Abstract:
An improved low profile mounting arrangement is provided for a telescoping tube construction applied to the roof of a vehicle. The lowest mast section is nested between two vertically upright shaft support plates which journal a pivot shaft rotatably secured to a collar affixed to the bottom of the lowest mast section whereby rotation of the pivot shaft causes the telescoping mast to rotate from a horizontal to a vertically upright position. A pivot link mounted to an end of the pivot shaft extends downward adjacent a support plate side opposite to the side facing the telescoping mast so that an actuator secured to the pivot link is mounted on the side of the telescoping mast construction to achieve a low profile mount with minimal vertical elevation.

Description:
INCORPORATION BY REFERENCE 
     The assignee&#39;s prior United States patents directed to various features of its telescoping mast construction are hereby incorporated by reference and made a part hereof: 
     U.S. Pat. No. 4,413,451 to Featherstone et al. issued Nov. 8, 1983, entitled “PNEUMATICALLY ACTUATED TILTING TELESCOPING MAST CONSTRUCTION”, 
     U.S. Pat. No. 5,572,837 to Featherstone et al. issued Nov. 12, 1996, entitled “PNEUMATIC TELESCOPING MAST”, and, 
     U.S. Pat. No. 5,743,635 to Hulse et al., issued Apr. 28, 1998, entitled “PNEUMATICALLY TELESCOPING MAST”. 
     The patents identified above are incorporated herein by reference so that details of telescoping mast constructions and applications known to those skilled in the art need not be restated or explained in detail herein. The above-identified patents do not, per se, form or comprise the present invention. 
    
    
     This invention relates generally to the art of vehicular mounted, pneumatically actuated telescoping masts, and more particularly to an improved mounting arrangement for the telescoping mast construction. 
     The invention is particularly applicable to and will be described with specific reference to a vehicular mounting arrangement for a pneumatically actuated telescoping mast used for positioning electrical devices, specifically utility lighting. However, the invention has broader application and may be used as a vehicular mount for any type of light weight tubular, telescoping mast constructions whether pneumatically, hydraulically or mechanically (chain driven) actuated and whether or not carrying electrical fixtures or other devices. 
     BACKGROUND 
     Pneumatically actuated telescoping masts are well known in the prior art and they are generally of such a nature that they may be mounted on the roof of a motor vehicle, such as an emergency vehicle or utility vehicle. In such applications, the mast is generally used for positioning electrical devices, particularly lighting fixtures, at an elevated point above the vehicle. The effect is to immediately light a large area above the vehicle to allow emergency procedures to be performed under the light, such as at accident scenes or by utility work crews such as after a storm. Pneumatically actuated telescoping masts are particularly advantageous in such situations because they are lightweight, compact in a retracted position and generally have fall, open and unobstructed mast sections which permit electrical wiring to pass within and through the telescopic tubular mast sections for controlling electrical devices or fixtures. 
     Typically, the telescoping mast is in a horizontal position when the mast is in a stored, retracted position on the vehicle. The mast construction is typically rotated to a vertical upright position whereat it is extended by adjacent mast sections telescoping out from one another. However, as discussed in the &#39;837 patent, there are emergency situations where the mast is desired to be raised at some angle relative to horizontal which is less than a vertically upright position. Further, there can be some applications where the mast is desired to be moved to the side of the vehicle and then raised. 
     The mounting arrangement typically used for securing the mast to the vehicle generally comprises a base plate which is secured to the vehicle and from which vertically extends a pair of transversely spaced, support plates which receives the lowest mast section therebetween. A pivot shaft or a pair of stubs shafts secured near to the bottom of the lowest mast section is journalled within the shaft support plates. Various lift mechanisms have been employed to rotate the telescoping mast construction about the pivot shaft from the horizontal to the vertical positions. All of these lift mechanisms are conceptually sound and adequately function to properly position the telescoping mast construction. However, the prior art lift mechanisms do not achieve the objectives of the present invention. 
     In the &#39;837 patent, a toothed bell crank attached to the swivel shaft cooperates with a rack pinion drive at one side of the support shaft to rotate the mast construction to any desired vertical angle. There are some disadvantages to having an exposed tooth/rack drive arrangement and the position of the swivel produces a higher vertical mount arrangement than desired for some vehicular applications. 
