Patent Application
20130062843
This invention relates to wheeled apparatus for transporting loads. It is applicable to such apparatus which is designed to carry a load placed on it, for example a dolly, cart, trolley or wheelbarrow, as well as to apparatus where there is some form of container which is fitted with wheels to assist in transporting the container, for example an article of luggage such as a suitcase or rucksack.
The terms “wheel” and “wheeled” used herein are intended to cover both standard wheels—usually discs with or without an outer peripheral cover or tyre, and other rotatable members which function as wheels, for example hemispherical or spherical rollers.
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 wheel or wheels is/are mounted so as to be freely rotatable about its/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.
Some load-carrying apparatus uses only a single wheel, for example a traditional wheelbarrow. In the case of wheelbarrows and analogous load-carrying apparatus, suggestions have been made to use a pair of wheels in place of the customary single wheel, for example as disclosed in U.S. Pat. No. 1,572,531, U.S. Pat. No. 3,743,312 and U.S. Pat. No. 6,341,787, but the stability and ease of handling of these types leave much to be desired.
However, for ease of operation and stability while moving, two or more spaced apart wheels are usually employed, so many carts, trolleys and wheeled luggage items use a pair of wheels which are designed to engage the ground and which are mounted on one or two axles. The arrangement is such that, on a horizontal support surface, the wheels are vertical and the axis of the axle or axles about which they rotate is horizontal. Examples of such constructions are disclosed in GB-A-138218, U.S. Pat. No. 5,313,817 and US-A-2008/0174078, while FR-A-2610586 and U.S. Pat. No. 4,523,774 disclose trolleys where the wheels are generally spherical.
Arrangements are known in which the two wheels or two major wheels of certain wheeled load-supporting apparatus are slightly outwardly inclined. This is the case with certain designs of wheelchair and other mobility assistance devices, e.g. as disclosed in US-A-2008/0276977 and US-A-2004/0231613. FR-A-2823708 describes a luggage-carrying cart on to which, for example, a rucksack may be strapped and which is pulled by means of a harness attached to the user. As shown in
GB-A-651501 discloses a golf trolley for a golfer to carry his golf bag on and which has a pair of wheels which are likewise slightly splayed outwardly. US-A-2004/0026896 discloses a pushchair for a child where the front wheels are slightly splayed outwardly.
U.S. Pat. No. 4,252,334 discloses a wheelbarrow where the normal front wheel is replaced by a pair of outwardly inclined wheels to improve stability. U.S. Pat. No. 690,762 discloses a lawn sprinkler with a pair of spaced outwardly inclined wheels, likewise to improve stability (when the item is pulled along by the hose). This approach has also been used in castors, as disclosed in U.S. Pat. No. 4,457,045 and, with the two floor-engaging members at a more extreme angle, in U.S. Pat. No. 4,161,803.
Finally, GB-A-770602 discloses a truck or the like with a wheel arrangement using conical wheels located rotatably in bearing blocks, and with the edge of the cone contacting the ground.
I have now found that useful load-carrying apparatus may be constructed using a pair of freely rotatable wheels or analogous rotatable ground-engaging members which engage the ground or other support surface on which the apparatus rests at spaced locations, and which rotate about axes fixed relative to one another but inclined to one another, and wherein means are provided to enable the angle between the plane containing both axes to be varied relative to the plane of the surface on which the apparatus is supported. When the two planes are orthogonal, the wheels may rotate easily as the apparatus is moved along the surface, both pushing and pulling. As the angle between the planes decreases, the wheels exert a progressively increasing braking effect between the apparatus and the surface, which can be of particular value in certain applications.
In accordance generally with the present invention, there is provided load-carrying apparatus comprising a base structure carrying a pair of spaced apart rotatable ground-engaging members each mounted for rotation on the base structure, the axes of rotation of the respective rotatable members being fixed relative to one another and coplanar but which extend 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 in which the axes of rotation extend may be varied. Preferably the axes of rotation intersect at a point above the surface on which the apparatus rests.
One way in which this may be achieved is by mounting the pair of rotatable ground-engaging members on the end of a frame which constitutes the base structure, with the plane containing the axes being at an angle to the direction in which of the frame extends away from the end carrying the rotatable members, the angle usually lying in the range of 25-80°.
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 apparatus may have just the two rotatable ground-engaging members or it may have more, in particular three or four.
