Abstract:
An energy-absorbing device for use with a counterbalance mechanism to relatively harmlessly absorb energy potentially released should a component of the counterbalance mechanism fail. A frame is attached to a portion of the counterbalance mechanism and supports an impact receiving member, and a plurality of deformable support members. In the event of a failure in the counterbalance mechanism, a part of the counterbalance mechanism strikes a face of the impact receiving member. Deformable support members are attached to the opposing face of the impact receiving member and are deformed by the impact and thus absorb the energy that is transferred by the impact. The deformable support members and the impact receiving member are readily replaceable.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to counterbalance mechanisms and in particular to a device for safely absorbing energy from a part of a counterbalance mechanism accidentally released by a failure of a part of such a counterbalance mechanism. 
         [0002]    Counterbalance mechanisms have long been used to make it possible to raise heavy objects by providing a force in opposition to the weight of such a heavy object. The force provided by the counterbalance mechanism typically is slightly less than a load that is desired to be balanced so that the counterbalance mechanism supports a large part of the load in a static condition. Such an arrangement allows for the load to be easily moved by applying a small additional force, in comparison to the force that would otherwise be required to move the load without the counterbalance mechanism. 
         [0003]    Counterbalance mechanisms have been used extensively in many mechanical devices, including lift bridges and the like. One such application is in a railroad freight car which has multiple decks that are capable of carrying cargo. U.S. Pat. Nos. 5,743,192, 5,794,537, and 5,979,335 disclose a multi-unit railroad freight car for carrying automobiles on multiple levels of decks. In each of the disclosed freight cars, a plurality of automobiles may be supported on decks that are adjustable in height. Each end portion of the middle level deck in each unit of the freight cars is mounted on a pivot axis at its inner end so that the outer end portion of the deck, located at the end of the car unit, may be raised and lowered to facilitate the loading and unloading of vehicles on the lowest level of the car. 
         [0004]    In U.S. Pat. No. 7,055,441, the specification of which is incorporated herein by reference, a counterbalance mechanism allows a pivoted end portion of the middle level deck of such a railroad freight car to be raised and lowered easily by its operator. The counterbalance mechanism has an elongate tension-carrying member, coupled to the hinged end portion of the deck, that applies a lifting force from a spring to allow a person to raise the hinged end portion of the deck with mere hand pressure. The lifting force provided by the counterbalance mechanism assists the operator in raising the hinged end portion of the deck by carrying much of its weight as it is moved between its raised and lowered positions. 
         [0005]    Such a counterbalance mechanism entails the risk that failure of a tension-carrying cable might free a powerful spring or a large counter-weight, causing damage to the counterbalance mechanism and potentially causing injury to an operator. In the event of a failure of the tension-bearing member, the counterbalance mechanism may release an amount of energy related to the force that was supporting the counterbalanced object, and a part of the counterbalance mechanism may be released to potentially cause structural damage and personal injury. The counterbalance mechanism for decks within a railroad freight car may be supporting more than a ton of weight, and the energy released if a failure occurs is potentially great. 
         [0006]    The energy that is potentially freed as a result of a failure in the counterbalance mechanism, thus presents a risk of damage to the remainder of a counterbalance mechanism and the associated structure of the freight car, and a risk of injury to nearby personnel. 
         [0007]    What is needed, then, is an energy-absorbing mechanism capable of absorbing a large portion of the energy that may be released in the event that a failure occurs in a counterbalance mechanism in a railroad freight car, so that the failure of the counterbalance mechanism will not result in structural damage to the railroad car or injury to nearby personnel. 
       SUMMARY OF THE DISCLOSURE 
       [0008]    The mechanism disclosed herein answers the aforementioned needs by providing an energy-absorbing device as defined by the appended claims. In one embodiment such a device may be associated with a counterbalance mechanism, to protect a railroad car and nearby personnel from injury in case of a failure of the counterbalance mechanism. 
         [0009]    In one embodiment the device disclosed includes a deformable support member that gives way in response to an impact resulting from a failure of a load supporting portion of a counterbalance mechanism. The energy-absorbing device is attached to a housing for a force-generating element of the counterbalance mechanism, such as a spring or a counterweight, and prevents a suddenly released force-generating element and force-transmitting member from damaging the structure of the freight car, by cushioning an impact and absorbing a large portion of the energy of the force-generating element. 
