FIELD OF THE INVENTION This invention relates to improvements relating to step/stair-climbing prams or like vehicles.

PRIOR ART Reference is made to patent document GB2483873 of one or more of the present inventors, also to GB2410474. The former was for a stair-climbing accessory for a pram stroller. The latter was for a stair-climbing baby buggy.

THE INVENTION

The present inventors have realised that, while both of these earlier cases had a pair of stair-climbing units, they had a somewhat limited application. The present inventors consider that it would be desirable to be able to apply such stair-climbing units to a collapsible stroller. In both of the earlier cases, the pair of stair-climbing units were (and had to be) mounted on a common support bar and therefore could not be applied to a collapsible stroller.

According to one aspect of the invention, there is provided, in or for a pram or like vehicle, a wheel arrangement comprising two laterally spaced apart wheel devices, each device being rotary about an axis and comprising at least three road wheels spaced around the rotary axis, and interconnecting means interconnecting the two devices so that they may be moved laterally together or apart.

According to one aspect of the invention there is provided a pram or like vehicle of a kind having front and rear wheels that is adapted to carry a baby or child and to be pulled backwards up steps by a person walking with the vehicle, which comprises a wheel arrangement comprising two laterally spaced apart wheel devices, each device being rotary about an axis and comprising at least three road wheels spaced around the rotary axis, the vehicle comprising interconnecting means interconnecting the two devices so that they may be moved laterally together or apart, the arrangement being located at the back of the vehicle and comprising said rear wheels and there being no such arrangement at the front of the vehicle.

The term "climbing" is used herein in reference to climbing up or down one or more steps or stairs. The term "prams or like vehicles", as used herein, refers to vehicles of the aforesaid "kind", namely "a kind having front and rear wheels that is adapted to carry a baby or child and to be pulled backwards up steps by a person walking with the vehicle", which includes prams, strollers, baby buggies. The embodiments described relate to vehicles whose road wheels are not driven. Embodiments of the invention may have any one or more of the following further features:

- said wheel arrangement comprises said interconnecting means and is detachable from the remainder of the vehicle.

- the two said devices are fixed in position in the vehicle and the vehicle is laterally collapsible so that the two devices may be moved as aforesaid.

- said interconnecting means comprise a foldable linkage to enable the two devices to be moved laterally together or apart.

- the road wheels are freewheeling.

- braking means for the road wheels.

- the braking means comprise a common actuating means connected to cause braking of at least one said road wheel of both of said devices. This will be a road wheel engaging the ground or step to support thereon part of the weight of the vehicle to give braking against traction.

- the braking means comprise a member arranged to effect braking of a road wheel by means of lateral movement between said member and said road wheel to cause engagement therebetween. - said member is mounted to rotate with rotation of a said device.

- a said road wheel comprises catch means (e.g. a track of catch means) and said member is arranged to engage laterally with said catch means to effect braking. - said member is arranged to bear laterally frictionally on a said road wheel to effect braking.

- said member is (e.g. resiliently) mounted to be able to rock so as bear laterally and simultaneously on a side of each of three said road wheels of a said device to effect braking. - the braking means are arranged for said member to move into engagement with a said road wheel to effect braking. - the braking means are arranged for a said road wheel to move into engagement with said member to effect braking.

- the braking means comprises an axle for rotation of a said device and said member is slidable on the axle to engage a road wheel of the device.

- said device can rotate on said axle.

- said device is fixed to said axle. - the braking means comprises an axle for rotation of a said device and said member is fixed on the axle and the axle is slidable for said member to engage a road wheel of the device to effect braking.

- separately actuable braking means for each said device.

- separately actuable braking means for each road wheel.

- a road wheel other than the aforesaid road wheels and braking means for this said other road wheel. The latter may be a front wheel, while the aforesaid road wheels are rear wheels.

- the arrangement is arranged to be normally (i.e. when the buggy is unfolded for use) in a braked condition and comprises an actuator such that only while the actuator is held actuated can the arrangement travel on its road wheels. For e.g. a disabled person, the actuator may be held actuated by a part of the body other than the hand, e.g. an elbow or foot.

