CA1241355A - Four wheeled push cart - Google Patents
Four wheeled push cartInfo
- Publication number
- CA1241355A CA1241355A CA000495831A CA495831A CA1241355A CA 1241355 A CA1241355 A CA 1241355A CA 000495831 A CA000495831 A CA 000495831A CA 495831 A CA495831 A CA 495831A CA 1241355 A CA1241355 A CA 1241355A
- Authority
- CA
- Canada
- Prior art keywords
- cart
- wheels
- axis
- frame
- caster
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Handcart (AREA)
Abstract
ABSTRACT
A four wheeled grocery or luggage cart with a rear handle-bar, two rear wheels in swivelling casters and two front wheels fixed against swivelling but rotatable about a coincident horizontal axis. Preferably the casters swivel about parallel axes tilted upwardly and forwardly from the vertical in a direction normal to the horizontal axis whereby the cart is easier to steer and the tendency of the front wheels to swing hack and forth on pushing the cart when unloaded, is reduced.
A four wheeled grocery or luggage cart with a rear handle-bar, two rear wheels in swivelling casters and two front wheels fixed against swivelling but rotatable about a coincident horizontal axis. Preferably the casters swivel about parallel axes tilted upwardly and forwardly from the vertical in a direction normal to the horizontal axis whereby the cart is easier to steer and the tendency of the front wheels to swing hack and forth on pushing the cart when unloaded, is reduced.
Description
This invention relates to wheeled hand carts and more particularly to four wheeled grocery carts having two swivelling wheels and two wheels fixed against swivelling.
BACKGROUND OF THE INVENTION
.
Many four wheeled dolleys and grocery carts aye known which have a pair of swivelling wheels and a pair of wheels fixed against swivelling. For example, well known grocery carts have apair of swivelling front wheels and a pair of rear wheels fixed against swlvelling. The front wheels swivel to permit steering of the cart by a person pushing the cart by a handle at the cart's rear.
Such grocery carts typicaIly nest wi-thin one another for storage A major disadvantage of known grocery carts with swivelling front wheels is that they are difficult to steer. The carts are typically provided with a handle bar at their rear by which the carts may be pushed and steered. With the swivelling wheels at the front, con-siderable forces are typically needed to be exerted on the rear of a loaded cart to turn the cart. Due to difficulties in turning, many users resort to skidding the rear wheels of the cart laterally across the floor to assist in turning the cart and steer it around obstacles. Such skidding 3~5 1 results in greatly reduced life of the xear wheels of the cart in bending o the forks of the rear wheels in increasing floor wear and maintenance.
Another disadvantage of known nesting grocery carts with swivelling front wheels is that once the forward portion of the cart becomes engaged with a pre-ceeding cart during nesting, frequently only by skidding of the rear wheels can the cart be forced to assume a proper nesting position, Another disadvantaye of known grocery car-ts is that their swi~elling ront wheels have a tendency when the cart is pushed to "chatter'7, that is, ko swing back and orth in an ossilating manner about the vertical axis about which the front wheels may swivel. Such "chattering" most frequently occurs when a cart is empty or only lightly loaded When the wheels "chatter", the cart may only with difficulty be steered by a user propelling the cart, _UMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to at least partially ovexcome these disadvantages o the prior art by providing a novel grocery cart with a pair of front wheels which are fixed against swivelling and a pair of rear wheels which swivel.
Another object is to at least partially overcome the disadvan-tages of the prior art by providing khe swivellin~
3~55 1 wheels so as to swivel about an axis inclined forwardly from a ver-tical in the direction -the cart is predominantly to be moved, ;~
Another object is -to at least partially overcome the disadvantages of the prior art by providing an improved configuration for a four wheeled cart with a greater por-tion of the weight of the cart on the swivelling wheels Another objec-t is -to provide a simplified method of modifying existing shopping carts to reduce "chattering".
Accordingly in a first aspect the present invention provides a four wheeled grocery or luggage cart comprising load carrying frame means, a pair of transversely spaced front wheels coupled to the frame means and journalled for xotation about a coincident transversely extending axis, a pair of swivelling castor means coupled -to the frame means spaced transversely from each other rearward of the front wheels, and transversely extending handle-bar means coupled to the frame means marginally rearward of the castor meats and at a height thereabove for manual grasping by the hands of a user to propel and steer the cart.
In a second aspect the present invention provides a wheeled manual push cart for rolling in predominantly a given forward direction, the cart comprising frame means, a pair of laterally spaced first wheels coupled to the frame and ~ournalled for rotation about a coincident 1 horizon-tal axis normal to the forward direction, caster means coupled to the frame spaced either forwardly or rearwardly :Erom the first wheels, the caster means comprising fork means journalled for rotation about a first axis :Eixed with respect to the frame and tilting forwardly away from a vert.ical as it extends upwardly, second wheel means carried by the fork means and journalled for rotation about a second axis normal -to the first axis and offset from the first axis so that the first and second axes do not intersect.
