surfaces of the wooden frame clad in plastics extrusions;

FIG. 9 is a section through a curtain wall system of the present invention showing its attachment to a concrete slab floor structure of a building on which the curtain wall system is used;

FIG. 10 is an elevation, partly in section, illustrating the operating mechanism of a double-glazed double-hung window system of the present invention for use in the curtain wall system;

FIG. 11 is a cross section on the line XI--XI of FIG. 10;

FIG. 12 is a cross section on the line XII--XII of FIG. 10;

FIG. 13 is a cross section through a double-hung window of the system of the present invention illustrating a novel feature thereof;

FIG. 14 is a section on the line XIV--XIV of FIG. 13;

FIG. 15 is a section on the line XV--XV of FIG. 13, and

FIG. 16 is a horizontal section through a portion of the window system of the present invention.

Referring to FIG. 1, there is shown in perspective a building in which the curtain wall window system of the present invention has been installed. The building indicated generally at 10 is provided with a front curtain wall 11 constructed in accordance with the present invention. As illustrated this curtain wall is made up of a plurality of window and opaque wall units including opaque panels 12, double-hung window units 13, fixed glazed window units 14 and sliding window units 15. The manner in which each of the movable and fixed elements of the window system of the present invention is constructed and is integrated with the overall frame of the window system will be detailed in connection with the remaining figures of the drawings. It should be noted that all vertical and horizontal frame members of the window system are preferably, in accordance with the present invention, formed of wood, such as Canadian Red Cedar, and all exposed exterior surfaces of the wooden frame are clad in extruded plastics' mouldings and preferably vinyl extrusions. In accordance with the invention such extrusions are manufactured separately from the window frames and are applied thereto in the manner specifically detailed hereinafter.

FIG. 2 is a cross section through a double-glazed double-hung window unit installed in the curtain wall system of the present invention. The window unit is shown as consisting of the sill member 20, a header member 21 and a jamb 22. The header 21 is provided with a pair of header tracks 22A and 23 which include weather strips 24 which are adapted to form a weathertight seal with the upper rails 25 affixed to the upper inner and outer glass panes 26 and 27. The lower edges of the upper panes 26 and 27 are provided with meeting rails 28, each of which includes a weatherstrip 29 and engages against a like meeting rail 30 affixed to each of the lower panes 31 and 32. The lower edges of the panes 31 and 32 are fitted with a lower rail 33 which grips the lower pane 31 or 32 and is provided with a lower channel 34 adapted to be contacted by a weatherstrip 35 mounted on the sealing flange 36. Sealing flanges 36 are mounted on flange carrying members 37 and 38 which snap into grooves provided in sill track 39. Sill track 39 is held to the wooden sill 20 by means of the barbed flange 40 engaged in the slot 41 in the wooden sill 20. Additionally the sill track 39 may be fastened at its outer edge to the sill 20 by any suitable means such as by a nail or other fastener driven through one of the slots in which the member 38 is snapped.

The sill 20 is further provided in accordance with the present invention with a sill-covering extrusion 42 having an upper surface 43, a front surface 44 and a lower notch-engaging portion 45 which is received within a channel in the lower surface of the wooden sill 20. The sill-covering extrusion 42 is held in place by the channel-engaging portion 45 and by the sill track 39 overlying the sill-covering extrusion 42.

The header 21 is provided with a header-covering extrusion 46 having a flange 47 engaged in a slot 48 in the header 21 and provided with a drip cap 49 and a snap-in flange 50 which is engaged in a slot provided in the header track 23. The header extrusion covering 46 is thus adapted to be snapped on to the wooden header 21 of a window to provide a weatherproof covering therefor.

Similarly the jamb 22 is provided with a jamb covering 51, the detail of which may be seen more clearly in FIG. 4, which jamb covering 51 engages with the jamb track system 52 in a manner which may more clearly be seen in FIG. 4.

