Patent Publication Number: US-6212830-B1

Title: Adjustable diagonal strut

Description:
FIELD OF THE INVENTION 
     This invention involves an adjustable strut adapted to support floor joists and other floor structures of a premanufactured building structure. More particularly, the invention is an adjustable strut for placement in a sloped attitude extending laterally and upwardly from an I-beam horizontal support and a floor joist or other floor structure that is supported directly on the I-beam, so as to stabilize the portion of the floor structure. 
     BACKGROUND OF THE INVENTION 
     In the production of inexpensive, premanufactured (hereinafter “manufactured”) building structures, such as “mobile homes,” it is desirable to utilize a pair of horizontally oriented, parallel I-beams as the base support for the structure, with the floor joist and other floor components being supported by the I-beams. With this arrangement, the floor joists extend laterally across the I-beams, with opposed ends of the floor joists extending beyond the I-beam in a cantilever arrangement, in that they overhang the I-beams. 
     One of the problems of this type of construction is that heavy loads are sometimes placed on the cantilevered portions of the floor structures, and the structures tend to slightly sag or give during normal wear and tear. For example, the floor structure at the entrance of a manufactured home which bears the repeated application of the weight of the people entering and exiting the home might need additional support to stabilize this area of the structure. In some instances, the placement of a heavy appliance or other spot loads are likely to need additional support in the floor structure. 
     While the joists utilized to form the manufactured home can be increased in size or number to accommodate the heavier and more frequent application of loads, it is considered wasteful to form the entire floor structure with an additional load-bearing capacity in order to accommodate the application of these loads at only a few locations about the entire structure. 
     Accordingly, diagonal struts have been utilized to support the cantilevered portions of a manufactured home. Typically, one end of a strut would be fastened to the cantilevered end portion of a floor joist, the strut would extend at a downwardly sloped angle to the lower flange of an I-beam, and engage the I-beam at the intersection of its lower flange and its central web. The strut would rely upon frictional engagement with the I-beam to remain in place. 
     More recently, an adjustable length strut has been developed which includes as its main body portion a cylindrical pipe section, with an adjustable nut and a threaded rod attached to the lower end for bearing against the I-beam and a thrust bracket connected to the upper end of the pipe for connection by means of screws or spikes to the floor joist. While this type of cylindrical pipe structure is adjustable and, therefore, an improvement over some of the prior art struts used for this purpose, the production of such a floor joist is expensive because it requires several parts, and the connection between the strut and the I-beam appears to be less than secure. Also, it is impossible to view the inside of the cylindrical pipe in order to determine the amount of the threaded rod that projects into the pipe or to determine the secure connection between the thrust bracket and the pipe, so that the installer or the maintenance person cannot be sure of proper mounting and maintenance of the product. 
     It is to these shortcomings that this invention is directed. 
     SUMMARY OF THE INVENTION 
     Briefly described, the present invention comprises an adjustable strut for supporting the floor joists of a manufactured building structure. The strut includes a unitary elongated strut plate having opposed first and second end portions, with the first end portion formed in a rectilinear C-shaped in cross-section support tube defining a longitudinal axis, and the second end portion formed in a substantially flat mounting plate typically oriented at an obtuse angle with respect to the longitudinal axis of the support tube, for fastening to the floor joist. A rectilinear shaft having external helical threads formed along at least a portion of its length has a first end portion for biasing against the I-beam that supports the floor joist and a second end portion that is telescopically received in the support tube of the strut assembly. A threaded adjustment nut rotatably engages the external helical threads of the rectilinear shaft and is movable along the length of the shaft in response to rotation about the shaft, and the nut is of larger breadth than the breadth of the support tube of the strut plate, for bearing against the end of the support tube. The nut includes a helical thread or other projection allowing for a rotation and an axial movement with respect to the shaft. The distal end of the shaft is formed in a non-circular engagement surface for engaging an I-beam of the manufactured building structure at the intersection of the lower flange of the I-beam and the central web of the I-beam. 
     With this arrangement, the strut is oriented with its engagement surface engaging the I-beam at the intersection of the lower flange and the web of the I-beam, and the mounting plate is placed in abutment with the cantilevered end of a joist of the floor of the manufactured building structure. Connectors, such as screws or spikes, are driven through the mounting plate into the joist. The adjustment nut is then rotated about the rectilinear shaft to progressively force the distal end portion of the shaft out of the support tube for bearing against the I-beam, thereby applying a lifting force to the joist of the manufactured building structure. The engagement surface which is non-circular preferably is designed as a chisel end of the rectilinear shaft and the chisel end engages the crotch of the intersection between the lower flange and the central web of the I-beam, assuring that the rectilinear shaft does not rotate in response to rotating the adjustable nut. 
     With this arrangement, the C-shaped support tube allows the installer to visually locate the internal end of the rectilinear shaft which is located inside the support tube, so as to determine the amount of shaft available for movement out of the tube. 
     Thus, it is an object of this invention to provide an improved adjustable length strut for supporting the cantilevered end of a floor joist of a building structure. 
