This invention relates to wheeled load-carrying apparatus, for example dollies, trolleys, carts, various articles of luggage and wheelbarrows.

Such items are known in very many forms. In all of them, the motive power to move the load is supplied by the person using the apparatus, and the wheels are mounted so as to be freely rotatable about their axes (hereinafter called wheel axes for simplicity). In some such apparatus, for example luggage trolleys, it is known to provide means to brake the apparatus against movement, for example by the use of one or more brake pads or bars which can be brought into engagement with one or more wheels to brake it or them against rotation.

WO 2009/098461 discloses wheeled apparatus for transporting loads where the apparatus has a base structure carrying a pair of spaced apart rotatable ground-engaging members, each mounted for free rotation on the base structure and with wheel axes being coplanar, but at an angle to one another of at least 10°, and the arrangement being such that the angle between the plane of a surface on which the apparatus rests and the plane of the wheel axes may be varied.

Such apparatus can be thought of as including a pair of wheels set at a substantial positive camber angle, in contrast to the few degrees of camber angle adopted in many four-wheeled vehicles for the pair of wheels by which the vehicle is steered.

The preferred rotatable ground-engaging members described in

WO2009/098461 are generally hemispherical members having an outer ground-engaging surface, which may be provided with a tread, and a central hub which fits the inclined axles on which each hemispherical member rotates. Such hemispherical members are included in the term "wheels" as T/GB2012/000682

2 used herein, as well as, for example, more standard types of wheel consisting of a hub, rim and tyre. Such wheels are also known for use in vehicles designed to travel over rugged terrain, as disclosed in US-A- . 4353428, which also discloses such wheels arranged at a substantial positive camber.

As explained in WO 2009/098461 , when the wheel axes are both in a vertical plane, the wheeled apparatus may be easily pulled along the ground in a direction perpendicular to that plane. If the wheel axes are moved out of a vertical plane, because of the substantial positive camber, the two wheels adopt, a splayed or "toed-in" configuration relative to the ground on which they rest, which exerts a braking effect on the apparatus. If the angle between the plane of the wheel axes and the ground deviates substantially from 90°, the apparatus is braked to such an extent that it no longer rolls easily along on the wheels, because each wheel tries to roll on the ground in different directions, though the apparatus can be rotated as a whole about a vertical axis, with each wheel then rolling along a horizontal circular arc centred on that vertical axis.

While the invention described in the international publication can be

embodied in a variety of articles such as trolleys, rucksacks and articles of luggage, as illustrated in the published international specification referred to, care needs to be taken when pulling or pushing them along to maintain the plane containing the wheel axes substantially vertical. If the plane containing the wheel axes moves materially away from the vertical, the braking effect arises and the article becomes harder to pull or push, and tends to judder. This can be inconvenient, particularly if the maintenance of the correct angle for easy rolling requires the user to raise or lower e.g. a pull handle forming part of the article away from a level above the ground which is comfortable for the user. This applies also to the articles of luggage illustrated in GB-A- 2472052. We have now found that if the wheels are mounted in such a way that the plane of the wheel axles stays vertical while the load carrying part of the apparatus can swivel over a small angular range relative to the wheels and wheel axles, this disadvantage may be reduced or overcome while maintaining the ability to 'brake' the apparatus by moving the plane containing the axes of rotation of the pair of wheels substantially away from the vertical. In other words, by allowing a limited degree of angular movement of the load carrying part of the apparatus about a horizontal axis between the wheels, the wheel axes can remain in a plane perpendicular to the ground while the load carrying apparatus may be rotated by a modest amount about that horizontal axis, thus avoiding the disadvantages referred to above.