FIG. 3 is a perspective view of a double-glazed sliding-type window for use in the curtain wall system of the present invention, the view being partly in section to illustrate the details of construction. As before a sill member 20, for example, of Canadian Red Cedar, is provided together with a header 21 and a jamb 22. A sill-covering extrusion 42 identical with the extrusion 42 of FIG. 2 is provided covering the sill 20. Similarly a header-covering extrusion 46' similar to the extrusion 46 of FIG. 2 is provided as before. It will be noted that the header-covering extrusion 46' of FIG. 3 is not identical with the extrusion 46 of FIG. 2 to account for the differences in structure between a sliding-type window and a double-hung window. A sill track 53 is mounted over the sill-covering extrusion 42 and is provided with slots in which glass panes such as 54 and 55 may slide. As before the sill track 53 is held in the slot 41 in the sill by a barbed flange 40. The sill track 53 is not of uniform depth so that the sill 20 may have an ample slope for drainage and at the same time the bottoms of the slots in the sill track 53 all lie in the same horizontal plane for proper operation of the sliding window panes 54 and 55. The window panes 54 and 55 are provided with side rails such as, for example, the side rail 56 which engages with a jamb track 57 in the jamb 22 as shown more completely in FIG. 5. The sliding window of FIG. 3 is further shown to include an insect screen 58 having a frame 59 retained within channels provided in the sill track 53 and the header system 60.

The header system 60 which is embodied in my prior application Ser. No. 11837/67 is received within a large recess in the header 21 and consists of a central box-shaped extrusion 61 and a pair of track-carrying members 62 and 63. Mounted above the members 62 and 63 are elastic fillers 64 and 65 which urge the members 62 and 63 away from the base of the box member 61. The members 62 and 63 are retained within the box member 61 by overlapping flanges on the respective outer edges of the members 62 and 63. The channels in the lower faces of the members 62 and 63 are provided with weatherstrips 66 to provide a seal with the glass panes 54 and 55. The box member 61 is also provided with external flanges 67 for interlocking engagement with header-covering extrusions such as 46'.

As shown in FIG. 2, the jamb 22 is provided with jamb-covering extrusions which interlock with the jamb tracks 57 in the jambs 22 to provide a completely plastics-covered window frame.

FIG. 4 is a section on the line IV--IV of FIG. 2. The jamb 22 shown in FIG. 4 will immediately be recognized as the same construction as the header 21 of FIG. 3. Not only is the wooden member 22 identical, but the box member 61, the track members 62 and 63 are also identical to the members bearing these numbers in FIG. 3. Thus one of the advantages of a system such as that of the present invention is apparent, the jamb structure of a double-hung window is identical with the header structure of a sliding window. The header-covering extrusion 46 with the drip cap 49 removed becomes the jamb covering 46 of FIG. 4. As before the member 46 of FIG. 4 is held in place by a flange 48 retained in a slot 49 in the jamb 22 and by the snapping together of the flange 66 of the member 46 and the flange 67 of the box member 61. It will be noted that the box member 61 is provided with a pair of flanges 67 so that plastics extrusions such as vinyl can be applied to both the inner and outer exposed faces of the frame member 22 to provide a complete covering of all exposed faces of the jamb 22.

FIG. 5 is a section on the line V--V of FIG. 3 and is a horizontal section through a double-glazed sliding window system of the present invention which window is provided with an insect screen as well as snap-on plastics extrusions covering all exposed faces of the frame. As before jamb tracks 57 are engaged by side rails 56 to provide a weather-stripped joint between the sliding pane and the jamb 22. An insect screen 58 having a frame 59 is provided for preventing the ingress of undesirable insects into the interior of the building when the window is open. The panes 54 and 55 are provided with meeting rails identical to the meeting rails 28 and 29 utilized in the double-hung window of FIG. 2. These meeting rails are provided with weatherstrips and are designed to overlap one another to provide an effective seal at the joint between the pairs of sliding glass panes when the window is closed. It should be particularly noted that the sliding window of FIG. 5 is provided with snap-on plastics extrusions 66 and 67 completely covering those portions of the frame 22 which are exposed when the completed window unit is mounted in the curtain wall system of the invention.

