GB2187145A - Foldable pushchair - Google Patents

Abstract

A push chair comprises two spaced apart side members 1,3 interconnected, one front side member and one rear side member, to define a pair of spaced apart X-shaped side structures, a U-shaped handle 5 pivotally connected to the side members 3, two spaced apart side links 6 connected between the respective side members 1 and the handle 5 so that each side link and the end of the handle to which it is connected defines a foldable support strut extending between the respective front side member at a point remote from the front wheel and the respective rear side member at a point between the rear wheel and the side pivot of that rear side member, wherein the handle can be secured in a predetermined orientation such that the front side members, the rear side members and the support struts defined by the side links and handle together define a pair of spaced apart triangular structures, the push chair being foldable by releasing the handle and folding the handle forwards so that the support struts are folded and each side of the handle lies adjacent the side members. <IMAGE>

Description

SPECIFICATION Push chair and wheel assemblies The present invention relates to push chairs and to wheel assemblies for push chairs.

Folding childrens push chairs have been known for many years but since the early 1960's one basic design of push chair has tended to increase in popularity. In this known design the push chair comprises side members linked by cross members arranged in pairs,the middle of one cross member being pivoted to the middle of the to form an X-shaped structure and the two ends of each cross member being pivotally connected to different side members. Thusthe push chaircan befolded up by moving the two side members together and thereby causing the interconnected cross members to fold together towards a mutually parallel configuration.

Over-centre latching devices are provided to brace the side members apartwhen the push chair is in its fully erect form. Afabric seat is supported from the side members so that the seat can fold up as the side members move together.

Generally the side members are made up of pivotally connected first, second and third elements whichwhen the push chair is i n in itsfullyerectform define a generally triangular structure. One ofthe three elements includes two pivotally connected sub-elements which when the push chair is fully erect are substantially parallel but which fold together when the push chair is folded. This enables the other elements of the side members to fold together also. Folding of the side members automatically causes the X-shaped structures defined by the cross members to fold also, thereby bringing the two side members in theirfolded condition towards each other.

In its basic form the known push chair comprises an X-shaped structure extending beneath the seat and an X-shaped structure extending behind the seat. This results in a very robust overall structure.

Increasing demands have been made howeverto provide a seat which is adjustable between upright and inclined positions so that a child when awake can sit upright or alternatively when asleep can be allowed to rest in a substantially horizontal position.

To meet these demands the basic structure ofthe known push chair has been altered by reducing the height of the X-structure located behind the seat.

This is necessary as in its basic form theX-structure behind the seat would prevent the seat from being inclined backwards. Unfortunately reducing the height ofthe X-structure behind the seat significantly reduces the strength of the overall structure and at least requires a foldable bracing member between the two side members ofthe structure above the seat. In practice it has been found very difficultto manufacture modified forms of the basic structure which are sufficiently robustto maintain reasonable rigidity and strength during prolonged use.

Furthermore, it is difficult to arrangeforthe structure to fold unless the seat portion is moved to a predetermined position before folding. Furthermore, as the seat has to be collapsible as the two side members move together during folding it must be fabricated from a relatively flimsy material. If this material is stretched between supports which are themselves pivotal relative to the side members this increases the difficultly of maintaining the rigidity of the structure.

It is a common feature ofthe known push chairsto provide four wheel assemblies each of which comprises two wheels spaced apart by a few inches on either side ofthe bottom end ofatubularframe.

The known arrangements have proved disadvantageous however because they are prone to premature failure given the fairly high loads applied to them or alternatively because they are unsightly particularly when it is necessary to provide some sort of springing for the wheels and some sort of locking mechanism to enable the wheels to be locked against rotation.

It is a first object ofthe present invention to provide an improved push chair which obviates or mitigates the problems outlined above. It is a second object ofthe present invention to provide an improvedsupportassemblyfora push chair which obviates or mitigates the problems outlined above which are associated with known wheel assemblies.

