Patent Application
20230416064
This invention relates generally to a wheel assembly for a material handling vehicle and in particular, to a multi-axle and multi-wheel assembly adapted for use in material handling vehicles, such as Class II narrow aisle trucks or forklifts.
Material handling vehicles are powered industrial trucks designed for use in warehouses and may be required to operate in narrow aisles, for example, aisles that are twelve feet wide or less. The vehicles are typically classified as Class II narrow aisle forklifts or trucks, and include reach trucks, orders pickers, and very narrow aisle forklifts, also referred to as turret trucks. Many such material handling vehicles are provided with base legs or outriggers, which extend outward from the main body of the vehicle, typically on either side of the forks or platform. The outriggers prevent the vehicle from tipping forward when the vehicle is loaded with material.
The ends of the outriggers incorporate a load wheel, which supports the vehicle, whether the vehicle is stationary or transporting material from one location to another. The wheels are designed to operate indoors and are typically solid. Each of the wheels is mounted on an axle, with the axle aligned perpendicular to the usual direction of travel of the vehicle. The axle may be supported by a bracket, and the bracket is supported by the outrigger. Alternatively, the axle may be directly supported by the outrigger.
The nature of the applications for which Class II material handling vehicles are employed requires that they be able to turn with a relatively short radius, i.e., less than 36 inches (whereas other trucks, such as Class I or Class III trucks, have a much larger turning radius and are used in applications which do not require regular small radius turning). More preferably, however, the vehicles should exhibit essentially static turning, i.e., a turning radius of zero inches or less than one inch. Additionally, the wheels and outriggers must be capable of fitting around pallets, under warehouse racking, and between racking supports commonly found in warehouse storage systems to function effectively. Typically, the maximum total height of the wheels must be no greater than 6 inches in North America and 8 inches in Europe so that the wheel and outrigger assemblies can accommodate working with industry-standard storage systems (typical systems in the remainder of the world follow one of these two standards). Thus, while the load-bearing capacity of the wheel may be increased by increasing the size of the wheel, operating restrictions in the warehouse environment limit the diameter and width of the wheel.
To increase the load capacity of the outriggers, two wheels are sometimes provided adjacent to the end of each outrigger. For example, a first wheel is mounted on a first axle, a second wheel is mounted on a second axle, and the first and second axles are mounted on the outrigger front-to-back, referred to herein as being in tandem. Accordingly, when the vehicle is moving forward, the first and second wheels roll in the direction of travel, that is, with the first and second axles aligned perpendicular to the direction of travel.
Operating a material handling vehicle in a warehouse requires that the vehicle be capable of pivoting in limited space. The pivot point of a typical Class II material handling vehicle is near the point of attachment of the outrigger to the body of the vehicle, referred to herein as the proximate end of the outrigger. For example, the vehicle may be equipped with two wheels at the back of the body and a wheel assembly at the distal end of each outrigger. The pivot point of the vehicle, when turning, is approximately midway between the back wheels and the wheel assemblies at the distal ends of the outriggers.
The positions of the load wheels located in the vehicle's outriggers are typically fixed.
For example, the load wheels are mounted on an axle and the axle may be oriented perpendicular to the linear extent of the outrigger. When the vehicle pivots, however, one side of each load wheel will be on the inside of the turn, and one side of each load wheel will be on the outside of the turn. It may be understood that when the vehicle pivots, the inside arc of the load wheel will travel less distance than the outside arc of the load wheel, which creates a scuffing action and extra wear on the tires of the load wheels. The wear may be seen as abrasion, coning and flat spotting on the tire of the load wheel. As the width of the wheel increases, for example, to accommodate heavier loads, the problem of extra wear is exacerbated.
