Abstract:
A cart for transporting material has wheels located intermediate to end wheels, the intermediate wheels extending downwardly a greater distance than the end wheels so that the cart may tilt and may be turned around the intermediate wheels. The wheels may be mounted on flanges depending from a frame of the cart, the flanges serving to protect the wheels and serving to support the cart in the event of a wheel failure. The cart may have a pair of wheels located intermediate to the end wheels so that traversing uneven terrain is improved and eased, and so that the intermediate wheels serve as backups to each other. The intermediate wheels may be a same or similar size, though mounted lower on the flanges, than the end wheels. The intermediate wheels may be larger than the end wheels.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to carts or other human-powered wheeled devices for transporting material and, in particular, to such carts having caster-less wheel assemblies. 
       BACKGROUND 
       [0002]    Many devices are known for transporting materials or items. As an example, what is commonly referred to as a shopping cart is used at a grocery store. The shopping cart includes a pair of rear wheels that are caster-less so that, other than rotating around their centerline and an axle, the wheels remain stationary relative to the cart. In other words, the rear wheels rotate around a horizontal axis, but do not rotate or pivot around a vertical or other non-horizontal axis. In order to turn the grocery cart, a pair of front wheels is provided with caster assemblies that allow the front wheels to rotate and be oriented in a direction other than parallel to the rear wheels. 
         [0003]    However, carts having casters are not suitable for transporting heavy loads, such as lumber, building materials, landscaping materials, or gas cylinders. In particular, many casters have ball bearings which may be crushed due to heavy loading or which may distort the races and raceways under heavy pressure. Bearing-less casters have lubricated friction surfaces which must slide against each other. Heavy loads press and expel the lubrication from between the friction surfaces, and the pressure can cause the friction surfaces to bind and/or distort, rendering them useless for turning. 
         [0004]    A known device or cart for transporting heavy loads utilizes a pair of caster-less front wheels, a pair of caster-less rear wheels, and a pair of caster-less intermediate wheels. In this arrangement, the lowermost extents of the front and rear wheels can be said to define a plane, and the lowermost extents of the intermediate wheels extend below such plane. Accordingly, such a cart may be tilted so that either the front or rear (or neither) wheels may be in contact with the ground, while the intermediate wheels are generally always in contact with the ground. Hence, such a cart may be referred to as a “tiltable” cart. As all these wheels are caster-less, they do not move relative to the cart other than rotating around their substantially horizontal central axes. This allows the cart to be turned by balancing the cart on only the intermediate or central wheels and rotating the cart around these central wheels. 
         [0005]    There are two basic configurations for having the intermediate wheels extend beyond the plane of the other wheels. First, the axles of the intermediate wheels may be mounted to the cart at a lower point than the axles for the other wheels. Thus, all the wheels may be of a substantially identical diametral size, and the intermediate wheels are positioned to allow the cart to tilt. In the second configuration, the axles for all the wheels are generally mounted at the same height of the cart, but the intermediate wheels are larger than the other wheels so that the intermediate wheels extend below the other wheels, again providing the tilting feature to the cart. 
         [0006]    A number of problems are encountered with these tiltable carts. The wheels are secured with the cart by mounting brackets principally comprising a pair of V-shaped tabs extending downward from the bottom of a base of the cart with the axle mounted thereon and the wheel therebetween. During operation, the weight is borne by the central portion of the cart to a greater degree than the sides, imposing a greater burden on the central or intermediate wheels. Accordingly, should a wheel break during service under load, it is typically one of the central wheels which tends to fail. Then cart will then collapse so that a front wheel and a rear wheel on one side support the cart, while the other side is supported be either the remaining central wheel solely, or by the remaining central wheel and one of the other rear or front wheels. Because the remaining central wheel extends below the plane of the other wheels, the cart will list to one side, and movement of the cart will be in a circular path. As such a path cannot be controlled, such condition requires the material on the cart be unloaded onto another cart for moving to the proper location or destination. 
         [0007]    Another problem inherent in these tiltable carts is encountered when going over, up, or down incongruities in the surface supporting the cart. For instance, an industrial area often has a poured concrete floor. The floor, like a sidewalk, will have expansion/contraction seams or grooves provided between sections of the floor. During pouring itself, or due to settling of the floor resulting in a crack at the seam, the floor sections may be uneven. With the single pair of central wheels, traversing over the seam from one floor section to a lower floor section often results in a jolt when the central wheels drop down to the lower floor section. The heavy loads then bounce somewhat, which may cause damage to them as well as may damage the wheels themselves. Conversely, going from one floor section to a higher floor section (or merely riding over the seam itself) requires significant additional force from an operator. 