According to the present invention, there is provided a push chair comprising two spaced apart front side members the forwardly extending ends of which supportfrontwheels, at least one cross member extending between the front side members, two spaced apart rear side members the rearwardly extending ends ofwhich support rearwheels, at least one cross member extending between the rear side members, a pair of axially aligned side pivots each interconnecting one front side member and one rear side memberto define a pair of spaced apart X-shaped side structures, a U-shaped handle, a pair of axially aligned handle pivots each interconnecting one side of the handle to a respective side member, two spaced apart side links, a first pair of axially aligned link pivots each interconnecting a respective side link and a respective side member, a second pair of axially aligned link pivots each interconnecting a respective side link and a respective side ofthe handle, each side link and the end ofthe handleto which it is connected defining a foldable support strut extending between the respective front side member at a point remote from the frontwheel and the respective rear side member at a point between the rear wheel and the side pivot of that rear side member, means forsecu ring the handle in a predetermined orientation such that the front side members, the rearside members and the support struts defined bytheside links and handle together define a pair of spaced apart triangular structures, and a foldable seat structure supported between the spaced apart side members, the push chair being foldable by releasing the securing means and pivoting the handle forwards so that the support struts are folded and each side of the handle lies adjacent the respective side members.

Preferably each end of the handle is connected by the respective handle pivot to a respective rear side member, and each side link is connected by the link pivots to a respective front side member and a respective side ofthe handle. The side links and/or the ends ofthe front side members to which the side links are connected may be bent such that when the push chair is folded the second link pivots move to an over-centre position relative to the front side members, whereby pulling on the handle alone is not sufficient to cause the push chair to assume its erect form. The seat structure may comprise a seat backframe pivoted to the front side members at a position between the side pivots and the first pair of link pivots, whereby lifting the seat back frame and thehandlesimultaneouslycausesthepushchairto assume its erect form.

Alternatively, one end of each side link may be connected by a first link pivotto a respective rear side member, the other end of each side link is connected by a second link pivot to a respective end ofthe handle, and each side ofthe handle is connected to a respective front side member by a respective handle pivot.The said other end of each side link may extend beyond the respective second link pivot and bears against the adjacent side ofthe handlewhen the chair is in its erect form to limit pivotal movement of the handle. The seatstructure may comprise a pairofspaced apartseatside links each ofwhich is pivotally connected at one end to the end of a respective rear side member remote from the rear wheels and at the other end is slidably and pivotally connected to a pivot pin supported by a respective front side member.The seat structure may further comprise a pair of spaced apart upper seat members each pivotally connected to a respective seat side line and at least one cross member extending between the upperseat members. The seat structure may further comprise a pair of spaced apart seat side members each pivotally connected at one end to the said one end of a respective seat side link, and a pair of spaced apart seat side struts each pivotally connected at one end to a respective seat side link and at the other end to a respective seat side member. An adjustable link may be arranged to interconnectthe side seat struts or the seat side members and the upper seat members.

In one arrangement, the adjustable link comprises a spring-biased U-shaped member extending rearwardly behind the upper seat members and incorporating adjustable latches adjacent its ends, the U-shaped member being positioned such that when the push chair is folded the U-shaped member releases the latches so thatthe upperseat members always assume a predetermined position when the push chair is folded regardless of the position ofthe upper seat members before the push chair is folded.

The latches comprise simple slots formed in the U-shaped member, a latch pin secured to each upper seat member being movable along the slot in a respective end of the U-shaped member so as to come to restin any one of a plurality of notches formed in one side of the slot.

In an alternative arrangement, the adjustable link comprises a spring-biased U-shaped member extending rearwardly behind the upper seat members and incorporating latches adjacent its ends adapted to engage pins supported by the upper seat members, The U'-sfiapedmembercompdsesa wire bent to define a plurality of U-shaped formations adapted to engage over the pins supported by the upper seat members.

The present invention also provides a support assembly for a push chair, the support assembly comprising a tubular support member, a pair of plate-shaped brackets secured on opposite sides of the support member so as to be pivotable about a common axis, each plate defining an elongate slot in which a common pin mounted onthesupport engages, a wheel axle extending through both the brackets and supporting a pair of wheels outside the brackets, a first tension spring extending between the brackets and secured at one end to the axle and at the other end to the supportmemberso asto biasthe brackets to a position in which the pin engages one end of the slots in the brackets, the arrangement being such that forces applied to the wheel in use tend to move the pin towards the other end ofthe slots, a brake lever mounted on the brackets and supporting a brake bar extending beyond each of the wheels, and a second tension spring extending between the brackets and secured at one end to the brake lever and at the other end to a pin secured between the brackets, the second tension spring being arranged to cause the leverto pivotto either a first over-centre position in which the bar presses against the wheels or a second over-centre position in which the bar is spaced from the wheels.