     The &#39;635 patent utilizes a mechanical actuator rod mechanism to avoid the exposed tooth/gear arrangement disclosed in the &#39;837 patent but positions the pivot shaft at the center of the lowest mast section similar to that disclosed in the &#39;837 patent. This results in the telescoping mast construction having a horizontal stored position vertically spaced from the vehicle&#39;s roof which is higher than what is otherwise possible. 
     In the &#39;451 patent, the stub shafts are journalled at a laterally offset axis relative to longitudinal centerline of the lowest mast section. However, a hydraulic actuator is utilized and an intermediate link is positioned between the stub shaft bell crank and the hydraulic cylinders actuator rod which is not a particularly advantageous arrangement. 
     An extremely robust, sound lift arrangement the assignee commercially utilizes for its mast constructions is diagrammatically illustrated in FIGS. 1A and 1B. As shown, the lowest mast section  1  has secured thereto pivot shaft  2  rotatable about an axis laterally spaced from the longitudinal centerline  3  of lowest mast section  1 . Mounted to the bottom end of lowest mast section  1  is a lift bracket  5  secured to the bottom of lowest mast section  1 . An actuator rod  6  pinned to the bottom of lift bracket  5  rotates the mast construction from horizontal to vertical positions set by angular limit switches such as illustrated in the &#39;635 patent. While positioning the lift bracket between the shaft support plates produces a lift arrangement which (unlike the &#39;837, the &#39;451 and the &#39;635 patents) does not produce any bending moment on the lift mechanism, the actuator must be positioned beneath lowest mast section  1  resulting in a higher elevation mount designated by reference arrow E than what may be desirable for certain vehicular applications. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a mount arrangement for a tubular mast construction which has a low profile and which can stably support the mast construction at any desired positional area on the vehicle&#39;s roof. 
     This object along with other features of the present invention is achieved in a telescoping mast construction which is adapted to be mounted on a vehicle roof and carrying at one of its ends, an electrical fixture assembly. The mast construction includes a plurality of adjacent telescoping mast sections slidable relative to one another between a retracted position such as when the longitudinal axis of the mast construction is horizontal and an extended position such as when the longitudinal axis of the mast construction is vertical and the mast construction is raised by telescoping the mast sections from the lowest mast section. The improvement includes a pair of longitudinally extending, transversely spaced shaft supports vertically extending from a base plate with the lowest mast section positioned between the shaft supports. A collar mount is secured to the bottom of the lowest mast section and a pivot shaft is secured to the collar mount and journalled with the shaft support plates to lie on an axis laterally offset from the longitudinal axis of the mast and adjacent the uppermost surface of the collar mount when the mast construction is horizontal. A pivot link rotatably secured to one axial end of the pivot shaft extends vertically downward adjacent a pivot support side which is opposite that pivot support side adjacent the lowest mast section and a linear actuator having an actuator rod movable into and out of an actuator housing is provided. The actuator rod is pivotably secured to the pivot link and the actuator housing is pivotably secured to the base plate whereby the length of the pivot link relative to the position of the pivot shaft provides a low profile mast mounting arrangement extending no higher than about the pivot shaft when the longitudinal axis of the mast construction is in its stored horizontal position. 
     In accordance with another aspect of the invention, first and second longitudinally adjustable and spaced actuator limit switches controlling movement of the actuator into and out of the actuator housing are provided with a contact member movable with the actuator rod for contacting a limit switch at extended and retracted positions of the actuator rod whereby the rotation of the pivot link is precisely controlled by the longitudinal positions of the limit switches. 
     In accordance with yet another aspect of the invention, a splined connection rotatably secures the pivot shaft to the collar mount and a splined connection secures the pivot lever to the pivot shaft whereby the position of the pivot lever relative to the actuator rod may be variably set during mounting of the mast construction to the vehicle to assure longitudinal movement of the actuator rod in a substantially horizontal plane minimizing binding within the linkage and allowing effective use of the actuator force to rotate the mast construction to its desired vertical and horizontal positions. 
     In accordance with a somewhat subtle feature of the invention, a clevis is provided for the pivot link to better dissipate the moment arm effects resulting from the side mounting of the lift actuator. 
