1. Field of the Invention
The present invention is broadly concerned with improved articulated casters designed to support heavy loads. The invention is particularly beneficial in facilitating traversal of the load over sloped or uneven surfaces, or when obstacles are encountered. More particularly, the invention is concerned with an articulated caster assembly having an inexpensive yet rugged pivot assembly for pivotally interconnecting an upright pivot arm and the base of a caster assembly.
2. Description of the Prior Art
Casters are well known devices that assist in the mobility of a great variety of equipment and other loads. They are used in industry, in the home, in the medical field, and in general wherever it is desirable to efficiently move objects over surfaces. While casters function well on smooth surfaces, they tend to operate less efficiently when used on uneven surfaces or when obstructions are encountered. In order to overcome this problem, articulated casters have been developed which are better adapted to maneuver over uneven surfaces and/or obstructions.
U.S. Pat. No. 5,507,069 describes a type of articulated caster of three-wheeled tricycle design. The casters of the '069 patent include a central upstanding pivot arm extending through the caster base and pivotally connected thereto. The upper end of the arm is designed to support loads. The pivot assembly described in this patent makes use of a ball joint housed within a slotted carrier. Such a pivot assembly, while useful for its intended purpose, is very costly to manufacture, requiring multiple fabrication steps.
There is accordingly a need in the art for improved articulated casters which afford a desirable degree of pivotal movement so as to traverse without difficulty uneven surfaces and the like, while at the same time having pivot coupling assemblies which are durable and inexpensive to manufacture from the standpoints of materials used and fabrication steps.
The present invention overcomes the problems outlined above, and provides an improved articulated caster characterized by reduced manufacturing costs and high operational deficiencies. According to one aspect of the present invention, the articulated caster generally includes a caster assembly, an upright pivot arm, and a pivot assembly. The caster assembly includes a base and at least three spaced apart caster wheels that are attached to and cooperatively support the base so that the caster assembly is self-supporting. The upright pivot arm has a lower end and an upper end adapted for connection with a load. The pivot assembly operably couples the lower end of the arm with the base. The pivot assembly includes an open-top housing receiving the lower end of the pivot arm. The pivot assembly further includes a connection assembly interconnecting the housing, base, and pivot arm in order to permit relative pivotal movement between the pivot arm and base about generally transverse first and second pivot axes.
Another aspect of the present invention concerns a carriage including a load-supporting component and two or more spaced apart wheeled supports, at least one of which is an articulated caster. The articulated caster is constructed as previously described.
In preferred forms, the pivot assembly housing is substantially quadrate in plan configuration, presenting opposed sidewalls and opposed end walls. The preferred pivot arm is of mating, square tubular design and is received between the housing sidewalls. The connection assembly includes a pair of low-cost bolt and nut connectors securing the base and end walls of the housing and defining a first pivot axis. Additionally, a second coupler connects the housing sidewalls and the lower end of the pivot arm to define a second horizontal pivot axis transverse to the first pivot axis.
Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures.
Preferred embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:
The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the preferred embodiments.
Turning now to the drawings, a wheeled carriage 10 is depicted in
In more detail, the base 18 is somewhat triangular in shape and presents three wheel-mounting apices 30, 32, and 34. The base 18 has a generally central opening 36 and depending strengthening webs 37. A pair of opposed depending triangular support legs 38 and 40 extend downwardly from the underside of base 18 and have aligned apertures 42. As best illustrated in
The caster wheels 20-24 are identical and each includes a mount 44 configured to mate with a corresponding base apex 30, 32, or 34, with fasteners 45 interconnecting the base apices and mounts. A swivel coupler 46 is secured to the underside of each mount 44 and a pair of opposed support arms 48 and 50 depend from the swivel coupler 46. A wheel 52 is secured between the arms 48 and 50 via fastener 54. It will thus be appreciated that the wheels 20-24 are independently pivotal about respective, upright pivot axes.
The base 18 and wheels 20-24 cooperatively form a caster assembly that is self-supporting and particularly effective in supporting, along with other similarly constructed caster assemblies, extraordinarily large loads. The illustrated caster assembly is similar to that disclosed and claimed in U.S. patent application Ser. No. 10/886,369, entitled ARTICULATED CASTER, filed Jul. 6, 2004; and U.S. patent application Ser. No. 11/277,538, entitled ARTICULATED CASTER, filed contemporaneously herewith; both of which are assigned of record to the assignee of the present application and are hereby incorporated by reference herein. However, those ordinarily skilled in the art will appreciate that certain principles of the present invention are applicable to other caster assembly designs. For example, although the illustrated design is most preferred, the caster assembly may be provided with more caster wheels than illustrated, the base can have alternative shapes, etc.
The illustrated pivot arm 26 is a rigid metallic part having an upper connection flange 56 and a depending arm member 58. The member 58 is of square tubular configuration and terminates in a lowermost tubular section 60 of reduced cross-sectional area, which is interfitted within the member 58. The section 60 carries a transversely extending bushing 62 forming a through passageway. Other suitable pivot arm designs are entirely within the ambit of the present invention, as will be subsequently described.
The illustrated pivot assembly 28 differs significantly from that disclosed in the incorporated applications. More specifically, the pivot assembly 28 includes an open-top housing 64 of generally quadrate plan configuration, presenting opposed sidewalls 66 and opposed end walls 68. As best seen in
The housing 64 is located between the lower ends of the support legs 38 and 40 with the apertures 42 thereof in alignment with the end wall apertures 72 of the housing. A pair of short bolt and nut assemblies 76 (bolt 76a, washer 76b, bushings 76c, and nut 76d) are used to secure the housing 64 to the legs 38 and 40, and to permit the housing to rotate about a pivot axis defined by the bolts 76a. Again referring to
The articulated casters of the present invention, making use of the open-top housing 64 secured to base 18 and to the lower end of pivot arm 26, provide a number of advantages as compared with prior art caster designs. For example, use of the pivot housing requires the pivot arm 26 to be only of simple square configuration versus prior art forked designs requiring multiple cutting, machining, welding, and/or casting operations to fabricate. Indeed, the housing 64 can readily be fabricated using a single laser cutting operation providing the rectangular configuration and the mounting apertures. Prior pivot block designs require at least four machining operations to give sizing and drilling of the center and end mounting apertures. Such pivot block units also require threading of the end holes. This is eliminated in the present invention where the housing apertures are unthreaded. The present pivot arm/pivot assembly is smaller and has a higher strength:weight ratio. Moreover, if it is desired to increase the strength of the pivot assembly, housing 64 can easily be increased in height without affecting the remainder of the caster assembly.
Because of the use of the articulated casters 14 and 16, the carriage is particularly effective in supporting large loads for traversal on uneven or inclined surfaces or across obstacles (such as debris on the surface). If desired, the carriage can be provided with more or less casters than depicted. Furthermore, each pivot arm can be associated with a gang of casters if desired. Another suitable but alternative carriage design is depicted in U.S. patent application Ser. No. 11/277,546, entitled QUAD-CASTER CARRIAGE WITH FORKLIFT ATTACHMENT, filed contemporaneously herewith, assigned of record to the assignee of the present application, and hereby incorporated by reference herein.
The principles of the present invention are equally applicable to other pivot assembly designs. For example,
The preferred forms of the invention described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention.
The inventor hereby states his intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.