Abstract:
A survey tripod assembly kit is disclosed that is easily adjustable in small increments to stable operational heights ranging from a few inches to eight feet or more and that can be easily disassembled and packed into a luggage-sized carrying case that is easily transportable from site to site. The subject survey tripod assembly desirably includes an instrument support plate, a plurality of cooperatively engageable leg sections comprising at least three leg sections of each of a plurality of different lengths that are each configured to be joined in threaded engagement to another leg section or to the instrument support plate, and three swiveling adjustable feet that are each configured to be joined in threaded engagement with at least one leg section or with the instrument support plate. A survey tripod assembly made from the subject kit is also disclosed.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a height-adjustable support device for survey instruments, and more particularly to a tripod assembly kit having a plurality of leg components that can be joined together in various combinations to make a survey tripod assembly so as to adjust the height of a plate onto which a survey instrument is or can be mounted. The subject device comprises swiveling adjustable feet for leveling to gravity and can be conveniently disassembled and packed into a carrying case for transport following use. 
       DESCRIPTION OF RELATED ART 
       [0002]    Conventional tripods intended for use in supporting survey instruments, photographic equipment, weapons, and the like, are well known. Historically, survey tripods were made with three wooden legs of fixed length that were hinged to a support plate attachable to a survey instrument and were height-adjustable primarily by spreading the legs outwardly relative to each other. More recently, tripods have been made using other materials, such as aluminum or metal alloys, and with legs having telescoping or otherwise extendable leg sections held in place by clamping devices of various types. Pointed metal tips or stakes are sometimes provided at the bottom of each leg to resist wear and to facilitate contact with and penetration into an underlying surface to enhance stability. Conventional survey tripods are typically configured for use at operational heights ranging from about four to six feet above ground level and are not collapsible to overall lengths less than about four feet. 
         [0003]    Prior patents disclosing surveyor tripods and ancillary pole supports include, for example, U.S. Pat. Nos. 4,192,076; 4,366,940; 4,641,804 5,622,344; 7,048,241; 7,124,985; 7,207,534; 7,222,827; 7,240,881; and 7,374,140. 
       SUMMARY OF THE INVENTION 
       [0004]    A survey tripod assembly kit is disclosed that is easily adjustable in small increments to stable operational heights ranging from a few inches to eight feet or more and that can be easily disassembled and packed into a luggage-sized carrying case that is easily transportable from site to site. The subject survey tripod assembly desirably includes an instrument support plate, three legs each comprising a plurality of cooperatively engageable leg sections in each of a plurality of different lengths, and at least three swiveling adjustable feet. The leg sections are each desirably configured to be releasably attachable to another leg section, or to the instrument support plate, or to one of the three swiveling adjustable feet. For some uses with very low operational heights, no leg sections are required and the swiveling adjustable feet are directly attachable to the underside of the instrument support plate. The instrument support plate of the subject survey tripod assembly desirably further comprises a survey instrument attachment device, a plurality of threaded receptacles each releasably engageable with a leg section at a predetermined attachment angle. According to another embodiment of the invention, the subject survey tripod assembly comprises at least one optional vertical extension member releasably engageable with the instrument support plate to elevate a survey instrument above the instrument support plate. 
