Abstract:
A railroad crossing gate comprising a crossing gate arm having a counterweight support structure and one or more counterweights supported by the counterweight support structure. The counterweight support structure includes a gear rack provided along a first portion of the crossing gate arm and a pinion gear operatively coupled to and selectively movable along the gear rack.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates generally to railroad crossing gates. More specifically, this invention relates to a railroad crossing gate having a rack and pinion counterweight adjustment system and universal crossing gate arms. 
         [0003]    2. Description of the Related Art 
         [0004]    Automatic railroad gates, which include one or more railroad crossing gate arms, are used at many crossings where a road intersects a railroad track. The typical railroad crossing gate arm is finely counterbalanced with a weight or weights so that only a relatively small, low horsepower, and low current consuming rotary electric motor having associated gears is necessary to move the railroad crossing gate arm up and down as needed. The use of low horsepower motors, which consume low power, is particularly important in situations where railroad gates are located in isolated or inaccessible places where they may have to be run from battery power or, in some modern installations, solar charged battery power. 
         [0005]    Due to a number of considerations, described below, frequent adjustments and realignments of the counterbalance weights are typically required in order to insure that the railroad crossing gate arm is able to be readily moved by the associated low horsepower motor. Such considerations include changing weather conditions, particularly changing temperatures with changing seasons, snow accumulation on the crossing gate arm, wear and tear on the operating motor, and changes in the power system, such as current source variations. Other factors which may disturb the balance or require readjustment include broken or damaged railroad crossing gate arms due to being struck by a vehicle or damage to the gate due to vandalism. 
         [0006]    The adjustment of existing counterbalance weight mechanisms is not, however, a simple task. A railroad crossing gate arm is a relatively heavy structure and, as a result, the counterbalance weights are also quite heavy. That is particularly true if the counterbalance arm is to be made relatively short in order to obtain maximum leverage. Adjusting counterbalance weights, which are usually in the form of metal plates, normally entails releasing a large bolt-type fitting or other fastening means which maintains the counterbalance weights in a particular longitudinal position with respect to the gate structure, and then moving such counterbalance weights to a different longitudinal or other position on the gate structure. Once the weights have been repositioned, the large bolts or other fastening means are retightened manually. Since the counterweights are quite heavy, the readjustment process requires a large weight to be supported by the maintenance personnel performing the readjustment during the entire process. As a result, it is not unusual for a manual adjustment of the weights on a gate to take several hours, incurring a very significant cost in manpower. Such personnel are particularly subject to strained muscles, hernias, and other like injuries while adjusting the counterweights. In other words, the readjustment process presents a great risk of injury to personnel. Additionally, as will be appreciated, the manual adjustment process is often quite time consuming. 
         [0007]    Furthermore, railroad crossing gate arms are designed to be mounted on a specific side of the housing that contains the railroad crossing gate mechanism. That is, railroad crossing gate arms are designed to be mounted on either the left side of the housing or on the right side of the housing only. Current railroad crossing gate arms are single-sided because the crossing gate arms have a hub receiving mechanism (i.e., a web or a flange) for receiving a motor hub that is disposed on only one side of the crossing gate arm and, therefore, permit mounting on only one side of the housing that houses the motor. If the railroad crossing gate arm is designed to be mounted on the left side of the housing, then the railroad crossing gate arm cannot be mounted on the right side of the housing and vice versa. This is problematic because a large stockpile of left and right sided railroad crossing gate arms has to be stored in a storage facility in the event that a railroad crossing gate arm has to be replaced. 
       SUMMARY OF THE INVENTION 
       [0008]    These needs and others are met by embodiments of the invention, which provide a railroad crossing gate having a universal crossing gate arm with a rack and pinion counterweight adjustment system. 
         [0009]    In accordance with one embodiment of the invention, a railroad crossing gate is provided that includes a crossing gate arm having a counterweight support structure and one or more counterweights supported by the counterweight support structure. The counterweight support structure includes a gear rack provided along a first portion of the crossing gate arm and a pinion gear operatively coupled to and selectively movable along the gear rack. The one or more counterweights are operatively coupled to the pinion gear and may be selectively moved along the first portion of the crossing gate arm by selectively moving the pinion gear along the gear rack. 
         [0010]    In accordance with another embodiment of the invention, a universal crossing gate arm for use in a railroad crossing gate. The railroad crossing gate has a motor for selectively rotating the universal crossing gate arm about an axis of rotation. The rotor has a driveshaft and a hub which is operatively coupled to the driveshaft. The universal crossing gate arm includes a first face, a second face, a first hub receiving element disposed on the first face, and a second hub receiving element disposed on the second face. The first and second hub receiving elements are structured to receive and engage with the hub of the motor. 
         [0011]    In accordance with yet another embodiment of the invention, a counterweight support structure for movably supporting one or more counterweights in a railroad crossing having a crossing gate arm. The counterweight support structure includes a gear rack provided along a first portion of the crossing gate arm, a pinion gear operatively coupled to and selectively movable along the gear rack, and means operatively coupled to the pinion gear for supporting the one or more counterweights. The counterweights may be selectively moved along the first portion of the crossing gate arm by selectively moving the pinion gear along the gear rack. 