According to the present invention, there is provided apparatus for transporting loads including a pair of freely rotatable ground-engaging wheels to enable the apparatus to be pulled or pushed along with the wheels in contact with the ground, a load-carrying frame or container supported on the wheels, wherein the wheels have a high positive camber angle and are each mounted for free rotation on a stub axle, a connector piece extends laterally from each stub axle and each connector piece is mounted at its end remote from the stub axle, to enable the connector piece to swivel, relative to the frame or container, about an axis which is horizontal when the apparatus is being used, over an angular range of 5 to 25°, and means enabling the frame or container to be rotated about a horizontal axis relative to the ground on which the apparatus rests. This horizontal axis may be thought of as running in the direction of a "load axle", i.e. the axle on which the load supported by the wheels may rest.

The connector pieces may be linked together, for example via an elongate rigid member constituting such a load axle, in order to coordinate the movement of the two wheels. In a second aspect, the present invention provides a wheeled support structure for use in apparatus as defined above consisting of a pair of wheels mounted on a pair of axles, the axles being inclined to one another by at least 10°, and preferably by 50° to 100°, the axles being mounted at each end of an elongate member constituting a load axle of the apparatus via a connector member at each end thereof, the connector members extending at an angle to the direction of the elongate member and to the axis of the axles, and each elongate member, the axles and the connector members being coplanar. Each connector member is fixed at one end to the elongate member and at the other end to the inclined axle on which the wheel is mounted. The elongate member may be of any appropriate length, and may consist of two elongate members connected together by means enabling the overall length to be varied.

In a simple embodiment, the wheel support structure is an elongate bar having a lateral extension at each end, the lateral extensions being coplanar, with the angled axles for the wheels mounted at the ends of the extension members and those axles being coplanar. The bar can be thought of as being a load axle cranked at each end to form a pair of wheel axles.

If a load-supporting structure such as a box or frame is now mounted on the load axle, because of the weight of the box or frame, the load axle tries to adopt a position with the extensions going up and the axles of the wheels extending downward from the tops of the extensions and in a vertical plane. The load axle is lower than the wheel axles.

Such a position can only be achieved if the box, frame or like structure is at the right angle to the ground, but in this position it may be pushed or pulled along with equal ease over a range of angles of inclination of the box or frame relative to the ground. Additionally, the wheeled support structure self- aligns with the elongate member rotating slightly if the wheels are on a sloping surface so that the elongate member and the wheel axles remain in a plane substantially perpendicular to the surface of the slope. The juddering problem noted above is avoided. This occurs because the wheeled support structure can rotate by a limited amount relative to the box or frame. A simple way of achieving this is to provide that the connector pieces are located for movement within a generally sector-shaped area having radial walls defining the angular range over which the connector pieces may swivel relative to the box or frame. In such an arrangement, if the box or frame is, for example, laid down on the ground or placed vertically, the connector pieces first move towards, and then come to rest against, one or other side wall of the sector-shaped area and subsequent movement of the box or frame then moves the axles of the wheels out of the vertical plane, which increasingly points the wheels in different directions and so exerts an increasing braking force on the apparatus, i.e. it can no longer be rolled easily along (though it can still be swivelled about a vertical axis if desired).

Mounting standard wheels so they can swivel about a horizontal axis offset from the axis of the wheel is known for a shopping trolley (see EP-A- 1 145931 ) and for a caster wheel on an unmanned conveyance vehicle (JP- A-2006 88137).

The present invention thus generally provides load-carrying apparatus comprising a box or frame structure adapted to receive or support a load, means enabling the box or frame structure to be rotated about a horizontal axis relative to the ground on which it rests, and two ground-engaging wheels mounted for free rotation on axles connected to the box or frame structure, wherein the axles can themselves swivel to a limited extent relative to the box or frame structure. The axles on which the two wheels rotate are coplanar in a vertical plane when the apparatus rests on a horizontal surface and are preferably inclined at 75° to 105° to one another, so as to provide a substantial camber angle between the two wheels. Each axle is mounted on the box or frame structure in a fashion allowing it to pivot re)at ^' ive thereto about an axis substantially parallel to the ground on which the wheels rest. In such apparatus, two wheel and mounting units may be used, each consisting of a wheel mounted on a stub shaft for rotation about a first axis, the stub shaft being mounted at or near one end of a radius arm, and the radius arm being rotatable about a second axis at or near its other end, the two axes being at an angle of at least 30°, preferably 35° to 55°. In order to achieve stability for a pair of such wheels mounted on stub axles which axles are in turn each mounted at the end of a crank or radius arm, so that they can rotate about an arcuate or circular path, the length of the crank or radius arm needs to be sufficient. This can be achieved if the axis around which the crank or radius arm rotates lies between the edge of the wheel where it contacts the ground and the end of the hub from which the stub axle emerges.