FIG. 6 is a vertical section through a header member of the present invention with a sliding window mounted beneath the header and a fixed double-glazed "Termopane" unit mounted above the header, in a curtain wall system. The header 21, preferably of wood such as Canadian Red Cedar, is provided with a box member 61 and track members 62 and 63 as well as resilient foam members 64 and 65 as previously shown in FIG. 3. A header-covering extrusion 70 with a drip cap 71 is provided on the exterior of the header 21, and a header-covering extrusion 72 is provided on the inner side of the header 21. The extrusions 70 and 72 are of the snap-on type engaging suitable slots in the box member 61 and the extrusions 72 is provided with a flange 73 engaging a slot 74 in the header 21. The extrusion 70 is provided with a second flange 75 engaging a slot in the extrusion 76 associated with the fixed double-glazed "Thermopane" unit 77. An extrusion 78 held to the header 21 by any suitable means such as by nailing through the flange 79 grips the fixed window unit 77 on one side, and an extruded member 80 held to the header member 21 by suitable means, such as screw 81, grips the window unit 77 on the other side. An elastomeric sealant 82 is provided between the fixed window member 77 and the extrusions 78 and 80 to provide a weathertight seal therebetween. Additionally elastomeric sealant will be used throughout the curtain wall system of the present invention for sealing those joints between either plastics extrusions or window units or opaque panels which require a suitable sealant to make the exterior of the building absolutely weathertight.

FIG. 7 is a cross section through a portion of a curtain wall system of the present invention including a sill member 20 fitted with a sill-covering extrusion 42 covering the external portion of the sill 20, over which a sill track 39 for a double-hung window (the glass portions of which are not shown) is mounted. The interior surface of the sill member 20 is covered by an interior sill snap-on covering 83 held in place by a flange of the sill track 39 and by a flange 84 engaged in the slot 85 of the sill member 20. Beneath the sill member 20 a fixed panel of insulating or like material 86 is fitted in the curtain wall system of the present invention. The fixed panel 86 may, for example, consist of an outer hard plastic sheet such as "Formica" 87, a central portion of insulation such as expanded polystyrene known as "styrofoam" 88, and an inner surface panel 89 which may be identical with the panel 87 or may alternatively, for example, be a suitable interior material such as wood panelling or the like. The fixed panel 86, it will also be observed, is mounted above a second sill member 20A identical to the sill member 20, which sill member 20A is provided with inner and outer snap-on plastics coverings 42 and 83 held in place as before. The fixed panel 86 is held in place by the extrusions 90, 91 and 92 bearing against the outer surface thereof and by the extrusions 93, 94 and 95 bearing against the inner surfaces thereof. The extrusion 90 is fastened to the lower surface of the sill 20 by means of a second extrusion 96 interlocked with the sill-covering extrusion 42 by means of an interlocking flange 97 projecting into the channel 45 of the sill-covering extrusion 42. The extrusion 96 is also held in place by means of a fastener 98 driven into the lower surface of sill member 20. A separate extrusion 99 is held to the sill member 20A by a fastener 100 and by the fixed panel 86, and holds the extrusion 92, which is identical in cross section with the extrusion 90 in place against the fixed panel 86. As before a suitable elastomeric sealant 82 seals the joint between the extrusions 90, 91 and 92 and the fixed panel 86. On the interior of the fixed panel 86 extrusions 93, 94 and 95 which are also all of the same cross section are held to the frame members by suitable fastening such as the screw 101 and serve to maintain the panel 86 in place.

It will be noted that beneath the sill 20A is a frame member 102 resting upon masonry 103 with a metal sill extension 104 serving to cover the joint between the sill member 20A and the exterior finish masonry 105 of the building. A suitable sealant 106 is provided behind the metal member 104 to seal the joint between the metal member and the frame member 102.