- the arrangement is arranged to be braked and comprises an override device arranged to allow temporary release of the braking. According to another aspect of the invention, there is provided a pram or like vehicle having road wheels and arranged to be normally (e.g. when unfolded for use, in a folding embodiment) in a braked condition and comprising an actuator such that only while the actuator is held actuated can the arrangement travel on its road wheels. According to another aspect of the invention, there is provided a pram or like vehicle arranged to be braked and comprising an override device arranged to allow temporary release of the braking. According to another aspect of the invention, there is provided a wheel arrangement as defined as set out above, adapted to be attached at the back of a vehicle as set out in either aspect of the invention as set out above, or any aspect of the invention with any one or more of the optional features described in relation to embodiments of the invention as set out above, to provide rear road wheels of the vehicle.

According to the present invention there is provided an apparatus as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows. PARTICULAR DESCRIPTION REFERRING TO THE DRAWINGS

Reference will now be made by way of example to the accompanying drawings, in which: Figure 1 is a schematic side view of a baby buggy embodying the invention, with a body that is laterally collapsible, showing how it is used to climb up or down stairs/steps;

Figure 2 is a schematic perspective view of the same (unfolded); Figure 3 is a view like Figure 2 when the buggy is collapsed (folded);

Figure 4 is an exploded perspective view of components of a multiple road wheel assembly thereof; Figure 5 is a perspective view of the same, assembled, showing how the assembly is fitted to a support fork of the buggy body;

Figure 6 is an exploded perspective view of a braking member assembly for the same; Figure 7 is a partial side view of the assembled braking member assembly, showing how the braking member is positioned before and after actuation;

Figure 8 is an exploded perspective view, from the inside, of another multiple road wheel assembly and braking member of an embodiment of the invention; Figure 9 is a corresponding view of this assembly and member, assembled;

Figure 10 is a partial schematic horizontal section of this assembly and member together with a brake actuator and mounting, in the unengaged position of the braking member;

Figure 1 1 is a corresponding view of the same, in the engaged position of the braking member;

Figure 12 is a partial perspective view of the same, partially exploded, showing the actuator not yet assembled to the other parts;

Figure 13 is a side view, from the inside, of the same, assembled;

Figure 14 is a schematic perspective side view, from the inside, of part of the same, showing the action of the braking member;

Figure 15 is a rear view of the two wheel-unit parts of the same embodiment, showing a common brake actuator mechanism, in the un-actuated position, with the buggy in its fully laterally extended position;

Figure 16 is a corresponding view, showing the brake actuator mechanism in the actuated (engaged) position;

Figure 17 is an enlarged corresponding view of an interconnection between respective actuating arms of the actuator mechanism;

Figure 18 is a series of three vertical cross-sections, on the dashed line of Figure 17, sequential in time, in order downwards as seen in Figure 18, showing how the actuating arms become locked together for the actuated position of the mechanism, moving from the position shown in Figures 15 and 17 to the position shown in Figure 16;

Figure 19 is a view corresponding to Figure 17, showing a brake pedal for actuation of the actuator mechanism;

Figure 20 is a view corresponding to Figure 15, with the buggy in its laterally collapsed position; Figure 21 is a view corresponding to the left-hand part of Figure 20 of another embodiment of the brake mechanism;

Figure 22 is a view corresponding to the right-hand part of Figure 20 of yet another embodiment of the brake mechanism;

Figure 23 is a view corresponding to Figure 15 of another embodiment with a Bowden cable device to operate the brake instead of a foot operation of the brake; Figure 24 is a view corresponding to Figure 23 of another embodiment in which the brake is permanently engaged except when released by a Bowden cable device; and

Figure 25 is a horizontal cross-section along the members 30 of a development of the Figure 16 embodiment in which the brake is foot-operated but can be temporarily released by a Bowden cable device.

Figures 23 to 25 also show the Bowden device actuating handle and handlebar, diagrammatically and to a different scale. Referring to the drawings, identical references refer to the same item in the same Figure or different Figures or items that are identical or similar or have similar functions, and references with the same first two digits refer to items that are identical or similar or have similar or related functions. Referring initially to Figures 1 to 7, in a baby carriage or buggy 10, a wheel arrangement