The above arrangement provides the wheels with a sprung suspension and at the same time enables thewheelsto be locked against rotation. Both ofthe springs are effectively concealed between the brackets which themselves are unobtrusive as they are located largely between the two wheels. Thus the support assembly provides a range of desirable features in a compact and visually appeaiing manner.

According to a further aspect ofthe present invention, there is provided a wheeled support assembly comprising a tubular support member, a pair of wheels mounted on a common axle extending through a substantially rigid body, a pivot pin secured atone end to the body, and a tubular member supported at the other end of the pivot pin, the pivot pin extending through the tubular member and being secured againstwithdrawal therefrom, and the tubular member being inserted into the end ofthetubular support member and secured therein by engagement with formations in the tubular support member.

The tubular member may be secured in position insidethetubularsupport member by pressing portions of the tubular support member inwards after insertion of the tubular member. The tubular member may define grooves or recesses to cooperate with the pressed in portions of the tubular support member.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure -1 is-a perspective view of the frame ofa child's push chair in accordance with a first embodiment ofthe present invention; Figures2, 3, 4and 5are side views of the major structural elements ofthe push chair illustrated in Figure1 illustratingthefoldingoftheframefrom its fullyerectform (Figure 2) to its fully folded form (Figure 5); Figures 6and 7 illustrate the relative orientations ofvarious components of the framework illustrated in Figure 1 when the framework is in its fully erect form and a sub-frame defining a seat portion is in the upright position (Figure 6) and the fully reclining position (Figure 7);; Figure 8 is a perspective view of a brake and suspension mechanism associated with the rear wheels ofthe push chair illustrated in Figure 1; Figures 9 and 10 are respectively sideviews and exploded views of the brake and suspension mechanism illustrated in Figure 8; Figure 11 illustrates the front wheel assembly of the chair shown in Figure 1; Figure 12 is a side view ofthe basic structure of a second embodiment ofthe present invention in its erect condition; Figure 13 is a partly cut away side view of the structure shown in Figure 12 in itsalmostfullyfolded condition; Figure 14 is an enl a rged view of the seat structure shown in Figure 12; Figure 15 is an enlarged view of the seat structure shown in Figure 15; and Figure 16 is a schematic illustration of a device for preventing accidental folding of the structure of Figure 12.

Referring to Figure 1, the illustrated push chair comprises two spaced apart front side members 1 supporting front wheels 2, two rear side members 3 supporting rearwheels 4, a U-shaped handle 5 and a pair of spaced apart side links 6. The front and rear side members are interconnected byaxiallyaligned side pivots 7 so astoform two spaced apart X-shaped structures. Each side link 6 is pivoted at its upper end by a first link pivot pin 8 to the upper end ofthefrontside member and at its lower end to the handle member by a second link pivot pin 9 (Figures 2 to 5).The lower ends ofthe handle are connected to axially aligned handle pivot pins 10 which are mounted on U-shaped brackets 11 secured to the rear side r,lembers 3. Thus each side link6 and the end of the handle to which it is secured by pivot pin 8 forms a foldable support strut extending between the respectivefrontand side members.

The front side members 1 are permanently secured in the illustrated spaced apart position bya tubularcross member 12 and a steel strip cross member 13. A permanenttubularcross memberl4 maintains the spacing between the bottom ends of the rearside member 3, the upper spacing of the side members being determined by their connection to the front side members at the pivot pins 7. Moulded blocks 15 are slidable along the handle 15 and incorporate a slot th rough which the upper ends of the side links 6 can be inserted. In the fully erect form ofthe chair as illustrated in Figure 1 the upper ends of the links 6 extend through these slots in the blocks 15 and as a result the blocks 15 lockthe handletothe side links.When it is desired to fold the chairthe blocks 15 are pushed uptowardsthetop end ofthe handle thereby releasing the interconnection between the handle and the side links. The chair frame can then be folded as described in more detail below.

