Patent Application
20100017976
This invention relates generally to dock levelers and, more particularly, to a method and apparatus for insulating the bottom surface thereof.
Dock levelers are used to compensate for height differences between a dock platform and the bed of a parked vehicle to permit forklift trucks and personnel to readily move on and off the vehicle during loading and unloading operations. A typical dock leveler is mounted within a pit and has a deck pivotally connected at its rear edge to a frame mounted within the pit for varying the height of the dock leveler in order to compensate for the height differences. An extension plate or lip is typically pivotally connected to the front edge of the deck for spanning the distance between the rear end of the vehicle bed and the outer front end of the deck and permitting forklift trucks and personnel to safely load and unload the truck without difficulty.
The deck is adapted to pivot between downwardly inclined or lowered positions, a horizontal or level position, and upwardly inclined or raised positions relative to the dock platform. When the dock leveler is not in use, the deck is substantially coplanar with the adjacent, upper surface of the dock. To permit such movement of the deck, a joint is typically formed along the adjacent edges of the deck and loading dock surface. Dock levelers typically have a portion of the pit and the associated portions of the dock leveler which extend into the interior of the building. Thus, even when the access door between the loading dock and the building interior is closed, drafts may be created or conditioned air may be lost through the joint unless some type of weather sealing is utilized between the dock leveler and the wall surfaces of the pit in which the leveler is mounted.
To help shield against weather while a vehicle is being serviced at the dock, some type of seal is usually installed around the perimeter of the doorway. Such seals are typically installed along the upper and side edges of the doorway to help seal any air gaps that may otherwise exist between the face of the building and the rear of the vehicle. The dock leveler lip resting upon the rear of the vehicle is often relied upon to seal most of the doorway's lower edge.
The area or pit underneath a dock leveler's deck, however, is usually exposed to outside air. This can create thermal problems (i.e. wet decks, corrosion, heat loss, etc.), particularly when there is a significant temperature differential between the indoor and outdoor air. Warm outside air, for example, may condense underneath a relatively cool deck of a dock leveler used in a cold storage warehouse. The condensation can promote corrosion of various parts of the dock leveler. Conversely, a heated building during the winter may loose a significant amount of heat by thermal conduction through the deck, as cold outside air cools the ramp from underneath. Thus, regardless of whether the outside air is colder or warmer than the inside air, it will generally be beneficial to shield the underside of a dock leveler from outside air.
One approach to this problem has been to provide a weather shield or curtain over the front face of the pit to prevent the flow of air between the pit cavity and the outside air. Examples of various devices to solve the problem in this manner are shown in U.S. Pat. Nos. 4,682,382; 6,502,268; 6,654,976; 7,146,673; 7,334,281. However, all of these approaches involve use of a relatively complicated combination of moving parts that are subject to wear and/or failure, and may be cause for shut down and/or frequent replacement of components. More importantly, however, is the recognition that, while such an approach reduces the heat transfer by way of convection, it does little in the way of reducing heat transfer by way of conduction and/or radiation. That is, since the pit is a relatively large space (i.e. approximately 100 ft3), the use of such a curtain does not create an effective so called “dead air space” which might otherwise provide protection from heat transfer by way of radiation and conduction. Therefore, even with such a curtain in place, the temperature in the pit will be substantially the same as that of the ambient air, and the temperature gradient between the air in the pit and the air in the warehouse will result in a substantial transfer of heat through the dock platform.
Another approach that has been taken to solve the problem is that of insulating the underside of the dock platform by the spraying of a coat of foam thereto. While such an approach is effective and easy to implement at the time when the dock leveler is manufactured in a plant, it is very difficult to implement by retrofitting units that are already installed in the field. That is, the application of a foam to the underside of an installed deck would require a through cleaning of the deck underside in order to remove the accumulated dirt and rust so that the foam would adhere to the surface. Further, the accessible of the necessary equipment for such application to the underside of the unit is severely limited because of the small space of the pit.
In accordance with one aspect of the invention, a sheet of insulative material is secured to the lower surface of the dock leveler platform so as to thereby reduce the heat transfer through the platform.
In accordance with another aspect of the invention, the insulative material is applied to the bottom surface, by way of sections whose width are selected to closely fit between adjacent support beams, and to facilitate the proper width selection, the insulative material is perforated in the longitudinal direction, with the perforations being laterally spaced at close intervals, so as to facilitate the easy tearing away of sections at proper widths.
By yet another aspect of the invention, the perforated material is attached to the lower deck surface by way of a plurality of magnetic fasteners that are adhered to the lower surface and hold a downwardly extending spike over which the perforated material can be easily placed, with a self locking washer then being installed on the extended end of the spike in order to secure the material to the spike.
By yet another aspect of the invention, a thin sheet of vinyl material is secured to one side of the insulative material so as to hold the perforated sections together prior to and during the installation process, and to act as a vapor barrier after the insulative material has been installed in position.
The invention is shown generally at 10 in
When not in use, the dock leveler is stored in a small place referred to a pit 19 as shown in
Attached to the bottom surface 26 by way of welding or the like, are a plurality of support beams 27 that extend longitudinally along the length of the deck 12 with adjacent beams being transversely spaced a distance D, a distance which will vary substantially between various types and sizes of dock levelers and may even vary within an individual dock leveler. For that reason, the idea of installing, on a retrofit basis, insulation between adjacent support beams is complicated, particularly when considering the very little space that is available for an installer within the pit 19.
Referring now to
In order to prevent the accidental tearing away, and to present a stiffness for handling the sheets prior to and during the installation process, a clear vinyl sheet 33 is applied to one side 34 of the sheet 28 as shown in
Having selected the proper width and reduced the width of the sheet 28 to the distance D between adjacent support beams 27, the sheet 28 must be installed in place on the bottom surface 26 of the deck 12. This is accomplished by way of the attachment mechanisms 36 as shown in
The magnet 37 may be of any suitable type, size and shape. Such magnets are commercially available from several sources. The self locking washer 41 should be formed of a robust material such as galvanized steel and should be of a size which will securely hold the sheet 28 in place without tearing through the material. The perforated central portion 42 is formed in the manner of a self locking washer which allows an easy insertion of the spike in one direction but does not allow an easy removal thereof in the other direction.
Considering now the steps of installing the sheet 28 in position between adjacent support beams 27, the spike 39 is first installed in the opening 38 of the magnet 37, and a plurality of these assemblies are put in place between the adjacent support beams 27, with the magnet 37 being magnetically attached to the bottom surface 26 of the planar deck 12 as shown in
It should be recognized that the order as discussed hereinabove can also be varied if desired. For example, it may be desirable to first attach the spike 39 and magnet 37 combinations in their installed positions with the spike 39 penetrating the sheet, and then place the combination in place between adjacent support beams 37. The self locking washer 41 can be installed either before or after placing the sheet in position between support beams 27.
While the present invention has been particularly shown and described with reference to the preferred mode as illustrated in the drawing, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention as defined by the claims.