By constructing a trolley, cart, wheelbarrow, piece of luggage or similar piece of apparatus in this way, the ease with which the apparatus may be rolled across a generally horizontal surface varies with the angle at which the frame of the item is held. The simplest case to consider is that of a two-wheeled luggage trolley having a frame with a pair of wheels mounted at one end and a pulling handle located at the other. When the handle is extended, and the user holds it at a convenient height, usually 50 to 100 cm above the (horizontal) ground, the plane containing the axes is arranged to be vertical, so when the apparatus is pulled along by the handle, the wheels turn without difficulty.
If the user raises or lowers his hand, the angle of the plane containing the wheel axes tilts, and progressively as the hand is raised or lowered further the wheels exert a braking effect. This is very easily felt by the person pulling the apparatus along, and this tactile feedback automatically prompts the user to adjust the angle for smooth running as the luggage trolley is pulled along. When, on the other hand, the user no longer wishes to pull it along, the handle is simply raised or lowered, so rotating the entire apparatus about a horizontal axis close to its base, so that it is either stood up with the handle extending substantially vertically, or laid down, for example to allow access to a side opening case mounted thereon, and with the handle resting on the ground. In either case, the plane containing the axes of rotation of the wheels is no longer vertical, and because the angle at which the wheels are mounted, movement of the trolley is essentially braked. This is achieved simply because the wheels would now try to travel along the ground, if rotated about their axes, in two directions at a substantial angle to one another and accordingly, with the handle up or down, the trolley will only move easily in rotation about a vertical axis. If an attempt is made to move it along the ground on which it rests, the wheels together exert a braking effect, and the trolley can only be forcibly dragged along.
Put another way, 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.
This braking effect means that care needs to be taken when pulling or pushing the apparatus 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.
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.
Thus, according to a preferred feature of the present invention, the apparatus for transporting loads includes 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, and wherein 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 further 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).
The present invention thus generally provides in a further aspect 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 relative 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.
As noted above, the present invention is characterised by having a pair of wheels mounted with their axes at an angle to one another and, furthermore, mounted so that the plane in which both the axes of rotation of the wheels lies can itself be rotated relative to the ground so that the wheels run smoothly or self-brake. Although this has obvious applications in the case of two-wheeled trolleys, carts, items of luggage and the like, as described above, the invention is not restricted to such apparatus containing only two wheels. One example of this is a conventional flatbed trolley, for example as used in transporting luggage in hotels or as a hand cart in a railway station or airport luggage-handling facility. If this is constructed with a pair of front wheels which are set non-coaxially, but on a framework which may be rotated about an axis parallel to the line joining the centres of rotation of the two wheels, then the trolley may be pulled along, but equally easily automatically braked in position during loading and unloading. The rear (or single wheel) of such a trolley may rotate conventionally about a horizontal axis, and may be castored if desired.
A further alternative construction is to mount three wheels, preferably equiangularly, on the end of an elongate arm or shaft, so that when that arm or shaft is held at an appropriate angle between horizontal and vertical, the plane containing the axes of rotation of the two wheels which are then lowermost, i.e. the ones engaging the ground, is vertical. This is of particular value in the construction of a shopping trolley which can be stood with the arm or shaft vertical for loading and unloading and, in that position, it is stable and braked, but then grasped easily and pulled along as desired once loaded. This is of particular value because the user does not have to twist the trolley about a vertical axis before starting; whichever two wheels are closest to the ground once the arm or shaft is moved from the top simply engage with the ground and, as the angle of the plane in which the axes of those two rotatable ground-engaging members lie comes to the vertical, the trolley may be rolled along.
In order to reduce the incidence of judder, as described above, in such three-wheeled items, each of the wheels may be mounted on the load-receiving part of the item via an intermediate swivellable member having on one side a stub axle on which the wheel is mounted and the intermediate member being mounted swivellably 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 rotatable members are preferably ones having a fairly substantial ground-engaging surface, so that they do not dig into soft ground, mud or sand. A preferred construction is to make the members essentially hemispherical. Hemispherical wheels are known for use in driven vehicles designed to operate on snow, mud or sand, for example from GB-A-757663 and U.S. Pat. No. 2,967,581. The wheels disclosed in these specifications are mounted on axes inclined to one another, but there is no disclosure of mounting them in any way whereby the angle of the plane containing those axes can be varied relative to the plane of the ground on which the vehicle rests. Likewise, U.S. Pat. No. 4,353,428 discloses the use of hemispherical wheels in driven vehicles, and on e.g. a pushed wheelchair, and with the wheels arranged at a high positive camber. However, the wheels may swivel independently of one another, and there is no suggestion of linking two spaced-apart wheels to achieve the braking effect secured in load-carrying apparatus according to the present invention.