Safety struts in the form of pivotally connected links 16 and 17 are connected on either side ofthe chairframe between pivots 7 and 9. Springs 18bias the pivot point 19 between the links 16 and 17 in a downwards direction until they assume an over-centre position in which the link 17 bears against a stop 20. This means that once the handle has been moved to the position shown in Figure 1 the chair can only be folded if the blocks 15 are disengaged from the links 6 and the pivots 19 are lifted to movethe links 16 and l7outofthe over-centre position. The links 16 and 17 thus provide an automatic safety device which prevents accidental folding of the chair frame.

The basic chairframe supports a chairsub4rame comprising upper side members 21 interconnected by a permanent cross member 22, seat side links 23, seat side members 24, seat side struts 25 and an adjustable link 26. A foot support is also provided in the form of foot support side members 27, side links 28, a permanent cross member 29 and a pair of moulded foot rests 30 secured to the cross member 29. Pivots 31 interconnect the upper ends of the rear side members 3 and respective seat side links 23, seat side members 24 and foot support side members 27. The seat side links 23 define slots 32 at their rear ends which are slidable on pivots 33 supported by the front side members 1. The seat side struts 25 are pivotally connected to the pivots 33.

Pivots 34 interconnect the seat side links 23 to the lower end ofthe upper side members 21. Pivots 35 interconnect the rearmost ends of the seat side links 28 and the bottom ends of the upper side members 21. The front ends ofthe seat side links 28 are connected by pivots 36 to the foot support side members 27. Thus the members 23,27,28 and 21 form a parallelogram such that adjustment of the angle between the upper seat side members 21 and the seat side links 23 causes a corresponding change in the angle between theseatside links 23 andthe foot support side members 27.As described in more detail below the adjustable link 26 which is pivotally connected at one end to the seat side struts 25 and adjustably connected at the other end to the upper seat side members 21 control the angle between the seat side links 23 and the upper seat side members 21.

Referring now to Figures 2to 5, the folding of the main frame ofthe push chair illustrated in Figure 1 will now be described. In the position shown in Figure 2, which corresponds to that illustrated in Figure 1,theside links 6 are covered by the handle 5.

As the handle 5 is swung forward in the direction of arrow 36 (Figure 3) the pivot point 7 moves downwards in the direction of arrow 37 and this downwards movement is continued as shown in Figure 4 asthe handle 5 swings down towardsthe upper end ofthe rear side member3. Afinal downward movement of the handle as indicated by the change between Figures 4 and 5 results in the pivot points 9 moving above the front side members 1 and as a result the folded assembly is in an over-centre position so that lifting the handle upwards from the position shown in Figure 5 does not result in the frame unfolding. It is therefore not necessaryto have any catch or sim ilar mem ber to lockthe handle 5 in the position shown in Figure 5 when for example the push chair is in storage or is being transported.The only way the push chair can be unfolded is by simultaneously lifting upwards the handle Sand the back of the seat sub4rame (not shown in Figures 2to 5). Liftingupthebackofthe seat sub-frame lifts the front side members 1 out of the over-centre position.

In the schematic illustration ofthe chair frame in its folded form as shown in Figure Sthe left most end of the front side members 1 extend in a horizontal direction slightly beyond the rear wheels 4. The dimensions ofthe various components can be arranged however such that the rear wheels 4 and the lefthand end (in Figure 5) ofthefrontside members and/orthe upperends ofthe upperseat side members 21 (Figure 1 when fullyfoided are all approximately in a common vertical plane. The chair can then be rotated through 90 from the position illustrated in Figure 5 so asto stand on the rearwheel 4 and the front side members 1 and/or upper seat side members 21.

Referring nowto Figures 6 and 7 in conjunction with Figure 1, the detailed structure and function of the adjustable link 26 will be described in greater detaii. A spring 38 (Figure 1) biases the adjustable link 26 downwards about pivots 39 supported on the seat side struts 25. Thus the adjustable link is biased in the direction of arrows40 in Figures 6 and 7. The inclination ofthe the upper seat side members 21 to the vertical is determined by the distance between the pivot pin 39 and pins 41 which are secured to the upper seat side members 21. This distance is determined bythe link 26.

Each side ofthe link defines a slot comprising an elongate main portion 42 and three side portions 43.