WO 2009/098461 also describes (and illustrates in Figure 5) a three-wheeled item of luggage such as a shopping bag, which rests on all three wheels when vertical and on just two of the three when inclined, so that it can be pushed or pulled along with rotation only of the two ground-engaging wheels. Applying the underlying concept of the present invention to such three wheeled items, each of the wheels is mounted on the load-receiving part of the item via an intermediate sw/vellable member having on one side a stub axle on which the wheel is mounted and the intermediate member being mounted swivelably about an axis at an angle to the direction of the stub axle. One way of achieving this is to provide on the side of the swivellable member away from the stub axle a set of mounting bars, each of which may slide in a slot in a base member fixed relative to the load-receiving portion. This enables the member to move relative to the base when the angle of the base to the horizontal is varied, i.e. when the item is tipped so as to rest on two wheels only of the three.

Preferably in an item of this type there are three mounting bars and three corresponding slots for each of the wheels. By arranging ramps relative to the slots, the angles of tilt of the stub axles on the two ground-contacting wheels changes as the handle position is varied. The bars and slots may be interchanged without affecting the working of the apparatus, e.g. the stub . - axle may be mounted on a cup-shaped base having three slots in it into which three bars fitted to the load-receiving portion of the apparatus are inserted.

The invention is illustrated by way of example with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a wheeled support structure;

Figure 2 is a diagrammatic drawing showing the wheeled support structure of Figure 1 and incorporating a supporting base member;

Figure 3 is a perspective drawing of an item of luggage including the wheeled support structure of Figure 2;

Figure 4 is a perspective view of a suitcase with a detachable wheeled support member;

Figure 5 is a section through part of the suitcase shown in Figure 4; and

Figures 6 and 7 show diagrammatically how the invention is applied to a three-wheeled bag.

Referring to Figures 1 to 5 of the drawings, Figure 1 shows diagrammatically an arrangement of a pair of generally hemispherical wheels 1 , 2, each having a central hub 3. The wheels are mounted on opposite ends of an elongate member which consists of a central straight bar 5 which act as a load axle. At each end of bar 5 is a laterally projecting short section 6. Each section 6 may be fixed to the end of the central bar 5, or it may be bent out from, and integral with, bar 5.

At the ends of the two sections 6 remote from bar 5 are affixed two stub axles 7, the wheel axles. These extend into the hubs 3 of the wheels 1 , 2, which can rotate freely on the stub axles 7.

If such a structure is placed on a horizontal surface such as the ground, it adopts the position much as drawn in Figure 1 with the load axis formed by central bar 5 horizontal and sections 6 arid stub axles 7 lying in a vertical plane. This means that the wheels , 2 are each freely reliable in the direction indicated by the double-headed arrows 8 on the drawing if. the bar 5 is moved transversely to its elongation.

Figure 2 shows the arrangement shown in Figure 1 set in a supporting base member 10 having a groove in it in which bar 5 is rotatably mounted. At each end of bar 5, section 6 lies within a generally triangular or sector-shaped recess 1 1 formed in base member 10; The sides of each recess limit the degree to which bar 5 can rotate about its elongate axis relative to base member 10.

Base member 10 may be attached to a box structure to form a wheeled article of luggage, as shown in Figure 3. Referring to Figure 3, the article of luggage consists of a box structure 15 having set into one side of it an extendable handle 16 which is set on a pair of struts 17 to enable it to be extended from, or stowed adjacent to, the box structure 15 in known fashion. The handle 16, struts 7 and the locking mechanism for locking struts 17 in position are of standard construction.