         [0008]    The carts are often moved from a floor to a truck, for instance, by forklifts. As should be readily apparent, the weight of the materials often renders the loaded cart difficult, if not dangerous, to push up a ramp into a vehicle. Forklifts may solve this problem, but they rely on inserting forklift tines underneath the base of the cart and between the wheels of each pair. Precise alignment of the forklift tines with the opening between the wheels of each pair, though not difficult, may be time consuming. As a time-savings measure, forklift operators or drivers commonly use the tines to move the cart itself into proper alignment, rather than the other way around. More specifically, forklift tines are movable in a vertical direction, may be tilted forward and backward, and may shift left to right (and vice versa) relative to the forklift itself. A forklift operator may place one tine between the wheels, and then move the tines in one direction to shift the cart into a desired or suitable orientation. In doing so, the surface against which the tine applies force is typically either the wheel or the mounting bracket thereof. Use of the forklift in this manner may easily damage the wheel or the mounting bracket, leading to failure of the bracket or the wheel. 
         [0009]    Another problem arises from the use of V-shaped tabs for the mounting brackets, noted above. When one wheel fails, its mounting bracket is often damaged as well so that the collapsing cart causes the tabs to bend and also collapse. This can result in severe listing or tilting of the cart, which may cause the heavy material to fall off the cart. It can also result in the broken mounting bracket to gouge into the floor, making any movement of the cart difficult. 
         [0010]    Accordingly, there has been a need for an improved tiltable cart for transporting material, in particular heavy loads of material. 
       SUMMARY 
       [0011]    In accordance with an aspect, a tiltable cart for transporting material is disclosed having a frame, and a plurality of wheels rotatably mounted to the frame in substantially parallel alignment and having lowermost points, a first pair of the wheels generally positioned at a first end of the cart, a second pair of the wheels positioned generally at a second end of the cart, and third and fourth pairs of the wheels being positioned generally intermediate the first and second pairs of the wheels. The third pair of the wheels is positioned in relative close proximity to the fourth pair of the wheels, the lowermost points of the first and second pairs of the wheels are tangent to a first plane below the frame, and the lowermost points of the third and fourth pairs of wheels are spaced further below the frame than the first plane. A first wheel of each respective pair may be secured on a first side of the frame, and a second wheel of each respective pair may be secured on a second side of the frame opposite the first side of the frame. The wheels of the third and fourth pairs may be larger than the wheels of the first and second pairs. 
         [0012]    In this manner, the cart is tiltable so that the first and second pairs of wheels are alternately contactable with an underlying ground surface, which allows the cart to be turned while having caster-less wheels. The third and fourth pairs of wheels allow the tiltable cart to move over uneven pavement surfaces without a jolt or impact from dropping down a level or without a user having to apply significantly greater force to move the cart up a level. The third and fourth pairs of wheels also serve as a backup in the event one of the wheels fails, allowing the cart to be operable even with a broken wheel. 
         [0013]    The cart may include a tower structure extending upwardly from the frame. The tower structure may include securement structure for receiving, supporting, or securing material therewith. The tower structure may be adapted for securing gas cylinders with the cart. 
         [0014]    The third and fourth pairs of wheels may be mounted lower on the frame than the first and second pairs of wheels. Alternatively or in addition, the third and fourth pairs of wheels may be larger than the first and second pairs of wheels. 
         [0015]    In another aspect, a cart for transporting material is disclosed having a frame including flange portions extending downwardly therefrom, and a plurality of wheels rotatably mounted to the flange portions in substantially parallel alignment and having lowermost points, a first pair of the wheels generally positioned at a first end of the cart, a second pair of the wheels positioned generally at a second end of the cart, and at least a third pair of the wheels being positioned generally intermediate the first and second pairs of the wheels, lowermost points of the wheels of the third pair being lower than the lowermost points of the first and second pairs of the wheels, the flange portions extending over sides of the wheels to a position in close proximity to a ground surface. In one form, the third pair of wheels is mounted lower on the frame than the first and second pairs of wheels. 
         [0016]    The wheels are mounted between a pair of flange portions. Preferably, first wheels of each respective pair of the wheels are secured on a first flange portion in substantially parallel alignment with each other, and second wheels of each respective pair of the wheels are secured on a second flange portion in substantially parallel alignment with each other. The first wheels are mounted between the first flange portion and a third flange portion, and the second wheels are mounted between the second flange portion and a fourth flange portion. The first wheels are mounted generally at one side of the frame, and the second wheels are mounted generally at a second side of the frame. 
         [0017]    In this aspect, the cart may further include a fourth pair of wheels positioned generally intermediate the first and second pairs of the wheels, the fourth pair of the wheels being positioned in relative close proximity to the third pair of the wheels, and the third and fourth pairs of wheels are mounted at approximately the same height on the flange portions. 