BRIEF DESCRIPI'ION OF THE DRAWINGS
. .
Other aspects and advantages of the present invention will appear from the following description, taken together with the accompanying drawings, in which:
Fi.gure 1 is a schematic pictorial view of a grocery cart in accordance with a first embodiment of the present invention, Figure 2 is a side view of a rear swivelling .
caster of the cart of Figure 1 seen as viewed from one side, Figure 3 is an end view of the caster shown in Figure 2, Figure 4 is an end view of an alternate wheel for use in the caster shown in Figure 3, and Fi.gure 5 is a schematic pictorial view of a luggage cart in accordance with a second embodiment of the present invent.ion.
Reference is made first to Figure 1 showing a schematic pictoria:l view of a grocery cart in accordance with a first embodiment of the present invention. The cart comprises a known tubular metal cart which has been modified in accordance with the first aspect of the present invention to provide swivelling wheels at its rearO
The cart 10 shown has a major, forwardly tapering, load-carrying frame generally designated 12 which carries forwardly therein a basket member generally designated 14.
Handle-bar 16 extends rearwardly from basket member 14.
Basket member l has a rear door 17 hinged about a hori-zontal cross bar 18 so as to swing upwardly and forwardly to permit nesting of carts with basket member 14 of a rear cart to swing door 17 of a pre-ceeding cart upward with the rear basket member 14 telescoping inside the preceeding cart's basket member 14 at the same time as tubular frame 12 of the rear cart extends under and inside the tubular frame 12 of the pre-ceeding cart. The frame 12 includes a substantiall.yrectangular support portion below basket member 14 formed by front cross member 19, rear cross member 20 and side members 21. Upright supports such as 22 and 23 carry basket member 14 and support handle-bar 16 marginally rearward of rear wheels 24 and at a height 1 thereabove Eor manual yrasping by the hands of a user to propel and steer -the cart.
ront wheels 26 are journalled for rotation about a horizontal axis in each of their forks 28, with forks 28 fixed to frame 12 against swivelliny. Front wheels 26 rotate about the same coincident axis indicated as 27.
Rear wheels 24 are carried by swivelling casters generally designated 30. Such casters are of well known construction as exemplified by United States Patents 2,828,392 and 3,942,608. Wheel 24 is journalled for rotation about an axle 32 carried by fork members 34.
As best seen in Figures 2 and 3, the forX member 34 is rotatably coupled to central upstanding post 36 by a known ball bearing coupling whereby fork member 34 is rotatable about axis 38 through the post. An upper circular lip 40 of the fork is rotatably secured between fixed plates 42 and 44 due to ball bearings disposed therebetween. Cen-ter post 36 is coupled to frame 12 as by welding. Center post 36 is secured to frame 12 to lock post 36 and its fixed pla-tes 42 and 44 against rotation.
Wheels 24 are journalled for rotation about axle 32 r the axis 50 of which is always normal to axis 38 about which fork member 34 and thereby wheel 24 swivel.
~2~
1 As is known wi-th conventional casters,axis 50 is offset from axis 38 in the sense that axis 50 does not intersec-t with axis 3~.
With swivelling wheels 2~ provided at the rear of the shopping cart, the cart is easier to steer. For a fully loaded cart, less force is required to be expended on handle-bar 16 to turn the cart than iE the swivelling wheels were at the front. With the cart tapering to be widest at its rear, in a fully loaded cart, a greater proportion of the total weight will be carried by the rear swivelling wheels than the front wheels, thus assisting in reducing chattering. Even in an unloaded cart, a greater proportion of the weight of the cart lies in the rear half of the cart and therefore over the rear wheels which will assist in reducing chattering even when empty. Moreover with the swivelling wheels at the rear closer to handle-bar 16, the user of the cart is better able to himseif resist chattering movement.
The second aspect of the present invention is to configure the cart so that the axes about which the swivelling casters swivel are fixed at angles tilted from the vertical to extend upwardly and forwardly in the direction the cart is predominantly to be pushed. In Figures 2 and 3 showing an enlarged view of a caster ~5 on the shopping cart of Figure 1, a horizontal floor is 1 shown by line 52~ As seen, post 36 is coupled to frame 12 so that post 3~ is angled with respect to the horizontal. Post 30 tilts upwardly and forwardly from a vertical with axis 38 through post 36 intersecting hori-zonta:L floor 52 at an angle.
With axis 38 til-ted upwardly and forwardly, the only vertical plane in which it may lie is a ver-tical plane passing from front to rear longitudinally of the cart, that is, normal axis 27 about which front wheels 26 are fixed for rotation. In that axis 50 about which rear wheels 24 rotate is always normal to axis 38, axis 50 will only be horizontal when axis 3g lies in the vertical plane passing front to rear, that is, when fork member 34 extends precisely rearwardly as shown in solid lines in Fiyure 2 or precisely forwardly as shown in dotted Hines in Figure 2~
As seen in Figure 2, the vertical height Hl between a lowermost horizontal tangent on the wheel 24 and point P, at the intersection of axis 38 with the upper surface of plate 42, is smallest when fork member 34 extends directly rearwardly as shown in solid lines.