     It is thus an object of the present invention to provide a low profile mounting arrangement for a telescoping mast construction. 
     Still another object of the invention is to provide a vehicular mounting arrangement for a telescoping mast which utilizes a side mount pivot lever to position the mast at a low vertical elevation from the vehicle&#39;s roof while stably supporting the mast during rotation by an outrigger mount. 
     Yet another object of the present invention is to provide a mounting arrangement for a telescoping mast construction which utilizes a lift mechanism which can accurately position the telescoping tubular mast construction between desired horizontal and vertical positions. 
     Still yet another object of the present invention is to provide a vehicular mounting arrangement for a telescoping tubular mast construction which utilizes a lift mechanism for the mast construction which can be easily adjusted when mounting the mast to the vehicle. 
     Yet another object of the invention is to provide a relatively simple and inexpensive vehicular mounting arrangement for a tubular, telescoping mast construction which arrangement rotates the mast construction from a horizontal to a vertical position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in the Detailed Description of the Invention which follows and illustrated in the accompanying drawings which form a part hereof and wherein: 
     FIGS. 1A and 1B are schematic, side and end views, respectively, of a telescoping mast construction of a prior art pivoted lift arrangement for a telescoping mast; 
     FIG. 2 is a side elevational view illustrating one use of the telescoping mast of the present invention; 
     FIG. 3 is a plan view, partially in section, of the telescoping mast construction shown in FIG. 2 taken along lines  3 — 3  thereof; 
     FIG. 4 is an elevation view, partially in section of the mast construction shown in FIG. 3 taken along lines  4 — 4  thereof; 
     FIG. 5 is an elevation view similar to FIG. 4 illustrating the position of the mast construction in a vertically upright, raised or extended position; 
     FIG. 6 is an end view, partially in section of the mounting arrangement for the mast construction taken along lines  6 — 6  of FIG. 3; 
     FIG. 7 is a schematic view, partially in section, of a conventional actuator used in the lift mechanism of the present invention; and, 
     FIGS. 8,  9  and  10  are schematic, end views showing various positions of the telescoping mast construction relative to a vehicular roof made possible by the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, wherein the showings are for the purpose of illustrating a preferred embodiment(s) of the invention only and not for the purpose of limiting same, FIG. 2 shows a telescoping mast construction  10  mounted on a roof  12  of a motorized vehicle  13 . Telescoping mast construction  10  is shown in solid lines in FIG. 2 in its retracted or stored position and in broken lines in its vertical or upright position. More particularly, and for definitional purposes, mast construction  10  extends along a longitudinal axis  14 . When mast  10  is in its retracted, stored position, its longitudinal axis  14  is horizontal and/or parallel to roof  12  of vehicle  13 . In accordance with the present invention, mast construction  10  is capable of being placed at a tilt angle between 0° and 90° where, for the purposes of this description, 0° is defined as being parallel with the vehicle roof  12  and generally horizontal while 90° is in a vertically upright position, as shown by the broken lines of FIG. 2, and generally perpendicular to vehicular roof  12 . It is to be clear that mast construction  10  can be placed at anywhere between 0° and 90°, although, in the normal usage, mast  10  is either positioned in its retracted, horizontal position or its vertically upright position, i.e., the two positions shown in FIG.  2 . 
     As shown, telescoping mast construction  10  is equipped with a utility light  16  at the upper end thereof. In the embodiment illustrated, there are two rectangular boxes  17 ,  18 , each containing a utility light and boxes  17 ,  18  can be remotely actuated to pivot in one plane and tilt in another plane and reference can be had to the patents incorporated by reference for a further description thereof. Telescoping mast construction  10  thus has the capability of providing the illumination to areas under bridges or over sharp drop-offs, such as cliffs and mountain roads. The telescoping mast construction can also be used to light the underside of an overpass or bridge. It should be appreciated that mast  10  may be outfitted with any desired electrical fixture, or with multiple light configurations depending on customer requirements and applications. It is also to be appreciated that telescoping mast construction  10  can be fitted with any number of devices and use of the term “electrical fixtures” covers all such devices whether or not electricity is conducted to the device. 
