Abstract:
A lock bar for controlling the position of a railroad warning gate includes an elongated body portion extending between a first end and a second end, a clutch mechanism disposed in the elongated body, the clutch mechanism permitting rotational movement in one direction but restricting rotational movement in the opposite direction and a hub disposed in the clutch mechanism for engaging a portion of a motor drive mechanism for a railroad warning gate such that the gate is permitted to move in one direction but is restricted from movement in the opposite direction. Indicia are preferably disposed on the opposing edges to indicate the position that the warning gate will be retained in. An oblong aperture defined through the lock bar receives a pin to hold the lock bar in engagement with the motor drive mechanism.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to apparatus for locking the gear train of a gate warning mechanism at a railroad crossing. More particularly, the present invention relates to improved apparatus that provides for positive locking of the gear train of a warning gate mechanism in a selected direction of movement. 
   BACKGROUND OF THE INVENTION 
     FIGS. 1 and 2  illustrate a prior art lock bar  20 , which is located in a warning gate control box, generally designated  21 . A box or housing  21  has a cover  27  which may be opened to access internal components. Lock bar  20  is used to lock the gear train  22  of a gate mechanism  23  from moving while a maintainer installs a gate arm  33 , such as in  FIG. 4 , to a conversion bracket or to a gate adaptor  24 . Lock bar  20  consists of a steel angle bar that is secured to a pin  25  on a bracket  26  for rotational movement about pin  25 . One end  28  of the lock bar  20  can be manually operated to catch in the teeth of a pinion gear  30  of the motor  32  ( FIG. 4 ) to prevent rotation of the gear train  22  and, hence, of the gate arm  33 . However, lock bar  20  may be used to restrict gear rotation in only one direction. If a maintainer lifts up on the gate while installing it, the lock bar  20  may become dislodged from the teeth of pinion gear  30 , and the gear train  22  will then be free to rotate, including the gate arm  33 . 
   This prior art lock bar  20  requires the maintainer to press a maintenance button located in the gate control box  21  and release it when the gate  33  is in the desired or required position. The end  28  of the lock bar  20  must then be quickly inserted into the teeth of the pinion gear  30  to prevent rotation. The mass of the counterweights  35  located on one end of the gate  33  exerts a force back through the gear train  22  keeping the lock bar  20  wedged in the teeth of the pinion gear  30 . Insertion of the lock bar  20  into the teeth of pinion gear  30  is rather tricky because the pinion gear  30  is often in motion. This can present a potential hazard if the lock bar  20  is used incorrectly or if it becomes disengaged. 
   As can be appreciated from  FIG. 1 , the lock bar  20  is rotated on the pivot pin  25  until the flat on the end  28  of the lock bar  20  settles in the teeth of pinion gear  30 . This “jamming operation” is frequently done with the gear  30  still moving. Any external force applied to the gate arm  33  or to the main shaft  24  ( FIG. 4 ) in the opposite direction will tend to force or push the lock bar  20  out of engagement with the teeth of gear  30 . When the maintenance is completed, the lock bar  20  can be removed from pin  25  at the slotted key hole area  29 , and repositioned with the enlarged portion of the slotted key hole  29  placed over bolt head  34  such that a slot  31  in end  28  of lock bar  20  rests against pin  25 . 
   A general object of the present invention is to provide an improved lock bar for restricting or limiting movement of a railroad crossing warning gate during maintenance. 
   Another object of the present invention is to provide a lock bar for restricting or limiting movement of a railroad crossing warning gate in either the up position or in the down position. 
   A further object of the present invention is to provide a lock bar in the form of a handle with a clutch assembly that permits rotation in one direction, but that restricts or limits rotation in an opposite direction. 
   Yet another object of the present invention is to provide a lock bar that must be removed when maintenance is completed and before a cover of the gate control box can be closed. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a lock bar for controlling the position of a railroad warning gate. The warning gate is moveable from a raised position to a lowered position by a motor drive mechanism. The lock bar includes an elongated body portion extending between a first end and a second end, a clutch mechanism disposed in the elongated body, the clutch mechanism permitting rotational movement in one direction but restricting rotational movement in an opposite direction and means disposed in the clutch mechanism for engaging a portion of the motor drive mechanism such that the railroad warning gate is permitted to move in one direction but is restricted from movement in the opposite direction. The means in said clutch mechanism for engaging a portion of the motor drive mechanism may include an internal hexagonal female surface for engaging a hexagonal shaft on the motor drive mechanism. 
