Patent Publication Number: US-6220553-B1

Title: Railroad switch stand

Description:
FIELD OF THE INVENTION 
     The present invention relates to railroad switch stands for moving a pair of switch points between two rails and diverting rolling stock from one track to another. More particularly, this invention relates to railroad switch stands that can remain operable after certain types of mechanical failures. 
     DESCRIPTION OF THE PRIOR ART 
     In switching rolling stock from one set of rails to another, a pair of stationary rails and a pair of switching rails are arranged so that the switching rails can be moved either to keep trains on a main track or divert them to a branch track. The switching rails are moved by a switching device which includes a connecting rod extending horizontally beneath the tracks that is connected to the switching rails. 
     The switching device typically includes a switch stand at one side of the rails which can be operated either manually or automatically. When operated by hand, a weighted lever arm lying horizontally on the ground or at the base of the switch stand can be lifted and thrown through an arc of 180° to the opposite side of the switch stand where it again will rest horizontally on the ground or base. The mechanism of the switch stand converts the rotational movement of the lever arm into the linear movement of the connecting rod which, in turn, controls the movement of the switching rails. 
     SUMMARY OF THE INVENTION 
     The principle object of this invention is to maintain a switch stand in operative condition if certain of the mechanical elements of the switch become disassociated from each other. 
     Another object of this invention is to provide means to permit a faulty switch stand to remain in operation until it can be repaired. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects of this invention can be understood by reference to the accompanying drawings in which: 
     FIG. 1 is a plan view of a pair of stock rails and a pair of switch points illustrating the connection of the switch points to a switch stand via a connecting rod. 
     FIG. 2 is a side view, partially in section, taken along section lines  2 — 2  of FIG. 1 illustrating a switch stand made in accordance with this invention. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Turning to FIG. 1 of the drawings it may be observed that a pair of switch points  10  and  12  lie between a pair of stock rails  14  and  16 . The switch points  10  and  12  are connected by a laterally extending switch rod  18 . A connecting rod  22  serves to link the switch rod  18  to a switch stand  30 . The switch stand  30  has a base  32  which enables mounting the stand on a pair of adjacent railroad ties  34  and  36 . 
     In the operating position of the switch stand  30  as depicted in FIG. 1, the switch point  10  rests against the stock rail  14 . Upon operation of the switch stand  30  to its second operating position the connecting rod  22  and the switch rod  18  are moved to the right such that the switch point  10  moves away from the stock rail  14  and switch point  12  is moved into contact with stock rail  16 . Thus, it may be understood that operation of the switch stand  30  between its two operating positions causes the connecting rod  22  to be extended in one direction to move the switch rod  18  and the switch points  10  and  12  from a position in which one switch point lies against one stock rail to a position in which the opposite switch point lies against the opposite stock rail. 
     FIG. 2 illustrates a portion of the working mechanisms of the switch stand  100  which enables switching rolling stock from one set of rails to another. Quite generally the switch stand  100  supports a spindle  102  which terminates at its lower in a stub shaft  110 . A crank  112  is mounted on the distal end of the stub shaft and is mechanically linked to the stub shalt  110  by means of hub  116 . The hub  116  is pinned to the stub shaft  110  by a cross pin  114  that passes diametrically through the hub  116  and the stub shaft  110 . The cross pin is not intended to transmit turning forces but only holds the hub  116  in proper vertical alignment with the stub shaft  110 . Were it not for the cross pin  114  the hub  116  could work its way downwardly on the stub shaft  110  until it became detached from the stub shaft  110  and the crank  112  could not be moved. 
     While not illustrated in the drawings it should be noted that the stub shaft  110  is of rectilinear cross section with flat outer surfaces that mate with similar flat surfaces on the inner surfaces of the hub  116 . These flat surfaces key the stub shaft  110  to the hub  116  and transmit rotational motion from the stub shaft  110  directly to the hub  116  which, in turn, causes rotation of the crank  112 . An upstanding shaft  101  is linked to the rotational mechanism and transmits the turning force to the spindle  102 . 
     The spindle  102  is surrounded by a housing  104 . A portion of the housing  104  is utilized as a sleeve bearing  106  which enables the spindle  102  and its machined surface  108  to rotate in the sleeve bearing  106 . 
     The motive force used to rotate the spindle is of no particular consequence in the practice of this invention. Thus a hydraulic or an electric motor may be used to rotate the spindle  102 . More conventionally, however, switch stands include a gear segment mounted at a right angle to the end of an operating lever (not shown) which engages a pinion gear (not shown) mounted on the shaft  101  that can be rotated through an arc of 180° to change the position of the switch points. The operating lever may be weighted at its free end—typically with a 20 or 30 pound weight—which insures that when manually operated from one position to another, the lever arm will seat in either the open or thrown position. A foot operated latch mechanism may be provided to secure the lever arm in its fixed position. 
     When the stub shaft  110  is rotated, the crank  112  will rotate with it and in turn, through an upstanding boss  108  the connecting rod  120  will be caused to move in essentially a linear manner to move the switch point from one position to another. 
     As described above, the crank  112  is held on the stub shaft  10  by means of a cross pin  114  that prevents the crank  112  from sliding down off of the stub shaft  110 . On occasions, as when the cross pin  114  is damaged or loosened, it may work its way out of the cross pin hole. If this occurs, the hub  116  will not be supported and the hub  116  and its crank  112  will be free to work their way down, with the aid of gravity, until they slip off and become disassociated with the end of the stub shaft. When the crank  112  and its hub  116  are no longer associated with the stub shaft  110 , rotation of the spindle  102  will not be translated into a movement of the connecting rod  112  and the railroad switch stand will not be operable. 
     In the practice of this invention a safety support  121 , which is shown in the drawing as a “U” shaped piece of metal, is mounted on the base of the switch stand. The safety support  121  is spaced slightly below the bottom of the stub shaft  110 . The spacing is such that if the cross pin  114  becomes dislodged, the hub  116  will be limited in its downward travel as it comes rest on the top surface of the safety support  121  and thus be prevented from disengaging from the stub shaft  110 . By these means, the continued operation of the switch stand will be assured. When the next routine inspection occurs, it can be observed that the cross pin  114  is no longer supporting the hub  116  on the stub shaft  10  and a new cross pin can be installed to restore the shift stand to its normal operation. 
     In a slightly different modification of the invention, the safety support is inverted and is mounted to depend from the housing  104 . It is of no consequence whether the safety support is mounted from above or below as it will function in an identical manner. 
     From the foregoing it can be understood that this invention provides a safety support to prevent the hub of a crank from becoming disassociated from the operating spindle of a switch stand.