Various attempts to develop an improved wheel assembly are discussed in the following patent references: Frischmann—U.S. Pat. No. 2,618,490; Bryntse—U.S. Pat. No. 3,814,456; and Passeri—US 2006/0232030 A1. However, these arrangements include several drawbacks, including large turning radiuses that are not capable of functioning in modern warehouse settings with narrow aisles, increased wear which negatively impacts wheel life and truck service downtime, and a limited load capacity not capable of meeting projected load demands. Thus, there remains a need for an improved truck incorporating a wheel assembly and outrigger capable of accommodating the requirements of modern warehousing.
In attempting to address increased load requirements, the conventional wisdom in the art has been to provide a single wide wheel per axle to maximize the contact area with the floor. This conventional approach has recently led industry participants to fabricate extra-wide outriggers (e.g., by modifying standard equipment via welding) capable of holding a wider wheel to provide a wheel capable of bearing additional load.
As detailed herein, the inventors of the present application have designed a wheel assembly and outrigger that proceeds against this conventional wisdom and provides enhanced load-bearing capacity and superior life with respect to conventional designs.
The present invention is directed to a wheel assembly for a material handling vehicle.
The wheel assembly may be mounted in the outrigger of a material handling vehicle. Thus, the present invention is also directed to an outrigger incorporating a wheel assembly, as well as a material handling vehicle incorporating such a wheel assembly. In one embodiment, the wheel assembly is provided with a first axle and at least two wheels mounted on the axle. The first axle may have more than two wheels mounted thereon, for example, three, four, or more wheels. Preferably, the wheels rotate independently of each other. Accordingly, when the vehicle incorporating the wheel assembly pivots, the wheel on the inside of the turning radius is free to travel less distance than the wheel on the outside of the turning radius. Such arrangement provides less contact surface per wheel overall but reduces the degree of coning as to each individual wheel. Such an arrangement also allows for a smaller turning radius—in some embodiments, the turning radius of a truck incorporating a wheel assembly provided herein is essentially zero. The embodiments discussed herein, when undergoing testing, also surprisingly provide a larger load capacity as compared to the traditional single-wheel arrangement.
The wheel assembly is also provided with a second axle and at least two wheels mounted on the second axle (three, four, or more wheels may also be provided). Preferably, the wheels of the second axle rotate independently of each other. The second axle and wheels may be identical to the arrangement of the first axle and wheels, or the second axle and wheels may be different. For example, the first axle may have two wheels and the second axle may have three wheels.
The first and second axles may be mounted directly on the outrigger of a material handling vehicle. For example, the outrigger may contain a recess at the distal end, that is, the end opposite the point of attachment to the body of the vehicle, and the first and second axles and wheels may be mounted on the outrigger in tandem. Alternatively, the first and second axles and wheels may be arranged in tandem, as part of a module that is mounted on the distal end of the outrigger.
Generally, material handling vehicles used in combination with the present invention will have two outriggers, for example, one on each side of the forks or platform at the front of the vehicle (a single outrigger or additional outriggers may be used, however). Accordingly, the wheel assembly of the present invention may be mounted at the end of each of the outriggers.
In another embodiment of the invention, the first and second axles and wheels are supported by brackets positioned at the ends of the axles, with the brackets aligned parallel to each other and perpendicular to the longitudinal extent of the axles. The wheel assembly, which in this embodiment includes the brackets, axles, and wheels, can then be pivotally mounted on the outrigger. The pivot point of the bracket assembly is between the first and second axles, but the pivot point, first axle, and second axle are not necessarily colinear or coplanar, and the pivot point may be offset to a position above the first and second axles with respect to the ground. By way of example, with the pivot point as the vertex, imaginary rays extending from the vertex to the first and second axles may form an angle from 20° to 180°, preferably greater than 30° and less than 180°, in particular, from 35° to 170°, and more particularly, from 40° to 150°.
