In one type of materials conveyor system, a series of rotatable wheels on shafts are arranged in fixed positions at varying distances between the source and the destination of the materials. The axis of rotation of each wheel is perpendicular to the direction of transport motion. If the wheels are arranged closely enough together by comparison to the dimensions of the transported goods, they may simply be placed upon the wheels nearest the source, from whence they can be pushed over the rolling wheels, from one wheel to the next, towards their destination. The wheel arrangement is better than having the whole shaft rotate because it minimizes the total area of bearing surfaces, permitting them to be more readily protected from contamination and lubricated. Commonly, housed ball bearings are utilized for this purpose. Where, as is usual, the goods are small in relation to the interwheel distance, they are loaded onto large flat pallets which ride between the goods and the roller wheels.
In order to reduce sidewise sliding of the pallets, avoid pallet injury, and reduce excessive noise, it is desired to cushion the bearings with rubber or similar material. More importantly, in inclined conveyor systems, where gravity provides the motive force, the hardness of the cushioning (as well as the number of wheels) is used to adjust transport speed to the desired rate. Such cushions or tires have been used by prior art bearings. In general, they have been either thermoplastic tires molded directly onto the bearings, or tires bonded securely onto the bearings by way of adhesive agents. But a tire can be expected to deteriorate in the course of use, and thus will often need replacing before the metal bearing which it cushions. This has presented a problem with prior art devices.
The bearing and tire of the present invention solve this problem by being so configured, with relation to each other, that the tire may be "snapped on" to the bearing by hand with only moderate exertion of axial (sidewise) force. Once snapped on to the tire, however, the bearing will not come off during use in the conveyor system. If it becomes necessary to replace the tire, it may be "snapped off" by applying axial force to the tire in one direction and a supporting axial force to the bearing hub in the other direction. This snapping off requires far greater forces than can be applied by hand or than can occur in the natural course of use. The tire may also be removed by cutting. A new tire is then merely snapped onto the bearing.
In addition to the benefits already discussed of cushioning the wheels, tires or cushions also decrease wear upon the bearings arising from shock or sudden impacts, wear upon the bearings and thus extend the lives of the bearings. The present invention takes advantage of this enhanced bearing life by making successive tire replacements practical.
Accordingly, it is an obejct of the present invention to provide an improved rotating bearing, and tire thereupon, which tire may be easily and quickly applied to the bearing.
Another object of the invention is to provide such a bearing and tire in which the tire may be easily replaced upon the bearing.