         [0010]    One embodiment of the energy-absorbing device is associated with a counterbalance mechanism that supports a movable hinged end portion of a deck of a railroad freight car. 
         [0011]    In one embodiment of the disclosed apparatus, the energy-absorbing device includes a blocking or impact receiving member mounted on a plurality of deformable support members. The impact receiving member is connected with a frame attached to an end of a housing for a movable part of the counterbalance mechanism. In the event of a failure, a released part of the counterbalance mechanism that moves toward the blocking or impact receiving member strikes the member on a face that is directed toward the interior of the housing. As a result of such an impact, the deformable support members are bent from their original configurations and thereby absorb the kinetic energy of the released part. 
         [0012]    In one embodiment, the energy-absorbing device is attached to a housing for a moving portion of a counterbalance mechanism and includes attachment bars extending away from an end of the housing. The deformable support members may be of a “U” shape and may be located where they are urged to bend in response to collision of released parts of a counterbalance mechanism against an impact receiving member so that they absorb the energy from moving parts released by failure of a part of the counterbalance mechanism. 
         [0013]    In one embodiment one end of each U-shaped deformable support member is attached to a side of the impact receiving member opposite a face which the moving force-generating element of the counterbalance mechanism would strike if set free as by a failed cable. The other end of each of the U-shaped deformable support members may be connected to the attachment bars by a detachable fastener such as a nut and bolt combination. This structure allows the deformed portion of energy-absorbing device to be replaced after an impact occurs, by simply detaching the deformable support members from the attachment bars. 
         [0014]    In one embodiment of the energy-absorbing device the blocking or impact receiving member may be a plate in the shape of an annular ring defining a central opening through which a fitting attached to an end of the counterbalance mechanism may fit. 
         [0015]    In one embodiment of the energy-absorbing device, the attachment bars are beveled to provide additional space into which the deformable support members may be deformed in order to absorb additional energy from a moving member of a counterbalance mechanism. 
         [0016]    The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0017]      FIG. 1  is a cutaway side elevational view of a portion of one unit of a multi-unit railroad freight car, showing a movable end portion of an automobile-carrying deck located in an upwardly inclined position. 
           [0018]      FIG. 2  is an interior detail view, at an enlarged scale, showing the uppermost portion of one side wall of the body of the unit of a railroad freight car shown in  FIG. 1 , showing an end of a deck in a raised position, and also showing a counterbalance mechanism equipped with an energy-absorbing mechanism. 
           [0019]      FIG. 3  is an isometric bottom view, at an enlarged scale, of the energy-absorbing mechanism shown in  FIG. 2 , also showing the bottom portion of a guide tube portion of the counterbalance mechanism. 
           [0020]      FIG. 4  is an exploded isometric bottom view of the energy-absorbing mechanism shown in  FIG. 3 . 
           [0021]      FIG. 5  is a sectional view, taken along line  5 - 5  of  FIG. 3 , showing a portion of the counterbalance apparatus in a lightly loaded condition within the guide tube. 
           [0022]      FIG. 6  is a sectional view, taken along line  5 - 5  of  FIG. 3 , showing a portion of the counterbalance apparatus after having struck the energy-absorbing device and also showing the deformable support members in a deformed state. 
           [0023]      FIG. 7A  is a sectional view of the combination of one of the deformable support members and an alternative embodiment of an attachment bar. 
           [0024]      FIG. 7B  is a sectional view of the support member and attachment bar shown in  FIG. 7A , showing the deformable support member in a deformed condition. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0025]    Referring to the drawings which form a part of the disclosure herein,  FIG. 1  shows part of a car body  10  of one car unit of a multi-unit railroad freight car that incorporates an energy absorber for a counterbalance mechanism. The freight car may include two or more adjacent car units, and each respective car unit may include a cargo well  12 , a middle deck  14 , and an upper deck  16 , for selectively supporting and storing automobiles  18  in a tri-level arrangement. Each deck preferably has a shape that provides ample strength for supporting automobiles  18 , while providing sufficient space to accommodate automobiles  18  of various heights that the car is desired to carry. 
