Patent Application
20070261610
A support for a portable structure such as a washstand or toilet that is resistant to wear, abrasion, incursion of moisture, rot, and splintering, and yet which is affordable and easy to maintain.
Pallet-type supports are widely used as a base for portable structures such as washstands and enclosed toilets. They customarily provide a platform with underneath runners that create a clearance for forklift blades. This is the preferred means of moving the assembly of support and structure from location to location. However, these are also often shoved along a surface which is rough-gravel or asphalt surfaces being common. Such movements cause heavy wear on conventional runners.
The most commonly used material for such supports is wood. While wood is comparatively inexpensive, still the use of wooden pallets involves problems which need not exist. Examples of problems are the rapid splintering of wood, the incursion of water into the wood leading to rot, and the necessity of frequent repair or disposal of worn pallets and/or their runners. In addition forests are depleted by the widespread consumption of wood for pallets.
It is an object of this invention to provide a suitable support for a structure which support has moisture-impermeable outer surfaces, wear-resistant shoes inserted in the undersurface of the runners, and structural integrity as good as or better than wood.
It is another object of this invention to provide the runners as separate bodies readily attached to the platform, with their wear-resistant shoes readily replaced in the runners when they wear out, thereby to reduce wear on the runner itself and to extend the life of the runners.
It is still another object of the invention to provide a platform of substantial size that can be made with the use of rotational moulding processes.
There results a strong, affordable and sufficient skid support for a portable structure.
A skid platform according to this invention includes a generally rectangular platform with a top surface to which a structure will be mounted, a bottom surface vertically spaced from the top surface, a peripheral wall between the surfaces forming a chamber, a pair of runners attached to the bottom surface spacing it from the ground, the bottom of each runner being fitted with a pair of spaced apart wear shoes which project beneath the bottom of their respective runner to take most of the wear that would otherwise wear out the runner itself.
According to a feature of this invention the runners are detachably attached to the platform, and the wear shoes are formed as inserts.
According to yet another preferred but optional feature of the invention, the platform portion of the support and the runners are formed as unitary pieces manufactured by the rotary-moulding process.
The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which:
Support 20 includes a platform 21 and a pair of runners 22,23. Its function is to provide support for a structure 25 such as a portable toilet or washstand. These structures are well-recognized, they generally include a surrounding wall with a door. Customarily they enclose a commode or urinal and often a washstand. The functional details of the structure are arbitrary and form no necessary part of this invention. It simply rests on this support.
The platform has four sides 30, 31, 32, 33, a floor 34 (
The floor and the base are vertically spaced apart from one another over most of their areas, by outside side walls 30 (
The floor is pierced by a rectangular opening 40 (
Adjacent to opening 40 there is a substructural planar stand area 42 of the floor for the user to stand on. Usually this will be a continuous flat surface. If desired, some or all of it can be cut out and covered with a grating or screen (not shown). This enables dirt and mud on the user's shoes to be scraped off and fall into region 44 between the runners.
Base 35 (
Runners 22 and 23 are identical so only runner 22 will be described in detail. It is an elongated member with a top surface 50 formed with a tongue 51 that fits in a respective groove 45 in the bottom surface of the sides of the platform. This tongue-in-groove arrangement holds the runner aligned with the edge of the platform. The top surface on each side engages the bottom surface of the platform on both sides of the groove. The runners are thereby held aligned and in place.
The bottom surface 52 of each runner faces the ground 53. Sidewalls of the runner join the top and bottom surfaces of the runner to form a chamber 56. A structural foam 57 is preferably formed in place in this chamber to give additional strength to the runners.
Each runner has an attachment flange 60,61 (
The materials of construction of this support provide substantial and certainly adequate wall, column and beam strength to support the structure, both when it rests on the ground, and when a forklift lifts it between the runners. The basic material of construction is an organic plastic which is impermeable to water. However, its abrasive resistance is less that one would prefer. Structures such as these are often shoved along a very rough surface. This is one reason why wooden runners require such frequent maintenance.
To overcome this disadvantage, each runner is provided with a pair of “wear shoes” 70. Each shoe has a tapered outer periphery 71, a wear surface 72, and a bolt hole 73 passing axially through it. Significantly, the socket 74 into which the shoe fits has a matching tapered hole 75 aligned with a port 76 in the bottom of the platform.
Inside port 76 there is a cast-in-place or an embedded threaded receptacle. To mount the shoe, one merely inserts a bolt 63a through hole 75 and threads the bolt into the receptacle. That is all. This both removably attaches the shoe and holds the runner to the platform. The head 78 of the bolt fits in a recess 79 in the shoe so that it is not contacted directly by the ground. A raised rim 80 on the face of the shoe can provide for first wear. When it is ground down, it is visually apparent that a replacement shoe will soon be needed.
Preferably the shoes are made with a vivid color such as a bright yellow that contrasts with a black runner. Their wear will then be more evident.
An engagement grove 85 is formed in the bottom of engagement flange 60 for engagement by a hook or cable for lifting the assembly, instead of rasing it by a forklift.
An examination of the drawings will show that the shape of the platform and runners are so complicated that it would not be affordable if made by most common manufacturing techniques. Instead, because it is amenable to use of rotational moulding process, the platform can be made in single piece. Also each runner can be made as a single piece. They are hollow structures which can be filled with a structural foam either while the outer wall is being formed, or after they are formed.
As such these runners provide a sufficient volumetric device to enable the use of forklifts and to hold the structure above the ground. Conventional pallets do this by nailing together pieces of wood with all of their costs and disadvantages.
The process known as rotational moulding, or sometimes “slush moulding”, is characterized by the use of a hollow mold whose inside surfaces are intended to be the mirror image of the surfaces formed against them. In practice, the mold shaped is closed after a sufficient amount of a plastic to be molded is put inside.
Then the mold is heated and rotated appropriately around axes of rotation. The organic plastic material is melted, and flows around the inside wall of the mold. After a sufficient length of time, the plastic will have been distributed and ready to be cured. The mold is allowed to cool, and is separated, and the product is removed. It is, of course, a hollow product.
Either as a secondary operation or a part of the initial formation, a foaming product is placed in the mold, where it forms a structural foam inside the molded structure. These techniques are well-known in the art.
Variations in the wall thickness, and localized thicker areas can be provided for by appropriate insulation on the tooling so that additional material will be deposited locally. Also, implants such as sockets can be placed in the tooling so they will be incorporated into the structure.
The wall thicknesses and structural strength of the materials are known so that a suitably strong structure will be made.
Any suitable heat curable organic plastic can be used which has sufficient strength properties. Polyethylene and polybutylene are commonly used.
This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of example and not of limitation, but only in accordance with the scope of the appended claims.