         [0005]    The survey tripod assembly of the invention is mechanically strong and stable, without relying on axially extending slip joints, compression clamps, folding hinges, or the like. Each of the three legs of the survey tripod assembly of the invention desirably comprises a plurality of leg sections having different lengths that are intended to produce a tripod assembly that can be configured in a variety of different tripod heights to accommodate various environments and conditions of use. By combining various numbers and lengths of leg sections, users can achieve many different operational height adjustments in relatively small increments, generally 2-3 inches or less, especially when taking into consideration the threaded adjustments on the swiveling feel at the base of each leg. Following use, the subject invention is easily disassembled and can be packed and transported inside a carrying case no larger than a conventional piece of luggage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The apparatus of the invention is further described and explained in relation to the following drawings wherein: 
           [0007]      FIG. 1  is a front elevation view of one embodiment of the survey tripod assembly of the invention with a survey instrument that forms no part of the invention shown in dashed outline; 
           [0008]      FIG. 2  is an exploded view of one embodiment of an instrument support plate that is supported by the three legs of the survey tripod assembly of the invention; 
           [0009]      FIG. 3  is a top plan view of the assembled instrument support plate of  FIG. 2  with the survey instrument attachment device installed; 
           [0010]      FIG. 4  is a front elevation view of the assembled instrument support plate of  FIG. 3 ; 
           [0011]      FIG. 5  is cross-sectional front elevation view taken along line  5 - 5  of  FIG. 3 ; 
           [0012]      FIG. 6  is a front elevation view of one embodiment of a leg section of the invention; 
           [0013]      FIG. 7  is a cross-sectional front elevation view taken along line  7 - 7  of  FIG. 5 ; 
           [0014]      FIG. 8  is a perspective view of elements included in one embodiment of the survey tripod assembly kit of the invention; and 
           [0015]      FIG. 9  is a front elevation view of an assembled survey tripod assembly having two vertical extension sections attached by the survey instrument attachment device to the instrument support plate. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]      FIG. 1  depicts for illustrative purposes an embodiment of survey tripod assembly  20  of the invention that comprises instrument support plate  22  having survey instrument attachment device  24  further comprising raised threaded section  28 . Survey instrument attachment device is secured in releasable fixed relation to instrument support plate  22  by a plurality of spaced-apart fasteners  26 . Three tripod legs (one being hidden behind the visible leg on the left) are releasably engaged at fixed predetermined attachment angle to instrument support plate  22  by externally threaded bolts  44  that extend through internally threaded bores  52  in receptacles  54  on the underside of instrument support plate  22  that are visible in  FIG. 2 . 
         [0017]    Referring again to  FIG. 1 , for illustrative purposes, each tripod leg is depicted with leg sections partially broken away. It should be understood, however, that upper leg section  32  and lower leg section  34  can be the opposite end parts of a single leg section or can be upper and lower end parts, respectively, of different leg sections, each of different lengths. The leg sections  32  (now used generically) are each cooperatively configured to releasably engage other leg sections and can be joined to produce a tripod leg of greater length than any single section. Each tripod leg can comprise one or a plurality of leg sections, depending upon the operational height that is desired for a survey instrument (as shown in dashed outline in  FIG. 1 ) being used in a particular application or environment. 
         [0018]    Also depicted in  FIG. 1  are two of the three swiveling adjustable feet  36  that provide stable contact between each tripod leg and an underlying support surface (not shown). Although the method of attachment of the adjustable swiveling feet  36  to the lower leg section  34  can vary, in this embodiment swiveling ball  42  is captured by ball housing  40  secured to base  38  that desirably comprises a non-slip lower surface. A limited degree of height adjustability for uneven support surfaces is provided by threaded bolts  43 ,  45  attached to mounting shafts fixed to swiveling balls  42 . In situations where a very low operational height for instrument support plate  22  is desired, threaded bolt  45  can be attached directly to instrument support plate  22  without using any leg sections  32 ,  34 , so that each tripod leg comprises only a swiveling adjustment foot  36 . 
         [0019]      FIG. 2  is an exploded lower perspective view of survey tripod assembly  20  of  FIG. 1  view that is helpful for visualizing how the constituent parts are configured and assembled. (It should be noted that  FIGS. 1 and 2  are not drawn to scale, and that only one leg section  32  of one tripod leg is depicted for illustrative purposes.) Referring to  FIG. 2 , it is seen that swiveling adjustment foot  36  comprising ball housing  40  and base  38  is releasably secured to the lower end of leg section  32  by cooperatively threaded adjustment bolt  43  and threaded attachment bolt  45 . The male threaded upper portion of attachment bolt  45  is configured to be received into and provided threaded engagement with cooperating female threads inside the bore of insert  58  disposed inside the bottom of tubular leg section  32 . Threaded adjustment bolts  43  and threaded attachment bolts  45  (only one being shown in  FIG. 2 ) are useful for attaching each swiveling adjustment foot  36  to a leg section  32  (or directly to the underside of instrument support plate  22  if desired to achieve the lowest possible operational height without using any leg section  32 ) and for leveling instrument support plate  22  to gravity. With this configuration, leveling instrument support plate  22  to the nearest arc-second is achievable. 
