Abstract:
Resilient shock absorbing pads that fully support ground contacting portions of machines, equipment or other loads and, thereby, provide protection from shocks and vibration. The pads receive the ground contacting portions of a load, such as a base plate. Described pads are square-shaped and are substantially formed of a resilient shock and vibration absorbing material, such as elastomer. It is particularly preferred that the pads be fashioned from compression-molded crumb rubber that is readily available from recycled tires. The pads also include structures, such as recessed portions or an upwardly extending rigid dowel, that help to stabilize a load.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to methods and devices for use with machinery, structures and other loads for absorbing or dampening shocks and vibrations. 
     2. Description of the Related Art 
     Environmental vibrations and shocks can damage or degrade the performance of machinery and devices that are located on the floor of a plant, such as mchines for manufacture or testing of a product, or those on the rooftop of a building, such as antennae or heating and cooling units. 
     It is desirable to protect such machinery as much as possible from vibration and shock in order to prevent or reduce possible damage to the equipment. Such vibration and shocks may have a number of causes. However, the most serious are shocks and vibrations caused by seismic activity, such as earthquakes and tremors. 
     A number of cushioning or dampening devices are known that attempt to reduce or eliminate shocks and vibrations of this type. U.S. Pat. No. 5,816,559, entitled “Seismic Isolation Device,” for example, describes a number of relatively complex mechanical arrangements for isolating portions of machinery for protection from shocks and Unfortunately, devices such as these often require significant amounts of maintenance and upkeep. 
     SUMMARY OF THE INVENTION 
     The devices and systems of the present invention provide resilient shock absorbing pads that fully support ground contacting portions of machines, equipment or other loads and, thereby, provide protection from shocks and vibration. In exemplary described embodiments, the pads provide cushioned recesses that receive the ground contacting portions of a load, such as a base plate. The pads are square-shaped and are substantially formed of a resilient shock and vibration absorbing material, such as elastomer. It is particularly preferred that the pads be fashioned from compression-molded crumb rubber that is readily available from recycled tires. The pads also include structures, such as recessed portions or an upwardly extending rigid dowel, that help to stabilize a load. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts an exemplary piece of machinery, an antenna mount in this case, that is isolated from the support surface using seismic pads. 
     FIG. 2 is an isometric view, partially cutaway, of a first type of seismic pad constructed in accordance with the present invention. 
     FIG. 3 is an isometric view, partially cutaway, of a second type of seismic pad constructed in accordance with the present invention. 
     FIG. 3A is a cross-sectional detail of a support cones used in the seismic pad shown in FIGS. 3 and 4. 
     FIG. 4 is a plan view of the seismic pad depicted in FIG.  3 . 
     FIG. 5 is an exploded view illustrating a third type of seismic pad. 
     FIG. 6 is a side view of the pad shown in FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The system and devices of the present invention are useful to isolate and protect a piece of equipment, or other structure, from shocks and vibration, including those associated with seismic activity. As an example, FIG. 1 illustrates a portion of a telecommunications antennae structure  10  that is disposed on a support surface  12 . The depicted arrangement is representative of the placement of such antenna structures on the rooftops of buildings. It is an object of the invention to reduce or dampen the amount of vibration or shocks that are transmitted from the support surface  12  to the antenna structure  10 . The antenna structure  10  has a central mounting shaft  14  with three support legs  16 ,  18 ,  20  that support the mounting shaft  14 . As can be seen, each of the legs  16 ,  18 ,  20  has a circular base plate  52  at its lower end. The base plate  52  is the portion of the structure  10  that is ground-contacting, or intended to contact the ground or support surface  12 . Base plates of this type are described in U.S. Pat. No. 5,816,554 entitled “Equipment Support Base” and issued to McCracken. That patent is incorporated herein by reference. The base plates  52  each reside within a seismic isolation pad  22  which is disposed upon the support surface  12 . The seismic isolation pads  22  may have one of several constructions, which are understood with reference to FIGS. 2-6 and the following descriptions. These different constructions are described separately as pads  50 ,  70  and  90 . 
     FIG. 2 depicts a first seismic isolation pad  50  that is used to isolate and protect base plate  52 . The substantially square isolation pad  50  is formed of a resilient, energy absorbent material. Preferably, the pad  50  is formed of molded elastomer. In a currently preferred embodiment, the pad  50  is made up of crumb rubber that is compression molded. It has been found that this type of material is readily available from recycled tires and can be easily compression molded and formed. Additionally, the crumb rubber may be easily colored using dyes or paints during the molding process. 
