Abstract:
A railroad gate release mechanism which attaches between the mount arms of a railroad gate actuator and a crossing arm to prevent breakage of the crossing arm due to impingement by a vehicle. The railroad gate release mechanism includes a pivotable arm assembly which allows movement of the crossing arm in two directions in response to the impingement and returns the crossing arm to the original and detented position subsequent to the impingement to maintain grade crossing protection. Spring assemblies, a shock absorber and a spring centering assembly act to return the pivotable arm assembly and attached crossing arm to the normal detented position.

Description:
CROSS REFERENCES TO CO-PENDING APPLICATIONS 
     None. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is for a railroad gate release mechanism, and in particular, is for a railroad gate release mechanism which allows for maintaining of structural integrity of a railroad grade crossing arm during and subsequent to being struck by an automotive vehicle. Although a railroad gate release mechanism is described, the release mechanism can be incorporated for other uses such as, but not limited to, parking lot gates, restricted access gates, road closure gates, toll gates, and the like. 
     2. Description of the Prior Art 
     Railroad crossing grades are protected by railroad grade crossing arms which are stored substantially in a vertical position and which are actuated by railroad gate actuators which reorient the crossing arms to a horizontal position across a railroad grade crossing to warn operators of vehicles of oncoming train traffic and to physically place a barrier in the form of a crossing arm at both sides of the railroad grade crossing to prevent passage of a vehicle into the railroad grade crossing. Motorists unaware of the movement of a crossing arm may impinge the crossing arm to the extent that physical damage occurs where the crossing arm is broken and parted from the railroad gate actuator. Such an occurrence can compromise the safety of the railroad grade crossing in that other motorists will not be warned of impending danger due to the destruction of the crossing arm. Such occurrences compromise safety, as well as add a financial maintenance burden. 
     SUMMARY OF THE INVENTION 
     The general purpose of the present invention is to provide a railroad gate release mechanism. 
     According to one embodiment of the present invention, there is provided a railroad gate release mechanism for attachment between a railroad gate actuator and a crossing arm including opposing channel-shaped brackets which attach to a railroad gate actuator and which also serve as mounting structure for other components of the railroad gate release mechanism. A pivotable arm assembly, to which a crossing arm is attached, pivotally mounts between bearing plates located on the inwardly facing surfaces of the opposing channel-shaped brackets. The pivotable arm assembly is influenced by a detent and plunger arrangement which maintains a perpendicular relationship of the pivotable arm assembly and the attached crossing arm with respect to the railroad gate actuator until acted upon by outside forces, such as a vehicle impinging the crossing arm. Such impingement causes the railroad gate release mechanism, with the attached crossing arm, to pivotally overcome the influence of the detent and plunger arrangement and to swing substantially horizontally out of the way of the impinging vehicle without functional damage to the crossing arm. Such pivotal breaking away substantially reduces the possibility of breakage of the crossing arm, as little bending moment is actually applied to the crossing arm itself due to the substantially unrestricted movement allowed by the railroad gate release mechanism. Subsequent to such impingement and when the vehicle has ceased to contact the crossing arm, spring assemblies function to return the pivotable arm assembly of the railroad gate release mechanism, with the attached crossing arm, to the detented position to continue to offer gated protection at the crossing grade. A shock absorber allows for rapid rate pivoting of the pivotable arm assembly in one direction during impingement and allows for a slower rate return of the pivotable arm assembly in the return direction subsequent to impingement. A centering spring assists in returning of the pivotable arm assembly to the detented position. 
     One significant aspect and feature of the present invention is a railroad gate release mechanism which secures between the mount arms of a railroad gate actuator and a crossing arm. 
     Another significant aspect and feature of the present invention is a railroad gate release mechanism which when impinged releasably allows breakaway pivoting in two directions of a crossing arm from a normal and detented position to prevent damage to the crossing arm. 
     Another significant aspect and feature of the present invention is a railroad gate release mechanism which allows return pivoting of a crossing arm to a normal and detented position subsequent to breakaway pivoting caused by impingement. 
     Still another significant aspect and feature of the present invention is a railroad gate release mechanism which offers grade crossing protection subsequent to crossing arm impingement. 
     Yet another significant aspect and feature of the present invention is the use of cables attached to a pivotable arm assembly which connect to springs in spring assemblies which are compressed during impingement with the front side of a crossing arm to subsequently power the return of the pivotable arm assembly and attached crossing arm to an original and detented position. 
     A further significant aspect and feature of the present invention is the use of a shock absorber which allows rapid deployment and release of a pivotable arm assembly and attached crossing arm during impingement and which allows return of the pivotable arm assembly and attached crossing arm at a slower rate subsequent to impingement, whereby the slower return rate reduces return overshoot of the pivotable arm assembly and the crossing arm. 
     A still further significant aspect and feature of the present invention is the use of a centering spring assembly which urges the pivotable arm assembly into a normal and detented position when the crossing arm is impinged from the rear side. 