         [0012]    One aspect to this invention is to provide a counterweight adjustment system that reduces the amount of time required to adjust the counterweights on a railroad crossing gate arm. 
         [0013]    Another aspect to this invention is to provide a railroad crossing gate arm that can be mounted on opposite sides of a housing that contains a railroad crossing gate mechanism. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    A full understanding of the disclosed and claimed concept can be gained from the following Description when read in conjunction with the accompanying drawings in which: 
           [0015]      FIG. 1  is an isometric view of a portion of an automatic railroad crossing gate in accordance with one embodiment of the invention; 
           [0016]      FIG. 2  is an exploded view of a universal crossing gate arm and a counterweight adjustment system forming a part of the automatic railroad crossing gate arm of  FIG. 1 ; 
           [0017]      FIGS. 3A and 3B  are left and right side elevation views of the universal crossing gate arm shown in  FIG. 2 , and 
           [0018]      FIG. 4  is an isometric view of a portion of the universal crossing gate arm and counterweight adjustment system shown in  FIGS. 1 and 2 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    As used herein, the term “universal railroad crossing gate arm” and variations thereof shall broadly refer to a crossing gate arm that can be positioned on either side of a housing that contains a railroad crossing gate mechanism used to move the railroad arm. 
         [0020]    As used herein, the term “mechanical fastener” or variations thereof shall broadly refer to any suitable fastening, connecting or tightening mechanism including, but not limited to, screws, bolts, nuts, and the combination of bolts and nuts or bolts/nuts and washers. 
         [0021]    Directional phrases used herein, such as, for example, upper, lower, left, right, vertical, horizontal, top, bottom, above, beneath, clockwise, counterclockwise and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein. 
         [0022]      FIG. 1  shows a portion of a railroad crossing gate  2  according to one embodiment of the present invention. The railroad crossing gate  2  includes a housing  4  that contains therein a rotary electric motor having associated gears (not shown) that selectively raises and lowers the universal crossing gate arms  6  (described below) and the elongated crossing gate arms that typically extend therefrom. As seen in  FIG. 1 , a circular hub  12  extends from the housing  4  on either side thereof. Each hub  12  is rotatably connected to the drive shaft of the motor contained within the housing  4  and is, therefore, rotatably driven thereby. In addition, each hub  12  has a plurality of bolts (not shown) which extend in a circular fashion around the outer periphery thereof. A central shaft  8  is disposed within the circular arrangement of bolts. 
         [0023]    As seen in  FIG. 1 , the railroad crossing gate  2  has two universal crossing gate arms  6  that are positioned on opposite sides of the housing  4 . It is noted, however, that in alternate embodiments the railroad crossing gate  2  can have a single universal crossing gate arm  6  as described herein. Each of the universal crossing gate arms  6  includes a hub receiving element  14 , such as a recessed web or a flange, on each side thereof (i.e., on both the left and right sides thereof as shown in  FIGS. 3A and 3B ). As described in greater detail hereinbelow, each hub receiving element  14  is structured to receive and engage with a selected one of the hubs  12  extending from the housing  4 . In this manner, each universal gate arm  6  may be selectively and rotatably attached to a chosen side of the housing  4  such that they may be driven by the motor (not shown) contained therein. Accordingly, the universal crossing gate arm  6 , unlike other current crossing gate arm designs, is capable of being mounted on either side of the housing  4 . 
         [0024]    Referring to  FIGS. 1 and 2 , each of the universal crossing gate arms  6  also includes a counterweight adjustment system  16 . The counterweight adjustment system  16  is shown in exploded fashion in  FIG. 2 . The counterweight adjustment system  16  comprises a gear rack  18  that is disposed on each side of the universal crossing gate arm  6 . The gear rack  18  is positioned adjacent to a bottom side of an elongated aperture  20  that extends along the length of the universal crossing gate arm  6 . The gear rack  18  has a plurality of teeth  22  extending from a top surface of the gear rack  18 . Adjacent to the top side of the elongated aperture  20  is a beam  24 , preferably having a length substantially equal to the gear rack  18 , which extends along the universal crossing gate arm  6  in a direction substantially parallel to the gear rack  18 . A plurality of elongated shafts  26 , each having a first end and a second end, extend through the elongated aperture  20  in a direction substantially perpendicular to the length of the gear rack  18  and the beam  24 . In the embodiment depicted in  FIGS. 1 and 2 , the elongated shafts  26  are threaded. 
