Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
2001-02-12
2003-02-25
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C198S780000
Reexamination Certificate
active
06523678
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to power transmission systems of the endless belt type and, more particularly, to such systems having powered and idler pulleys as components thereof
BACKGROUND OF THE INVENTION
A typical endless-belt conveyor system has a head or driving pulley and a tail or idler pulley. Also typically, the axes of rotation of such pulleys are generally parallel to one another and horizontal, although neither parameter is an absolute requirement. An endless belt is mounted on and supported by such pulleys and, when viewed toward the belt edge, such belt defines what might be described as a very-elongate race track shape. The top portion of the belt is driven by the head pulley and is in tension. The lower portion may be somewhat slack.
Endless-belt conveyor systems are used for a wide variety of purposes. An example is a conveyor system moving granular or containerized products from one location to another. Another example, used in a commercial airport, moves passenger baggage from the baggage cart offloading area to the carousels at which passengers retrieve such baggage.
In conventional arrangements, a pulley (head or tail) has a one-piece shaft extending entirely through the pulley. Such shaft protrudes from either side by dimensions sufficient to mount the shaft ends on respective supporting bearings and (in the case of a powered head pulley) to apply driving torque to one end. An example of a type of conveyor having a narrow pulley and a through shaft is disclosed in U.S. Pat. No. 6,000,531 (Martin).
Like all mechanical structures, such conveyor systems experience failure, e.g., bearing failure, from time to time. And, often, the shaft supported by such bearing is damaged so as to require replacement. In a conventional system, the failure of a bearing requires that the pulley be entirely removed from the conveyor structure. This is so since the pulley shaft is a one-piece shaft. And it is highly desirable to leave the belt in place while effecting repairs. Often, the pulley is removed to another site for repair or substitution.
This is time consuming and runs the risk of damaging the pulley outer shell during handling. And when re-installed, the pulley outer shell, replacement shaft and other components must be precisely concentrically aligned or the pulley will “wobble”, result in undue belt wear and unduly stress the bearings.
And that is not all. A pulley is very heavy, difficult to handle and, therefore, difficult to re-align and mount following repair. If the conveyor system (including the failed pulley) is closely adjacent to another conveyor system (as is common in airport baggage handling arrangements) or to some other obstruction, the difficulty of repair is exacerbated. The system having the failed pulley (or the adjacent work-impeding structure) may have to be elevated with jacks in order to get at and remove the affected pulley, shaft and bearing.
An improved conveyor roller which addresses problems of known pulleys would be an important advance in the art.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a conveyor pulley overcoming some of the problems and shortcomings of prior art pulleys.
Another object of the invention is to provide a conveyor pulley which is easy to replace.
Another object of the invention is to provide a conveyor pulley configured to permit bearing or shaft replacement while yet avoiding removal of the pulley from the conveyor system.
Still another object of the invention is to provide a conveyor pulley which is less costly to repair that known pulleys.
Yet another object of the invention is to provide a conveyor pulley which may be readily serviced, notwithstanding the proximity of other equipment or of an obstruction.
Another object of the invention is to provide a conveyor pulley which, when compared to a similar prior art pulley, is lighter in weight. How these and other objects are accomplished will become apparent from the following descriptions and the drawings.
SUMMARY OF THE INVENTION
The new conveyor pulley is configured to revolve about an axis of rotation. Such pulley includes a cylindrical drum or shell and first and second bushing portions supported within the shell. A first shaft portion is in torque-transmitting engagement with the first bushing portion; and a second shaft portion is in torque-transmitting engagement with the second bushing portion.
The first and second shaft portions are restrained from axial movement with respect to the first and second bushing portions, respectively. In a specific embodiment, such restraint is provided by fasteners coupling a shaft portion and its respective bushing portion to one another. The first and second shaft portions are spaced from one another, that is, such shaft portions are separate components independently replaceable.
In a highly preferred embodiment, the first shaft portion includes a flange (a “first” flange) which might be described as “race track shaped”. Such flange has a pair of arcuate ends (of the same radius of curvature) which are joined by a pair of linear sides. The first bushing portion includes a “first” face and the first shaft portion is restrained by at least one fastener—a “first” fastener—and, preferably, by plural fasteners such as cap screws which engage the flange and the face.
In other aspects of the inventive pulley, the first bushing portion includes a groove having at least one linear edge and extending along a groove axis. Such axis is generally perpendicular to the axis of rotation. The flange is received in the groove and bears against the edge. Considered another way, the groove and the flange are conformably shaped and sized in such a way that the flange may be fitted into the groove with closely-fitted sliding clearance so as to avoid rotational “play” between the shaft portion and bushing portion. The first bushing portion and first shaft portion are at one end of the pulley, the other end is similarly configured in that such end is substantially a “mirror image” of the first end.
More specifically, the second bushing portion includes a second face, the second shaft portion includes a second flange and the second shaft portion is restrained by at least a second fastener engaging the second flange and the second face. Most preferably, the second shaft portion and the second bushing portion are secured to one another by plural fasteners.
In other aspects of the inventive pulley, a first support structure is interposed between the shell and the first bushing portion. Similarly, a second support structure interposed between the shell and the second bushing portion. Such support structures retain, respectively, the first and second bushing portions in fixed positions with respect to the shell. While such support structures may be configured as “spiders”, support rods or the like, in a highly preferred embodiment, the first and second support structures include, respectively, annular members. Each annular member is affixed to the shell and to its respective bushing portion by welding, for example. Most preferably, each support structure comprises a pair of spaced-apart annular webs affixed to the shell and respective bushing portions. A preferred web is “washer like” and disc-shaped.
While it is preferred to construct the new pulley with two spaced-apart bushing portions (as separate pieces secured within the pulley shell), that is not the only way to construct an operative pulley although it may be the lowest-cost configuration consistent with the required rigidity, “robustness” and the like. In an alternate embodiment, the pulley includes a single bushing tube extending along the pulley axis of rotation. Such tube has first and second ends, the first shaft portion terminates at the first end and the second shaft portion terminates at the second end.
In the embodiments described, the shell, shaft portions and bushing portions are all concentric with the pulley axis of rotation. The shaft portions are independently removable from their respective bushing portions and, most preferably,
Roessler David A.
Rorke Kevin C.
Stelter Anthony J.
Thimmel Frederick H.
Bryant Products, Inc.
Crawford Gene O.
Ellis Christopher P.
Jansson & Shupe & Munger Ltd.
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