On rotation of fork member 34 from the rearward position in solid lines to the forward position shown in dotted lines, this height increases to become a maximum H2.
Therefore, caster 50 will have an inherent bias to assume d~L~
1 the rearwardmost position and -to swivel the caster away from positions which require marginal additional liftiny of the rear end of the cart by tilting of the cart about front wheels 26.
If wheel 24 has an exactly cylindrical outer suxface 54 as shown in Figure 3, -then on swivelling of fork member 34, axis 38 about which wheel 2~ is rotatable becomes tilted from the horizontal with the cylindrical outer surface 54 removed from contact with -the floor, contact being merely on one of the narrow edges 56 between surface 54 and side walls 58. The wheel will have maximum surface area in contact with the floor when in the rearward or forward posi-tions. With maximum surface area of the wheel in contact with the floor when the wheel is in a rearward position, if a wheel has a tendency to "chatter", that is to swing back and forth, then in each swing of the wheel, upon the wheel assuming the precisely rearward position will stop or at least dampen the swinging back and for-th.
Figure 4 shows a preferred configuration for a wheel 24 for the swivelling casters in accordance with the present invention. Wheel 24 has a major central cylindrical portion 60 and marginally rounded edge portions 62. The rounded shoulders provide a pre-ferable surface to engage the floor on swivelling of the caster necessary for turning compared -to the ra-ther sharp edge 56 of the wheel shown in E'ig~lre 3.
~9 _ 1 I'he extent to which axis 38 is tilted with respect to the vertical will determ;ne the extent -to which chattering is dampened. angles of 0 to 30~ may be acceptable with preerred angles between 1 and 10, Choice of angles which are too large will prevent the caster from easily being urged to roll rearwardly as the caster will have a large inherent bias to resist swivelling to the forward position shown in dotted lines in Figure 2. Choice of an appropriate angle will also be dependent upon the configuration of the surface of the wheels to contact the floor, The grocery cart shown in Figure 1 has rear swivelling casters in accordance with the first aspect of the present invention, In accordance with the first aspect, the axes about itch the rear wheels 24 swivel need not be tilted from the vertical. The second aspect of the present invention lies in the provision of the axis about which the swivelling wheels swivel to extend upwardly and forwardly. An advantageous embodiment of the presen-t invention lies in a combination of the first and second aspects to provide a grocery or luggage cart with rear swivelling wheels which swivel about an axis tilted forwardly and upwardly.
Conventional carts are configured with their front, swivelling caster wheels disposed to swivel about a 1 vertical axis Conventional carts which have front swivelling wheels may readily be modified to conform to the second aspect of the invention, For example, the swivelling front wheels of a grocexy cart may be replaced by a smaller diameter wheel while otherwise utilizing the original caster assembly, Reduction of the wheel diameter causes the whole frame to tilt forwardly and downwardly by rotating ahout the axis of the rear wheels whereby the axis about which the front casters swivel becomes tilted forwardly and upwardly, Replacing 5 inch front wheels by 4 inch front wheels in a conventional shopping cart has been found to significantly reduce chattering, yet not impair the ability of the carts to nest. Alternate ways to tilt the axis about which front casters of a conventional cart swivel include increasing the diameter of the rear wheels or providing new front casters of lesser height. The simple substitution of smaller diameter front wheels has the advantage of being substan-tially simpler and less expensive. In a conventional grocery cart with swivelling front wheels which has been modified to tilt its frame forwardly and downwardly,as contrasted with an identical cart in which the frame 12 is horizontal, has,due to the frame 12 tilting forwardly,a greater proportion of the weight of the cart carried by the swivelling wheels. This is advan-tageous in reducing "chattering" and rendering steering easier.
~2~ S
1 Reference is now made to Figuxe 5 which shows a .nesting luggage cart 6~ in accordance with a second embodiment of the present invention. Cart 64 is useful, for example, to move luggage by passengers in an airport.
Cart 6~ has a tubular metal peripheral frame 66 with a forward segment 68 and side segments 7~ merging into upstanding rear segments 72 terminating at their upper ends as a rearwardly extending substantially horizon-tally disposed handle-bar or handle portion 74.
A plurality of metal, rod-like cross members 76 extend between side segments 70 to define therewith a substantially rectangular support portion disposed proximate the wheels, Additional rear cross-members 78 extend between rear segments 72, A pair of front wheels 80 are shown ~ournalled on an axle forming rod 81 coupled to frame 66. Use of such a simple axle forming rod.81 is typically less-expensive than the fork and axle assembly of the front wheels in Figure 1. The provision of non-swivelling front wheels has the advantage of permitting the use of such less expensive axle forming rod 81 which when provided at the front of the cart does not interfere with nesting of the carts Rearward nesting of the carts typically precludes use of such a single axle rod 81 at the rear of a conventional cart.