         [0025]    Referring to  FIGS. 2 and 4 , in order to prevent the elongated shafts  26  from mechanically engaging with the teeth  22  of the gear rack  18 , each of the elongated shafts  26  extend through a corresponding sleeve  28  that is positioned within the elongated aperture  20 . The first end of each elongated shaft  26  is positioned on the side of the universal crossing gate arm  6  that is adjacent to the housing  4  (i.e., the inner side of the universal crossing gate arm  6 ). Each elongated shaft  26  is selectively movably secured to the universal crossing gate arm  6  by a mechanical fastener, such as a bolt  30  and washer  32 , which is fastened to the first end of the elongated shaft  26 . As can be seen from  FIG. 1  (and in the detailed portion thereof shown in  FIG. 4 ), the washers  32  do not come into contact with the teeth  22  of the gear rack  18 , but rather the washers  32  contact the outer surface  34  of the gear rack  18 . On the opposite side of the universal crossing gate arm  6  (i.e., the outer side which faces away from the housing) is a support plate  36  having a plurality of apertures  38  through which the elongated shafts  26  extend. The counterweights (not shown) are structured to be mounted on the elongated shafts  26  and the support plate  36 . In the embodiment depicted in  FIGS. 1 and 2 , the apertures  38  in the support plate  36  are threaded. Accordingly, each elongated shaft  26  mechanically engages the corresponding aperture  38  through which it extends, thereby securing the elongated shaft  26  to the support plate  36 . 
         [0026]    A pinion gear  40  is positioned between the elongated shafts  26  on the inner side of the universal crossing gate arm  6  (i.e., the side adjacent to the housing  4 ). The pinion gear  40  is structured to mechanically engage with the gear rack  18  (specifically, the teeth  22  of the gear rack  18 ) that is provided on the inner side of the universal crossing gate arm  6 . The pinion gear  40  is secured to the support plate  36  by a mechanical fastener  42  that extends through the pinion gear  40  and into an aperture  44  disposed on the support plate  36 . Rotation of the pinion gear  40  as shown by the arrows  46  will cause the support plate  36  and the elongated shafts  26  (hereafter, the pinion gear  40 , the elongated shafts  26 , the support plate  36 , and any associated structures shall collectively be referred to as the counterweight support structure) to move along the gear rack  18  in either direction therealong. As will be discussed in greater detail below, the location of the counterweights that are mounted to the universal crossing gate arms  6  can be adjusted by rotation of the pinion gear  40  in this manner. 
         [0027]    Referring to  FIGS. 3A and 3B , the hub receiving element  14  that is disposed on each side of the universal crossing gate arm  6  allows the universal crossing gate arm  6  to be mounted on either side of the housing  4 . As can be seen from these figures, the hub receiving element  14  is comprised of a central aperture  10  that is surrounded by a plurality of apertures  48 . In the embodiment depicted in  FIGS. 3A and 3B , the central aperture  10  is surrounded by twelve apertures  48 . The central aperture  10  is adapted to receive the central shaft  8  of the hub  12  while the apertures  48  are adapted to receive the bolts (not shown) positioned around the outer periphery of the hub  12 . The hub  12  is then fastened to the universal crossing gate arm  6  by a plurality of mechanical fasteners (not shown), such as nuts, that engage the bolts that surround the central aperture  10 . Once the hub  12  is fastened to the universal crossing gate arm  6 , the universal crossing gate arm  6  can be raised and/or lowered by the motor provided within the housing  4 . Moreover, to facilitate the universal nature of the universal crossing gate arm  6  (i.e., to allow it to be mounted on either side of the housing  4  along with a functioning counterweights support structure), the gear rack  18  as well as the beam  24  is also disposed on each side of the universal crossing gate arm  6  adjacent to the elongated aperture  20  in the manner described herein. 
         [0028]    When the position of the counterweight support structure, including the counterweights that are mounted on the counterweight support structure, needs to be adjusted, the mechanical fasteners that secure the elongated shafts  26  to the universal crossing gate arm  6  are loosened to permit the counterweight support structure to be relocated. Once the mechanical fasteners on the elongated shafts  26  are loosened, the pinion gear  40  is rotated. Rotation of the pinion gear  40  moves the counterweight support structure in the direction that the pinion gear  40  is being rotated. Once the counterweight support structure is in the desired location, the mechanical fasteners on the elongated shafts  26  are retightened, thereby securing the counterweight support structure to the universal crossing gate arm  6 . 
         [0029]    In accordance with another embodiment of the invention, the elongated shaft is smooth and is secured to the support plate  36  by a mechanical fastener that is either positioned between the support plate  36  and a side of the universal crossing gate arm  6  or adjacent to a side of the support plate  36 . 
         [0030]    In accordance with another embodiment of the invention, the pinion gear  40  is located adjacent to only one elongated shaft  26 . 
         [0031]    In accordance with yet another embodiment of the invention, the gear rack  18  and beam  24  are cast with the universal crossing gate arm  6 . 
         [0032]    In accordance with yet another embodiment of the invention, the gear rack  18  and beam  24  are welded and/or mechanically fastened onto the universal crossing gate arm  6 . 
         [0033]    The accompanying figures and the description that follows set forth this invention in its preferred embodiments. It is, however, contemplated that persons generally familiar with railroad crossing gates will be able to apply the novel characteristics of the structures and methods illustrated and described herein in other contexts by modification of certain details. Accordingly, the figures and description are not to be taken as restrictive on the scope of this invention, but are to be understood as broad and general teachings.