         [0020]    Upwardly extending male threaded bolt  44  of insert  64  ( FIGS. 6-7 , discussed below) at the upper end of tubular leg section  32  is desirably provided for use in releasably attaching leg section  32  of the associated tripod leg to the horizontally level instrument support plate  22  at a predetermined attachment angle. This releasable attachment can be achieved, for example, by providing a plurality of evenly spaced-apart receptacles  54  in bottom  50  of instrument support plate  22 , with each receptacle  54  desirably having female threaded through-bores  52  that are drilled in evenly spaced-apart circumferential relation to the center of instrument support plate  22  at a desired predetermined attachment angle that is the same for each through-bore  52 . The attachment angle is desirably chosen to provide a desired spread between the tripod legs and swiveling adjustable feet  36  at the base of the subject survey tripod assembly  20 . Although the attachment angle can vary within the scope of the invention, an attachment angle of about 22 degrees from vertical, plus or minus up to about 5 degrees, can be utilized satisfactorily for most survey tripods intended for general use. For specialized applications or designs, other acute attachment angles may be preferred. The inside surface of each receptacle  54  is desirably configured to provide stable contacting engagement with each leg bolt  44  (when used with leg sections  32 ), insert  64 , or threaded adjustment bolt  45  (where no leg section  32  is used), so that no unintended significant relative movement occurs between instrument support plate  22  and the tripod legs. It will be appreciated upon reading this disclosure that the distance of the spread between the three tripod legs of survey tripod assembly  20  can vary according to the overall length of each assembled tripod leg, which will in turn depend upon the number and length of the leg sections used in each tripod leg, as is further discussed below. 
         [0021]    A significant advantage of survey tripod assembly  20  as compared to those disclosed in the prior art is the ability to easily and conveniently adjust the operational height of the instrument support plate  22  for a particular use. This is generally achieved by selecting different numbers and lengths of leg sections  32  when assembling the tripod legs, although the overall length of the assembled leg sections  32  and the predetermined attachment angle at which the tripod legs are attached to instrument support plate  22  will both affect the operational height of tripod assembly  20 . 
         [0022]    Referring to  FIGS. 2-5 , survey instrument support device  24  is desirably a metal plate lesser in thickness than instrument support plate  22  and further comprises a plurality of circumferentially spaced apertures  48  through which male threaded fasteners  26  can be inserted for attachment to correspondingly threaded female bores (not visible in  FIG. 2  but visible in  FIG. 5 ) in the upwardly facing surface of instrument support plate  22 . Reference numeral  75  is used in  FIGS. 2-5, 8 and 9  to designate the assembled unit formed when survey instrument attachment device  24  is secured to instrument support plate  22 . As seen in  FIG. 3 , fasteners  26  are flat-headed Allen screws that do not interfere with the subsequent mounting of a survey instrument. Centrally disposed, internally threaded through-bore  60  is provided in instrument support plate  22  for possible insertion of a mounting screw for a survey instrument or for possible use in determining whether the instrument support plate  22  is plumb with an underlying support surface. As best seen in  FIGS. 1 and 4-5 , survey instrument support device  24  preferably further comprises an upwardly facing male threaded collar  28  for possible use in attaching either a downwardly facing female threaded attachment collar of a survey instrument (as suggested by the dashed outline in  FIG. 1 ) or for attaching a vertical extension member  102  as shown in  FIG. 9  for use in positioning a survey instrument in a higher position relative to the top of a survey tripod assembly  20  ( FIG. 1 ) of the invention. 
         [0023]    Referring to  FIGS. 6-7 , a typical leg section  32  for use in the invention is further described. According to one embodiment of the invention, leg section  32  is constructed from a tubular sleeve  62  that is preferably made of lightweight metal such as aluminum or another metal alloy such as brass, bronze, boron, titanium or the like. Strength and rigidity are desirable for use in fabricating the leg sections, but cost and weight are also significant considerations. Although wood, stainless steel or engineered polymeric materials can also be used for making the elongate body portions of leg section  32 , the use of aluminum sleeves  62  with press-fit stainless steel inserts  64 ,  66  is presently considered to be a satisfactory way of constructing leg sections such as leg section  32 . For longer leg sections, other internal reinforcement structures known to those of skill in the art can also be used. Externally threaded bolt  44  is desirably provided at one end of each leg section of the invention as represented by leg section  32 , and internally threaded bore  70  is desirably provided at the other end. The bolts and bores for the leg sections are desirably configured and made of materials that will provide tight engagement but release relatively easily without use of tools, and can remain serviceable over long periods of regular use without significant wear or degradation. Recesses  68  ( FIG. 7 ) can also be provided at one or both ends of leg sections  32  to facilitate the possible use of washers, bushings or compressible materials between adjacent leg sections or between a leg section and the instrument support plate or a swiveling adjustable foot if desired. 