3~
1 A pair of swivelliny caster assemblies designated 82 are coupled to the rear corners of the frame for swivelling about an axis either vertical or tilted foxwardly and upwardly as discussed in accordance with the first embodimen-t of this invention, Cart 6~ is adapted for nesting with one cart telescoping into a preceeding cart.
To permi-t nesting side segments 70 converge forwardly and as well reduce in height above the floor forwardly.
y providing swivelling casters 82 at the rear ox the cart, due to the increased width of the cart at its rear, and rear segments 72 of the frame and rear handle portion 74, the swivelling casters 82 carry a greater proportion of the weight of the cart than the front wheels, This is an advantage in reducing the tendency of the wheels to chatter in an unloaded position.
Also with the cart widening rearward and having rear segments 72, a user of the cart has a propensity to place larger objects and more wieght on the rear portions ox the cart, thereby,in a loaded cart, this advantageously increasing the portion of the weight on the rear swivelling casters and reduces their tendency to chatter.
Location of the swivelling wheels at the rear of the nesting cart shown in Figure.5 has the advantage of facilitating the steering of a cart into a nesting position with a preceeding cart. If only the front wheels swivel, then the cart cannot readily be manipulated -:l3-1 to a preferred nesting position once the swivelling front wheels have ~een~xolled partially inside the preceeding cart, As seen casters 82 have cylindrical tube position 8~ welded to frame 66 with a lower horn~~orming portion 86 rota-tably coupled to portion 8~ for swivelling about an axis either vertical or -tilted marginally wheel 88 is rotatably coupled to portion 86.
Shopping carts having rear swivelling wheels, such as illustrated in Figure 1, are easier to turn than similar carts with front swivelling wheels. Due to ease of turning, carts with rear swivelling wheels may more readily be turned within a smaller radius. Tess space need be provided for turning and hence a store may have narrower isles.
While the invention has been described with reference to two preferred embodiments it is not so limited. Many variations and modifications will now occur to those skilled in this art. For a definition of the invention reference is maae to -the following claims.
BACKGROUND OF THE INVENTION
.
Many four wheeled dolleys and grocery carts aye known which have a pair of swivelling wheels and a pair of wheels fixed against swivelling. For example, well known grocery carts have apair of swivelling front wheels and a pair of rear wheels fixed against swlvelling. The front wheels swivel to permit steering of the cart by a person pushing the cart by a handle at the cart's rear.
Such grocery carts typicaIly nest wi-thin one another for storage A major disadvantage of known grocery carts with swivelling front wheels is that they are difficult to steer. The carts are typically provided with a handle bar at their rear by which the carts may be pushed and steered. With the swivelling wheels at the front, con-siderable forces are typically needed to be exerted on the rear of a loaded cart to turn the cart. Due to difficulties in turning, many users resort to skidding the rear wheels of the cart laterally across the floor to assist in turning the cart and steer it around obstacles. Such skidding 3~5 1 results in greatly reduced life of the xear wheels of the cart in bending o the forks of the rear wheels in increasing floor wear and maintenance.
Another disadvantage of known nesting grocery carts with swivelling front wheels is that once the forward portion of the cart becomes engaged with a pre-ceeding cart during nesting, frequently only by skidding of the rear wheels can the cart be forced to assume a proper nesting position, Another disadvantaye of known grocery car-ts is that their swi~elling ront wheels have a tendency when the cart is pushed to "chatter'7, that is, ko swing back and orth in an ossilating manner about the vertical axis about which the front wheels may swivel. Such "chattering" most frequently occurs when a cart is empty or only lightly loaded When the wheels "chatter", the cart may only with difficulty be steered by a user propelling the cart, _UMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to at least partially ovexcome these disadvantages o the prior art by providing a novel grocery cart with a pair of front wheels which are fixed against swivelling and a pair of rear wheels which swivel.
Another object is to at least partially overcome the disadvan-tages of the prior art by providing khe swivellin~
3~55 1 wheels so as to swivel about an axis inclined forwardly from a ver-tical in the direction -the cart is predominantly to be moved, ;~
Another object is -to at least partially overcome the disadvantages of the prior art by providing an improved configuration for a four wheeled cart with a greater por-tion of the weight of the cart on the swivelling wheels Another objec-t is -to provide a simplified method of modifying existing shopping carts to reduce "chattering".
Accordingly in a first aspect the present invention provides a four wheeled grocery or luggage cart comprising load carrying frame means, a pair of transversely spaced front wheels coupled to the frame means and journalled for xotation about a coincident transversely extending axis, a pair of swivelling castor means coupled -to the frame means spaced transversely from each other rearward of the front wheels, and transversely extending handle-bar means coupled to the frame means marginally rearward of the castor meats and at a height thereabove for manual grasping by the hands of a user to propel and steer the cart.