12, 14, 16 comprises two laterally spaced apart wheel devices 12, 14 (each being a road wheel assembly, as illustrated in Figures 4 and 5) and a buggy body 16, each device 12, 14 being rotary about an axle 18 and comprising at least three road wheels 20 spaced around the rotary axle 18. The arrangement further comprises interconnecting means 16 in the form of the buggy body frame 16 interconnecting the two devices 12, 14 so that these may be moved laterally together or apart by collapsing or extending the buggy body 16, e.g. using hinges, e.g. 24. The two said devices 12, 14 are fixed in position in the buggy 10 and the buggy 10 is laterally collapsible so that the two devices 12, 14 may be moved as aforesaid. Said interconnecting means 16 comprise a linkage 16 (foldable by means of the hinges, e.g. 24) in the form of frame 16 to enable the two devices 12, 14 to be moved laterally together or apart. The road wheels 20 are mounted on axles 19 so as to be freewheeling, i.e. not power-driven. The buggy 10 is pushed or pulled along by means of handlebars 161. The arrangement 12, 14, 16 comprises braking means 26 for the road wheels 20, illustrated in Figures 6 and 7.

In the embodiment of Figures 8 to 20, the braking means 30, 32, 34 comprise a common actuating means 30 (comprising a pair of members 30, 30 hinged together by means of a hinge 301 at an actuating pedal 38), connected to cause braking of at least one said road wheel 20 of both of said devices 12,14, in fact all three road wheels 20 of both of said devices 12, 14. The braking means 30, 32, 34 comprise a thrust plate member 32 arranged to effect braking of a road 15 wheel 20 by means of lateral movement between said member 32 and said road wheel to cause engagement therebetween, more particularly between pins 34 of braking means 30, 32, 34 and catch means 36 of each road wheel 20. Said member 32 is mounted to rotate with rotation of a said device 12, 14.

Each said road wheel 20 comprises a track of the catch means 36, as seen clearly in Figures 8, 13 and 14, and said member 32 is arranged to engage laterally with a said catch means 36 to effect braking. For this purpose, the catch means 36 are the axial-radial sides of radial slots 36 moulded into each road wheel 20.

In the embodiment of Figure 21 , said member 32 is arranged to bear laterally frictionally on a said road wheel 20 to effect braking, in fact bearing thus on all three road wheels 20 of a device 12 or 14. Said member 32 is resiliently (and sufficiently loosely) mounted on axle 18 to be able to rock so as bear laterally and simultaneously on a side of the three said road wheels 20 of a said device 12, 14 to effect braking, even if road wheels 20 are slightly out of true.

In the embodiment of Figures 8 to 21 , the braking means 30, 32 are arranged for said member 32 to move into engagement with a said road wheel 20 to effect braking.

In the embodiment of Figure 22, the braking means 30, 32 are arranged for a said road wheel 20 (and in fact the whole device 12, 14) to move into engagement with said member 32 to effect braking. In the embodiments of Figures 8 to 22, the braking means 30, 32, 34 comprise an axle

18 for rotation of a said device 12, 14 and said member 32 is slidable on the axle 18 to engage a road wheel 20 of the device 12, 14.

In the embodiments of Figures 8 to 21 , the device 12, 14 can rotate on said axle 18. In the embodiment of Figure 22, said device 12, 14 is fixed to said axle 18. The braking means 30, 32 comprises an axle 18 for rotation of a said device 12, 14, said member 32 is fixed on the axle 18 and the axle 18 is axially slidable for said member 32 to engage a road wheel 20 of the device 12, 14 to effect braking.

The embodiment of Figures 2 to 7, comprises separately actuable braking means 26 for each said device 12, 14 (unlike the arrangement 30, 32, 36 of Figures 15 to 22 in which there is a common actuator 30 for both of the devices 12, 14), and in fact separately actuable braking means 26 for each road wheel 20

A variation of the Figure 1 embodiment comprises a road wheel 21 , e.g. at the front of the buggy 10, so that it is other than the aforesaid road wheels 20, which are at the rear of the buggy 10, and comprises braking means 26 (not visible in Figure 1 because it is on the remote side from the viewer) similar to, and operated similarly to, braking means 26 of Figures 4 to 7.

In a further arrangement, not shown, there is provided a wheel arrangement according to the arrangement comprising road wheel devices 12, 14 of any of the embodiments illustrated in the accompanying drawings but, similarly to our earlier patent document GB2483873, this is provided as an attachment for a collapsible buggy, with the exception that there is a collapsible interconnecting means interconnecting the two road wheel devices 12, 14 so that these may be moved laterally together or apart by collapsing or extending such interconnecting means, e.g. while the arrangement is attached to the collapsible buggy and simultaneously with the latter being collapsed or extended. Such interconnecting means acts in the same way as the collapsible frame 16 interconnecting the road wheel devices 12, 14 in the embodiments illustrated in the accompanying drawings.