         [0018]    As such, the flanges serve to protect the wheels from damage, particularly due to use with a forklift. The flanges also serve to reduce the amount of tilting or listing that may occur should a wheel break. That is, the flanges positioned closely to the ground or underlying support surface permit only a short drop by the cart should a wheel break, thereby reducing how much the cart leans or lists due to the wheel failure. Furthermore, the flanges provide support should such wheel failure occur, and the load required to crush the flanges in such an event is relatively high in comparison to the mounting structures of other tiltable carts. 
         [0019]    In a further aspect, a cart for transporting material is disclosed having a frame, and a plurality of wheels rotatably mounted to the frame in substantially parallel alignment, a first pair of the wheels generally positioned at a first end of the cart, a second pair of the wheels positioned generally at a second end of the cart, and third and fourth pairs of the wheels being positioned generally intermediate the first and second pairs of the wheels, wherein the third pair of the wheels is positioned in relative close proximity to the fourth pair of the wheels, and the third and fourth pairs of wheels are tangent to a first plane and the first and second pairs are tangent to a second plane, the first plane spaced further below the frame than the second plane. The third and forth pairs of wheels may be mounted lower on the frame than the first and second pairs of wheels. A first wheel of each respective pair may be secured on a first side of the frame, and a second wheel of each respective pair may be secured on a second side of the frame opposite the first side of the frame. The cart may be tiltable so that the first and second pairs of wheels are alternatively contactable with an underlying support surface. The cart may includes a tower structure extending upwardly from the frame, the tower structure including securement structure for receiving, supporting, or securing material therewith. The tower structure may be adapted for securing gas cylinders. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a perspective view of an embodiment of a material transport cart of the present invention; 
           [0021]      FIG. 2  is a side elevational view of the cart of  FIG. 1 ; 
           [0022]      FIG. 3  is a bottom plan view of the cart of  FIG. 1 ; 
           [0023]      FIG. 4  is a fragmentary perspective view of a bottom side of the cart of  FIG. 1 ; and 
           [0024]      FIG. 5  is a side elevational view of a second form of a material transport cart of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Referring initially to  FIGS. 1 and 2 , a material transport cart  10  is shown having a front end  12 , a rear end  14 , and left and right lateral sides  16 ,  18 . It should be noted that usage of the terms front, rear, left, and right, as used herein, is for convenience, and that the cart  10  may be propelled or pushed in a direction so that either the front or rear end is a leading end when moved. The cart  10 , as shown, is designed to carry cylinders (not shown) of compressed gas. Towards this end, the cart  10  includes frame in the form of a base  20  including a generally flat support plate  22 , and a retention wall  24  around the periphery of the support plate  22 . The gas cylinders may be placed on the support plate  22  and within the retention wall  24  to restrict or prevent movement thereof when the cart  10  is loaded and moved. Reinforcing members (not shown) may be mounted to an underside of the support plate  22  for increased strength and support. The cart  10  further includes a superstructure tower or support stanchion  30  extending substantially vertically from the support plate  22 . The support stanchion  30  includes a pair of substantially tubular vertical supports  32  which support upper and lower retention braces  34  and  36 . In some forms, the retention braces  34 ,  36  may be adjustable vertically along the vertical supports  32 , and the lower retention brace  36  may have side pieces that are releasably secured to allow gas cylinders to be loaded or unloaded therefrom. 
         [0026]    In order to permit the cart  10  to be moved, caster-less wheels  40  are provided along the left and right lateral sides  16 ,  18 . More specifically, a left row  42  of wheels  40  is provided on the left side  16  and a right row  44  of wheels  40  is provided on the right side  18 . Each wheel  40  has a rotational axis  46 , and the wheels  40  are generally aligned so that all the axes  46  of each wheel  40  of either row  42 ,  44  are generally parallel. Preferably, the wheels  40  of each row  42  are also aligned so that they are co-planar, that is, so that the wheels  40  of each row  42 ,  44  have a common central plane of rotation perpendicular to the axes  46 . 
         [0027]    The wheels  40  are referred to herein by their relationship to the front end  12  and rear end  14 , as well as to the left and right sides  16 ,  18 . Accordingly, the front end  16  of the cart  10  has a left front wheel  50  (of the left row  42 ) and a right front wheel  52  (of the right row  44 ). The rear end  14  has a left rear wheel  54  and a right rear wheel  56 . 
         [0028]    With reference to  FIGS. 2 and 3 , additional wheels  40  are positioned between the front and rear ends  12 ,  14 . More specifically, the left row  42  includes a pair of left intermediate wheels  58 , and the right row  44  includes a pair of right intermediate wheels  60 . Each intermediate wheel  58 ,  60  is positioned closely adjacent to the other intermediate wheel  58 ,  60  of its respective pair. 