The configuration of the slot is best seen from Figure 6. The slot is covered by a safety plate 44 defining an elongate slot 45. The safety plate 44 is pivotal about the pi n 39. Normally the spring 38 ensu res thatthe pin 41 is retained within one ofthe three side portions 43 ofthe slot in the adjustable link 26. When itis desired to changethe angle of inclination ofthe seat on the chair it is simply necessary to liftthe adjustable link 26 upwards againstthe force ofthe spring 38.This has the effect of moving the pins into the lower elongate portion 42 of the slots in the adjustable link 26, the safety plate 44 sliding across the surface of the adjustable link 26 as a result ofthe engagement of the slot 45 in the safety plate with the pin 41.The angle of inclination ofthe seat backcan then be adjusted as desired by pushing the seatto the required position. This causes the pin 41 to slide along the elongate portion 42 of the slot in the adjustable link 26. The adjustable link 26 is then released and the spring 38 ensures thatthe pin 41 engages with one of the side portions 43 of the slot in the adjustable link 26. Thus the userwith one hand can release the latching mechanism by lifting up the adjustable link 26 and with the other move the seat backto the desired position. This is very easy to do.

The safety plate 44 makes it very difficult for a child to insert a finger into the slots in the adjustable link 26 and accordingly the mechanism is inherently safe.

The provision ofthree side portions 43 in the slots in the adjustable link 26 provides for three possible angles of inclination of the seat back, the steepest reclining position being shown in Figure 7 and the most upright position being shown in Figure 6. It would of course be possible to provide for a greater range of possibilities by an appropriate adjustment to the formation of the slots in the side link 26.

Figures 6 and 7 more clearly illustrate the relationship of the sloE 32 in the seat side link23 and the pivot pin 33 in the front side member 1.The slot is required as when the main frame is folded the distance between the pivot pins 31 and 33 increases, the length ofthe slot 32 corresponding to this increase in distance.

When the seat is folded the adjustable link 26 comes into contact with the cross member 13 and as a resultthe adjustable link 26 is pivoted againstthe force of the springs 38, thereby moving the pins 41 into the elongate portions 42 of the slots in the adjustable link 26. Effectivelythis releases the seat back adjusting mechanism and accordingly the seat can be folded regardless of the angle of inclination of the seat back. When the seat is unfolded the spring 38 ensures that the seat back is locked in the upright position.

Although the push chair frame and seat sub-assembly has been described and illustrated without reference to a seat body upon which a child occupying the push chair would sit it will ofcourse be appreciated that a foldable seat body will be supported on the seat sub-assembly. Because the seat body does not have to collapse as a result of the two seat side frames moving together as in prior art push chairs the seat body can incorporate a stiffened seat and back portion providing the seat and back portions can fold relative to each other. The seat body can be secured by for example appropriate straps secured to the seat side links 23 and loops attachedtothe upperseatside members21.In addition stiffened side panels can be provided extending along each side of the seat back and hooked onto the ends of the cross member 22. This increases comfort in that a child's head can be allowed to rest against these side portions.

Conventional child safety harnesses can be secured by for example hooking them into holes provided in the seat side links 23.

Referring nowto Figures 8,9 and 10, a rearwheel assembly of the push chair shown in Figure 1 will be described in detail. The illustrated wheel assembly comprises brackets 46 and 47 pivotally secured by a bolt 48 to the bottom end 49 of one of the tubular rear side members 3.

Each bracket defines a slot 50 through which a further bolt 51 extends, the bolt 51 also extending through a hole in the side member 49. Thus the brackets 46 and 47 are pivotal relative to the side member to an extent determined by the length of the slot 50.

Wheels 52 and 53 are supported on a common axle 54 that extends through a bush 55 supported bythe brackets 46 and 47. Atension spring 56 is positioned between the brackets 46 and 47 and secured at one end around the bush 55 and at the other end in an aperture 57 formed in the side member 49.

A lever 58 is supported on a pivot pin 59 secured to each of the brackets. The lever itself supports a braking bar 60 and defines a slot 61 into which a flat bar 62 is inserted and secured by a screw 63. A tension spring 64 extends between the bar 60 and a further pin 65 secured between the brackets 46 and 47.

If no wheels are present on the axle 54the lever can be swung between the two over-centre positions illustrated in Figure 9. In the upper position the bar60 is clear of the outer periphery of wheels supported by the axle 54. In the lower position the bar 60 is below the outer periphery of those wheels and accordingly if wheels are provided on the axle the bar 60 bears against the periphery of those wheels with a force determined by the strength of the spring 64. Thus when the lever 58 is swung down tithe lower position the bar 60 locks the wheels against rotation.