In a second aspect the present invention provides a wheeled manual push cart for rolling in predominantly a given forward direction, the cart comprising frame means, a pair of laterally spaced first wheels coupled to the frame and ~ournalled for rotation about a coincident 1 horizon-tal axis normal to the forward direction, caster means coupled to the frame spaced either forwardly or rearwardly :Erom the first wheels, the caster means comprising fork means journalled for rotation about a first axis :Eixed with respect to the frame and tilting forwardly away from a vert.ical as it extends upwardly, second wheel means carried by the fork means and journalled for rotation about a second axis normal -to the first axis and offset from the first axis so that the first and second axes do not intersect.
BRIEF DESCRIPI'ION OF THE DRAWINGS
. .
Other aspects and advantages of the present invention will appear from the following description, taken together with the accompanying drawings, in which:
Fi.gure 1 is a schematic pictorial view of a grocery cart in accordance with a first embodiment of the present invention, Figure 2 is a side view of a rear swivelling .
caster of the cart of Figure 1 seen as viewed from one side, Figure 3 is an end view of the caster shown in Figure 2, Figure 4 is an end view of an alternate wheel for use in the caster shown in Figure 3, and Fi.gure 5 is a schematic pictorial view of a luggage cart in accordance with a second embodiment of the present invent.ion.
Reference is made first to Figure 1 showing a schematic pictoria:l view of a grocery cart in accordance with a first embodiment of the present invention. The cart comprises a known tubular metal cart which has been modified in accordance with the first aspect of the present invention to provide swivelling wheels at its rearO
The cart 10 shown has a major, forwardly tapering, load-carrying frame generally designated 12 which carries forwardly therein a basket member generally designated 14.
Handle-bar 16 extends rearwardly from basket member 14.
Basket member l has a rear door 17 hinged about a hori-zontal cross bar 18 so as to swing upwardly and forwardly to permit nesting of carts with basket member 14 of a rear cart to swing door 17 of a pre-ceeding cart upward with the rear basket member 14 telescoping inside the preceeding cart's basket member 14 at the same time as tubular frame 12 of the rear cart extends under and inside the tubular frame 12 of the pre-ceeding cart. The frame 12 includes a substantiall.yrectangular support portion below basket member 14 formed by front cross member 19, rear cross member 20 and side members 21. Upright supports such as 22 and 23 carry basket member 14 and support handle-bar 16 marginally rearward of rear wheels 24 and at a height 1 thereabove Eor manual yrasping by the hands of a user to propel and steer -the cart.
ront wheels 26 are journalled for rotation about a horizontal axis in each of their forks 28, with forks 28 fixed to frame 12 against swivelliny. Front wheels 26 rotate about the same coincident axis indicated as 27.
Rear wheels 24 are carried by swivelling casters generally designated 30. Such casters are of well known construction as exemplified by United States Patents 2,828,392 and 3,942,608. Wheel 24 is journalled for rotation about an axle 32 carried by fork members 34.
As best seen in Figures 2 and 3, the forX member 34 is rotatably coupled to central upstanding post 36 by a known ball bearing coupling whereby fork member 34 is rotatable about axis 38 through the post. An upper circular lip 40 of the fork is rotatably secured between fixed plates 42 and 44 due to ball bearings disposed therebetween. Cen-ter post 36 is coupled to frame 12 as by welding. Center post 36 is secured to frame 12 to lock post 36 and its fixed pla-tes 42 and 44 against rotation.
Wheels 24 are journalled for rotation about axle 32 r the axis 50 of which is always normal to axis 38 about which fork member 34 and thereby wheel 24 swivel.
~2~
1 As is known wi-th conventional casters,axis 50 is offset from axis 38 in the sense that axis 50 does not intersec-t with axis 3~.
With swivelling wheels 2~ provided at the rear of the shopping cart, the cart is easier to steer. For a fully loaded cart, less force is required to be expended on handle-bar 16 to turn the cart than iE the swivelling wheels were at the front. With the cart tapering to be widest at its rear, in a fully loaded cart, a greater proportion of the total weight will be carried by the rear swivelling wheels than the front wheels, thus assisting in reducing chattering. Even in an unloaded cart, a greater proportion of the weight of the cart lies in the rear half of the cart and therefore over the rear wheels which will assist in reducing chattering even when empty. Moreover with the swivelling wheels at the rear closer to handle-bar 16, the user of the cart is better able to himseif resist chattering movement.
The second aspect of the present invention is to configure the cart so that the axes about which the swivelling casters swivel are fixed at angles tilted from the vertical to extend upwardly and forwardly in the direction the cart is predominantly to be pushed. In Figures 2 and 3 showing an enlarged view of a caster ~5 on the shopping cart of Figure 1, a horizontal floor is 1 shown by line 52~ As seen, post 36 is coupled to frame 12 so that post 3~ is angled with respect to the horizontal. Post 30 tilts upwardly and forwardly from a vertical with axis 38 through post 36 intersecting hori-zonta:L floor 52 at an angle.