The wheel assembly can be pivotally mounted to the outrigger in a variety of ways. For example, a shaft may extend from the first bracket to the second bracket, parallel to the first and second axles, and the shaft may engage the outrigger. Alternatively, the first and second brackets may be provided with outwardly facing projections, and the projections may engage the outrigger. Alternatively, the outrigger may be provided with inwardly facing projections, and the projects may engage the first and/or second bracket. Alternatively, the outrigger and the first and/or second brackets may have a recess configured to accommodate mounting hardware such as a shaft, bolt, or the like.
The inventors of the present application have determined that the relationship between the distance from the first axle to the second axle and the aggregate width of the wheels on an axle exerts a strong influence on the performance of the wheel assembly. In the case of two wheels mounted on an axle, the aggregate width of the wheels is measured from the outwardly facing side of the first wheel to the outwardly facing side of the second wheel. In the case of three or more wheels mounted on the axle, the aggregate width is measured from the outwardly facing side of the first wheel to the outwardly facing side of the wheel farthest from the first wheel. The distance between the axles is measured from the center line of the first axle to the center line of the second axle. If the distance between the axles is X, and the aggregate width of the wheels on an axle is Y, then the ratio of X:Y may be between 0.5 and 1.3, in particular, between 0.5 and 1.2, more particularly, between 0.6 and 1.1. If the aggregate width of the wheels on the first axle and the second axle is different, then X is the higher of the aggregate widths.
The inventors of the present application have also determined that the relationship between the distance from the first axle to the pivot point of the wheel assembly and the distance from the second axle to the pivot point of the wheel assembly also exerts an influence on the performance of the wheel assembly. In particular, where the distance between the first axle and the pivot point is D, and the distance between the second axle and the pivot point is E, then the ratio of D:E should be between 1:4 to 4:1, and, in particular, from 1:2.3 to 2.3:1, and more particularly, from 1:1.5 to 1.5:1.
The inventors of the present application have also determined the distance from the first axle to the second axle should be less than two times the mean wheel diameter for the wheels used on the first and second axles. More preferably, the distance should be less than 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, or 1.1 times the mean wheel diameter. Most preferably, the distance from the first axle to the second axle should be 1.1 or 1.05 times the mean wheel diameter, i.e., locating the wheels as close as possible while leaving sufficient room for debris to pass between the wheels without causing damage or becoming lodged in the wheel assembly.
The wheel assemblies and outriggers described herein may incorporate materials commonly used in wheel assemblies and outriggers. For example, the wheels include a tire made of a solid elastomer, such as a polyurethane, a rim made of a metal alloy, and a bearing. The brackets, brace, outriggers, and associated mounting projections and/or shafts are made of a metal alloy.
To be compatible with typical material handling vehicles and modern warehouse configurations, the wheel assembly of the present application preferably has a total width of less than seven inches and a total height of less than six inches (North America) or eight inches (Europe). The present invention has a number of advantages. Two axles and sets of wheels are provided to distribute the load. Yet instead of increasing the resistance to pivoting a material handling vehicle incorporating the wheel assembly, the wheels along each axle are able to rotate independently, thereby decreasing the resistance. Furthermore, in the embodiment in which the wheel assembly is pivotally mounted on an outrigger, the wheel assembly is generally able to keep both wheels in contact with the floor, even if the floor is uneven, thereby distributing the load.
Further objects, features, and advantages of the present application will become apparent from the detailed description of preferred embodiments, which is set forth below, when considered together with the figures of drawing.
Without intending to limit the scope of the invention, the preferred embodiments and features are hereinafter set forth. All the United States patents and published patent applications cited in the specification are incorporated herein by reference. As used herein, the term “wheel” is intended to encompass a tire, which may be a solid elastomer, such as a polyurethane, a rim on which the tire is mounted, and a set of bearing within the rim.
As referred to herein, the term “powered industrial truck” means a mobile, power-propelled truck used to carry, push, pull, lift, stack, or tier material. Vehicles that are used for earth moving and over-the-road hauling are excluded. Under OSHA regulations, there are seven classes of powered industrial trucks:
As indicated herein, the present application relates primarily to Class II powered industrial trucks, i.e., narrow aisle forklifts or trucks, including reach trucks, orders pickers, and very narrow aisle forklifts, also referred to as turret trucks, and, more specifically, to wheel assemblies and outriggers used therein.