     Having thus described an embodiment of the present invention and set forth significant aspects and features thereof, it is the principal object of the present invention to provide a railroad gate release mechanism. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects of the present invention and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof and wherein: 
     FIG. 1 illustrates an isometric view of a railroad gate release mechanism, the present invention, along with portions of mount arms and a crossing arm which are associated therewith in use; 
     FIG. 1 a  illustrates the use of the railroad gate release mechanism of the present invention in combination with a prior art actuator; 
     FIG. 2 illustrates the railroad gate release mechanism with an upper bracket removed; 
     FIG. 3 illustrates a rear isometric view of the elements of FIG. 2; 
     FIG. 4 illustrates an isometric view of the pivotable arm assembly; 
     FIG. 5 illustrates an end view of the railroad gate release mechanism; 
     FIG. 6 illustrates a side view of the railroad gate release mechanism; 
     FIG. 7 illustrates a top view of the railroad gate release mechanism in partial cutaway showing its normal position when in use; and, 
     FIG. 8 illustrates a top view of the railroad gate release mechanism in partial cutaway showing how it moves when the crossing arm is impinged by a vehicle or other object. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates an isometric view of the railroad gate release mechanism  10 , the present invention, shown in the position which it has between mount arms  20  and  22  of a railroad gate actuator  23  (FIG. 1 a ) and a crossing arm  12  when the crossing arm  12  is in the horizontal position, such as for stopping of traffic at a railroad grade crossing. 
     FIG. 2 illustrates the railroad gate release mechanism  10  with an upper bracket  14  removed for the purpose of clarity. With respect to FIGS. 1 and 2, the invention is further described. Partial or fully visible components of the railroad gate release mechanism  10  include opposing upper and lower brackets  14  and  16  each having a plurality of mounting holes  18   a - 18   n  for attachment to the mount arms  20  and  22  of a railroad gate actuator  23 , as well as other holes for mounting of other components thereto. Opposing upper and lower bearing plates  24  and  26  suitably secure to the inwardly facing surfaces of the upper and lower brackets  14  and  16  to accommodate a vertically oriented pivot pin  28  and a pivotable arm assembly  30 . The pivotable arm assembly  30  aligns between the upper and lower brackets  14  and  16  and is pivotally secured therebetween by the pivot pin  28 . The pivotable arm assembly  30  includes, in part, an arm  50  and opposing geometrically configured and horizontally aligned upper and a lower swing plates  32  and  34 . Arm  50  serves as a mount for the crossing arm  12 , shown in FIG.  1 . One end of the lower swing plate  34  is in the shape of an arc to which opposing cable guide plates  36  and  38  are opposingly and suitably secured. The cable guide plates  36  and  38  extend beyond the arced end of the lower swing plate  34  to form a cable channel  40  therebetween. A semi-circular detent  42  is comprised of semi-circular cutouts in each of the cable guide plates  36  and  38  the combination of which forms detent  42 . The upper swing plate  32  is fashioned similarly to the lower swing plate  34  and includes opposing cable guide plates  44  and  46  to form a cable channel  48 . Brace plates  49  and  51  (FIG. 4) also align between the upper swing plate  32  and the lower swing plate  34  and abut opposing sides of a right arm plate  52 . The arm  50  aligns and suitably secures between the upper swing plate  32  and the lower swing plate  34 . The arm  50  includes the right arm plate  52  aligned between the full length of the upper swing plate  32  and the lower swing plate  34 . The right arm plate  52  extends outwardly beyond the upper swing plate  32  and the lower swing plate  34  and, as such, serves as a mount for a left arm plate  54  and spacer bars  56  and  58  disposed therebetween. A portion of the right arm plate  52  extends along the length of the upper swing plate  32  and the lower swing plate  34 . A right brace plate  62  and a left brace plate  64  are mounted vertically between the upper bracket  14  and the lower bracket  16 . A plunger housing  66  including a spring loaded movable plunger  68  mounts to the right brace plate  62 . The plunger  68  engages the detent  42  of the pivotable arm assembly  30  to maintain the position of the pivotable arm assembly  30  where the crossing arm  12  is extended across a grade crossing. The left brace plate  64  also serves as a mounting plate for upper and lower spring assemblies  70  and  72 , a shock absorber  74 , and a centering spring assembly  76 . 