With axis 38 til-ted upwardly and forwardly, the only vertical plane in which it may lie is a ver-tical plane passing from front to rear longitudinally of the cart, that is, normal axis 27 about which front wheels 26 are fixed for rotation. In that axis 50 about which rear wheels 24 rotate is always normal to axis 38, axis 50 will only be horizontal when axis 3g lies in the vertical plane passing front to rear, that is, when fork member 34 extends precisely rearwardly as shown in solid lines in Fiyure 2 or precisely forwardly as shown in dotted Hines in Figure 2~
As seen in Figure 2, the vertical height Hl between a lowermost horizontal tangent on the wheel 24 and point P, at the intersection of axis 38 with the upper surface of plate 42, is smallest when fork member 34 extends directly rearwardly as shown in solid lines.
On rotation of fork member 34 from the rearward position in solid lines to the forward position shown in dotted lines, this height increases to become a maximum H2.
Therefore, caster 50 will have an inherent bias to assume d~L~
1 the rearwardmost position and -to swivel the caster away from positions which require marginal additional liftiny of the rear end of the cart by tilting of the cart about front wheels 26.
If wheel 24 has an exactly cylindrical outer suxface 54 as shown in Figure 3, -then on swivelling of fork member 34, axis 38 about which wheel 2~ is rotatable becomes tilted from the horizontal with the cylindrical outer surface 54 removed from contact with -the floor, contact being merely on one of the narrow edges 56 between surface 54 and side walls 58. The wheel will have maximum surface area in contact with the floor when in the rearward or forward posi-tions. With maximum surface area of the wheel in contact with the floor when the wheel is in a rearward position, if a wheel has a tendency to "chatter", that is to swing back and forth, then in each swing of the wheel, upon the wheel assuming the precisely rearward position will stop or at least dampen the swinging back and for-th.
Figure 4 shows a preferred configuration for a wheel 24 for the swivelling casters in accordance with the present invention. Wheel 24 has a major central cylindrical portion 60 and marginally rounded edge portions 62. The rounded shoulders provide a pre-ferable surface to engage the floor on swivelling of the caster necessary for turning compared -to the ra-ther sharp edge 56 of the wheel shown in E'ig~lre 3.
~9 _ 1 I'he extent to which axis 38 is tilted with respect to the vertical will determ;ne the extent -to which chattering is dampened. angles of 0 to 30~ may be acceptable with preerred angles between 1 and 10, Choice of angles which are too large will prevent the caster from easily being urged to roll rearwardly as the caster will have a large inherent bias to resist swivelling to the forward position shown in dotted lines in Figure 2. Choice of an appropriate angle will also be dependent upon the configuration of the surface of the wheels to contact the floor, The grocery cart shown in Figure 1 has rear swivelling casters in accordance with the first aspect of the present invention, In accordance with the first aspect, the axes about itch the rear wheels 24 swivel need not be tilted from the vertical. The second aspect of the present invention lies in the provision of the axis about which the swivelling wheels swivel to extend upwardly and forwardly. An advantageous embodiment of the presen-t invention lies in a combination of the first and second aspects to provide a grocery or luggage cart with rear swivelling wheels which swivel about an axis tilted forwardly and upwardly.
Conventional carts are configured with their front, swivelling caster wheels disposed to swivel about a 1 vertical axis Conventional carts which have front swivelling wheels may readily be modified to conform to the second aspect of the invention, For example, the swivelling front wheels of a grocexy cart may be replaced by a smaller diameter wheel while otherwise utilizing the original caster assembly, Reduction of the wheel diameter causes the whole frame to tilt forwardly and downwardly by rotating ahout the axis of the rear wheels whereby the axis about which the front casters swivel becomes tilted forwardly and upwardly, Replacing 5 inch front wheels by 4 inch front wheels in a conventional shopping cart has been found to significantly reduce chattering, yet not impair the ability of the carts to nest. Alternate ways to tilt the axis about which front casters of a conventional cart swivel include increasing the diameter of the rear wheels or providing new front casters of lesser height. The simple substitution of smaller diameter front wheels has the advantage of being substan-tially simpler and less expensive. In a conventional grocery cart with swivelling front wheels which has been modified to tilt its frame forwardly and downwardly,as contrasted with an identical cart in which the frame 12 is horizontal, has,due to the frame 12 tilting forwardly,a greater proportion of the weight of the cart carried by the swivelling wheels. This is advan-tageous in reducing "chattering" and rendering steering easier.
~2~ S
1 Reference is now made to Figuxe 5 which shows a .nesting luggage cart 6~ in accordance with a second embodiment of the present invention. Cart 64 is useful, for example, to move luggage by passengers in an airport.
Cart 6~ has a tubular metal peripheral frame 66 with a forward segment 68 and side segments 7~ merging into upstanding rear segments 72 terminating at their upper ends as a rearwardly extending substantially horizon-tally disposed handle-bar or handle portion 74.
A plurality of metal, rod-like cross members 76 extend between side segments 70 to define therewith a substantially rectangular support portion disposed proximate the wheels, Additional rear cross-members 78 extend between rear segments 72, A pair of front wheels 80 are shown ~ournalled on an axle forming rod 81 coupled to frame 66. Use of such a simple axle forming rod.81 is typically less-expensive than the fork and axle assembly of the front wheels in Figure 1. The provision of non-swivelling front wheels has the advantage of permitting the use of such less expensive axle forming rod 81 which when provided at the front of the cart does not interfere with nesting of the carts Rearward nesting of the carts typically precludes use of such a single axle rod 81 at the rear of a conventional cart.