     Referring now to FIG. 3, mast construction  10  comprises a plurality of adjacent mast sections. In the preferred embodiment, there are four adjacent mast telescoping sections designated  20 A through  20 D. The lowest mast section about which mast construction  10  pivots is designated  20 A and the highest or top mast section is designated  20 D. Because a pneumatic telescoping mast construction  10  is shown, each mast section is pneumatically sealed as by o-rings  21  and telescopes relative to an adjacent mast section except for lowest mast section  20 A which is stationary. Thus, mast section  20 B telescopes into an out of mast section  20 A, mast section  20 C telescopes into and out of mast section  20 B and top mast section  20 D telescopes into and out of mast section  20 C. As indicated in the Background discussion, a pneumatic telescoping tubular construction is preferred because of its weight and because the space within mast sections  20 - 20 D is hollow thus permitting threading electrical wires  22  therethrough for powering utility light  16  and actuating the motors which tilt and pivot light boxes  17  and  18 . Signals carried by wiring  22  are generated and under the control of the mast construction&#39;s printed circuit board  23 . Air pressure to actuate telescoping mast  10  is supplied through a mast compressor  24  under the control of a solenoid actuated valve(s)  25  with the compressor and valve regulated by printed circuit board  23  which is intelligent and carries its own CPU. While a pneumatic mast construction  10  is illustrated and preferred for reasons noted, the invention is not necessarily limited to a pneumatic telescoping mast but can function if the mast was telescoped by mechanical drives such as chains or if the mast was actuated by a hydraulic arrangement. 
     As thus far described, mast construction  10  is entirely conventional. 
     Referring now to FIGS. 3 through 6, the mounting arrangement of the present invention includes a generally flat base plate  30  which, as shown, rests on the vehicle&#39;s roof  12 . Extending vertically upward from base plate  30  is a pair of first and second shaft support plates  32 ,  33 . Shaft support plates  32 ,  33  are longitudinally extending and transversely spaced from one another to receive therebetween lowest mast section  20 A. At or adjacent the bottom end  35  of lowest mast section  20 A is a collar  36  circumscribing and permanently affixed to lowest mast section  20 A such as by weldment or otherwise. Extending through collar  36  is a pivot shaft opening  38  concentric about a pivot shaft centerline  39  and grooved, in the preferred embodiment, for a splined connection (although the collar connection can alternatively be a pinned connection). Received within pivot shaft opening  38  is a pivot shaft  40  which in the preferred embodiment is splined over that portion of its length which is received within collar  36 . 
     As best shown in FIG. 6, one pivot shaft end  41  adjacent second support plate  33  is cylindrical and journalled within second bushing  42  pressed into a second saddle or bearing block  43  secured to the uppermost end of second shaft support plate  33 . Similarly, a cylindrical section of pivot shaft  40  is likewise journalled in a first bushing  44  pressed into a first bearing block  45  secured to the exposed end of first support shaft plate  32 . A splined end  46  of pivot shaft  40  extends beyond first bushing  44  for purposes which will be shortly explained. It should be clear that pivot shaft  40  when rotated and because of its splined connection with collar  36 , will raise and lower mast construction  10  between the positions shown in FIGS. 2,  4  and  5 . 
     Importantly, pivot shaft centerline  39 , as best shown in FIGS. 4 and 6, is transversely spaced from mast centerline  14 . Specifically, with mast construction  10  in its horizontal, retracted stored position, as best shown in FIG. 4, pivot shaft centerline  39  is adjacent the vertically highest position of lowest mast section  20 A. Thus, the highest elevation point of mast construction  10  (the surface furthestmost displaced vertically upward from roof  12 ) is pivot shaft  40 . By maintaining pivot shaft centerline  39  at a minimum elevation from roof  12 , indicated by reference letter E as shown in FIG. 4, a low profile mount arrangement results. 