     Another object of this invention is to provide an adjustable length strut that is formed of a minimum number of parts and which provides the necessary strength for supporting an object and which provides a means for observing the amount of expansion length that remains available to the installer or maintenance person. 
     Other objects, features and advantages of this invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of the I-beam and a floor joist of a manufactured building structure, showing the adjustable length strut installed between the I-beam and the floor joist. 
     FIG. 2 is a plan view of a blank of a strut plate before it is formed into its useable shape. 
     FIG. 3 is an expanded perspective illustration of the adjustable length strut. 
     FIG. 4 is an end cross-sectional view of the strut, taken along lines  4 — 4  of FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     Referring now in more detail to the drawings in which like numerals indicate like parts throughout the several views, FIG. 1 illustrates a portion of a manufactured home  10  which illustrates one of the typical I-beams  12  and a floor joist  14  mounted on the I-beam. It will be understood that there are two I-beams arranged parallel to each other that form the support structure for the manufactured building. An end portion  16  of the floor joist  14  is arranged in a cantilever fashion with respect to the I-beam  12 . 
     The I-beam  12  includes a central web  18 , a lower flange  19  and an upper flange  20 . The I-beams  12  typically are mounted on piers formed of support blocks, jacks, or other suitable structures (not shown). 
     When sufficient weight is applied to the distal end  17  of the cantilevered end portion  16  of a floor joist  14 , there is a likelihood of downward flexing of the cantilevered end portion, which is undesirable. In order to provide additional support to the cantilevered end portion  16  of the floor joist  14 , an adjustable strut  25  is extended between the I-beam  18  and a distal end  17  of the floor joist  14 . As illustrated in FIGS. 1 and 2, the adjustable length strut  25  includes a unitary elongated formed strut plate  26  having opposed first and second end portions  28  and  30  (FIG.  2 ). The strut plate  26  is initially a flat segment of sheet material as shown in FIG.  2 . The first end portion  28  of the strut plate  26  is formed into a C-shaped in cross-section support tube  32  which defines the longitudinal axis  34  (FIG.  3 ), and the second end portion  30  is formed in a substantially flat mounting plate  36 , with the mounting plate  36  defining a series of screw openings  38 , for fastening the mounting plate  36  to the joist  14 . Typically, screws or spikes  40  (FIG. 1) are used to connect the mounting plate  36  to the joist  14 . The support tube  32  defines a rectilinear slot  42  extending along its entire length. 
     As shown in FIG. 2, there is a segment  44  of reduced strength between the mounting plate  36  and the support tube  32  formed in the strut plate  26 . In this embodiment, the segment of reduced strength  44  is formed by notches  45  and  46  which extend inwardly from the side edges  47  and  48  of the strut plate  26 . This permits the mounting plate  36  to be bent at the segment of reduced thickness  44  from an attitude approximately parallel to the longitudinal axis  34  to a sloped attitude as illustrated in FIG.  1 . This reorientation of the mounting plate  36  is usually accomplished either at the factory or in the field by the installer during the installation procedures. 
     The distal end  50  of the support tube  32  is formed at a right angle with respect to the longitudinal axis  34  and functions as a bearing surface for the adjustment nut. 
     A rectilinear shaft  52  has external helical threads formed thereabout and along its length, and includes a first or proximal end portion  56  and a second or distal end portion  58 . The distal end portion  58  terminates in a non-cylindrical engagement surface, such as chisel blade  60 . An internally threaded adjustment nut  62  is threaded onto the shaft  52 . 
     The proximal end  56  of the shaft  52  is inserted telescopically into the open end  49  of the support tube  32  until the adjustment nut  62  bears against the end  50  of the support tube  32  so that the end  50  functions as a bearing surface for the adjustment nut. 
     When the adjustable strut  25  is to be installed at the manufactured building structure, the chisel blade  60  of the rectilinear threaded shaft  52  is placed at the crotch  21  or intersection between the lower flange  19  and the central web  18  of the I-beam  12 , and the mounting plate  36  is placed in abutment with the lower edge of the cantilevered end portion  16  of the floor joist  14 . If necessary, the mounting plate  36  will be oriented at an obtuse angle with respect to the longitudinal axis of the support tube  32 , so that the mounting plate  36  is in flat abutment with the bottom surface of the joist  14  when the support tube is oriented at a sloped attitude as shown in FIG.  1 . The installer then inserts screws, spikes or other fasteners  40  through the openings  38  in the mounting plate  36 . The installer then rotates the nut  62  so as to distend the rectilinear shaft  52 , causing the non-circular blade  60  to bear against the crotch  21  of the I-beam  12 . This applies compression from the I-beam  12  sloped upwardly through the adjustable strut  25  to the distal end  17  of the floor joist  14 . This arrangement adds stability to the cantilevered end portion  16  of the joist  14 . 
     The installer is capable of determining the amount of length of the proximal end portion  56  of the shaft  52  remaining in the support tube  32  by viewing the shaft through the rectilinear slot  42  of the support tube  32 . 
     Although a preferred embodiment of the invention has been disclosed in detail herein, it will be obvious to those skilled in the art that variations and modifications of the disclosed embodiment can be made without departing from the spirit and scope of the invention as set forth in the following claims.