FIG. 8 is a cross section through a portion of a curtain wall system of the present invention in which the frame members enclose a fixed double-glazed window unit 107 of the type known as a "Thermopane" unit. As before a header 108 and a sill 109 are clad in snap-on plastics extrusions 110 and 111 which serve to cover the exterior of the header 108 and the sill 109 and, the interior faces of the header 108 and the sill 109 may also optionally be clad in snap-on extrusions 112 and 113. The fixed double-glazed window 107 is held in place as in FIG. 7 by extrusions 90, 91 and 92 on the exterior thereof, all of which are of identical cross section, and on the interior is held in place by extrusions 93, 94 and 95, all of which are of identical cross section. The upper extrusion 90 on the outer surface of the window 107 is held by an extrusion 114 which may be fastened to the header 108 by any suitable means such as by nailing, which extrusion 114 also serves to hold the inner flange of the snap-on header covering 110. Similarily an extrusion 115 mounted on the sill covering 111 serves to hold extrusion 92 in operative position. As before elastomeric sealant 82 is provided to form a weathertight seal between the window unit 107 and extrusions 90, 91 and 92. Optionally a sealant 82 may also be applied to the interior seams of the window assembly.

FIG. 9 is a vertical cross section through a portion of the curtain wall system of the present invention illustrating the attachment of the curtain wall to a concrete floor slab of a multistory building. A slab 120 is shown which is provided with key blocks 121 to which are fastened such as by nailing, anchor blocks 122 serving to anchor the curtain wall system of the invention to the structure of the building. The outer face of the slab 120 is covered by a suitable insulating material such as styrofoam. An outside panel 125 is positioned between sills 126 and 127, each of which is provided with a set of snap-on plastics extrusions covering all exposed surfaces thereof. The outside panel 125 is backed by a suitable layer of insulation 128 such as styrofoam, and is held in place by extrusions 129, 130 and 131 all of which are of the same cross section. In the same way as shown in FIG. 7, extrusions 129 and 131 are held in place by supporting extrusions 132 and 133. An interior finishing panel 134 is provided to complete the interior of the curtain wall and depending upon the structure of the building an interior finishing panel 135 may also be included in the structure. Alternatively a false ceiling 136 may be suspended from the slab 120 by means well known to those skilled in the building arts. As before the joint between the extrusions 129, 130 and 131 and the outside panel 125 is caulked with an elastomeric caulking compound shown at 137.

Beneath the sill 127, a header 138 is shown, being the header for an additional window unit such as, for example, a double-glazed double-hung window. As before, the header 138 is provided with snap-on extrusions of plastics material such as vinyl 139 and 140. The space between the sill 127 and the header 138 is filled with a suitable insulating material 141 such as, for example, fiber glass wool. In accordance with the invention an expansion joint 142 is provided connecting between the sill 127 and the header 138. The expansion joint 142 is held in place by snapping into the channel 143 of the sill cover 144 and the expansion joint 142 is provided with a flange 145 engaging the vertical face of the extrusion 139. A suitable elastomeric caulking compound 146 serves to seal the joint between the flange 145 and the extrusion 139.

It will be appreciated that if exposed wooden framework is preferred on the interior of the building that the snap-on coverings may be omitted from the interior faces of the curtain wall of the invention and a pleasing wood frame may be exposed which may be finished in any manner according to the taste of the occupant of the building.

In accordance with the present invention, a novel operating system for double-glazed double-hung windows is provided, the details of which may be more readily seen from FIGS. 10, 11, 12, 13, 14 and 15.