         [0029]    The left front and rear wheels  50 ,  54  and the right front and rear wheels  52 ,  56  are mounted so that they extend below the cart base  20 , and lowermost points  62  on each of these wheels  50 ,  52 ,  54 ,  56  generally define a plane P 1 . The intermediate wheels  58 ,  60  also are mounted so that they extend below the cart base  20 ; however, these wheels  58 ,  60  extend below the cart base  20  to an extent such that their lowermost points  64  form a plane P 2  that is below the plane P 1 . In other words, the plane P 2  of the intermediate wheels  58  is spaced further from the base  20  than is the plane P 1  of the front and rear wheels  50 ,  52 ,  54 ,  56 . 
         [0030]    Thus, the intermediate wheels  58 ,  60  allow the cart  10  to be tilted and are used to turn the cart  10 . As the cart  10  is moved over a bump of an underlying support surface (such as a crack or a concrete expansion seam), the cart  10  may be tilted rearward to allow first intermediate wheels  58   a ,  60   a  ( FIG. 3 ) to pass over or beyond the bump either to a higher or lower elevation. Once the first intermediate wheels  58   a ,  60   a  pass beyond the bump, the cart  10  may be tilted forward so that first intermediate wheels  58   a ,  60   a , as well as the front left and right wheels  50 ,  52 , are brought into contact with the surface. Movement of the cart  10  may then continue so that second intermediate wheels  58   b ,  60   b  ( FIG. 3 ), as well as the rear left and right wheels  54 ,  56 , pass over the bump. In this manner, the cart  10  reduces or substantially eliminates any sharp jolt when going down a bump and the difficulty of pushing a loaded cart up a bump, which are problems associated with other tiltable carts. It should also be noted that, in the event one of the intermediate wheels  58 ,  60  should fail (i.e., break or be crushed), the remaining intermediate wheels  58 ,  60  would provide sufficient support for the cart  10  to still be moved without unloading or being carried by a forklift. 
         [0031]    The wheels  40  are mounted on axles  70 , typically formed by a bolt, secured with mounting flanges  71  that depend from the bottom side of the cart base  20 . Each row  42 ,  44  is provided with an inner and outer flange  72 ,  74  that generally extend the length of the respective side  16 ,  18 . The axles  70  pass through the wheels  40  and are secured with the inner and outer flanges  72 ,  74 . The inner flanges  72  are positioned apart a distance sufficient to permit forklift tines to be received therebetween for lifting the cart  10 , such as for placing the cart  10  on a truck. The flanges  72 ,  74  extend downwardly to a position close to the lowermost points of the intermediate wheels  58 ,  60  so that the majority of each wheel  40  is covered on both its inner and outer sides. In this manner, the wheels  40  are protected from the forklift tines, either when a forklift is used to move the cart  10  or to lift the cart  10 , as well as from accidental contact to the outside of the wheels  40 . A further benefit of the flanges  72 ,  74  is that, should one or more wheels  40  fail, the cart  10  will only drop to a level where the flanges  72 ,  74  contact the ground surface. This minimizes the listing of the cart  10  so that material thereon is less likely to fall off and is easier to unload, if necessary. Furthermore, when compared to wheel mounting tabs of known tiltable carts, the flanges  72 ,  74  provide additional strength to minimize likelihood of failure by the mounting structure. Should a wheel  40  fail, the flanges  72 ,  74  are less likely to also fail when they, under load, come into contact with the ground surface. 
         [0032]    With reference to  FIG. 2 , one form of the cart  10  is shown having the intermediate wheels  58 ,  60  extending below the plane P 1  formed by the lowermost points of the front and rear wheels  50 ,  52 ,  54 ,  56 . As can be seen, axles  70   a  for the intermediate wheels  58 ,  60  are mounted on the flanges  72 ,  74  at a level below that of axles  70   b  for the front and rear wheels  50 ,  52 ,  54 ,  56 . In this form, the intermediate wheels  58 ,  60  may be substantially of the same size as the front and rear wheels  50 ,  52 ,  54 ,  56 . 
         [0033]    In an alternative form, shown in  FIG. 5 , the axles  70   a  for the intermediate wheels  58 ,  60  may be mounted at generally a same level as the axles  70   b  for the front and rear wheels  50 ,  52 ,  54 ,  56 . In this form, the intermediate wheels  58 ,  60  have a larger diametral size than the front and rear wheels  50 ,  52 ,  54 ,  56  so that the intermediate wheels  58 ,  60  extend below the cart base  20  to a greater extent than do the front and rear wheels  50 ,  52 ,  54 ,  56 . In this manner, the intermediate wheels  58 ,  60  extend below the plane P 1  formed by the lowermost points of the front and rear wheels  50 ,  52 ,  54 ,  56 , allowing the cart  10  to tilt as described. 
         [0034]    While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.