The bar 62 is provided to linktwo identical levers of two identical wheel support assemblies on the push chairof Figure 1.

It will be appreciated that with the illustrated arrangement the mechanism which provides both locking and sprung suspension is concealed between the two brackets 46 and 47. The two brackets may be formed from a single sheet of material folded into a generally U-shapetofurther conceal the components located between the two brackets. Thus a highly effective and yet visually appealing structure can be provided.

Referring now to Figure 11,the structure of a front wheel assembly of the push chair of Figure 1 is illustrated. In the illustrated arrangement two wheels 66 and 67 are supported on an axle 68 extending through a body 69 which may be moulded from a suitable plastics materia I . Thus the wheels 66 and 67 can freely rotate relative to the body 69 on the axle 68.

The body is connected to a tubular member 70 by a pin 71 which extends through the member 70 and through a passageway 72 in the body 69. The two ends ofthe pin 71 support conventional caps which prevent removal of the pin 71 from either the member70orthe body69.Themember70is inserted into the end 73 of one ofthe front side members 1 (Figure 1). Awasher74 may be provided between the body 69 and the member 70 to assist rotation of one relative to the other.

The member 70 is retained within the frame 73 by firstly simply pushing it into the frame and then indenting the walls of the frame member 73 to define pushed in portions 75. The portions 75 bite into the member 70 and prevent it from being pulled out. The member70 may be provided with recesses or grooves (not shown) to cooperate with the pushed in portions 75.

Thus in the arrangement of Figure 11 a robustand easyto assemble arrangement is provided for supporting a pair of wheels pivotally at the end of a tubularframe.

Referring to Figures 12 to 16, the illustrated second embodiment ofthe invention is similar in many respects to that of Figures 1 to 11 and accordingly will now be described in such great detail. As shown in Figure 12, the basic seat structure comprises a pair of spaced apart rigidly interconnected front side members 76 supporting wheels 77 of the type illustrated in Figure 11 and a pairofspaced apart rigidly interconnected rear side members 78 supporting wheels 79 of the type illustrated in Figures 8 to 10. The side members are interconnected by side pivots 80. A U-shaped handle 81 is connected by handle pivots 82 to the ends ofthe front side members 76. Spaced apart side links 83 are connected by first link pivots 84 to the rear side members and second link pivots 85 to the ends ofthe handle 81.The side links 83 and the ends ofthe handle thus form foldable support struts which when the push chair is erect form triangular structures giving high strength and stability. Acarrier basket 86 is suspended from the side members and does not have to be removed when the chair is folded.

The seat structure comprises spaced apart rigidly interconnected upper seat members 87, spaced apart rigidly interconnected seat side links 88, spaced apart seat side members 89 and spaced apart seat side struts 90. The rear side members 78, seat side links88and seatside members are interconnected on each side ofthe chair by common pivots 91. The seat side struts 90 and the front side members 76 are interconnected on each side of the chair by common pivots 92, the side links 88 defining slots 93 which are slidably and pivotally supported on the pivots 92. An adjustable U-shaped link 94 formed from bent wire is pivotally connected to each seat side member 89 by pivots 95 and extends behind the seat side members.The link 94 defines three U-shaped latches any one ofwhich may engage over pins 96 supported on each ofthe upper seat members 87, the link 94 being biassed by a spring (Figure 14) connected to a cross member (not shown) linking the front side members. Thus by adjusting the position of the pins 96 relative to the link94theinclination oftheseatbackcanbe adjusted.

Foot rests 97 are supported on spaced apart rigidly connected side members 98, the side members 98 being pivotally connected to respective side links 88 by pivots 99. Atie rod 100 is pivotally connected to the side members 98 and the upper seat members by pivots 101 and 102. Thus the foot rests swing up as the seat back swings backwards.

As shown in Figure 13, the front side members 76 support plates 103 which when the chair is erect are positioned adjacent to and between the links ofthe handle 81. The handle supports mouldings 104 which can beslippedalongthehandletoengagethe plates, preventing rotation of the handle relative to the front side members 76. As shown in Figure 16, a safety latch is also provided on one side ofthe chair to prevent accidental folding of the chair when the mouldings are disengaged. The safety latch comprises a plate 105 pivotally mounted on pin 106 supported by a side link 83 adjacent the link pivot 85.