As mentioned previously in relation to FIGS. 3 and 4, the header for a sliding-type window and the jamb for a double-hung window in accordance with the system of the invention are identical in construction. The system of the present invention includes a novel operating mechanism for a double-glazed double-hung window, the detail structure of which is illustrated in FIGS. 10 through 15. FIG. 10 is a cross section on the line X-X of FIG. 4. The jamb unit of the present invention is shown as numeral 52 on FIG. 2 and as shown in FIG. 4 consists of a box section 61 and track members 62 and 63. Mounted above the track members 62 and 63 is a pulley box 147 (FIG. 10) within which journal blocks 152 and 153 are positioned. The pulley box 147 and the journal blocks 152 and 153 are accurately positioned in relation to the jamb tracks 62 and 63 by means of the projecting parts 148 and 149 on the pulley blocks 152 and 153 respectively which engage the box openings 150 and 151 in the track member 62 and 63. The box openings 150 and 151 may be more clearly seen in FIG. 4 of the drawings. Returning to FIG. 10, pulleys 154, 155, 156 and 157 are mounted in pulley blocks 152 and 153 and are journaled therein freely to rotate. Cable 158 passes over pulleys 154 and 157 and is connected by means to be detailed later to two of the panes of the double-hung windows. Similarly cable 159 passes over pulleys 155 and 156 and is coupled by means to be described in detail below to the remaining two panes of the double-glazed double-hung window. It will be noted that the pulleys 154 and 155 are journaled at different heights and similarly the pulleys 156 and 157 are journaled at different heights so that the cables 158 and 159 clear each other across the top of the jamb system.

It will be observed that the arrangement of cables is such that the inside upper and outside lower windows are coupled together by the cable 159 and the inside lower and outside upper panes are connected together by the cable 158. Thus by raising the inside lower pane of the double-hung window the outside upper pane is lowered permitting the flow of air above the outside upper pane down through the space between the panes and beneath the inside lower pane. Similarly if the inside upper pane is lowered the outside lower pane is correspondingly raised providing a passage for the flow of air beneath the outside lower pane through the space between the windows and above the inside upper pane to the interior of the building.

The panes of the applicant's double-glazed double-hung window are suspended from the cables 158 and 159 by means of the applicant's novel cable suspension devices. These devices may be clearly seen from the several views of FIGS. 10, 11 and 12. The upper pane suspension members of the system of the present invention include a cable connecting block 160 provided with a slotted opening through which the end of the cable 158 having a metal sleeve 161 crimped thereon may be inserted, the sleeve 161 serving to prevent the end of the cable 158 from being pulled out of the suspension member 160. The suspension member 160 is adapted to run in the deepest part of the track slot 162 of the track unit 62. Projecting inward toward the center of the window and through the narrower portion of the track slot which is weatherstripped, is a web shown as 163 in FIG. 11 on the end of which are a series of tinelike projections 164, a support block 165 having a plurality of slots 166 engages the tines 164 and provides a convenient adjustable means for supporting the upper panes of the applicant's double-hung window unit. It will be noted that both upper panes are provided with identical supporting structure for connection to the cables 158 and 159 and accordingly the preceding description in relation to the outside upper pane is equally applicable to the termination of the cable 159 connected to the inside upper pane.

In the same way both lower panes of applicant's double-glazed double-hung window are connected to the applicant's double-hung window system by identical members 170. The lower pane suspension members are provided with a slot and notch similar to the structure for the upper pane suspension members in which the end of the cable bearing a metallic sleeve 171 is entered and which sleeve 171 serves to retain the end of the cable in engagement with the member 170. The member 170 extends substantially the full width of the track in the members 62 and 63 and is provided with a leg 172 which projects past the weatherstrip in the tracks and engages in a box section opening provided in the lower rail 33 (FIG. 2) for positively coupling the lower pane of the double-hung window structure to the cable system of the invention, thus movement of either lower pane causes corresponding motion of the associated upper pane by means of the cables 158 and 159 as detailed above.

