Abstract:
A heavy-duty caster of relatively concise configuration wherein a vertical kingpin interconnects the basic components, and the kingpin is vertically adjustable relative to its supporting structure to permit the vertical height of the caster to be readily varied.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention pertains to heavy-duty casters utilizing a central kingpin, the kingpin being vertically adjustable to vary the caster vertical dimension.  
         DESCRIPTION OF THE RELATED ART  
         [0002]    Casters, both those rotatable about a vertical axis and the non-rotatable type, find wide usage in industrial applications, and are commonly used with material handling vehicles such as hand trucks, bins, receptacles, tables, and the like. In most instances, there is no necessity to vary the vertical dimension of the caster.  
           [0003]    However, in some installations, vertical adjustment of the caster is highly desirable. For instance, hand operated pallet lift trucks commonly use heavy-duty casters to support relatively heavy loads. The wheels of such casters wear, and it is often necessary to adjust the vertical position of the caster to compensate for wheel wear and achieve the desired load sharing and bearing characteristics of the caster to obtain optimum results. As such small pallet lift trucks are built close to the ground and have limited vertical dimension, it is often important that the heavy-duty casters associated therewith be of a relatively concise vertical dimension, and heretofore, it has been difficult to provide a caster having vertical dimension adjustable characteristics which was of a heavy-duty type capable of supporting significant loads.  
         OBJECTS OF THE INVENTION  
         [0004]    It is an object of the invention to provide a caster having a kingpin for assembling the basic components wherein the kingpin is adjustable permitting the overall height of the caster to be varied.  
           [0005]    Another object of the invention is to provide a heavy-duty caster having an adjustable kingpin wherein sufficient lateral support for the caster is provided even though the adjustability of the caster in a vertical direction is significant.  
         SUMMARY OF THE INVENTION  
         [0006]    A basic component of a caster in accord with the invention is the support bracket which is usually affixed to the underside of the truck, bin, table, or other item which is to be supported upon casters. The support bracket is provided with a central threaded opening into which the upper portion of the kingpin is threaded, and the lock nut threaded on the kingpin bears against the support bracket to adjust the vertical position of the kingpin relative to the support bracket.  
           [0007]    The support bracket includes a downwardly open cavity, preferably of a cylindrical configuration, and having an open end. The cavity is preferably defined by cylindrical sidewalls.  
           [0008]    A bearing bracket is received within the support bracket cavity and is of a peripheral configuration corresponding to the walls of the support bracket cavity wherein the bearing bracket might be considered to constitute a “piston” closely received within the support bracket cavity and axially adjustable therein. The kingpin is centrally fixed within the bearing bracket whereby adjustment of the kingpin relative to the support bracket by rotating the kingpin within the support bracket opening causes the bearing bracket to slide within the support bracket cavity to axially slide within the support bracket cavity vertically adjusting the bearing bracket with respect to the support bracket and providing lateral stability between the support bracket and bearing bracket.  
           [0009]    The lower threaded portion of the kingpin extends below the bearing bracket and through thrust bearing components and an alignment bearing associated with a lower bearing block to which the caster arms are affixed and depend therefrom. The caster wheel is rotatably mounted upon the caster arms. Vertical adjustment of the kingpin relative to the support bracket will, accordingly, vertically adjust the bearing bracket, bearing block, caster arms and caster wheel to provide the desired vertical caster variation.  
           [0010]    The components of the adjustable caster in accord with the invention are readily manufactured, and economically produced. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The aforementioned objects and advantages of the invention will be appreciated from the following description and accompanying drawings wherein:  
         [0012]    [0012]FIG. 1 is a perspective view of a caster incorporating the features of the invention,  
         [0013]    [0013]FIG. 2 is an elevational view of the caster of the invention,  
         [0014]    [0014]FIG. 3 is a diametrical, sectional, elevational view of the caster as taken through the axis of the kingpin, and  
         [0015]    [0015]FIG. 4 is a plan view of the support bracket and bearing bracket and kingpin as taken along Section  4 - 4  of FIG. 2. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    The assembled caster is represented at  10  and includes a support bracket  12  having ears  14  welded thereto in which holes  16  are defined for attaching the support bracket and caster  10  to the caster supported structure, such as a hand truck, bin, receptacle, or the like. Fasteners such as bolts, not shown, extending through holes  16  firmly attach the caster as desired.  