The rotatable members may be constructed of a fairly high friction material, for example rubber, or may be faced with such material; the greater the frictional properties, the more effective the braking action when the plane of the axles is not perpendicular to the ground on which the device sits. The frictional properties of the exterior surface of the rotatable members can vary, for example as between a relatively low friction area which contacts the ground when the apparatus is being wheeled along and relatively higher friction areas which contact the ground when the plane containing the axes of rotation is not vertical. Parts of the exterior of the rotatable members may be provided with a tread, analogous to the tread on a motor vehicle tyre.
The exterior of the rotatable members may be rigid or yielding. In the latter case, by suitable construction of the exterior of the members, it is possible to provide a certain amount of “shock absorbing” properties to those members, which makes moving the apparatus across a rough hard surface, for example cobblestones, more comfortable. In particular, if the rotatable member has a raised resilient circular belt, which engages the ground when the plane containing the axes of rotation is vertical, this provides a resilience when the apparatus is moved, as well as widening the angular range within which the apparatus may comfortably be pulled along as the distance between the contact points with the ground widens slightly when the apparatus is loaded.
In this way, the rotatable members may impart a degree of suspension to the apparatus, cushioning the impact of rough terrain on the load carried by the apparatus. Additionally, or alternatively, the rotatable members may be mounted via a suspension system of known type.
If the rotatable members are hollow hemispherical ones, then the interior of the rotatable members may be used as a space for stowing part of the load. The rotatable members may be integrated into the overall designs so that their edge lies flush with the contour of a load-carrying chamber mounted on the frame.
Although the rotatable members may be supported on axles of any length, it is preferred to mount them on short stub axles fixed to either side of the frame so as to reduce the bending moment on each. Using hemispherical members, the stub axle is preferably substantially vertically above the ground-contacting part of the rotatable member.
A particularly preferred way of mounting the rotatable members is to provide in each a socket adapted to fit over a stub axle, the socket having a wear-resistant end piece against which the tip of the axle bears in use. The socket may be lined with a self-lubricating inner sleeve, e.g. of oil-impregnated porous engineering plastics material, or be made of such material. Clip means may be provided to retain the stub axle in the socket. In this way, a very easy running, low friction mounting arrangement may be constructed without the use of, for example, a taper roller thrust bearing or like component.
The angle between the two axes about which the two rotatable members rotate is, as noted above, more than 10°. It is very convenient in design terms to make the angle between 50° and 100°, most preferably 80° to 100°, which enables the rotatable members essentially to be placed one side of a load or load-carrying member such as a case or box. This lowers the centre of gravity of the loaded apparatus, leading to easier manoeuvrability.
The attached drawings show by way of example a number of ways in which the present invention may be put into effect. In the drawings:
a,
1
b and 1c show respectively diagrammatic side, end and perspective views of the underlying structure of a two-wheeled trolley apparatus according to the present invention;
Referring to
As can be seen from the drawings, when the apparatus is in the position illustrated, the frame 1 is inclined relative to the ground (horizontal surface 10) and the higher end of the frame is a distance “A” from the ground of between 50 and 150 cm.
As evident from an inspection of
In this position, the apparatus may be moved to the left or right as seen in
Put very simply, a two-wheeled trolley constructed on a framework of the type diagrammatically illustrated in
Mounted to each side of the box-like structure 12 are hollow part spherical wheels 18 which are mounted on short stub axles so that they rotate around an axis 19. Axis 19 is in a vertical plane when the wheels 18 are rested on the ground and the handle grip 16 is held in the hand of the user and from 50 to 150 cm above the ground. It can be easily pulled across the ground to the desired picnic site, at which point it may be swivelled to allow the handle 14 to extend generally vertically and the front end of the box-like structure, denoted 21 in
As visible in
When the right-hand end of the frame 40 as shown in
Referring now to
As shown in
In the position shown, the device is stable, particularly when loaded, and does not tend to roll in any direction (though it may be spun around a vertical axis if desired). When it is loaded and the user wishes to move what is inside it, he or she simply grasps handle 51 and pulls it to the side. This will lift one of the rotatable members 55 off the ground and leave the unit supported simply on the other two rotatable members 55. As the handle is moved outwards and downwards, the position is rapidly and easily achieved in which the axes of rotation of the two ground-engaging rotatable members lie in a common vertical plane, at which point the trolley may easily be moved along. The swivel mounting of handle 51 enables this action to take place automatically and without any strain on the user's hand as the trolley adopts its position with two only of the members 55 engaging the ground.