     Affixed by a spline connection to splined end portion  46  of pivot shaft  40  is a pivot link  50 . Pivot link  50  extends adjacent a side  48  of first bearing block  45  which is opposite side  49  of first shaft support plate  32  that is facing lowest mast section  20 A. Preferably pivot link  50  is in the form of a clevis having a pair of transversely spaced legs  52 ,  53  connected at a longitudinally extending bight portion  54  which has grooved openings  55  for receiving splines of spline end  46  of pivot shaft  40 . The clevis arrangement is preferred because the length of bight portion  54  of the clevis dissipates the moment arm effect resulting from the side mount of pivot link  50  as described while the spline arrangement permits pivot link  50  to be variably mounted relative to the position of telescoping mast construction  10  so that its arcuate path remains essentially horizontal. 
     An actuator  58  is provided for rotating pivot shaft  40  through pivot link  50 . As best shown in FIG. 7, actuator  58 , which is a conventional device, includes an electric motor  59  which through a beveled gear arrangement  60  rotates a shaft  62  through a torque bearing  63  connected to an actuator rod  64  functioning as a lead screw. While this drive is conventional (available from Linak U.S. Inc.) and other drives such as a ball screw or a hydraulic driven actuator or a pneumatic actuator could be used as lift actuators, the selection of this particular drive is preferred because the electric driven gear arrangement provides high torque output while the lead screw arrangement permits precise mechanical positioning of actuator rod  64 . 
     As best shown in FIGS. 3 through 5, actuator rod  64  is pinned at  66  while the actuator housing  67  is pinned at  68  to a bracket  69  secured to base plate  30 . Extending from actuator rod  64  is a contact arm which, in the preferred embodiment, takes the shape of a contact rod  70  which moves with actuator rod  64  for actuation of a pair of adjustable micro limit switches  72 ,  73  which are adjustably mounted on a guide (not shown) parallel to the directional travel of contact rod  70 . Positioning limit switches  72 ,  73  as shown in FIGS. 4 and 5, determines the extended and retracted positions of actuator rod  64  which, in turn, sets the horizontal and vertical positions of mast construction  10 . Heretofore, limit switches were set and triggered based on the angular position of the pivot shaft or the lift bracket and while these limit switches adequately perform their intended function, the angular position of mast construction  10  could not be set with the precision achieved by utilizing the longer linear travel of actuator rod  64  as in the present invention. Further, the adjustment of the limit switch arrangement of the present invention is easily accomplished for any desired vertically tilted angle of the mast. 
     Further, as best shown by viewing FIGS. 4 and 5, actuator  58  is pinned at 2 points but remains substantially horizontal throughout the 90° rotation of mast construction  10  from its horizontal to its vertically upright position. This results from the short length of pivot link  50  and the positioning of pivot link  50  relative to stationary shaft supports  32 ,  33 . Preferably, as shown in FIGS. 4 and 5, pivot link  50  is at a 45° angle relative to vertical when the mast construction  10  is horizontal and at a 45° angle on the other side of the vertical axis when mast construction  10  is upright. This positioning is achieved during assembly vis-a-vis the spline connection as discussed. The short pivot link arrangement increases the force required of actuator  58  which is the reason why a gear drive actuator with a precise lead screw position was selected and the spline connection permitting accurate positioning of pivot link  50  was similarly selected so that the force of the actuator could be efficiently utilized in a non-binding linkage arrangement. As noted, the side mount arrangement of actuator  58  produces a bending moment about pivot shaft  40 . This moment tends to cause binding at pivot points  66 ,  68  which becomes excessive or aggravated should actuator  58  significantly pivot about its axis when raising and lowering mast construction  10 . By maintaining longitudinal axis of actuator  58  substantially horizontal throughout the rotation of pivot link  50 , the actuator force is directed to lifting mast construction  10  and is not directed to overcoming binding forces otherwise occurring at pivot connections  66 ,  68 . 