         [0017]    The support bracket  12  centrally includes a threaded opening  18  defined in the center recess  20 . The bracket  12  further includes a cylindrical body  21  internally defining the cavity  22  by the cavity&#39;s cylindrical side  24 , FIG. 4.  
         [0018]    A bearing bracket  26  is received within the cavity  22  and includes a base  28  from which extends an annular flanged periphery  30  slidingly engaging the cavity sides  24 . On its underside, bearing bracket  26  includes the annular seal recess  31 , and a cylindrical opening  32  extends through the bearing bracket base  28 .  
         [0019]    A kingpin  34  interconnects the support bracket  12  and the bearing bracket  26 . In the following description and claims, the terms “upper” and “lower” are used to describe caster components, including the kingpin, and it is to be appreciated that these terms are only used for definitive purposes and are not considered limiting, as it would be possible to install the caster  10  in such a manner that the kingpin  34  would not be vertically oriented in the manner illustrated in the drawings.  
         [0020]    The kingpin  34  includes a threaded upper end  36  which threads through the support bracket threaded opening  18 , and tightening of the locknut  40  on the kingpin end  36  against the support bracket center  20  will fix the desired relationship and spacing between the support bracket  12  and bearing bracket  26 .  
         [0021]    The kingpin  34  includes a central cylindrical head  38  which is press fitted or welded into the opening  32  in the bearing bracket such that the kingpin  34  becomes an integral part of the bearing bracket  26 .  
         [0022]    The kingpin lower end  42  extends below the bearing bracket brace  28  and extends through the bearing block  44  having a central opening  46  defined therein for receiving the kingpin lower end  42 . An annular thrust washer, FIG. 3, is interposed between the bearing block  44  and the bearing bracket  26  received within the recess  31  defined in the bearing bracket, and a similar recess is defined in the bearing block whereby the thrust washer  48  is capable of transmitting the force through the caster while permitting the lower portion of the caster to rotate relative to the upper portion, as later described. An annular felt seal  50  surrounds the thrust washer  48  and is located within the thrust washer recesses, as shown in FIG. 3.  
         [0023]    An alignment bearing between the non-rotatable bearing bracket  26  and the rotatable bearing block  44  consists of a cone bearing  52  affixed to the bearing bracket  26  and a cup bearing  52  attached to the bearing block  44 . The bearings  52  and  54  are of annular configuration and the kingpin lower end  42  extends therethrough, and these bearings maintain alignment between the non-rotating and rotating components of the caster.  
         [0024]    A slotted nut  56  is threaded upon the kingpin lower end  42 , and a pin  58 , such as a cotter pin, extends through the kingpin lower end and is received within slots in the nut  56  to prevent rotation of the nut on the kingpin.  
         [0025]    Caster arms  60  are attached to the bearing block  44  and extend downwardly in spaced relationship to each other. Axle  62  extending between the arms  60  rotatably supports the caster wheel  64 .  
         [0026]    As the bearing block  44  and the bearings  52  and  54  rotate relative to the bearing bracket  26 , it will be appreciated that the wheel  64  is capable of pivoting about the kingpin axis relative to the support bracket  12 . If it is desired to change the vertical dimension of the entire caster  10 , as may be necessary due to wear of the wheel  64 , the caster  10  is removed from its attached structure, not shown, by removing the fasteners extending through the hole  16 , the locknut  40  is loosened, and the lower portion of the caster, including bearing bracket  26  and bearing block  44 , are rotated relative to the support bracket. This rotation threads the kingpin upper end  36  within the support bracket opening  18  changing the location of the bearing bracket within the support bracket cavity  22 , and thereby adjusting the overall vertical height of the caster  10 . The locknut  40  is re-tightened against the support bracket center  20  and the caster  10  is re-mounted.  
         [0027]    It will be appreciated from the above description that the caster components described above can be economically formed and the caster easily assembled. It will be appreciated that various modifications to the inventive concepts may be apparent to those skilled in the art without departing from the spirit and scope of the invention.