Patent Application
20090265874
This invention pertains to load wheels for material handling vehicles, and more particularly to improving the service life of the load wheel by preventing premature failure. Load wheels are a device with no individual moving parts. Load wheels are used in Class II material handing vehicles; for example, a fork lift or an order picker. Load wheels are also used in Class III material handing vehicles such as, a pallet jack or lift truck. Load wheels are used to support the material moved or handled by the truck or vehicle. Unlike tires, load wheels do not brake, articulate, or turn.
During use, load wheels pick up dust, dirt and other fine particles from the floor. Fine debris such as dust and dirt generally do not harm a load wheel. Small debris such as nails, screws, bits of metal, wood, concrete, stones and pebbles, however, are harmful to load wheels. Small debris become imbedded into the load wheel, and causes the load wheel to go out of round. Once out of round, the wheel develops a flat spot.
Once a flat spot develops, increased stress is imparted to the load wheel causing the tread material separate from the hub. Once the tread material separates from the hub, the load wheel is unusable and must be replaced. In addition to ruining the load wheel, flat spotting is detrimental to the ride of the material handling vehicle. The poor ride makes the lift material difficult to handle and presents a safety concern if the poor ride destabilizes the load carried by the vehicle.
The invention described herein prevents debris, such as nails and screws, from becoming embedded into load wheels. The invention prevents debris from becoming embedded into load wheels by sweeping the debris out of the path of the load wheel as it traverses the floor. By sweeping the debris from the path of the load wheel, the debris will not become embedded in the load wheel tread material, thereby preventing the wheel from going out of round.
The invention is superior to other methods that may be used to prevent material from being embedded into the load wheel. For example a fixed scraper could be placed in front of the load wheel to deflect debris out of the path of the load wheel. Another approach would be to place a brush like device in front of the load wheel. Both devices could deflect debris, but each has its shortcomings compared to the invention described herein.
A fixed scraper cannot articulate over obstructions commonly encountered in a material handling environment. For example, a scraper blade may get caught on the bottom cross member of a shipping pallet or a loading dock plate. Increasing the clearance between the floor and the scraper blade would reduce the efficiency of the scraper blade to clear materials from the path of the load wheel. Furthermore, debris could become wedged between the floor and the scraper blade requiring the operator to stop and remove the debris.
Using a brush device would solve the clearance problem inherent to using a fixed scraper blade. However, bristles of the brush will become saturated and will no longer catch debris until they are replaced or cleaned. In addition, rigid pieces of debris may simply push their way through the bristles and become embedded into the load wheel.
The invention described herein alleviates both these problems by careful articulation of the debris evacuator. By carefully controlling the amount of articulation of the evacuator, debris can be deflected from the load wheel surface; while at the same time, the load wheel will be free to move over other obstacles such as pallet support members and loading dock plates. By allowing the debris evacuator to articulate, the shortcomings of a scraper blade or brush are eliminated.
In accordance with the preferred embodiment of this invention, it is now possible to increase the service life of load wheels by preventing flat spotting. Flat spotting, caused by debris being embedded in the wheel, is prevented by placing a debris evacuator in front of and behind the load wheel. The invention deflects debris away from the load wheel, while at the same time allowing the load wheel to roll over obstacles such as pallet cross members and loading dock plates.
The following example is submitted to illustrate but not to limit this invention. Referring to
In a second embodiment of the invention,
Having set forth the general nature and specific embodiments of the present invention, the true scope is now particularly pointed in the appended claims.
