US3442399A - Apparatus for raising and lowering cover plates - Google Patents

Description

May 6, 1969 D. D. SNAVELY 3,442,399

APPARATUS FOR RAISING AND LOWERING COVER PLATES I Filed Oct. 28, 1966 ow /vroe DONALD 0. SNAVELY Bx/ojdn'y United States Patent 3,442,399 APPARATUS FOR RAISING AND LOWERING COVER PLATES Donald D. Snavely, Atlanta, Ga., assignor to H. H.

Robertson Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 28, 1966, Ser. No. 590,272 Int. Cl. B66c 1/42 US. Cl. 214-1 7 Claims ABSTRACT OF THE DISCLOSURE A portable device for removing and replacing a metal cover plate of an electrical trench. The device includes ground engaging elements positioned to straddle the electrical trench and is pivotal about a pivotal axis extending between the ground engaging elements. The device includes one or more magnet means which are spaced from the ground engaging elements and remote from the pivotal axis. The cover plate is moved relative to the electrical trench by energizing the magnet means to retain the cover plate by magnetic attraction and pivoting the device about the pivotal axis with the cover plate thus retained.

This invention relates to apparatus for raising and lowering cover plates, and more particularly to apparatus for raising and lowering steel cover plates associated with electrical trenches and without marring a decorative coating applied to the cover plates and the surrounding floor.

Electrical trench assemblies provide an electrical conductor carrying channel of great capacity. See US. Patent Nos. 3,262,238 and 3,237,356. Accessibility to the interior of the trench assembly is essential to accommodate frequent alterations in the use of electrical energy. Accordingly, all trench assemblies are provided with removable cover plates. Also in modern building floor constructions, a decorative coating is normally applied over the exposed floor surface, for example, linoleum, asphalt tile, rubber tile, ceramic tile and the like. The decorative coating is also applied over the cover plates of the trench assemblies to blend the cover plates with the remaining floor area.

The cover plates normally comprise heavy steel plates which are capable of supporting relatively heavy loads as well as personnel trafiic. For example, cover plates onequarter inch thick, eighteen inches wide and three feet long are common. The cover plates are quite heavy, ranging in weight from 45 to 60 pounds, and are relatively difiicult to handle when removed or replaced in the trench assemblies. To further aggravate the problem, the cover plates are normally installed in the trench assemblies in end-to-end abutting relation, that is, with little or no space between adjacent cover plates. The cover plates have been removed by inserting a tool, such as a screwdriver, between adjoining cover plates, prying up that plate which is to be removed and sliding it over adjacent floor covering materials.

As should be evident, the decorative coating edges and surfaces of adjoining cover plates are prone to damage, as by cracking, gouging and the like. The surrounding floor tile also is damaged by customary handling procedures-most damage occurring during removal or replacement of the cover plates.

OBJECTS Accordingly, as an overall object, the present invention seeks to provide a portable device for raising and lowering steel cover plates from electrical trenches without damaging the decorative coating provided on the cover plates.

Another object of the present invention is to provide a portable device employing magnet means for attracting and retaining the cover plates while they are raised and lowered relative to the trench assembly, whereby no damage occurs to the decorative coating.

A further object of the present invention is to provide a portable device by which raising and lowering of heavy steel cover plates is accomplished in a rapid and relatively easy manner.

STATEMENT OF INVENTION In accordance with the present invention, a portable device is provided for raising and lowering steel cover plates from electrical trenches without damaging the decorative coating applied to the steel cover plates. The portable device comprises a frame including a carrier arm and a handle angularly extended from the carrier arm. A pair of ground engaging elements such as wheels is connected to the frame and positioned to straddle the electrical trench. An electromagnet is mounted on the carrier arm at a position spaced from the ground engaging elements. Means for energizing and deenergizing the electromagnet when desired is also provided. The overall arrangement is such that the frame may be pivoted or rocked about the ground engaging elements whereby the electromagnet is lowered into engagement with the cover plate to magnetically attract and hold the same and then raised thereby lifting the cover plate from the electrical trench. Replacement of the cover plate is accomplished by reversing the above-described operation.

In accordance with the preferred embodiment of the present invention, the ground engaging elements and the electromagnet are positioned at opposite ends of the carrier arm and spaced apart by a distance substantially equal to the length of the cover plate. With this arrangement, the electromagnet attracts one end of the cover plate and when the electromagnet is raised, the cover plate is tilted about its opposite end which is adjacent to the ground engaging elements. Complete removal of the cover plate may now be accomplished with little chance of damaging the decorative coating.

In accordance with an alternative embodiment of the present invention, the ground engaging elements are positioned at a central location on the carrier arm. Two electromagnets are employed, one positioned at each end of the carrier arm. The overall arrangement is such that the frame may be rocked about the ground engaging elements to lower one of the electromagnets into engagement with the cover plate to magnetically attract and hold a first end thereof and then pivoted in the opposite direction to lower the second electromagnet into engagement with the opposite end of the cover plate to magnetically attract and hold the same. Rotation of the carrier arm into a horizontal position causes the cover plate to be raised, in its entirety, for transport to another location.