3~
1 A pair of swivelliny caster assemblies designated 82 are coupled to the rear corners of the frame for swivelling about an axis either vertical or tilted foxwardly and upwardly as discussed in accordance with the first embodimen-t of this invention, Cart 6~ is adapted for nesting with one cart telescoping into a preceeding cart.
To permi-t nesting side segments 70 converge forwardly and as well reduce in height above the floor forwardly.
y providing swivelling casters 82 at the rear ox the cart, due to the increased width of the cart at its rear, and rear segments 72 of the frame and rear handle portion 74, the swivelling casters 82 carry a greater proportion of the weight of the cart than the front wheels, This is an advantage in reducing the tendency of the wheels to chatter in an unloaded position.
Also with the cart widening rearward and having rear segments 72, a user of the cart has a propensity to place larger objects and more wieght on the rear portions ox the cart, thereby,in a loaded cart, this advantageously increasing the portion of the weight on the rear swivelling casters and reduces their tendency to chatter.
Location of the swivelling wheels at the rear of the nesting cart shown in Figure.5 has the advantage of facilitating the steering of a cart into a nesting position with a preceeding cart. If only the front wheels swivel, then the cart cannot readily be manipulated -:l3-1 to a preferred nesting position once the swivelling front wheels have ~een~xolled partially inside the preceeding cart, As seen casters 82 have cylindrical tube position 8~ welded to frame 66 with a lower horn~~orming portion 86 rota-tably coupled to portion 8~ for swivelling about an axis either vertical or -tilted marginally wheel 88 is rotatably coupled to portion 86.
Shopping carts having rear swivelling wheels, such as illustrated in Figure 1, are easier to turn than similar carts with front swivelling wheels. Due to ease of turning, carts with rear swivelling wheels may more readily be turned within a smaller radius. Tess space need be provided for turning and hence a store may have narrower isles.
While the invention has been described with reference to two preferred embodiments it is not so limited. Many variations and modifications will now occur to those skilled in this art. For a definition of the invention reference is maae to -the following claims.
Claims (14)
1. A four wheeled grocery or luggage cart comprising:
load carrying frame means;
a pair of transversely spaced front wheels coupled to the frame means and journalled for rotation about a coincident transversely extending axis;
a pair of swivelling caster means coupled to the frame means spaced transversely from each other rearward of the front wheels; and transversely extending handle-bar means coupled to the frame means marginally rearward of the caster means and at a height thereabove for manual grasping by the hands of a user to propel and steer the cart.
load carrying frame means;
a pair of transversely spaced front wheels coupled to the frame means and journalled for rotation about a coincident transversely extending axis;
a pair of swivelling caster means coupled to the frame means spaced transversely from each other rearward of the front wheels; and transversely extending handle-bar means coupled to the frame means marginally rearward of the caster means and at a height thereabove for manual grasping by the hands of a user to propel and steer the cart.
2. The cart of claim 1 wherein the cart permits telescopic nesting of a plurality of identical said carts with one cart telescopically receivable into the rear of a preceeding cart, the cart including a transversely-extending axle-forming,rod means coupled to forward portions of the frame means, each front wheel journalled for rotation on said rod means,
3. The cart of claim 1 wherein each swivelling caster means comprises a caster fork journalled for rotation about a first axis fixed with respect to the frame lying in a vertical plane normal to the forward direction and tilting forwardly away from the vertical as it extends upwardly, and a rear wheel carried by fork and journalled for rotation about second axis normal to the respective first axis and offset therefrom to that the first axis and second axis do not intersect.
4. A four wheeled push cart for rolling over a horizontal floor in predominantly a given forward direction comprising:
frame means, a pair of laterally spaced first wheels coupled to the frame means and journalled for rotation about a coincident horizontal axis normal to the forward direction, a pair of swivelling caster means coupled to the frame means laterally from each other, both spaced forward or rearward of the first wheels, the caster means comprising fork means journalled for rotation with respect to the frame means about first, parallel axes fixed with respect to the frame means and tilted in the forward direction from a vertical as they extend upwardly, each caster means including a second wheel carried by the fork means and journalled thereto for
4. A four wheeled push cart for rolling over a horizontal floor in predominantly a given forward direction comprising:
frame means, a pair of laterally spaced first wheels coupled to the frame means and journalled for rotation about a coincident horizontal axis normal to the forward direction, a pair of swivelling caster means coupled to the frame means laterally from each other, both spaced forward or rearward of the first wheels, the caster means comprising fork means journalled for rotation with respect to the frame means about first, parallel axes fixed with respect to the frame means and tilted in the forward direction from a vertical as they extend upwardly, each caster means including a second wheel carried by the fork means and journalled thereto for
Claim 4 continued ...
rotation about a respective second axis normal to its respective first axis and offset from its respective first axis so that the first and second axes do not intersect.
rotation about a respective second axis normal to its respective first axis and offset from its respective first axis so that the first and second axes do not intersect.
