Patent Application
20180291566
This disclosure generally relates to timber access mats and, more particularly, to timber access mats with integrated grounding features. Specifically, the disclosure relates to grounding devices that can be added to and then removed from traditional timber access mats to allow the mats to be used when electrical grounding is necessary.
Timber access mats, which are also known as rig mats, rig pads and road mats, are used to provide support for vehicles on soft ground where paved roads are not present. Timber access mats reduce damage to softer ground and prevent motor vehicles from becoming stuck in the softer ground. Conventional mats are constructed as generally rectangular wood platforms formed by overlapping wooden beams in alternating directions. Three layers of typical 2×6 or 2×8 lumber can be used to form the mats. The body members also may be formed from polymer body members or other non-conducting materials. These mats work well when simply used to provide vehicle access and to protect the softer ground. These mats are used for high voltage line maintenance where the high voltage lines cut across the countryside. However, vehicles providing access to high voltage electrical wiring must be grounded. Grounding vehicles supported by timber access mats has created problems. There is also a problem with providing proper grounding to workers standing on the mats.
The disclosure provides timber access mats with electrical conductors disposed at the support surface to provide electrical grounding to the mat.
The electrical conductors are provided in different forms. In one configuration, the conductors are parallel and disposed slightly above the upper surface of the body members of the mat. These parallel connectors are joined about the perimeter of the mat by a frame. Another configuration uses a mesh screen or web disposed over the top of the body members of the mat. The screen or web is connected to a frame or it can be wrapped around the edges of the mat. An optional filler such as a polymer or rubber may be disposed in the openings of the screen or web. The screen or web can be formed from flexible wires or a more rigid material such as sheets of expanded metal such as steel. Another configuration uses a thin sheet of conductive material disposed over the top of the body members of the mat. The thin sheet may be perforated or expanded to define openings. The sheet can be joined to the perimeter frame or its own perimeter frame.
The perimeter frame and metal conductive layer can be added over the top of traditional wooden-body or polymer-body timber access mats when electrical grounding is required and then removed and stored when grounding is not required.
The mats include electrical links that are used to electrically connect one mat to another such that each and every mat does not have to be individually pinned to the ground. This is beneficial when a platform is assembled from a plurality of mats. The electrical links can be wires such as steel cable leads. The steel cable leads can be located at each corner and across the width or length of the mat. A pair of leads can extend from each corner to connect other mats. Any of these cable leads can be pinned to the ground.
Another configuration of the timber access mat includes a frame configuration with electrical connector tabs that are offset on opposite sides of the mat frame so that a plurality of mats can be arranged in an abutting array to form a multiple mat platform. The opposed edges of each mat complement each other to allow the edges to abut without connector tabs interfering with each other.
The connector tabs allow electrical link cables to be attached from the top of the platform without requiring access to the bottom of the connector tab. This allows the mats to be connected and disconnected from above with a simple tool like a nut driver or a socket wrench.
Another configuration of the timber access mat includes cable guides disposed in tandem with the connector tab to manage the location of the grounding cable and/or the electrical link cable leads. The cable guides protect the cable from damage by preventing pinching between mats and preventing the cable leads from dropping down and being trapped under the mats.
The preceding non-limiting aspects, as well as others, are more particularly described below. A more complete understanding of the processes and the structures of the timber access mats can be obtained by reference to the accompanying drawings, which are not intended to indicate relative size and dimensions of the assemblies or components thereof. In those drawings and the description below, like numeric designations refer to components of like function. Specific terms used in that description are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure.
In the configuration of
An alternative configuration uses a filler material or a filler strip disposed between slats 8 to provide a flat surface to mat 2.
Flexible electrical cable leads 10 are connected to frame 6. Cable leads 10 can be located near the corners of frame 6. A pair or a plurality of cable leads 10 can extend from each location. Cable leads 10 are used to connect mats 2 or connect mat 2 to a grounding pin that is driven into the ground. Cable leads 10 can be bolted to frame 6 but also can be welded to frame 6. Each cable lead 10 can carry a bolt receiver at its loose end for receiving a bolt that is used to secure cable lead 10 to another mat 2 or to the grounding pin.
The mat configurations of
In the configurations using expanded metal sheets as conductive cover layer 12, each sheet of expanded metal can be lag bolted down into the body members of the mat with washers cooperating with the bolt heads to grip the expanded metal sheet. The lag bolts and washers allow the expanded metal layer 12 and frame 6 to be to and removed from the body members 4. This allows existing non-grounding timber access mats to be converted to grounding mats as needed. The edges of adjacent expanded metal sheets 12 are overlapped and either secured with bolts or welds or left loose. The expanded metal sheets 12 are welded or bolted to frame 6. An upper leg of frame 6 extends over an upper perimeter portion of the body with the edges of the expanded metal sheets disposed under the upper leg of frame 6. Another leg of frame 6 extends down the side of the body of the mat. The two legs cooperate to define an L-shaped cross section such that frame 6 sits over and surrounds the upper corners of the mat body. The upper leg of frame 6 is secured with connectors such as lag bolts directly down into the body members of the mat.
The grounding pin 18 is connected to frame 6 with a flexible cable 10. The flexible cable is connected at a raised U or C-shaped cleat that allows a tight bolted connection to be made between the flexible cable 10 and the frame 6. A plurality of flexible cables 10 can extend from a single cleat. The flexible cables 10 allow multiple mats to be electrically connected to a single grounding pin 18.
This configuration of
A filler material can be used to fill the openings defined by the material of cover 12. The filler can be a rubber or polymer material that is sprayed onto the top of mat 2 in an amount thin enough to leave the upper surfaces of cover 12 exposed.
In the configuration of
A plurality of connector tabs 30 extend from the vertical walls 32 of frame 6. Connector tabs 30 extend generally horizontal from vertical walls 32. Connector tabs 30 can be formed by welding or securing with mechanical connectors L-shaped lengths of metal to the outer side surfaces of frame 6. Connector tabs 30 are arranged in complementary positions on opposite walls of frame 6 such that mats 20 can be arranged side-by-side without connector tabs 30 interfering with each other.
The metal frame 6 and conductive cover layer 12 can be galvanized. In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the descriptions and illustrations of the exemplary configurations are examples and the claimed invention is not limited to the exact details shown or described. Throughout the description and claims of this specification the words “comprise” and “include” as well as variations of those words, such as “comprises,” “includes,” “comprising,” and “including” are not intended to exclude additives, components, integers, or steps.
This application is a continuation application claiming priority to U.S. patent application Ser. No. 15/280,478 filed Sep. 29, 2016, which is a continuation application claiming priority to U.S. Pat. No. 9,458,578 issued on Oct. 4, 2016, which claims the benefit of U.S. Provisional Patent application Nos. 62/077,014 filed Nov. 7, 2014, 62/080,343 filed Nov. 16, 2014, and 62/092,088 filed Dec. 15, 2014; the disclosures of each are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62077014 | Nov 2014 | US | |
| 62080343 | Nov 2014 | US | |
| 62092088 | Dec 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15280478 | Sep 2016 | US |
| Child | 16001610 | US | |
| Parent | 14936489 | Nov 2015 | US |
| Child | 15280478 | US |
