Abstract:
A hydraulic parking brake assembly for a railroad vehicle braking system comprising a hydraulic actuator capable of being mounted on or engagable with the braking system and a lever arrangement connected to the hydraulic actuator which moves in accordance with activation of the hydraulic actuator and initiates a braking sequence. The lever arrangement is associated with the force transfer lever of the air cylinder such that upon movement of the lever arrangement, a force is applied to this force transfer lever causing this force transfer lever to rotate in a counterclockwise direction to apply the appropriate forces to the push rod within the brake cylinder and to a force transmitting member within the braking system to effect activation of the parking brake assembly.

Description:
FIELD OF THE INVENTION 
     The present invention relates, in general, to a parking brake arrangement for a railroad vehicle type braking system and, more particularly, this invention relates to a hydraulic type parking brake lever arrangement for a railroad vehicle braking system, especially truck mounted brake assemblies. 
     BACKGROUND OF THE INVENTION 
     As is generally well known in the railway industry, when railway cars are taken out of a train and parked at a siding or yard, the hand brake or parking brake on at least some of these cars are applied as a precaution against unwanted or unexpected movement of the cars. A typical railway car hand brake system normally consists of an apparatus for manually applying and biasing one or more brake shoes against the tread of one or more wheels of the railway car by either turning a hand wheel or pumping a ratchet handle on a hand brake mechanism attached to the railway car. 
     As illustrated in FIG. 2, in truck mounted braking systems, the hand brake mechanism is usually either a cast or stamped metal gear housing usually attached to an outside end wall of the railway car and having a rotatable chain drum therein which can be rotated by turning the hand wheel to wind a brake chain onto the chain drum. The other end of the brake chain normally extends through the bottom of the gear housing and is interconnected with cable or other linkage, such as a hand brake lever, to the brake beam which carries the brake shoes such that winding of the brake chain onto the chain drum will apply tension to the brake chain and linkage as necessary to draw the interconnected brake shoes against the tread surfaces of adjacent railway car wheels and, accordingly, apply the hand brake as intended. 
     A disadvantage of this prior art type hand brake arrangement is that operation of the handwheel requires exerting a considerable amount of physical force from an awkward position. This, in turn, makes the hand brake difficult to apply and could present a possible injury hazard. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a hydraulic parking brake lever arrangement for a railway vehicle braking system which is an ergonomic alternative to the currently used manually activated hand brake assemblies. The hydraulic parking brake lever arrangement of the present invention is particularly applicable to truck mounted braking systems and may be used to replace the currently used manually activated handwheel type hand brakes. 
     A further object of the present invention is to provide a hydraulic parking brake lever arrangement which is easy to apply and provides a reduced chance of injury to the operator applying this brake. 
     Briefly, and in accordance with the forgoing objects, the invention comprises a hydraulic actuator which is mounted on the braking assembly. The hydraulic actuator includes a piston which moves outward from the hydraulic actuator upon activation of the actuator. The piston includes a connecting means, such as in the form of a clamp, which is connected at its end opposite from the hydraulic actuator. This connecting means is attached to a lever arrangement and the lever arrangement is associated with the force transfer lever of the air cylinder. Activation of the hydraulic actuator causes the lever arrangement to apply a force to the force transfer lever causing this force transfer lever to rotate in a counterclockwise direction to apply the appropriate forces to the push rod within the brake cylinder and to the slack adjuster assembly in order to effect activation of the parking brake assembly. 
     The hydraulic actuator of the invention may be mounted in a variety of locations and in a variety of directions within the braking assembly. Depending upon the mounting location and direction of the hydraulic actuator, several different lever arrangements may be used in order to achieve the counterclockwise rotation of the force transfer lever of the air cylinder assembly in order to apply the appropriate forces to the push rod and the slack adjuster so that actuation of the parking brake assembly can be achieved. 
     Although a number of objects and advantages of the present invention have been described in some detail above, various additional objects and advantages of the hydraulic parking brake lever arrangement of the present invention will become more readily apparent to those persons who are skilled in the art from the following more detailed description of the invention, particularly, when such detailed description of the invention is taken in conjunction with both the attached drawing figures and with the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view which shows a truck-mounted brake assembly including a conventional handbrake lever as is described above, and is accordingly labeled “Prior Art”. 
     FIG. 1A is an expanded view of the brake cylinder illustrated in FIG. 1 which is currently in use and is accordingly label “Prior Art”. 
     FIG. 2 is a plan view which shows a truck-mounted brake assembly having a conventional prior art handwheel hand brake or parking brake, as described above, and is accordingly labeled “Prior Art”. 