Referring now to
The socket 61 receives a moulded lubricating bearing insert 65 made of self-lubricated engineering plastics material. It is preferably a press fit into socket 61. The centre of moulded component 65 has a straight cylindrical bore for the reception of a stub shaft 66 in which the rotatable member is to be mounted, and it is dimensioned to be neither too tight, which would reduce the ease of rotation, nor too loose, which would lead to wear and incorrect running.
As can be seen in
Referring now to
At each end of cross-member 74, there is an offset stub axle 75 and mounted on that is a substantially hemispherical ground-engaging rotatable member 76. Also fixed to the cross-member is a stirrup 78 connected via a shaft 79 to an actuation handle 80.
Ground-engaging members 76 are arranged as in other load-carrying apparatus according to the present invention with their respective rotational axles at an angle to one another. In the position shown, the stirrup 78 has come to rest against the front of support bow 72 (caused by the downward pressure of the flat bed 70 itself, including any load on it, on support plate 73) and, in this position, the stub axles 75 extend in a plane which is inclined to the vertical and upwardly away from the viewer in
When it is desired to move the trolley, handle 80 is moved in the direction of arrow 81 and this causes the support plate 73 to rise a little, but, much more importantly, to rotate cross-member 74 until the axes of the stub axles 75 both lie in a vertical plane, at which point the trolley can easily be pulled along.
The rear wheels of the trolley 71 may be of conventional construction or they may likewise be substantially hemispherical ground-engaging members also set on a stub axle pointing downwards, but since the plane in which the axes of the two stub axles for the rear wheels 71 are located in such a case is not rotatable relative to the plane of flat bed 70, the rear wheels 71 always rotate easily.
There may be just one wheel underneath flat bed 70 if desired replacing both wheels 71. The wheels 71 may also be conventional horizontal axis wheels mounted on a bearing on a support plate so that they may rotate about a vertical axis, i.e. they may castor, so enabling the overall apparatus to be more easily manoeuvred.
Referring now to
At the ends of the two sections 106 remote from bar 105 are affixed two stub axles 107, the wheel axles. These extend into the hubs 103 of the wheels 101, 102, which can rotate freely on the stub axles 107.
If such a structure is placed on a horizontal surface such as the ground, it adopts the position much as drawn in
Base member 110 may be attached to a box structure to form a wheeled article of luggage, as shown in
At the end of the box structure 115 opposite handle 116, there is fixed the wheeled support structure shown in
The angles and dimensions are such that when the handle 116 is extended and the user wishes to pull or push the case along, usually with the telescopic members 117 lying in a plane inclined at 30 to 45° to the horizontal, the sections 106 lie within the boundaries of recesses 111 and central bar 105, sections 106 and the stub axles 107, 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 115 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 101, 102 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 105 is mounted in a channel lying at the lower end of base member 110, it does not impinge on the space inside base member 110 which can accordingly be utilised to the full as space for containing items the user wishes to pack into the base member 110 and transport where they wish to go.
A noticeable advantage in manoeuvring an item of luggage as shown in
The ease of handling of the article illustrated in
In accordance with the present invention, in place of the conventional pair of small wheels set in mountings on the corners denoted 125 and 126 in
Referring now to
| Number | Date | Country | Kind |
|---|---|---|---|
| 0802312.9 | Feb 2008 | GB | national |
| 0819092.8 | Oct 2008 | GB | national |
| 1114836.8 | Aug 2011 | GB | national |
This application is a continuation-in-part of application Ser. No. 12/320,877 filed 6 Feb. 2009, which in turn claims benefit of U.S. Provisional Application No. 61/064,253 filed Feb. 25, 2008.
| Number | Date | Country | |
|---|---|---|---|
| 61064253 | Feb 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12320877 | Feb 2009 | US |
| Child | 13506872 | US |