In order to lock the lower panes of the double-hung windows of the system of the present invention in closed position a lock as disclosed in U.S. Pat. No. 3,339,957 issued to R. M. Dallaire on Sept. 5, 1967 and in particular FIG. 2 thereof may be used. This locking member is positioned over an inward facing flange shown as 180 in FIG. 2, and cooperates with the locking member of FIGS. 13 and 15 shown as reference numeral 181 which is held to the jamb of the window by suitable means such as screws 182 and 183. The cooperating member 181 is provided with a ramp surface 184 for urging the locking member away from the jamb during closing of the window and is provided with a retaining surface 185 for holding the lower pane in locked position.

A feature of the double-hung window of the present invention is illustrated in FIGS. 13 and 14. It is desirable from time to time to remove the panes from a double-hung window for cleaning or maintenance purposes and with the counterbalanced system of double-hung window in accordance with the present invention, some means must be provided for retaining the upper panes of the window in closed position when the lower panes are removed. Such means includes the movable stop member 190 shown in elevation in FIG. 13 and in cross section in FIG. 14, which is provided with an elongated pin 191 about which the stop member 190 may be pivoted. A leg 192 is also provided on the stop member 190 adapted to be snapped into the track of the lower pane and permitting the suspension member 165 to rest against the horizontal surface of the stop member 190 to prevent the upper pane 27 from descending when the lower pane to which it is connected has been removed from the window.

FIG. 16, which is on the same sheet of drawings as FIGS. 14 and 15, illustrates a means in accordance with the present invention for covering the joint between two adjacent jambs of a curtain wall system of the present invention. This jamb joint strip consists of an outer flat surface 200 with inwardly directed flanges 201 and 202 and a securing barbed flange 203 retained between the snap-on jamb covering extrusions 204 and 205.

Claims

We claim:

1. In a double-glazed double-hung counterbalanced window of the type having upper and lower, inner and outer panes, a frame consisting of a header, a pair of jambs and a sill defining a window opening, and having a header track in which the top edges of the upper panes are received, jamb tracks having slots in which the vertical edges of the panes slide, and a sill track to receive the bottom edges of the lower panes, the improvement comprising a suspension system for providing counterbalanced operation of the panes, said suspension system including, for each side of said window, a pair of cables, a pulley box mounted on the top end of the jamb track, a pair of journal blocks in said pulley box, each journal block being provided with a downwardly extending leg to be received within a recess in the jamb track and position said journal block with respect to the jamb track, a pair of pulleys journaled for rotation in each of said journal blocks, the outer pulley of each pair being mounted higher than the inner pulley of said pair, openings in said pulley box beneath the outer rims of said pulleys and aligned with said slots in said jamb tracks through which said cables may pass for connection to the panes of the window, and connection means on the ends of said cables for coupling said cables to the panes of the window, a first of said cables connecting the outer upper and inner lower panes, the second of said pair of cables connecting the outer lower and inner upper panes, said first cable passing over said outer two pulleys and said second cable passing over the inner two pulleys, the connection means on the end of said cables connected to the upper panes being provided with means for adjusting the fit of the panes of the window when closed.

2. A suspension system as claimed in claim 1 wherein said cables are formed of metal and said pulleys, journal blocks and pulley box are formed of nylon.

3. In a window system as defined in claim 1 said connection means on the end of the cable including a metallic sleeve crimped on the end of the cable, and a moulded nylon pane-engaging member having an opening therein and a slit extending upwardly from said opening, said metallic sleeve being received in said opening, said cable extending through said slit, said sleeve engaging the upper end of said opening to connect said pane-engaging member to said cable.

4. In a window system as defined in claim 3 the pane-engaging member on the ends of the cables connected to the upper panes of said window is formed of two portions which may be adjusted with respect to each other, a first portion of said pane-engaging members being connected to the cable and having a series of laterally extending projections on one face thereof and the second portion of said member having a series of mating recesses, adjustment of said connecting means being obtained by varying the recesses in which said projections are inserted, said projections being a light force fit in said recesses.