5. The cart claimed in claim 4 wherein each second wheel has a major substantially cylindrical central floor contacting surface.
6. The cart claimed in claim 5 wherein the caster means are located rearward of the first wheels.
7. The cart claimed in claim 5 wherein the caster means are located forward of the first wheels.
8. The cart of claim 6 wherein the caster means bear a greater proportion of the weight of the cart when unloaded than the first wheels.
9. The cart of claim 8 wherein the caster means are located rearward of the first wheels, and the cart comprises a luggage cart tapering forwardly to permit telescoping nesting of one cart in the rear of a preceeding cart.
10. The carts of claim 6 wherein said cart comprises a nesting grocery cart.
11. The cart of claim 4 wherein the first axes are tilted forwardly and upwardly to form an angle of between 1 and 30° with a vertical.
12. The cart of claim 4 wherein the first axes are tilted forwardly and upwardly to form an angle of between 1 and 10° with a vertical.
13. The cart of claim 1 wherein the first axes are tilted forwardly and upwardly to form an angle of between 1 and 10° with a vertical.
14. A wheeled grocery or luggage cart for rolling in predominately a given forward direction, the cart comprising:
frame means, a pair of laterally spaced first wheels coupled to the frame and journalled for rotation about a coincident horizontal axis normal to the forward direction, caster means coupled to the frame spaced either forwardly or rearwardly from the first wheels, said swivelling caster wheels comprising fork means journalled for rotation about a 2nd axis fixed with respect to the frame lying in a vertical plane normal to the
14. A wheeled grocery or luggage cart for rolling in predominately a given forward direction, the cart comprising:
frame means, a pair of laterally spaced first wheels coupled to the frame and journalled for rotation about a coincident horizontal axis normal to the forward direction, caster means coupled to the frame spaced either forwardly or rearwardly from the first wheels, said swivelling caster wheels comprising fork means journalled for rotation about a 2nd axis fixed with respect to the frame lying in a vertical plane normal to the
Claim 14 continued ...
forward direction and tilting forwardly away from a vertical as it extends upwardly, and rear wheels carried by the fork means and journalled for rotation about a second axis normal to the first axis and offset from the first axis so that the first and second axis do not intersect.
forward direction and tilting forwardly away from a vertical as it extends upwardly, and rear wheels carried by the fork means and journalled for rotation about a second axis normal to the first axis and offset from the first axis so that the first and second axis do not intersect.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000495831A CA1241355A (en) | 1985-11-21 | 1985-11-21 | Four wheeled push cart |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000495831A CA1241355A (en) | 1985-11-21 | 1985-11-21 | Four wheeled push cart |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1241355A true CA1241355A (en) | 1988-08-30 |
Family
ID=4131927
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000495831A Expired CA1241355A (en) | 1985-11-21 | 1985-11-21 | Four wheeled push cart |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1241355A (en) |
-
1985
- 1985-11-21 CA CA000495831A patent/CA1241355A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP1028882B1 (en) | Steerable load-carrying assembly | |
| NL193529C (en) | Convertible vehicle for personal use. | |
| US4826186A (en) | Hand-pushed carrier trolley | |
| US8413999B2 (en) | Wheeled apparatus having multiple wheelbase configurations | |
| US20240227904A9 (en) | Tip limiting member for wheeled cart and assemblies thereof | |
| CA2405305A1 (en) | Baggage item with rollers | |
| US4684148A (en) | Perambulator | |
| US4765636A (en) | Steerable wheeled pushcart | |
| US7464947B2 (en) | Hand truck capable of multi-directional movement | |
| US4854601A (en) | Swivel wheel wheelbarrow | |
| CA1241355A (en) | Four wheeled push cart | |
| EP0958150B1 (en) | Improvements in or relating to castor wheels | |
| GB2192595A (en) | Kerb climbing device for a wheeled vehicle | |
| GB2278773A (en) | Steerable mobile load carrier: swivel castor | |
| EP0662881A1 (en) | A wheeled vehicle and a castorable wheel | |
| US7198279B2 (en) | Guide wheel assembly for carts | |
| GB2333698A (en) | Castor with variable inclination of swivel axis | |
| US20130062843A1 (en) | Wheeled apparatus for transporting loads | |
| US8714580B2 (en) | Kit for providing wheeled apparatus having multiple wheelbase use configurations | |
| EP0403265A2 (en) | A steerable mobile load carrier | |
| US11685188B2 (en) | Dual-state caster and method | |
| GB2274979A (en) | Trolley castor | |
| EP1666273A1 (en) | Steerable load-carrying assemblies | |
| AU746765B2 (en) | Steerable load-carrying assemblies | |
| US20070007739A1 (en) | Steerable Carriage Apparatus |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |