Patent Publication Number: US-7594357-B2

Title: Manual lift gate system

Description:
PRIORITY CLAIM 
   This application is a nonprovisional application of and claims priority from U.S. Provisional Patent Application No. 60/899,500, filed Feb. 6, 2007, the contents of which are incorporated herein by reference in their entirety. 

   TECHNICAL FIELD 
   The present invention relates generally to barrier systems, such as walls or fences, and more particularly, to gated openings in such barrier systems. 
   BACKGROUND OF THE INVENTION 
   There have been all types of protected barrier openings (or gates), used throughout history. Most gates can be categorized as having one of two common types of movement to clear the path which they protect. These movements are typically either a sliding motion or a swinging motion along a path that is parallel to the ground. In either case, the motion is most often initiated and sustained by some type of human or other mechanical force. 
   Once in motion, a swing-style gate will pivot, generally parallel to the ground, around a single fixed point to which it is hinged. A sliding gate will slide along a prescribed path, also generally parallel to the ground, guided with the aid of a rail or roller system to which it is attached. Both systems can be employed in a variety of ways. Unfortunately, however, in outside applications each system may experience some difficulties maneuvering around, over, or through certain elements. 
   Long grass or deep snow, for instance, can impede the path of either a swing-type or sliding-type gate, making it difficult or impossible to operate the gate under such conditions. The presence of these elements or other obstacles can also restrict how close a bottom of the gate can be arranged with respect to the ground, which can result in leaving an area below the barrier open or exposed. 
   Another difficulty that can be encountered with these movement styles for gates is in the topography of the land surrounding the barrier. The barrier may, for instance, be located at the base of incline where a swing-motion gate would hit the ground in one direction before achieving an open position. On the other hand, a swing-style barrier located at the top of a decline would experience an increase in distance between the gate and the ground when operated toward the decline, making it awkward for a user to operate. 
   For a sliding gate, the topography must be substantially level along the area of the protected opening and the area where the gate must slide. Some installation conditions do not allow for such a setup and must therefore be modified to accommodate the barrier. This can significantly increase the installation costs. 
   In a manual application, another issue with these opening styles is the range over which a person must apply and maintain force in order to fully open or close the gate. For both motions, the manual operator (person), must frequently move along almost the entire distance of the opening in the barrier that the gate covers in order to maintain adequate force throughout the opening or closing procedure. 
   These and other issues make it desirable to find a way to move a gate from a protected barrier opening in such a way that snow, grass, land topography, or other obstacles would not affect the motion of the gate. It would also be desirable to have a gate style that would decrease the range of motion and the amount of force needed for a manual operator to open or close the gate. The present invention fulfills these needs and provides other related advantages. 
   SUMMARY OF THE INVENTION 
   A gate assembly constructed according to principles of the present invention enables a gate to rotate upwardly to clear an opening. The gate assembly can include a biasing member capable of supplying the force necessary to sustain the opening and closing motions of the gate with only a minimal initial application of force (activation force). The gate assembly can have the ability, for instance, with only a small amount of manual force, to lift and rotate a gate (for instance, such as a gate from 0 to 14′ ft (or longer) in length) vertically and thus remove it from the path. 
   In one embodiment, the opening and/or closing biasing force can be evenly sustained over the course of gate travel by a system of springs that maintain a balance between the weight of the barrier and the force of the springs. The motion can, for example, be manually-activated or it may be activated by an electrical signal to a motor, a hydraulic cylinder, or other force-producing electrical device. 
   The system can include a pivot arm to which the gate is attached. This pivot arm preferably pivots at a pivot point about a bottom pivot axis, such as with a pin and bearing setup that is attached to a main frame. A spring adjustment sleeve (slide) can fit around the pivot arm in a sliding relationship. This sleeve is preferably attached to a spring or a series of springs, with the exact number and/or tension of the springs varying depending on the weight of the gate. The slide is preferably moveable up and down on the pivot arm by sliding the springs pull point in either desired direction to change the amount of tension on the arm and thereby provide adequate tension for the weight of the barrier. The springs are also preferably attached to a main frame of the gate on a side opposite the pivot axis. The main frame can be covered in sheet metal, vinyl, or other material to cover the internal components for both safety and aesthetics. 
   In operation, the gate assembly, when in a closed position, preferably hangs from the pivot arm and maintains its position by having the weight of the gate balanced by the force of the spring tension pulling in the opposite direction. When this balance is maintained, the barrier can be easily opened by applying a small amount of force in an upward direction anywhere along the body of the barrier. Upon applying an appropriate amount of force, the springs will aid with the rotation of the mechanical pivot arm about the bottom pivot axis. The barrier then rotates vertically out of the way and comes to a rest partially inside the main frame work. To close the barrier, force can again be applied anywhere along the body of the barrier, this time in a downward direction. Once a certain point is reached, gravity will take over as the force necessary to close the barrier. If properly balanced, the springs will allow the barrier to rotate downwardly only to a certain predetermined point and then the force of the spring tension, balanced by the weight of the gate, will again hold it in place in its closed position. 
   In one embodiment, a gate operating mechanism is provided by the gate itself, which is attached to the pivot arm. The spring adjustment slide can be placed around the pivot arm and can be configured to slide up and down the pivot arm to adjust the spring tension. The spring adjustment slide can include, for instance, a piece of all thread held out by angle iron tabs welded to the pivot arm. The all thread can be placed through an oversized hole of a protruding plate affixed to the slide. Nuts can be threaded on the all thread and placed on either side of the plate to enable the slide to move up or down the pivot arm and to secure the slide in a desired position along the pivot arm once the tension of the springs and the weight of the barrier are in balance. 
   Of course, other types of mechanisms and connections could also be used to provide the biasing force and to provide an adjustment mechanism for configuring an amount of biasing force to be applied to the gate during its opening and closing motions. These mechanisms and connections can further provide the ability to control the amount of force applied to the gate at various points along its course of travel. 
   In one embodiment, the pivot arm can be configured to pivot upwardly from a downward position and downwardly from an upward position about a bottom pivot axis located at a pivot point. This can be accomplished, for instance, by way of a solid shaft centrally affixed to the bottom of the pivot arm at the desired pivot point and then placed through bearings or a set of bushing attached to the base of a main frame work. Again, of course, other types of mechanisms and connections could be used to enable the gate to pivot about a desired pivot axis. 
   The pivot arm can be connected to a spring or series of springs via the spring adjustment slide. The main frame work (or frame) can house the spring(s). The springs can be fastened to the frame on a side of the frame opposite (or otherwise separated from) the pivot point. The frame or the gate can have a guide or set of guides to slide the barrier into a central location within the main frame work and to further function as a stop for the gate once it has achieved a full open position. The frame or the gate can also have a set of guides arranged opposite each other on either side of the frame or the gate to maintain a central stance for the bottom of the gate within the main frame work. The frame can be fastened to the ground or base just to the side of the barrier opening which the gate will protect. 
   Although most elements of this particular embodiment can be made of steel, tube steel, and plate steel, any other suitable material or materials could also be used. In construction, each piece is preferably sized in proportion to the rest of the invention, generally as shown in the accompanying figures. In the case of steel, for instance, the connections can be solid welds or bolt connections. Other connections known within the art are also contemplated, however, as being within the scope of this invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and additional objects, features, and advantages of the present invention will become more readily apparent from the following detailed description, made with reference to the accompanying figures, in which: 
       FIG. 1  is a somewhat schematic cutaway perspective view of a gate assembly according to one embodiment of the present invention; 
       FIG. 2  is a somewhat schematic exploded perspective drawing of a pivot arm and related components as used in the gate assembly of  FIG. 1 ; 
       FIG. 3  is a somewhat schematic side view of another embodiment of the pivot arm of  FIG. 2 , shown in a fully open position; 
       FIGS. 4A and 4B  provide two somewhat schematic perspective views of the gate assembly of  FIG. 1 , illustrating both a fully closed and a fully open position of the gate assembly, respectively; 
       FIG. 5  is a somewhat schematic perspective view of a frame work of the gate assembly of  FIG. 1 ; 
       FIG. 6  is a somewhat schematic exploded perspective drawing of a pivot arm and related components, having a slide adjustment mechanism and a spring adjustment mechanism according to another embodiment of the present invention; 
       FIG. 7  is a somewhat schematic enlarged exploded perspective view of the spring adjustment mechanism shown in  FIG. 6 ; and 
       FIG. 8  is a somewhat schematic enlarged perspective view of the slide adjustment mechanism shown in  FIG. 6 . 
   

   DETAILED DESCRIPTION 
   In the following detailed description, reference is made to the accompanying drawings, which form part thereof, and in which are shown, by way of illustration, exemplary embodiments illustrating various principles of the present invention and how it may be practiced. 
     FIG. 1  is a somewhat schematic cutaway perspective view of a gate assembly  5  according to one embodiment of the present invention.  FIG. 2  provides a more detailed view of a pivot arm  9  and related components as used in the gate assembly  5  of  FIG. 1 .  FIG. 3  shows an alternative embodiment of the pivot arm  9  assembly in a fully open position. And  FIGS. 4A  and  4 B provide two somewhat schematic perspective views of the gate assembly  5  of  FIG. 1 , illustrating the gate  6  in both a fully closed and a fully open position, respectively. 
   Referring to  FIGS. 1 through 4B , a gate assembly  5  provides a moveable security barrier. The security barrier shown in this embodiment is a metal wrought-iron gate  6 , but the inventive concepts of the present invention can be implemented using any of a variety of materials and designs including, for instance, wood picket, vinyl, or chain-link fencing. The gate  6  can be mounted to the main pivot arm  9  of the gate assembly  5 . A plurality of metal plates  14  can, for instance, be welded or bolted to the body of the gate and attached to the pivot arm  9  using bolts of an appropriate size, depending upon the size and weight of the gate  6 . 
   The pivot arm  9  can consist of a main piece of steel tubing having a square (or rectangular) cross-section, which is attached in a hinged connection to a main frame work (frame)  26  (depicted in further detail in  FIG. 5 ). The pivot arm  9  preferably has holes  9   a ,  9   b  drilled through its entire width near each end of the steel tube. These holes  9   a ,  9   b  allow the plates  14 , attached to the gate  6 , to be bolted to the arm  9 . A larger hole  9   c  is preferably also drilled through the width of the pivot arm  9 , at a position above the bottom hole  9   b.    
   The hinged connection between the gate  6  and the frame  26  can, for instance, be provided by a pin  27  and bushing  13  system. Alternatively, however, a standard bearing may replace the bushing  13 . The pin  27  is preferably arranged through the hole  9   c  such that an equal amount protrudes out of the arm  9  on either side. The pin  27  can, for instance, be made from steel round stock. The pin  27  can then be solidly attached to the pivot arm  9 , such as by welding. The pin and arm assembly is preferably arranged through the two bushings  13 , which can be securely welded to the main frame  26 . The bushings  13  can comprise a steel sleeve with a piece of round bronze pressed into the tube for wear purposes. The steel round pin  27  can be arranged through a hole in the bronze piece of the bushing  13  to rotate as the gate  6  is lifted and closed. A washer can be welded to the pin  27  on the outside of the bushing as a keeper, to prevent side to side movement of the pin  27 . 
   The pivot arm  9  can further include an angled connection piece  19 , which can be a piece of angle iron, for example. The angled piece  19  is secured (e.g., by welding) to a side of the pivot arm  9  that does not include the holes  9   a ,  9   b ,  9   c . This angled piece  19  preferably has a hole  19   a  formed centrally through a flange  19   b  that extends perpendicular to the arm  9 . A piece of all thread  15  can be arranged having one end  15   a  arranged through the hole  19   a . The all thread  15  can, for instance, be a piece of steel round stock that has been threaded along its entire length or it can simply be threaded for a predetermined distance at each end  15   a ,  15   b . Other types of adjustment mechanisms could also be used, however, to adjust the location of the adjustment slide  16 , and thus the spring connection location, along the pivot arm  29 . 
   After the all thread  15  is placed through the hole  19   a , a nut  29   a  is preferably placed on the end  15   a  to prevent it from falling all of the way through the hole and to further provide a place for adjustment of the adjustment slide  16 . A second nut (not shown) could also be placed on the all thread  15  on an opposite side of the flange  19   b.    
   The adjustment slide  16  is preferably arranged on the pivot arm  9  in a sliding relationship. The adjustment slide  16  can, for instance, be a piece of steel tubing with a slightly larger cross-sectional opening (ID) than the outside perimeter (OD) of the arm  9 , such that the slide  16  can thereby be placed in a sliding relationship around the arm  9 . The slide  16  preferably has an angled piece  21  attached to it that is similar to the angled piece  19  arranged on the arm  9 . Also similar to the angled piece  19 , the angled piece  21  preferably includes a hole  21   a  formed through a flange  21   b  extending perpendicular from the slide  16 . An opposite end  15   b  of the all thread  15  can then be placed through this hole  21   a . A pair of nuts  29   b ,  29   c  are preferably threaded onto the all thread  15  on opposite sides of the flange  21   b.    
   Two additional angled pieces  20   a ,  20   b  can also be affixed (e.g., welded) proximal to each other on the slide  16 , preferably in an opposing relationship with a gap between them. The gap is preferably large enough to receive a connecting piece  18   a  for the chain  18 . These angled pieces  20   a ,  20   b  also preferably have a common hole  20   c  drilled through both of them. The connecting piece  18   a  of the chain  18  can then be placed between the angled pieces  20   a ,  20   b  and a bolt can be arranged through the hole  20   c  and the connecting piece  18   a  to connect the slide  16  to the chain  18 . Alternatively, as shown in  FIG. 3 , the chain can be directly connected to a single angle piece  20 . Again, of course, any other mechanism for connecting the spring to the slide adjustment mechanism  16  is also within the contemplation of this invention. 