MORE PARTICULAR DESCRIPTION OF SOME DETAILS Referring to Figures 2 and 3, it is to be noted that the frame 16 is shown only schematically, and not accurately, since the only requirement is that the buggy 10 should be collapsible laterally; and various ways of making this possible will be readily apparent one skilled in the art. The essential, for the purposes of braking in the embodiments of Figures 8 to 22, is that the buggy 10 should have a maximum lateral extension, e.g. when strut 17 is straightened out at its hinge 24, as is the case for Figures 15 and 16.

Referring to Figures 2, 4 and 5, a support 40 for the road wheels 20 comprises two substantially triangular plates 42 and this is mounted on axle 18 between the prongs 44 of a vertical frame member 46 of the buggy body 16. Referring to Figures 6 and 7, braking member 26 pivots on pin 264 and can be pressed down to engage braking of a road wheel 20 by applying the foot to lug 261 , causing lug 262 to engage in 264 to which wheel 20 is fixed, or can be pressed up to disengage braking by applying the foot to lug 263. Member 26 is held in the engaged or disengaged position by spring means (not shown) which will be apparent to one skilled in the art.

In the embodiment of Figures 8 to 20, the support 40 is a moulded substantially triangular body 40 with respective recesses 201 for the three road wheels 20, each mounted to freewheel on a pin 19. Body 40 is pierced by three corresponding holes 401 into which pins 34 of brake member 32 slide to allow the latter to reciprocate against springs 341 (see especially Figures 10 and 11), while rotating with road wheel support 40 on axle 18. As seen in Figures 10 to 14, the actuator 30 is hinged (for vertical movement only) at hinge 31 to a U-shaped bar 33, the arms 331 and 332 of which slide horizontally in a block 441 fixed to prong 44 of frame 16. The free ends of the arms 331 and 332 of bar 33, which does not rotate, are able to bear on thrust plate member 32, which rotates with road wheel device 14. Referring additionally to Figures 15 and 16, when pedal 38 is pressed down, going from the Figure 15 position to the Figure 16 position, this straightens out actuator 30, effectively extending its ends outwardly from the Figure 10 position to the Figure 11 position, and (at each end of actuator 30) thrusting arms 331 and 332 against thrust plate member 32, to slide its pins 34 into engagement with catch means 36 of all three road wheels 20. (It is to be noted that the braking action is to prevent travel movement of the buggy 10, not to slow it down; although the frictional braking of the embodiments of Figures 4 to 7 and 21 might be used to slow down travel movement of a buggy 10.) When the pedal 38 is released (e.g. by kicking it upwards) the U-shaped bar 33 is withdrawn and the springs 341 move the thrust plate member 32 out of braking engagement with road wheels 20. In the disengaged position, a stop (not shown, in the form of a bush on axle 18) may be provided to limit the withdrawal of member 32 under the action of springs 341 and springs 333 may cause additional withdrawal of U-shaped rod 33 so that its ends 331 and 332 no longer bear against member 32 during travel. In the embodiment of Figure 21 , the support 40 comprises rotary support plates 42 similar to those shown in Figure 4, except that one of them also acts as thrust member 32 being able to slide on axle 18 against the bias of a spring 35 under the thrust of actuator 30 (exerted through non-rotary plate 33 slidable on axle 18) towards the side of road wheel 20 to engage the latter by friction.

In the embodiment of Figure 22, support 40 of e.g. device 14 can rotate but not slide on axle 18, braking member 32 can rotate (with support 40 because its pins 34 engage support 40), and slide on, axle 18, and axle 18 can be moved axially (to the right as seen in Figure 22) under the action of actuator 30, which movement of axle 18 carries with it support 40 to approach member 32 against the bias of a spring 35 to cause each road wheel 20 to engage pins 34. When actuator 30 is released, axle 18 slides axially (to the left as seen in Figure 22) under the bias of spring 35, to carry with it support 40 and thereby disengage road wheel 20 from pins 34.