     FIG. 3 illustrates a rear isometric view of the elements of FIG.  2 . Illustrated in particular is the relationship of the pivotable arm assembly  30  to the upper and lower spring assemblies  70  and  72 , the centering spring assembly  76 , and the shock absorber  74 . opposing mounting brackets  78  and  80  align and suitably secure into slots  82  and  84 , respectively, in the left brace plate  64 . One end of the shock absorber  74  pivotally secures to the mounting brackets  78  and  80 , and the other end of the shock absorber  74  pivotally secures to a pair of mounting brackets on the arm  50 . The shock absorber  74  when moved to the compressed position allows rapid movement of the pivotable arm assembly  30  and allows a slower rate of movement when returning to the extended position to suitably control the return rate of the pivotable arm assembly  30  subsequent to impingement of the crossing arm  12 . The horizontally oriented upper and lower spring assemblies  70  and  72  align and suitably secure in bores  86  and  88  in the left brace plate  64 . One end of cables  90  and  92  secure by ball ends  94  and  96  (FIG. 2) and align in the cable channels  40  and  48  of the lower and upper swing plates  34  and  32 , respectively. The other ends of the cables  90  and  92  secure to circular plates  98  and  100  located inside of the lower and upper spring assemblies  72  and  70 . Springs  102  and  104  are located interior to the lower and upper spring assemblies  72  and  70  between the circular plates  98  and  100  and the inward facing ends  106  and  108  of the lower and upper spring assemblies  72  and  70 . Movement of the pivotable arm assembly  30  including its arm  50  in a direction as indicated by arrow  110  causes compression of the springs  102  and  104  to provide for subsequent spring powered action of the pivotable arm assembly  30  to return the pivotable arm assembly  30  to its normal detented position subsequent to impingement of the crossing arm  12 . 
     FIG. 4 illustrates an isometric view of the pivotable arm assembly  30 . Illustrated in particular are the tabbed brace plates  49  and  51  extending vertically and secured between the upper swing plate  32  and the lower swing plate  34 . One set of mounting brackets  112  secures at one end of the right arm plate  52  to serve as a mount for one end of the centering spring assembly  76  (FIG.  3 ), and another set of mounting brackets  114  secures at a mid-position on the left arm plate  54  to serve as a mount for one end of the shock absorber  74  of FIG.  1 . 
     FIG. 5 illustrates an end view of the railroad gate release mechanism  10 . A rectangular hole  65  is provided in the right mounting plate  62  to accommodate the plunger  68  and to accommodate other mounting geometry of the plunger housing  66 . 
     FIG. 6 illustrates a side view of the railroad gate release mechanism  10 , where all numerals correspond to those elements previously described. 
     FIG. 7 illustrates a top view of the railroad gate release mechanism  10  in partial cutaway showing its normal position when in use, where all numerals correspond to those elements previously described. The cable guide plate  44  and underlying cable guide plate  46  are shown in partial cutaway to reveal the detent  42  in the lower swing plate  34  of the pivotable arm assembly  30 . The spring loaded plunger  68  engages the detent  42  of the pivotable arm assembly  30  to maintain the position of the pivotable arm assembly  30  where the crossing arm  12  (FIG. 1) is extended across a grade crossing. The spring loaded plunger  68  is of sufficient strength to maintain the pivotable arm assembly  30  including its arm  50  and an attached crossing arm  12  in the desired orientation during raising and lowering and to maintain the desired orientation extending across the crossing grade unless impinged by a vehicle. 
     FIG. 8 illustrates a top view of the railroad gate release mechanism  10  in partial cutaway and best illustrates the mode of operation of the railroad gate release mechanism  10 , where all numerals correspond to those elements previously described. Pivotal arm relief is provided for front side or rear side impingement of the attached crossing arm  12 . Impingement of the front side of the attached crossing arm  12  by a vehicle or other object forces pivoting of the pivotable arm assembly  30  about the pivot pin  28 , as shown by arrow  110 . Such pivoting allows, for purposes of example and illustration, rotation of 40° of the pivoting arm assembly  30  about the pivot pin  28 . Such forced pivoting causes disengagement of the spring loaded plunger  68  from the detent  42  of the pivotable arm assembly  30 , thus allowing the pivotable arm assembly  30  and attached crossing arm  12  to pivot, thereby preserving the integrity of the attached crossing arm  12 . Pivoting of the pivotable arm assembly  30  and attached crossing arm  12  is allowed at a suitable and rapid rate and is not greatly influenced by the shock absorber  74 . However, return of the pivotable arm assembly  30  and attached crossing arm  12  to the detented position is influenced by the shock absorber  74  which acts to allow return pivoting at a rate much less than that during impingement-caused pivoting. During impingement-caused pivoting of the pivotable arm assembly  30  and attached crossing arm  12 , spring  104  in the upper spring assembly  70  and spring  102  in the lower spring assembly  72  are compressed by the movement of the cables  92  and  90 , respectively, which are attached in the cable channels  48  and  40  located on the ends of the upper swing plate  32  and the lower swing plate  34 , respectively. Such spring compression provides force to return the pivotable arm assembly  30  and attached crossing arm  12  towards and into the detented position at a controlled rate as provided by the shock absorber  74 , as previously described. 
     Impingement of the rear side of the attached crossing arm  12  provides for disengagement of the spring loaded plunger  68  from the detent  42  of the pivotable arm assembly  30 , thus allowing the pivotable arm assembly  30  and attached crossing arm  12  to pivot, thereby preserving the integrity of the crossing arm  12 . Such pivoting allows, for purposes of example and illustration, rotation of 15° of the pivoting arm assembly  30  about the pivot pin  28  as generally shown by arrow  116 . The centering spring assembly  76  urges and assists the pivotable arm assembly  30  to return to a normal and detented position. 
     Various modifications can be made to the present invention without departing from the apparent scope hereof.