Afurtherpin 107 is secured tothe handle 81 and extends through an L-shaped slot 108 in the plate 105. As the chair is unfolded, the pin 107 slides to the right in Figure 16 along the slot 108 until it reaches the carrier of the L-shaped slot. Atension spring 109 then biases the plate so that the pin 107 is received at the end ofthe slot. The chair can then only be folded by lifting up the plate to release the pin 107 so that it can slide back to the other end of the slot.

One advantage of the illustrated arrangement is that the chair can be fully reclined to a horizontal position with a child lying in it, and without moving or disturbing the child the chair can then be folded.

As in the case ofthe embodiment of Figure 1,the front sidle members are bent outwards adjacentthe front wheels to avoid obstructing the folding of the foot rests.

Claims (23)

1. Apush chaircomprising two spaced apart front side members the forwardly extending ends of which supportfrontwheels, at least one cross member extending between the front side members, two spaced apart rear side members the rearwardly extending ends of which supportrearwheels, at least one cross member extending between the rear side members, a pair of axially aligned side pivots each interconnecting one front side member and one rear side memberto define a pair of spaced apart X-shaped side structures, a U-shaped handle, a pair of axially aligned handle pivots each interconnecting one side ofthe handle to a respective side member, two spaced apart side links, a first pair of axially aligned link pivots each interconnecting a respective side link and a respective side member, a second pair of axially aligned link pivots each interconnecting a respective side link and a respective side ofthe handle, each side link and the end ofthe handleto which it is connected defining a foldable support strut extending between the respective front side member at a point remote from the front wheel and the respective rear side member at a point between the rear wheel and the side pivot ofthat rear side member, means for securing the handle in a predetermined orientation such thatthefront side members, the rear side members and the support struts defined by the side links and handle together define a pair of spaced aparttriangular structures, and a foldable seat structure supported between the spaced apart side members, the push chair being foldable by releasing the securing means and pivoting the handle forwards so that the support struts are folded and each side of the handle lies adjacent the respective side members.

2. Apushchairaccordingtoclaim 1,wherein each end ofthe handle is connected by the respective handle pivot to a respective rear side member, and each side link is connected bythelinkpivotstoa respective front side member and a respective side ofthe handle.

3. A push chair according to claim 2, wherein the side links and/orthe ends of the front side members to which the side links are connected are bent such thatwhen the push chair is folded the second link pivots move to an over-centre position relative to the front side members, whereby pulling on the handle alone is not sufficient to cause the push chair to assume its erect form.

4. A push chair according to claim 3, wherein the seat structure comprises a seat back frame pivoted to the front side members at a position between the side pivots and the first pair of link pivots, whereby lifting the seat back frame and the handle simultaneously causes the push chair to assume its erectform.

5. A push chair according to claim 1, wherein one end of each side link is connected by a first link pivot to a respective rear side member, the other end of each side link is connected by a second linkpivotto a respective end ofthe handle, and each side ofthe handle is connected to a respective front side member by a respective handle pivot.

6. A push chair according to claimS, wherein the said other end of each side link extends beyond the respective second link pivot and bears against the adjacent side of the handle when the chair is in its erect form to limit pivotal movement of the handle.

7. A push chair according to any preceding claim, wherein the seat structure comprises a pair of spaced apart seat side links each ofwhich is pivotally connected at one end to the end of a respective rear side member remote from the rear wheels and atthe other end is slidably and pivotally connected to a pivot pin supported buy a respective front side member.

8. A push chair according to claim 7,wherein the seat structure further comprises a pair of spaced apart upper seat members each pivotally connected to a respective seat side link, and at least one cross member extending between the upperseat members.

9. A push chair according to claim 8, wherein the seat structure further comprises a pair of spaced apart seat side members each pivotally connected at one end to the said one end of a respective seat side link, and a pair of spaced apart seat side struts each pivotally connected at one end to a respective seat side link and at the otherendto a respective seat side member.

10. A push chair according to claim 9, comprising an adjustable link arranged to interconnectthe side seat struts and the upper seat members.

11. A push chair according to claim 10, wherein the adjustable link comprises a spring-biased U-shaped member extending rearwardly behind the upper seat members and incorporating adjustable latches adjacent its ends, the U-shaped member being positioned such that when the push chair is folded the U-shaped member releases the latches so that the upper seat members always assume a predetermined position when the push chair is folded regardless ofthe position ofthe upperseat members beforethe push chairisfolded.