In the Figure 23 embodiment, a Bowden cable device 50 (comprising a sheath 501 and a core 502) is actuable by means of a releasably latched rotary handle 504 of an actuator 503 mounted on handlebar 161 to operate the brake (comprising braking means 32, 33, 34), instead of a foot operation as in the Figure 15 embodiment. Instead of using a pedal 38, hand actuation of lever 504 draws together ends 302, 303 of hinged-together pair of members 30, which by cranked lever action about pivot 301 thereby extends the ends of the pair to effect braking via rods 33 acting against springs 333, each constrained between fork 44 and lug 334, to thrust outwardly its braking member 32. In the Figure 24 embodiment, each spring 333 and its lug 334 are arranged on the opposite side of its fork 44 (compared with the Figure 23 embodiment) so that the brake is permanently engaged except when released by the Bowden cable device 50. It is to be noted that in this arrangement, even with the brake engaged, the two members 30 never open out to be completely in line with each other but make a maximum angle with each other of about 120°, so that each makes a minimum angle with the horizontal of approximately 30° when the buggy 10 is on the level. This means that the buggy 10 can only be moved along while the handle 504 is squeezed towards the handlebar 161. It is a failsafe device because inadvertent (or deliberate) release of handle 504 engages the brake. Although the braking means is mainly intended to be a parking brake, in the event of failure to retain hold of (or squeeze) the handle 504, the buggy 10 will rapidly be halted.

The Figure 25 embodiment is the Figure 15 embodiment with the extra feature shown in Figure 25. The brake is foot-operated but can be temporarily released by the Bowden cable device 50. Each of the members 30 is a hollow rod 30 with an internal telescopic extension 302, normally urged outwardly by a spring 304 acting against an internal cylindrical lug- and-guide 305, so that, as described above, depressing of pedal 38 engages the brake and this latches in the braked position shown in Figure 16. Each of the slidable extensions 302 is fixed to an L-shaped traction member 306 having an external end projecting through a slot 307 in its rod 30, and guidedly slidable in lug-and-guide 305. The Bowden device 50 is connected to these external ends so that operation of its handle 504 draws these ends together and thereby retracts the extensions 302 into rods 30, thereby releasing the brake, temporarily so long as handle 504 is squeezed towards handlebar 161 . This allows the user to put on the brakes as a safety device and then temporarily release them in the failsafe manner of the Figure 24 embodiment. For normal travel, there is an extended part 162 of handle 161 that can be grasped unencumbered by handle 504. The Figure 25 arrangement may be applied by means of a second Bowden cable to the Figure 23 embodiment.

Part of the brake control connection/s, e.g. at least from the actuator (handle 38 or pedal 504) to the operative (braking or unbraking) member 33, 306, of the embodiments of Figures 1 to 22 is tied to or dictated by the buggy frame 16 (e.g. if the actuator should be on the handlebar 161 , connecting levers, tie rods, or the like can be mounted to the frame 16), while in the embodiments of Figures 23 to 25, the Bowden cable runs free of the frame 16, between its two ends. Other forms of free-form connection can be used, e.g. an electric actuator connected by wires to solenoid-operated operative members, or connected thereto by a radiation connection, e.g. an ultrasonic, radio or infrared connection.

Again, there could be a separate control connection to the operative member at each said wheel device at each side at the back of buggy 10, or a bifurcated connection from a single said actuator to the respective operative members. However, it is more convenient to have a single connection that operates the respective operative members jointly through a single mechanism, as shown in the embodiments of 5 Figures 15 to 25. In particular, e.g. for such a centralised mechanism, as seen in Figure 25, there is effectively an equalising mechanism in that, for the one wheel device 14, on one side, lug 305 limits the withdrawal movement of its member 302, so that (e.g. if movement of that member 302 on one side is stiffer (e.g. encounters more friction) than that of the opposite member 302, on the other side) continued squeezing of the actuator handle 38 will then withdraw the opposite member 302 from braking engagement with the opposite wheel device 14, on the other side. It will be apparent to one skilled in the art, that features of the different embodiments disclosed herein may be omitted, selected, combined or exchanged and the invention is considered to extend to any new and inventive combination thus formed. Where a preference or particularisation is stated, there is implied the possibility of its negative, i.e. a case in which that preference or particularisation is absent.

Many variations of the invention and embodiments hereinbefore described will be apparent to people skilled in the art and all such variations are to be considered as falling within the scope of the invention.