     FIG. 3 is a partial plan view illustrating an end portion of the truck mounted brake assembly of FIG. 1 having the hydraulic parking brake lever arrangement according to a first embodiment of the present invention mounted thereon. 
     FIG. 4 is partial plan view illustrating an end portion of the truck mounted brake assembly of FIG. 1 having the hydraulic parking brake lever arrangement according to a second embodiment of the present invention mounted thereon. 
     FIG. 5 is partial plan view illustrating an end portion of the truck mounted brake assembly of FIG. 1 having the hydraulic parking brake lever arrangement according to a third embodiment of the present invention mounted thereon. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Prior to proceeding with the more detailed description of the present invention, a description of a truck mounted braking system and its functioning should prove helpful in understanding the present invention. Also, it should be noted that for the sake of clarity, identical components which have identical functions have been identified with identical reference numerals throughout the several views illustrated in the attached drawing figures. 
     Referring to FIG. 1, there is shown a truck-mounted brake assembly, generally designated  10 , for a railway car (not shown) including a conventional handbrake lever  50 . This brake assembly  10  comprises brake beams, generally designated  2  and  3 , which are substantially identical, each comprising a compression member  4 , a tension member  6 , and a strut member  8 . The opposite ends of the compression member  4  and the tension member  6  may be permanently connected together, preferably by welding along an outer segment  4   a - 6   a ,  4   b - 6   b  at the opposite ends of the compression member  4  and the tension member  6 . At a location midway between their opposite ends, the compression member  4  and the tension member  6  of the respective beams  2  and  3  are spaced apart sufficiently to allow connection of the strut member  8  therebetween. Mounted on the respective outer end segments  4   a - 6   a  and  4   b - 6   b  of the brake beams  2  and  3  are brake heads  12 . 
     A pair of force-transfer levers  14  and  16  are pivotally connected by pins  18  to the strut member  8  of the respective brake beams  2  and  3 . Each end  24  and  26  of the respective force-transfer levers  14  and  16  is interconnected via the force-transmitting member  28 , which may be in the form of an automatic slack adjuster device. The opposite end  36  of the force-transfer lever  16  is connected to the pressure head  19  of the brake cylinder assembly  20  via a force-transmitting member or a return push rod assembly  32 . 
     Referring to FIG. 1A of an expanded view of the brake cylinder of FIG. 1, a piston rod  37  of the brake cylinder assembly  20  is connected to the end of a push rod  38  which is, in turn, connected to the force transfer lever  14 . The brake cylinder assembly  20  is connected to the strut member  8  adjacent one side thereof and to the compression member  4  in the space between the compression member  4  and the tension member  5 . The weight of the brake cylinder device and the force-transmitting members is thus carried by the brake beams  2  and  3 , which are, in turn, supported by the truck side frame (not shown). 
     When a brake application is made, pressurization of the brake cylinder assembly  20  results in actuation of the brake cylinder piston rod  38  located in the brake cylinder assembly  20 . This actuation of the piston rod  38  causes a spring  39 , also located in the brake cylinder assembly, to compress, resulting in movement of a push rod  38  in a direction to effect counterclockwise rotation of the force-transfer lever  14 . The force-transfer lever  14 , in turn actuates the slack adjuster assembly  28  to effect counterclockwise rotation of the force-transfer lever  16  and consequent actuation of the return push rod assembly  32 . 
     The force-transfer levers  14  and  16 , along with the slack adjuster assembly  28 , the return push rod assembly  32 , and the brake cylinder assembly  20  comprise a brake beam actuating linkage that interconnects the brake beams  2  and  3  via pivot pins  18  and thus the required brake actuation forces effectively act along these pins  18 . The resultant of these forces is shown at X. Since the length of the slack adjuster assembly  28  increases with actuation of the brake cylinder piston rod  37 , it follows that brake beams  2  and  3  are moved apart by the brake beams linkage until the brake shoe engagement with the tread surface of the vehicle wheels occurs. 
     During a parking situation when the railway cars are taken out of the train and parked at a siding or yard, the pneumatic braking system, as described above, can no longer be used. Thus, in order to apply the brake as a precaution against unwanted or unexpected movement of the cars, a hand brake mechanism, which is mounted on each car, can be employed. 
     Referring to FIG. 2, a currently used handbrake mechanism, generally designated as  40 , on a truck-mounted brake assembly is shown. The brake mechanism  40  has a housing, generally designated as  42 , which comprises a back plate or wall  44 , mountable on a railway car, and a cover  46 . The cover  46  is secured to the back wall  44 . 
     A chain  48 , for application or release of the brakes, is connected, as is conventional, to the brake rigging via a hand brake lever  50 , which chain  48  is attached to and wound on a winding drum  52 . The hand brake lever  50  is, in turn, connected to an air cylinder transfer lever or force transfer lever  14 . 