   The lock bar includes opposing edges disposed along the elongated body portion, and preferably includes indicia disposed on a first of the opposing edges for indicating a first position that the warning gate will be retained in if the lock bar is installed on the motor drive mechanism with the first opposing edge in a generally upright manner. Preferably, the lock bar also includes indicia disposed on a second of the opposing edges for indicating a second position that the warning gate will be retained in if the lock bar is installed on the motor drive mechanism with the second opposing edge in a generally upright manner. For example, the first position of retaining the railroad warning gate may be an up position and the second position may be a down position. 
   The lock bar may also include an aperture defined through the lock bar, the aperture suited for receiving a pin of the motor drive mechanism therethrough to hold the lock bar in engagement with the motor drive mechanism. The aperture may be in the form of an oblong slot. The lock bar may include a lanyard, with a first end of the lanyard secured to the lock bar, and with a second end of the lanyard including means to mate the lanyard with the pin of the motor drive mechanism to secure the lock bar about the pin. The means to secure the lanyard to the pin may be a hairpin or a cotter key. 
   The motor drive mechanism is provided with a housing, including a cover for enclosing the motor drive mechanism. The lock bar is preferably of sufficient length between the first and second ends to prevent closure of the cover of the housing while the lock bar remains engaged with the motor drive mechanism. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, together with its objects and the advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures, and in which: 
       FIG. 1  is a partial elevational view, taken in cross-section through the gate control box, illustrating a prior art technique of locking the gear train of the gate mechanism with a lock bar to hold the gate in a desired position during maintenance; 
       FIG. 2  is also a partial elevational view, taken in cross-section through the gate control box, illustrating the prior art lock bar of  FIG. 1  stored in the gate control box when not in use; 
       FIG. 3  is a perspective exploded view which illustrates the various components of the lock bar of the present invention; 
       FIG. 4  is an elevational view illustrating a gate control box with the lock bar shown in  FIG. 3  installed on the end of the motor shaft in accordance with the present invention; 
       FIG. 5  is an enlarged elevational view illustrating the lock bar shown in  FIGS. 3 and 4  installed on the end of the motor shaft in a first orientation to keep the gate up during maintenance in accordance with the present invention; 
       FIG. 6  is an enlarged elevational view illustrating the lock bar shown in  FIGS. 3-5  installed on the end of the motor shaft in a second orientation to keep the gate down during maintenance also in accordance with the present invention; and 
       FIG. 7  is a perspective view of an alternative embodiment of the lock bar which includes a selector lever that determines whether the gate will be kept up or down, also in accordance with the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   It will be understood that the invention may be embodied in other specific forms without departing from the spirit thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. 
   With reference to the drawing Figures,  FIG. 3  illustrates an exploded view of a bi-directional lock bar  40  of the present invention. This lock bar  40  uses an over running bearing/clutch assembly  42  that prevents rotation in one direction but that permits rotation in an opposite direction, such as in the manner of a ratcheting mechanism. This ratcheting assembly  42  is installed in an aperture  43  defined near a first end  45  of the handle  44 . A hub  46  fits concentrically and axially within the clutch assembly  42 . Hub  46  may have a hexagonal interior female portion  47 . Both the clutch assembly  42  and the hub  46  are retained within the aperture  43  of handle  40  by snap rings  48  and  49  disposed in grooves  50  and  51  defined about the outer periphery of hub  46 . 
   A lanyard  58  is used to secure the lock bar  40  in an operational position, as will be further appreciated below. Lanyard  58  has an eyelet end  59  that may be secured to lock bar  40 , as by a threaded fastener  60  in an aperture  61 . Lanyard  58  also has an opposite loop end  62  for receiving a hairpin  63  therethrough. Hairpin  63  may alternatively be in the form of a cotter key or other suitable retaining means. An oblong hole or slot  52  is further defined through lock bar  40  at an intermediate position between the first end  45  and the second end  55 . The use of slot  52  is presented below. 
   Preferably, lock bar  40  has some indicia  53  to indicate how the orientation of the lock bar will limit movement of the gate  33  that is attached to the shaft  24  ( FIG. 4 ) of the gate control box  21 . This is because the clutch assembly  42  may limit rotation of the gate  33  to only one direction, as discussed above. For example, one side  54  of the lock bar may have indicia to the effect “keeps gate down” when lock bar  40  is oriented with side  54  up. An opposite side  57  may have indicia to the effect “keeps gate up” when lock bar  40  is oriented with side  57  up. Thus, a maintainer using lock bar  40  will know to orient the lock bar  40  in the orientation with side  54  up, as shown in  FIG. 3 , to keep the gate  33  down during maintenance, or to orient the lock bar with side  57  up to keep the gate  33  up. 