     The pad  50  has a substantially flat base portion  54  upon which the base plate  52  is seated. The base portion  54  of the pad  50  has a thickness of approximately 1 inch. An upwardly protruding flange  56  is disposed along the perimeter of the pad  54 , thereby making the base portion  54  recessed with respect to the flange  56 . The lower portion of FIG. 2 is a partial cutaway with a portion of the flange  56  not visible. It is preferred that the pad  50  be sized so that there is always a slight gap between the inner wall  58  of the flange  56  and the outer edge  60  of the base plate  52 . The flange  56  preferably has a height (as measured upwardly from the base portion  54 ) of 1 inch. The flange  56  helps ensure that the base plate  52  does not inadvertently slide off of the pad  50 . 
     The pad  50  has four comer portions  62 . There are perforations, scoring or other lines of structural weakness  64  disposed within the material of the pad  50  so that the corner portions  62  may be easily broken away and removed from the pad  50 . One of the four corner portion  62  is shown broken away in FIG.  2 . When the corner portions  62  are removed, openings  66  (one shown) are formed that allow water within the pad  50  to drain out of the interior of the pad  50 . 
     FIGS. 3,  3 A and  4  depict an alternative, and currently preferred, isolation pad  70  that is also being used to isolate and protect a base plate  52 . The pad  70  is similar in many respects to the pad  50  described previously. There are some differences, however. The pad  70  includes a recessed base portion  72  having a substantially flat surface from which a number of frustoconical support cones  74  project upwardly. One of the support cones  74  is shown in cross-section in FIG.  3 A. It is preferred that the support cones  74  be integrally molded with the base portion  72  during fabrication of the pad  70 . Each of the support cones  74  has a tapered side surface  76  and a flat top surface  78  upon which the base plate  52  or other structure may rest. The lower end of each support cone  74  is wider than the upper end by virtue of the tapered side surface  76 . In the currently preferred embodiment, the upper end of the cone  74  has a diameter of one inch while the lower end of the cone  74  has a diameter of 1¼ inches. 
     Like the first isolation pad  50 , the isolation pad  70  has a flange  80  that surrounds the perimeter of the pad  70 . In a currently preferred embodiment, the flange  80  has a total height (as measured from its top end to its bottom end) of four inches. The base portion  72  has a thickness of 1 inch and each of the support cones  74  has a height of 1½ inches. Breakaway corner portions  82 , similar to the corner portions  62  are provided as well to allow drainage of the pad  70 . 
     Unlike the pad  50 , the pad  70  contains a sheet  84  of reinforcing material that is embedded or molded into the base portion  72 . The sheet is formed of a woven cloth material to resist tensile forces that might tend to rupture the pad  70 . 
     The pad  70  is also sized so that a gap is provided between the inner surface  86  of the flange  80  and the outer rim  60  of the base plate  52 . The base plate  52 , therefore, rests entirely on the support cones  74  of the pad  70 . 
     FIGS. 5 and 6 illustrate a third exemplary embodiment for an isolation pad  90 . The isolation pad  90  is actually an assembly of three separate components and, thus, is illustrated using an exploded view. The pad  90  includes a base pad member  92 , dowel plate  94  and cover pad  96 . The base pad member  92  and cover pad  96  are both formed of the same resilient shock absorbent material as the pads  50  and  70  described earlier. The dowel plate  94  is formed of wood, metal or another rigid material. 
     The base pad  92  is the part of the isolation pad  90  that rests on the support surface. The base pad  92  includes a square, recessed central area  98  and a raised lip  99  that surrounds that recessed area  98 . 
     The base pad  92  is the part of the isolation pad  90  that rests on the support surface. The base pad  92  includes a square, recessed central area  98  and a raised lip  99  that surrounds that recessed area  98 . 
     The dowel plate  94  has a flat plate portion  100  and a centrally located dowel  102  that projects upwardly from the plate portion  100 . The cover pad  96  has a centrally located aperture  104  through which the dowel  102  is disposed when the cover pad  96  is placed over the dowel plate  94 . When the pad  90  is assembled, the dowel  102  projects upwardly and is disposed through the central cavity  108  of base plate  52  and fit within the center  110  of a support leg  112 . (see FIG.  5 ). In this manner, the dowel  102  contacts at least the leg  112  of the supported structure and stabilizes it with respect to the support surface below. 
     In use, individual base plates  52  or other ground-contacting portions of a structure to be isolated are disposed upon pads having constructions such as those shown in FIGS. 2-5. Shocks and vibrations are substantially absorbed by the pads. A plurality of pads are placed under a plurality of ground contacting portions of a machine or other load in order to provide a system that will isolate the machine or load from the support structure as well as environmental shocks and vibrations. 
     The ground-contacting portion of the supported structure is stabilized with respect to the pad by a structure on the pad itself to help ensure that the structure does not indvertently slide off of the pad. When pads having the construction of the pads  50  or  70  are used, the side flanges  56 ,  80  help to stabilize the base plate  52 . When the pad  90  is used, the dowel  102  stabilizes the base plate  52 . The pads  50 ,  70  and  90  are modular, preformed and lightweight. They are also essentially maintenance-free. The pads may be easily stacked and transported. 
     While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes within departing from the scope of the invention.