     In order to apply the brakes, a hand wheel  54  is rotated in a clockwise direction to wind the chain  48  about the winding drum  52  and to cause the hand brake lever  50  to be pulled in an outward direction away from the brake rigging  10 . This causes the force transfer lever  14  to be rotated in a counterclockwise direction resulting in the piston push rod being pulled in an outward direction and the required force being applied to the slack adjuster assembly  28 . This force is similar to the force which is applied by the brake cylinder piston rod, not shown, of the air cylinder assembly  20  when such is pressurized. 
     The present invention would replace this manually actuated hand wheel/chain/hand brake lever system with a hydraulic parking brake lever arrangement. FIG. 3 shows the hydraulic parking brake lever arrangement, according to a first embodiment of the present invention, mounted to an end portion of a truck mounted brake assembly, generally designated as  55 . In this embodiment, a hydraulic actuator  56  is mounted alongside the air cylinder  20 . This hydraulic actuator  56  includes a piston  58  for movement outwardly from the hydraulic actuator  56  upon activation of such hydraulic actuator  56 . 
     Any well known liquid may be used for activating this hydraulic actuator such as water, oil, and the like. The piston  58  includes a connecting means  62 , such as a clamp, for connecting the piston  58  to a center portion or at a midpoint  65  of a lever  64 . The lever  64  is pivotally connected at its outboard end  63  to a fixed bracket  67 . This bracket  67  is attached to the compression member  4  of the brake assembly. The lever  64  is also pinned at its inboard location  66  to the air system push rod, element  38  as shown in FIG. 1A, as well as, the force transfer lever  14 . The force transfer lever  14  is connected to a slack adjuster assembly  28 , as illustrated in FIG.  1 . 
     Upon activation of such hydraulic actuator  56 , a force is applied to the piston  58  which causes the lever  64  to be forced outward from the braking assembly, as shown by arrow B. This outward movement of the lever  64  causes the force transfer lever  14  to rotate in a counterclockwise direction causing the air cylinder push rod  38  to move in an outward direction and to apply an inward force to the slack adjuster assembly  28 , thus causing a chain reaction, similar to what occurs during an air cylinder activated braking situation, to activate the parking brake assembly. 
     FIG. 4 shows the hydraulic parking brake lever arrangement according to a second embodiment of the present invention. In this embodiment, the hydraulic actuator  56  is mounted opposite the air cylinder  20  and oriented toward the truck bolster (not shown). This embodiment of the parking brake lever arrangement includes two lever members  68  and  69  pivotally connected at  70 . The piston of the actuator  56  is connected to a first member  68  of the lever arrangement substantially at its midpoint  71 . 
     Actuation of the hydraulic actuator  56  causes the piston  58  to apply a force so as to cause the first and second lever members  68  and  69 , of the lever arrangement, to move inwardly toward the brake assembly, as shown by arrow C. The inboard end  72  of the second lever member  69 , of the lever arrangement, is linked to an extension lever  73  of the slack adjuster end  74  of the force transfer lever  14 . Thus, the inward movement of the first and second lever members  68  and  69  of the lever arrangement causes the extension lever  73  to apply a force, as depicted by arrow D, causing the force transfer lever  14  to rotate in a counterclockwise direction and to activate the parking brake assembly in a manner similar to that of the FIG. 3 embodiment. 
     FIG. 5 shows a third embodiment of the hydraulic parking brake assembly, according to the present invention, in which the hydraulic actuator  56  is mounted opposite or at a remote location from the air cylinder  20  and oriented toward the axle (not shown). 
     The piston of the hydraulic actuator  56  is connected via connecting means  62  to the outboard end  77  of a 2:3 ratio lever  76 . The opposite end  78  of this 2:3 ratio lever  76  is pinned at  79  to the slack adjuster end  74  of the force transfer lever  14 . The 2:3 ratio lever  76  is also pivotally connected at  83  to a fixed bracket member  82 . Activation of the hydraulic actuator  56  causes the 2:3 ratio lever  76  to move outward from the brake assembly, as depicted by arrow E, and due to the 2:3 ratio lever  76  being pivotally connected to the fixed bracket member  82 , the 2:3 ratio lever  76  rotates in a clockwise direction and resultantly causes the force transfer lever  14  to rotate in a counterclockwise rotation. This counterclockwise rotation applies a force to the air cylinder push rod  38  and the slack adjuster assembly  28  which causes the parking brake assembly to be activated. 
     Thus, the present invention has been described in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same. It will be understood that variations, modifications, equivalents, and substitutions for components of the specifically described embodiments of the invention may be made by those skilled in the art without departing from the spirit and scope of the invention as set forth in the appended claims.