As referred to herein, disclosures of ranges are, unless specified otherwise, inclusive of endpoints and include all distinct values and further divided ranges within the entire range. Thus, for example, a range of “from A to B” or “from about A to about B” is inclusive of A and of B. Disclosure of values and ranges of values for specific parameters (such as amounts, weight percentages, etc.) are not exclusive of other values and ranges of values useful herein. It is envisioned that two or more specific exemplified values for a given parameter may define endpoints for a range of values that may be claimed for the parameter. For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that Parameter X may have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if Parameter X is exemplified herein to have values in the range of 1-10, or 2-9, or 3-8, it is also envisioned that Parameter X may have other ranges of values including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3, 3-10, 3-9, and so on.
Each of outriggers 6 and 7 has first axle 8, with a plurality of wheels mounted thereon, and second axle 9, with a plurality of wheels mounted thereon. First axle 8 and second axle 9 are arranged in tandem, with the axles aligned perpendicular to the longitudinal extend of the outrigger, which in this case is the ordinary direction of travel of vehicle 1.
Referring to
Wheel assembly 10 is provided with mounting hardware, for pivotally engaging an outrigger of a material handling vehicle. In the embodiment illustrated in
Wheel assembly 20 has first axle 21, with wheels 22a, 22b and 22c mounted thereon. Wheels 22a, 22b and 22c rotate independently of each other. Wheel assembly 20 is provided with second axle 23, with wheels 24a, 24b and 24c mounted thereon, which also rotate independently of each other. Axles 21 and 23 each have one end supported by bracket 25 and the axles each have an opposite end supported by bracket 26. Brackets 25 and 26 are joined together by shaft 27, which maintains the brackets in parallel relationship, perpendicular to the axles. When wheel assembly 20 is mounted on an outrigger, wheel assembly 20 pivots on an axis extending through shaft 27. Thus, wheel assembly 20 forms a complete module, which can be mounted on the outrigger of a material handling vehicle.
It has been found to be advantageous to offset the axis on which the wheel assembly pivots from the first and second axles. In other words, the pivot point, first axle and second axle may not necessarily be in a straight line. For example, if the pivot point of the wheel assembly is taken as the vertex, then a ray extending from the vertex to the first axle forms one arm of an angle and a ray extending from the vertex to the second axle fom1s a second am1 of an angle.
The angle between the pivot point, first axle and second axle may range from 20° to 180°, preferably greater than 30° and less than 180°, in particular, from 35° to 170°, and more particularly, from 40° to 150°. Referring to
Referring to
The present invention has been described in relation to a material handling vehicle having outriggers or legs, extending from the body of the vehicle, for example, laterally in the direction of the forks or platform that is raised to retrieve pallets and goods stored in a warehouse. A pair of the subject wheel assemblies may also be employed to replace a set of load wheels positioned in the back or front of the body of the vehicle, that is, directly under the body, rather than in an outrigger.
There are, of course, many alternative embodiments and modifications of the invention intended to be included in the scope of the claims.
A-1. A wheel assembly for an outrigger of a material handling vehicle, comprising:
The foregoing description of preferred embodiments has been presented for purposes of illustration and description only. It is not intended to be exhaustive or to limit the application to the precise form disclosed, and modifications and variations are possible and/or would be apparent in light of the above teachings or may be acquired from practice of the application. The embodiments were chosen and described in order to explain the principles of the application and its practical application to enable one skilled in the art to utilize the application in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the application be defined by the claims appended hereto and that the claims encompass all embodiments of the application, including the disclosed embodiments and their equivalents.
This application is based upon and claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 63/354,270, filed Jun. 22, 2022, the entire contents of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63354270 | Jun 2022 | US |