12. A push chair according to claim 11, wherein the latches comprise simple slots formed in the U-shaped member, a latch pin secured to each upper seat member being movable along the slot in a respective end of the U-shaped member so asto come to rest in any one of a plurality of notches formed in one side of the slot.

13. A push chair according to claim 9, comprising an adjustable link arranged to interconnect the seat side members and the upper seat members.

14. Apushchairaccordingtoclaim 13,wherein the adjustable link comprises a spring-biased U-shaped member extending rearwardly behind the upper seat members and incorporating latches adjacent its ends adapted to engage pins supported by the upper seat members.

15. A push chair according to claim 14, wherein the U-shaped member comprises a wire bentto define a plurality of U-shaped formations adapted to engage over the pins supported by the upper seat members.

16. Apush chair according to any preceding claim, comprising a wheel support assembly secured to each rear side member, each support assembly comprising a pair of plate-shaped brackets secured on opposite sides of the respective rear side member so as to be pivotable about a common axis, each plate defining an elongate slot in which a common pin mounted on the rearside member engages, a wheel axle extending through both the brackets and supporting a pair of wheels outside the brackets, a first tension spring extending between the brackets and secured at one end to the axle and at the other end to the rearside member so asto bias the brackets to a position in which the pin engages one end of the slots in the brackets, the arrangement being such thatforces applied tothewheel in use tend to move the pin towardsthe other end ofthe slots, a brake lever mounted on the brackets and supporting a brake bar extending beyond each ofthe wheels, and a second tension spring extending between the brackets and secured at one end to the brake lever and atthe other end to a pin secured between the brackets, the second tension spring being arranged to cause the lever to pivot to either a first over-centre position in which the bar presses against the wheels or a second over-centre position in which the bar is spaced from the wheels.

17. A push chair according to claim 16, comprising a cross member extending between the brake levers of the support assemblies.

18. A push chairaccording to any preceding claim, comprising a wheel supportassembly secured to each front side member, each support assembly comprising a pairofwheels mounted on a common axle extending through a substantially rigid body, a pivot pin secured at one end to the body, and a tubular member supported attheother end of the pivot pin, the pivot pin extending through the tubular member and being secured against withdrawal therefrom, and the tubular member being inserted into the end of the front side member and secured therein by engagement with formations in the front side member.

19. A push chair according to claim 18, wherein the tubular member is secured inside the respective front side member by pressed in portions ofthefront side member, the tubular member defining grooves or recesses to cooperate with the pressed in portions ofthefrontside member.

20. A support assemblyfor a push chair, the support assembly comprising a tubular support member, a pair of plate-shaped brackets secured on opposite sides ofthe support member so as to be pivotable about a common axis, each plate defining an elongate slot in which a common pin mounted on thesupportengages, awheel axle extending through both the brackets and supporting a pair of wheels outside the brackets, a first tension spring extending between the brackets and secured at one end to the axle and at the other end to the support member so as to bias the brackets to a position in which the pin engages one end ofthe slots in the brackets, the arrangement being such thatforces applied to the wheel in use tend to move the pin towards the other end of the slots, a brake lever mounted on the brackets and supporting a brake bar extending beyond each ofthewheels, and a second tension spring extending between the brackets and secured at one end to the brake lever and at the other end to a pin secured between the brackets, the second tension spring being arranged to cause the lever two pivot to either a first over-centre position in which the bar presses against the wheels or a second over-centre position in which the bar is spaced from the wheels.

21. A wheeled su pport assem bly com prising a tubular support member, a pair of wheels mounted on a common axle extending through a substantially rigid body, a pivot pin secured at one end to the body, and atubular membersupported atthe other end of the pivot pin, the pivot pin extending through the tubular member and being secured against withdrawal therefrom, and the tubular member being inserted into the end ofthe tubular support member and secured therein by engagement with formations in the tubular support member.

22. Apush chairsubstantiallyashereinbefore described with reference to Figures 1 to 7 or Figures 12 to 16 ofthe accompanying drawings.

23. A wheeled support assembly for a push chair substantially as hereinbefore described with reference to Figures 8to 10 or Figure 11 ofthe accompanying drawings.