The above and other objects and advantages of the present invention will become apparent from the following detailed description by reference to the accompanying drawings, in which:

FIGURE 1 is a fragmentary isometric view of a building floor incorporating an electrical trench and illustrating the use of the present portable device;

FIG. 2 is a cross-sectional view taken subtsantially along the line II-II of FIG. 1, illustrating the initial position of the present portable device;

FIG. 3 is a cross-sectional view taken along the line HII'II of FIG. 2;

FIGS. 4 and 5 are cross-sectional views, similar to FIG. 2, illustrating successive steps employed in raising or lowering the cover plate; and

FIGS. 6 and 7 are side views schematically illustrating alternative embodiments of the present portable device.

Referring now to FIG. 1, there is illustrated a building floor structure 10 comprising a cellular metal subfloor 12 providing a plurality of electrical raceways 14; an electrical trench 16 disposed above the cellular metal subfloor 12; and a layer of concrete 18 poured over the cellular metal subfloor 12 and about the electrical trench 16. Although not shown, the electrical trench 16 communicates with certain of the electrical raceways 14 and cooperates therewith to distribute the power and communication cables throughout the floor area. A decorative coating 20, such as linoleum, asphalt tile, rubber tile, ceramic tile and the like, is applied over the layer of concrete 18.

The electrical trench 16 provides an electrical conductor carrying channel 22 of great capacity. The electrical trench 16 includes a plurality of removable cover plates 24 which overlie the channel 22 and are positioned in end-to-end abutting relation. The decorative coating 20 is also applied to the cover plates 24 so as to blend the cover plates 24 with the remaining floor area. Because the cover plates 24 are positioned in end-to-end abutting relation, it is difficult to remove the cover plates 24 without marring the decorative coating 20.

Referring now to FIGS. 1, 2 and 3, there is illustrated a portable device 26 shown positioned over the electrical trench 16 preparatory to raising one of the cover plates 24. The portable device 26 comprises a frame 28 including a carrier arm 30 and a handle 32 angularly extended from the carrier arm 30. A pair of ground engaging'elements preferably comprising wheels 34, is connected to the frame 28 and positioned to straddle the electrical trench 16. An electromagnet 36 is mounted on the carrier arm 30 and is spaced from the wheels 34. The electromagnet 36 is pivotally mounted on rod elements 38 extended from the carrier arm 30, for free pivotal movement about a horizontal axis indicated by the dash dot line 40 (FIG. 3). In this manner, the lower or active face 42 of the electromagnet 36 will normally be horizontally oriented and ready to enter a flush engagement with a cover plate.

A grip 44 is provided on the handle 32 and has a power cord 46 extending therefrom to a power source which supplies electrical energy to the electromagnet 36. Switch means 48 may be incorporated into the grip 44 to energize and deenergize the electromagnet 36.

As can best be seen in FIG. 2, the present portable device 26 is positioned to straddle the electrical trench 16 and is pivotal about the wheels 34. To remove one of the cover plates 24, the handle 32 is pushed forwardly so as to lower the electromagnet 36 into engagement with a subjacent cover plate 24A, as shown in FIG. 4. Thereafter, the handle 32 is pivoted toward the trench 16 so as to raise the electromagnet 36 and the subjacent cover plate 24A attracted thereto. Thereafter, the subjacent cover plate 24A may be removed manually to a different location on the floor area.

It is to be noted at this time that only the electromagnet 36 comes into direct contact with the decorative coating 20. Inasmuch as the frame 28 is rollably supported by the wheels 34 and since the electromagnet 36 is pivotally mounted, raising or lowering of the subjacent cover plate 24A is accomplished with no relative motion occurring between the electromagnet 36 and the subjacent cover plate 24. Consequently, the electromagnet 36 does not mar the decorative coating 20. Furthermore, since the electromagnet 36 attracts one end of the subjacent cover plate 24A and tilts the same about its opposite end, the electromagnet 36 is required to support less than the total weight of the cover plate 24A.

In order to replace a cover plate which has been removed, the cover plate 24A is initially positioned as shown in FIG. with the energized electromagnet 36 engaged therewith. Thereafter, the handle 32 is pushed forwardly thereby lowering the cover plate 24A into a properly seated relation with respect to the adjacent cover plates 24B as illustrated in FIG. 2. The electromagnet 36 is then deenergized and raised, as shown in FIG. 2, and the portable device 26 is then moved. Again, there is no relative movement between the electromagnet 36 and the cover plate 24 and, consequently, the decorative coating 20 is not marred.

The present invention also provides a novel method for raising and lowering the steel cover plates without marring the decorative coating 20. As can be seen in FIGS. 2, 4 and 5, the cover plates are positioned in end-toend closely adjacent relation in the electrical trench 16. For example, the subjacent cover plate 24B and the decorative coating 20 thereof present opposite end edges 50A, 52A which are closely adjacent to opposite end edges 50B, 52B, respectively, of the adjacent cover plate 24B.