     A hollow tubular outrigger  80  longitudinally extends in a direction transverse to longitudinal axis  14  of mast construction  10 . Tubular outrigger  80  slidably extends through outrigger openings  82 ,  83  formed in first and second shaft support plates  32 ,  33  and first and second bearing blocks  45 ,  43  respectively. As best shown in FIG. 6, at each end of tubular outrigger  80  is an angle mounting bracket  85 . Horizontal leg  86  of mounting bracket  85  is adapted to be fastened directly (or indirectly) to the vehicle&#39;s roof  12 . The upright leg  87  of mounting bracket  85  has an opening  88 , preferably a slotted opening, for receiving a threaded fastener  89 . First and second cylindrical cam members  90 ,  91  having diameters less than the inside diameter of tubular outrigger  80  are provided for each end of tubular outrigger  80 . Each cam member  90 ,  91  has an angular cam face surface  92 ,  93  respectively which, in the assembled position shown in FIG. 6, face one another and slide relative to one another. Second cam member  91  has a centrally positioned threaded opening longitudinally extending from its cam face surface  93 . First cylindrical cam member  90  has a central opening  98  longitudinally extending therethrough. Central opening  98  is larger in diameter than that of threaded fastener  89  and may, alternatively, be formed in a slot. With the first and second cam members  90 ,  91  fitted into an open end of tubular outrigger  80 , at least to a distance whereat each cam member&#39;s cam face surface  92 ,  93  is within the tube, tightening of threaded fastener  89  into second cam member&#39;s threaded opening  95  will cause one of the cam members (or both) to slide along cam face surface  92 ,  93  until contacting the interior diameter of tubular outrigger  80 . Continued tightening of threaded fastener  89  will wedge cam members  90 ,  91  against the inside surface of tubular outrigger  80  thus locking tubular outrigger  80  to mounting bracket  85  and to vehicle&#39;s roof  12 . This mounting arrangement is not dissimilar to that used to attach the handle bars of a bicycle to the front wheel&#39;s bicycle fork. Heretofore, the mounting arrangement for mast constructions simply bolted base plate  30  to the vehicle&#39;s roof. 
     Tubular outrigger  80  provides several advantages. As already discussed, the side actuated/pivot shaft position discussed above achieves the desired low profile so that vehicles equipped with mast construction  10  can be stored or parked in normal garages and the like or pass under bridges or overhangs without raising significant concerns about the vertical clearance of the vehicle. Tubular outrigger  80  provides a stabilizing beam which not only renders the entire mounting arrangement more secure, but also counteracts any tendency of the unit to twist or skew as a result of the moment arm effect attributed to the side mount of actuator  58 . Additionally, the arrangement permits attachment to the curved portions of vehicle roof  12  such as shown in FIG.  10 . In such applications, base plate  30  will not uniformly contact the roof surface over its area. In addition, by the position of mounting brackets  85  at the ends of tubular outrigger  80 , the attachment points are more towards the transverse edges of the vehicle&#39;s roof which is a stronger more secure roof section than attaching the assembly at the center of a curved roof. Finally, while light fixture  16  can pivot and rotate as described above, use situations may very well occur where the lateral position of mast construction  10  relative to the side of the vehicle must be shifted. Tubular outrigger  80  allows for the shift such as illustrated by the position shown in FIG.  9 . In this regard, it should be noted that in a typical mounting of tubular mast construction  10  onto roof  12  of a vehicle, base plate  30  with its associated components, but less tubular mast construction  10  is placed onto the vehicle&#39;s roof and mounting brackets  85  secured. Then, a fastener(s)  99  may secure base plate  30  directly to roof  12 . Alternatively, or in addition to fastener(s)  99 , a set screw  100  at shaft support plates  32 ,  33  can lock tubular outrigger  80  to shaft support plates  32 ,  33 , and thus, to base plate  30 . Release of set screws  100  will allow optional movement to the position shown in the alternative embodiment shown in FIG.  9 . Once base plate  30  and tubular outrigger  80  are affixed to the vehicle&#39;s roof, tubular mast construction  10  with collar  36  is inserted in the horizontal position illustrated in FIG.  4 . Utility light  16  can rest on the light support bracket  102 . Pivot shaft  40  is then inserted into pivot shaft opening  38  of collar  36  and pivot link  50  adjustably positioned at its preferred position as described above and pinned to actuator rod  64 . Limit switches  72 ,  73  are set at the desired position and the electrical and pneumatic connections with tubular mast construction  10  made. A weatherproof low profile cover  103  is provided to protect and shield the mast operating elements from the weather. 
     The invention has been described with reference to a preferred embodiment and modifications thereof. Further modifications and alterations will become apparent or obvious to those skilled in the art upon reading and understanding the Detailed Description of the Invention. It is intended to include all such modifications and alterations insofar as they come within the scope of the present invention.