         [0024]    Referring to  FIG. 8 , one embodiment of a survey tripod assembly kit  80  is depicted that comprises a unit  75  comprising an assembled instrument support plate and survey instrument attachment plate as described above, and five different sets  82 ,  84 ,  86 ,  88 ,  90  of leg sections. Each set contains three leg sections of the same length, but the length of the leg sections in different sets is different. The number of sets in each tripod assembly or kit can vary, but should include a plurality of sets and desirably from at least three to at least five sets. At least three leg sections of the same length should be included in each set so that three tripod legs of equal length can be assembled using leg sections from any set or combination of sets. 
         [0025]    As depicted in  FIG. 8 , a swiveling adjustment foot  92  comprising a swiveling ball  94  and a threaded adjustment bolt  96  is pre-attached to the bottom end of each leg section in set  90 . It will be appreciated, however, that the swiveling adjustable feet  92  can be packed and transported while detached from any of the leg units if desired. A male threaded attachment bolt  95  projects upwardly from the other end of each leg section of each set  82 ,  84 ,  86 ,  88 ,  90 , although it should be understood that other similarly effective, coaxially aligned attachment means can also be substituted for the threaded connectors if desired. For purposes of this invention, it is important, however, that each leg section be selectively attachable to another leg section or to the instrument support plate or to a swiveling adjustment foot as desired or needed when assembling the tripod legs to produce three tripod legs, typically of co-equal length, for use in the survey tripod assembly  20  ( FIG. 1 ) of the invention. The various elements of survey tripod assembly kit  80  can be conveniently packed in a bag, suitcase-type carrier or other similarly effective container for transport and storage between uses. 
         [0026]    It is emphasized that the number of sets of leg sections can vary within the scope of the invention. All leg sections will not necessarily be used in every application of the subject survey tripod assembly  20  or survey tripod assembly kit  80 , and in some cases, no leg sections  32  will be used. Referring to  FIG. 9 , a survey tripod assembly of the invention is depicted that comprises unit  75  comprising an instrument support plate and a survey instrument attachment device as previously described, and three tripod leg assemblies (two of which are visible). Each tripod leg assembly comprises five leg sections of different, unequal lengths, consisting of one leg section from each of the plurality of sets  82 ,  84 ,  86 ,  88 ,  90 . It will be appreciated upon reading this disclosure that survey tripod assemblies  20  having different operational heights can be assembled from a single kit  80  by selecting leg sections only from the sets having lengths needed to reach the desired overall length for each tripod leg. Although the tripod leg assemblies will typically need to be of equal lengths for a particular combination, a combination of one, two, three, four, five or more leg sections, each from a different set (or, alternatively, simply a swiveling adjustment foot  92 ) may be needed to achieve a tripod leg assembly having the desired overall length. The order of assembly of the different-length leg sections  82 - 90  of each tripod leg does is not critical even though the tripod legs are depicted in  FIG. 9  as decreasing from longest to shortest from top to bottom. For most purposes, it has been found that sets having leg section lengths (when assembled) of 3, 5, 10, 20 and 30 inches, with three leg sections of each length in a given set, are adequate for assembling stable survey tripods with operational heights ranging from a few inches to more than five feet in increments of 2-3 inches, even without the use of vertical extension members  100 ,  102  disposed above unit  75 . For example, three tripod legs of 35 inches overall length (without considering the swiveling adjustable foot) can be made by using three leg sections of 20, 10 and 5 inches for each leg, or leg sections of 30 and 5 inches for each leg, or a mixture of the two. Because each leg, when attached to the instrument support plate, will be disposed at a slight angle from vertical in order to obtain a spread of the legs, the operational height of the tripod assembly may be somewhat less or more than 35 inches when the thickness of the plate and the height of the foot is also added. For survey tripod assemblies designed specifically for particular intended uses, the number of sets of leg sections and the length of the leg sections in each set can vary within the scope of the invention. As disclosed above, it is not required in some situations that any leg section be used in making the survey tripod assembly of the invention. 
         [0027]    Again referring to  FIG. 9 , the useful height of the subject survey tripod assembly can be further extended upwardly by the use of one or more vertical extension members  100 ,  102  of various lengths that are attachable to both unit  75  and a survey instrument (shown in dashed outline). 
         [0028]    Other alterations and modifications of the invention will likewise become apparent to those of ordinary skill in the art upon reading this specification in view of the accompanying drawings, and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventor and Applicant is legally entitled.