Material or article handling – Self-loading or unloading vehicles – Conveyor
Reexamination Certificate
1999-06-21
2001-02-13
Keenan, James W. (Department: 3652)
Material or article handling
Self-loading or unloading vehicles
Conveyor
C198S833000, C198S840000
Reexamination Certificate
active
06186732
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to conveyor equipment and, in a particular use, to a conveyor mechanism for loading and unloading cargo from a trailer or the like.
BACKGROUND OF THE INVENTION
Conveyor mechanisms for loading and unloading cargo are well known. Such conveyor mechanisms are commonly used, for example, to load and unload various products (e.g., bulk agricultural crops, aggregate material, construction material, boxes, crates, etc.) from a vehicle (e.g., a trailer, a semi-trailer, a wagon, a truck, etc.).
Such conveyor mechanisms typically include a pair of chain loops disposed within and along the floor (or bed) of the trailer. The chain loops are usually engaged by a pair of drive sprockets arranged on a first axle and also by a pair of associated idler sprockets arranged on a second axle. Because the axles are ordinarily disposed at opposite ends of the trailer, the chain loops are generally obround in shape. A plurality of transverse slats extending between links of the opposed chains provide support to the chain loops and enable the conveyor mechanism to transport heavier loads. Such conveyor mechanisms are commonly known as slat-type conveyors. Examples of these types of devices are provided by U.S. Pat. Nos. 3,876,089 (Moser), 4,055,265 (Eisenman), 4,664,583 (Gust), and 5,102,285 (Gust).
In order to prevent abrasive material from damaging the chains, some slat-type conveyors include flexible belting which spans the width between the chains. By way of example, U.S. Pat. No. 4,664,583 (Gust) discloses a slat-type conveyor in which a plurality of segmented belts are attached to the slats. U.S. Pat. No. 5,102,285 (Gust), in contrast, discloses a slat-type conveyor in which a single continuous belt which is wrapped around the chains and is affixed to the various slats. The single belt slat-type conveyor disclosed in U.S. Pat. No. 5,102,285 (Gust), however, suffers from noted deficiencies which will be discussed herein.
First, in order to prevent slipping, bunching, and/or stretching of the belt at the points where the chains reverse direction (i.e., at the ends of the generally obround chain loops), the pitch diameter of the chains must coincide with the pitch diameter of the belt. In order to align these pitch diameters, however, the chain loops must be located outboard (i.e., beyond the width) of the belt. As a result, the belt cannot be wrapped around the chain loops, but must instead be wrapped around the slats which interconnect the chain loops. Furthermore, single belt slat-type conveyors of this type are limited to only two chain loops (i.e., one chain loop on either side of the width of the belt).
Second, single belt slat-type conveyors of this type are expensive to manufacture and service. For instance, because the load of the cargo is ultimately shared by only two chain loops, both of these chains need to be very sturdy (i.e., large and expensive). In a like manner, the slats interconnecting the two chain loops need to be spaced-apart at relatively close intervals (i.e., numerous slats are required). Also, the belt needs to be joined to the slats at regular intervals. This not only significantly increases assembly labor, but also makes field disassembly and repair extremely difficult and time consuming.
Third, single belt slat-type conveyors of this type are subject to damage by the contents of the cargo. The slats, for example, are susceptible to deformation by rocks or other solid objects in the trailer. The chains are also prone to damage because they ultimately support the weight of the cargo. More significantly, however, should one of the chains break during use, virtually all of the slats would be destroyed.
Fourth, single belt slat-type conveyors of this type are subject to inherently high frictional losses caused, in part, by the weight of the cargo. More specifically, the weight of the cargo frequently causes the slats to wear or rub against the bed of the trailer which, in turn, increases the power requirements of the motor.
SUMMARY OF THE INVENTION
In our parent application we disclosed a conveyor mechanism having a single belt driven by a plurality of chains which underlie and support the belt. The chains and the belt are turned on different guiding rollers so as to avoid bunching or slippage at the turning points, but on the main horizontal run of the belt, the belt and the chains move at the same speed. The chains are carried in supporting tracks, and the plurality of chains in their respective tracks both supports and drives the load carried on the belt.
The load on the belt can be significant and at times will attempt to cause the belt to move laterally as it is driven along the longitudinal axis for loading or unloading. There are some materials, such as for example loads of large rocks which can impose uneven loading on the belt, and cause the mechanism to deviate from the normal longitudinal rotation for which it is designed. There are other cases where loads, such as hot blacktop material can creep under the belt and foul the drive mechanism if the belt tracks away from its centered lateral position.
The present invention has for its aim the further improvement of our conveyor mechanism to assure that side to side lateral tracking is maintained.
Thus, it is an object of the invention to enhance our conveyor apparatus with a simple and very reliable mechanism for maintaining lateral tracking of the belt, and without substantially complicating the simplicity or compromising the ruggedness of the conveyor apparatus.
A further object of the invention is to provide such a mechanism which does not substantially increase the load on the prime mover which drives the belt.
It is a related object to provide a mechanism for maintaining lateral tracking of the belt in a live bottom trailer conveyor mechanism which does not substantially increase the cost or compromise the reliability of the basic live bottom trailer apparatus.
A further object of the present invention is to provide a single belt conveyor mechanism which is capable of supporting and moving relatively heavy cargo loads without danger of the belt laterally deviating from its intended path.
Another object of the present invention is to provide a single belt conveyor mechanism that which is less susceptible to damage than presently-employed single belt slat-type conveyor mechanisms, and is not prone to lateral mistracking of the belt.
Yet another object of the present invention is to provide a single belt conveyor mechanism which is less prone to frictional losses than presently-employed single belt slat-type conveyor mechanisms and is also configured to avoid lateral mistracking of the belt.
Other objects and advantages will become apparent upon reference to the following detailed description when taken in conjunction with the drawings and which:
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Bertsch James K.
Brown Thomas R.
O'Brien Patrick C.
Zerbe Randal L.
E.D. Etnyre & Co.
Keenan James W.
Leydig , Voit & Mayer, Ltd.
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