   The chain  18  is preferably connected to a spring  22  via a connector  28 . The other end of the spring  22  can be attached to another connector  28 . The connectors  28  preferably include a hole formed therethrough to connect to the chain  18  or a steel pin  23 . The steel pin  23  is preferably arranged through, and affixed to, two connecting members  24  on the main frame  26 . 
   Referring now specifically to  FIGS. 4A and 4B , in operation, the gate  6  is raised and rotated from its closed position (shown in  FIG. 4A ), out of the way of the barrier opening, by lifting up on one or more of the handles  7 . The gate  6 , through its connection to the pivot arm  9 , is hinged to the main frame work (or box)  26 . With the assistance of the biasing force provided by the tension of the spring  22 , the gate preferably rotates smoothly and gently into the box  26  and comes to rest against the stop  11 . The stop  11  is preferably connected to the main frame  26  to receive the gate  6  in its full up position (as shown in  FIG. 4B ) and position it centrally between the walls of the frame  26 . 
   In the full up position, the top  6   a  of the gate  6  is preferably supported by the wedge shaped notch in the stop  11 , while the bottom  6   b  of the gate  6  is preferably supported in the frame  26  by wedges  12  connected to opposing sides of the bottom  6   b  of the gate  6 . The stop  11  on the frame  26  and the wedges  12  on the gate  6  keep the gate  6  properly oriented in a square and straight position while in the gate  6  is up (open). 
   While in the down (closed) position, the gate is  6  is preferably held in place by the tension of the spring  22 . The tension can be adjusted to compensate for the weight of the gate  6  by adjusting the position of the slide  16  on the pivot arm  9 . More specifically, by moving the nuts  29   b ,  29   c  on the all thread  15  up or down in relation to the angle piece  21  on the slide  16 , the tension of the spring  22  can be increased or decreased. In one configuration, the proper tension of the spring  22  can be such that the gate “floats” inches from the ground and level with the box  26 , with the spring  22  providing enough tension that with less than approximately 5 lbs. of force, the gate rotates vertically in a smooth and steady motion and comes to rest in the box  26  against the stop  11 . The entire apparatus can be secured to the ground through the main frame  26  by way of metal pads  10  which can, for example, be either bolted to concrete or welded to metal concrete imbeds. 
     FIGS. 6-8  are perspective illustrations showing an alternate embodiment of a pivot arm  9  and related components incorporating principles of the present invention. More particularly, in the embodiment shown in  FIGS. 6-8 , a spring adjustment member  30  is preferably arranged along the axis of the spring  22  and a connector (such as a bolt  29   a ′,  29   b ′) can be permanently affixed to one or more of the angled pieces  19 ,  21 . 
   Referring first to  FIGS. 6-7 , in this alternate embodiment, a separate spring adjustment mechanism  30  can be provided to adjust the tension of the spring  22  and hence the force applied to the gate  6  (see  FIG. 1 ). The spring adjustment mechanism  30  can include a bracket  32  having holes  32   b  that receive the steel pin  23 . An opposite end of the bracket  32  can include a hole  32   a  that receives an adjustment member  31 . The adjustment member  31  can, for instance, be a threaded rod (or all thread). The adjustment member  31  is preferably adjustably connected between the frame  26  and the bracket  32  to adjust the distance between the bracket  32  and the frame  26  and hence the tension on the spring  22 . The adjustment member  31  may, for instance, be threadably engaged by a bolt  33   c  permanently affixed to the bracket  32 . Additional bolts  33   a ,  33   b  may connect the adjustment member  31  to the frame  26 . The spring adjustment mechanism  30  can be used instead of, or in addition to, the adjustment slide  16 . 
   Referring now to  FIGS. 6 and 8 , a slide adjustment mechanism can also be provided. In this alternate embodiment, one or both of the angled pieces  19 ,  21  can include a bolt  29   a ′,  29   b ′ that is permanently affixed (e.g., by welding or other mechanical or chemical attachment) to the respective angled piece  19 ,  21 . Alternatively, an end  15   a  or  15   b  of the all thread  15  can have a bolt  29   a ′ or  29   b ′ permanently affixed thereto with an opposite end  15   a  or  15   b  of the all thread  15  arranged in another bolt  29   a ′ or  29   b ′. The bolts  29   a ′,  29   b ′,  33   a ,  33   b ,  33   c  are preferably all of the same, standard size so that a single tool can be used to make all the necessary adjustments. The adjustment tool can be provided to a customer purchasing the gate  6 . 
   Having described and illustrated principles of the present invention in various preferred embodiments thereof, it should be apparent that the invention can be modified in arrangement and detail without departing from such principles. I therefore claim all modifications and variations coming within the spirit and scope of the following claims.