   As can be seen in  FIG. 5 , a maintainer can install the lock bar  40  in a first orientation with side  57  in an upward orientation by sliding the oblong hole  52  in the bar over a reaction pin  64  that extends from a motor adaptor plate  65 . At the same time, the internal female hexagonal surface  47  of the hub  46  near the first end  45  of the lock bar  40  slides over a corresponding male hexagonal surface on a motor output shaft  66  that extends outwardly from the pinion gear  30 . The lock bar  40  can then secured to the reaction pin  64  by means of the hairpin  63  on the tether or the lanyard  58 . Of course, other means of restricting movement the lock bar  40  will be apparent to those skilled in the art. For example, lock bar  40  may simply limit its movement by coming to rest on some portion of the housing  21  or some other portion of the apparatus. 
   The oblong or slotted hole  52  provides for off-center clearance in case the distance from the hexagonal motor shaft  66  and the reaction pin  64  is not uniform in all motor drive mechanisms. Thus, slotted hole  52  is preferably designed for ample longitudinal clearance between motor shaft  66  and reaction pin  64 , as well ample transverse clearance, such as in case the motor shaft  66  or the reaction pin is slightly bent, or the like. Ample clearance provided by slotted hole  52  therefore makes installation of the lock bar  40  easier. 
   Once the lock bar  40  is installed on the reaction pin  64  and the output shaft  66  of the motor  32 , the maintainer can then press a maintenance button  68  on an electrical printed circuit board (PCB)  69  in the housing of the gate control box  21  to power the gate arm  33  to the down or horizontal position. As soon as the maintainer releases the maintenance button  68 , the gate  33  will stay in this position due to the lock feature of the bearing/clutch  42  of the lock bar  40 . Due to the clutch design, the gate  33  can only move one direction. If any force is applied in the opposite direction, the clutch  42  will lock and prevent movement in the opposite direction. The lock bar  40  thus prevents upward movement of the gate  33  when installed in the orientation shown in  FIG. 6 , i.e., keeps the gate in a down position, such as during maintenance. 
     FIG. 5  illustrates the lock bar  40  installed in a second orientation with side  54  in an upward orientation to prevent downward movement of the gate  33 , i.e., keeps the gate in an up position. This second orientation of  FIG. 6  differs from the first orientation of  FIG. 5  in that the lock bar  40  has been rotated 180 degrees about its longitudinal axis into the second orientation shown in  FIG. 6  before installation on the reaction pin  64  and the motor output shaft  66 . 
   A significant advantage of the lock bar  40  of the present invention is that the lock bar can be installed prior to any need for the warning gate  33  to be locked in the desired direction. For example, if a new crossing gate is being installed, or if the gate arm  33  has been broken off and needs replacement, due to gravity of the counterweights  35  at the opposite end, the gate will be in the vertical or up position. 
   Another feature of the lock bar  40  can be utilized during adjustment of the counterweights  35  on the gate  33 . If the ratcheting lock bar  40  is installed 180 degrees from the position above, downward movement will be restricted. This can be used when the maintainer is changing or setting up the horizontal and vertical torque on the gate mechanism  22 . The procedure is as follows. The lock bar  40  is installed as described above, the gate  33  is powered to the vertical position and gate control is removed. The gate  33  would normally power down when gate control is removed. However, the clutch bearing  42  of the lock bar  40  prevents the gate  33  from lowering. The maintainer can then adjust the counterweights  35  and remove the lock bar  40  when finished. 
   The lock bar  40  is preferably elongated between the first and second ends  45  and  55  such that the lock bar cannot be inadvertently left in place when attempting to close the cover  27  of the gate control box  21  after maintenance procedures have been completed. To this end and as can be appreciated in the drawing figures, the length of the lock bar  40  prevents the cover  27  of the gate control box  21  from being closed when the lock bar is installed in either of the orientations shown in  FIGS. 5  or  6 . Thus, the lock bar  40  cannot be inadvertently left installed on the gear drive mechanism, thereby limiting or preventing movement of the gate  33  after completion of maintenance. 
     FIG. 7  illustrates another embodiment of a lock bar  70 . Lock bar  70  is similar to the previously described lock bar  40 , except that lock bar  70  includes a selector lever  71  to select the direction, clockwise or counterclockwise, of permitted movement of the ratcheting mechanism or clutch assembly  42 . For example, in a first position, selector lever will keep the gate  33  down and in a second position, selector lever  71  will keep the gate  33  up. This embodiment of lock bar  70  has an advantage over lock bar  40  in that lock bar  70  does not need to be removed and reinstalled on the motor drive assembly in an opposite orientation to limit movement in an opposite direction. Instead, selector lever  71  is moved to its opposite position. 
   While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made therein without departing from the invention in its broader aspects.