In practicing the method of the present invention, an end region 54 of the subjacent cover plate 24A, for example, is attracted by permeating the same with magnetic flux radiating from the magnet means 36 engaged therewith. Thereafter the magnet means 36 and the end region 54 are moved as a unit to effect tilting of the subjacent cover plate 24A about its opposite end 52A and relative to the electrical trench 16. The end edge 50A is moved substantially perpendicular relative to the end edge 52B of the adjacent cover plate 24B whereby the decorative coatings 20 of the subjacent cover plate 24A and of the adjacent cover plates 24B are unharmed.

ALTERNATIVE EMBODIMENTS Two alternative embodiments of the present portable device will now be described with reference to FIGS. 6 and 7. Corresponding numerals will be employed to identify corresponding parts heretofore described.

Referring in particular to FIG. 6, there is illustrated a portable device 26' wherein the electromagnet 36 is pivotally supported adjacent to the handle 32 while the wheels 34 are carried at the opposite end of the carrier arm 30. Operation of the portable device 26 corresponds to the operation of the portable device 26, as described above.

Referring now to FIG. 7 there is illustrated a portable device 56 wherein the wheels 34 are mounted at a central location on the carrier arm 30. A pair of electromagnets 58, 60 is pivotally mounted at the opposite ends of the carrier arm 30. In this embodiment, the arrangement is such that the frame 28 may be rocked about the wheels 34 such that first the electromagnet 58 is lowered into engagement with the subjacent cover plate 240 and to magnetically attract one end thereof, and thereafter rocked in the opposite direction about the wheels 34 such that the second electromagnet 60 is lowered into engagement with the opposite end of the subjacent cover plate 240. Thereafter, the carrier arm 30 is positioned horizontally and the subjacent cover plate 240 is removed from the trench 16 and is vertically spaced therefrom. The portable device 56 may now be rolled away to transport the subjacent cover plate 24C to a different location. It should be evident that by reversing the above-described procedure, the subjacent cover plate 24C may be replaced in the electrical trench 16.

SUMMARY The present invention provides a portable device which raises or lowers heavy steel cover plates from electrical trenches without damaging the decorative coating provided on the cover plates. Furthermore, means in the form of a portable device, is provided by which the raising or lowering of heavy steel cover plates is accomplished in a rapid and relatively easy manner. Also, the present invention provides a novel method for raising and lowering heavy steel cover plates which substantially completely eliminates the chance of damaging the decorative coating.

I claim as my invention: 1. The combination of a steel cover plate of an electrical trench and a portable device for raising and lowering said steel cover plate wherein said device comprises:

a [frame including a carrier arm and a handle angularly extended from said carrier arm;

a pair of ground engaging elements connected to said carrier arm and positioned to straddle said steel cover plate;

said frame being pivotal about a pivotal axis extending between said ground engaging elements;

magnet means mounted on said carrier arm at a position spaced from said ground engaging elements and remote from said pivotal axis; and

means for energizing and deenergizing said magnet means when desired;

whereby said cover plate may be moved relative to said electrical trench .by energizing said magnet means to retain said cover plate by magnetic attraction and by pivoting said device about said pivotal axis with said cover plate thus retained.

2. The portable device as defined in claim 1 wherein said magnet means is pivotally mounted on said carrier arm whereby a lower face of said magnet means is positioned for fiush engagement with said cover plate.

3. The portable device as defined in claim 1 including:

second magnet means mounted on said carrier arm at a position spaced from the first said magnet means and remote from said pivotal axis; and

means for energizing and deenergizing said second magnet means when desired;

the first said magnet means and said second magnet means cooperating to lift a said cover plate in its entirety from said electrical trench and for transport away from said electrical trench.

4. The portable device as defined in claim 3 wherein said ground engaging elements are positioned intermediate of the first said magnet means and said second magnet means.

5. The device of claim 1 wherein the said handle connects to said carrier arm at the rear end of said carrier arm;

said ground engaging elements are connected to said carrier arm adjacent to said rear end; and

said magnet means is connected to said carrier arm adjacent to the forward end of said carrier arm.

6. The device of claim 1 wherein said handle connects to said carrier arm at the rear end of said carrier arm;

said ground engaging elements are connected to said carrier arm adjacent to the forward end of said carrier arm; and

said magnet means is connected to said carrier arm adjacent to said rear end of said carrier arm.

7. The device of claim 4 wherein the first said magnet means and said second magnet means are pivotally mounted on said carrier arm whereby a lower face of the first said magnet means and a lower'face of said second magnet means are positioned for flush engagement with said cover plate.

References Cited UNITED STATES PATENTS 710,041 9/ 1902 Clark 294 .5 1,539,891 6/1925 Wood 294-65.5 X 2,379,596 7/ 1945 Seamans 294-65 .5 2,952,373 9/1960 Bie 214-375 FOREIGN PATENTS 311,343 7/1917 Ger-many.

ALBERT I. MAKAY, Primary Examiner.

US. Cl. X.R. 214-384; 254-8, 131; 294-655

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