At the end of the box structure 15 opposite handle 16, there is fixed the wheeled support structure shown in Figure 2. B2012/000682

The angles and dimensions are such that when the handle 16 is extended and the user wishes to pull or push the case along, usually with the · telescopic members 17 lying in a plane inclined at 30 to 45° to the horizontal, the sections 6 lie within the boundaries of recesses and central bar 5, sections 6 and the stub axles 7,. all lie in an essentially vertical plane. They continue to lie in that vertical plane even if the general angle of inclination of the body 15 to the horizontal is varied within the e.g. 30 to 45° range.

However, if the case is laid down flat or stood up vertically, then the wheels 1 , 2 wish to roll in different directions along the ground and accordingly exert a braking effect on the item.

It should be noted that because bar 5 is mounted in a channel lying at the lower end of base member 0, it does not impinge on the space inside base member 10 which can accordingly be utilised to the full as space for containing items the user wishes to pack into the base member 0 and transport where they wish to go.

A noticeable advantage in manoeuvring an item of luggage as shown in Figure 3 of the accompanying drawings is also that the ability of the

assembly, consisting of the wheels and the connecting member between the wheels, to rotate about a horizontal axis materially assists the ease with which the item may be moved across steps either upwards or downwards. Because of the component of force on the central section being inclined towards the ground, the ease of rolling is maintained even if the luggage is being moved up or down a slope such as a ramp or gangway.

The ease of handling of the article illustrated in Figure 3 is considerably improved compared with the ease of handling the articles of luggage described in WO 2009/098461 because of the use of a two-wheeled support structure of the type described above and illustrated in Figure 1 . Figure 4 and Figure 5 show an alternative construction. Figure 4 shows the general outline of a standard type of suitcase having a main body 20, a carrying handle 2 on one side and an extending pulling bar 22 with a transverse handle 23 set in it.

In accordance with this invention, in place of the conventional pair of small wheels set in mountings on the corners denoted 25 and 26 in Figure 4, a wheeled supporting assembly 27 may be affixed to the end of the body 20 by any convenient means. As can be seen, the unit 27 consists basically of a plastics moulding 28 which may be affixed e.g. by studs 29 shown in Figure 5 to the case body 20. The plastics moulding 28 has a pair of wheels 30, 31 mounted on it via a elongate member 32 having a central straight section, two upwardly inclined sections to each side of the straight section and, as seen in Figure 5, two downwardly inclined stub axles on either ^' end, consisting wheel axles on which the wheels 30 and 31 are journalled.

Referring now to Figures 6 and 7, these show diagrammatically how the ease of handling of a three-wheeled bag may be improved. Figure 6 is a cross-section through a corner of the bag, which has a fabric liner 39. It shows a wheel 40 running on a stub axle 41 which is fixed to a plate 42 which itself has three pins 44 protruding from the back of it. These pins 44 pass through slots 45 in a moulding 46 (which forms the base of the bag) and are held captive by suitable heads 47 so that the plate 42 is fixed to the moulding 46, but can move according to the shape of the slots 45. However, the slots 45 are not simply cut through a flat plane; the edges of the slots 45 are ramped in such a way that the plate 42 when it moves, as pins 44 slide in, the slots 45, tilts relative to its starting plane. When two of the wheels 40 are engaged with the ground, the positions of the pins 44 and slots 45 and the shaping of the ramps enable the plates, and hence the stub axles 41 and wheels 40, to swivel relative to moulding 46. This motion is repeated for each two-wheel combination due to the symmetry of the system. The start angle for this effect will be the same as for the fixed axle three-wheeler shown in 00682

1 1

Figure 5 of WO 2009/089461 where the wheels run true. If the handle of the bag is lowered from this position, the lowest pin 44 acts as a pivot, and gravity forces the other pins 44 to move along the prescribed paths defined by slots 45, urging the plate to tilt which in effect aligns the wheels to each other. This happens until the pins reach the ends of their respective slots 45.