         [0026]    As can be seen in  FIG. 1 , the automobiles  18  stored on the lowest level of the freight car body  10  rest in the respective cargo well  12  of each car unit. In order to maximize use of the available vertical space in the upper two cargo levels, the middle deck  14  is positioned where it would prevent the loading and unloading of automobiles  18  from the cargo well  12  were it not for a hinged end portion  20  of the middle deck  14  that may be selectively raised while automobiles  18  are loaded into or unloaded from the cargo well  12 . It is to be understood that each of the car units may have a middle deck  14  and an upper deck  16 , and that the middle deck  14  in each car unit may include a hinged end portion  20  at either or each end. 
         [0027]    A respective counterbalance apparatus  22  is provided at each side of the car unit to carry part of the weight of the hinged end portion  20  so that it may be raised easily when necessary. The counterbalance apparatus includes an energy-absorbing device  24  in order to absorb energy that may be released should a failure of the counterbalance apparatus  22  occur and result a part of the counterbalance apparatus  22  being freed to move. The energy-absorbing device  24  prevents an impact of such a freed part of the counterbalance apparatus from causing substantial damage to the counterbalance apparatus  22  to an associated housing, or to the associated supporting structure of the freight car body  10 . Furthermore, a portion of the energy-absorbing device  24  may be replaced after an impact and thus can reduce costs for repairs if a failure of the counterbalance apparatus  22  occurs. 
         [0028]    Each counterbalance apparatus  22  may include a force-transmitting member, such as a cable  28  or chain (not shown) that interconnects and transmits forces between a counterbalanced object such as the hinged end portion  20  and a force-generating element, such as a spring  32  or a counterweight (not shown). The force-generating elements of the counterbalance mechanisms  22  together may generate a lifting force that is slightly less than the applied portion of the weight of the hinged end portion  20 . Each force-transmitting member may include a first elongate tension carrying segment  34  operatively connected to, and extending upward from, the hinged end portion  20  and a second elongate tension carrying segment  36  operatively interconnected with the force-generating element so that tension in the first elongate tension carrying segment  34  is caused by tension in the second elongate tension carrying segment  36 , which in turn is caused by the force-generating element. 
         [0029]    In a simple counterbalance mechanism, the force-transmitting member may be a cable  28 , and the force-generating element may include the spring  32 . In that instance, it may be appropriate to include a direction changing force transfer device  42 , including one or more sheaves  44 , or other mechanisms such as bell cranks (not shown). The direction changing force transfer devices  42  may be positioned between the first elongate tension carrying segment  34  and the second elongate tension carrying segment  36 . In a more complex counterbalance mechanism, an appropriate force-transmitting arrangement might include gears, rigid members, bell cranks, etc. 
         [0030]    The middle deck  14  may be provided in the form of three segments arranged end-to-end, with the center segment fastened securely and tightly to the side posts  40  by bolts or other releasable but secure fasteners so that the middle deck  14  is incorporated structurally in, and adds rigidity to, the entire car unit as well as being solidly supported by the side walls  46 . 
         [0031]    Hinges  47  pivotally attach the hinged end portion  20  to two horizontal support beams  48  that extend longitudinally along the opposite side walls  46  of the car body  10  at equal heights and that are rigidly fastened to the side walls  46  by fasteners such as bolts. Each of the horizontal support beams  48  extends inwardly from the side walls  46 , so that when the hinged end portion  20  is in a lowered position it is supported along its lateral margins by the horizontal support beams  48 . In this manner, the horizontal support beams  48  support the portion of the weight of the hinged end portion  20  and any automobiles  18  or other cargo carried on the hinged end portion  20  in excess of the weight supported by the counterbalance apparatus  22 . Each of the horizontal support beams  48  is positioned at a vertical height along its respective side wall  46  where the hinged end portion  20  abuts the fixed portion of the middle deck  14  at a pivot axis defined by the hinges  47  through which the inner end of the hinged end portion  20  is attached. The hinges may allow an outer end  50  of the hinged end portion  20  of the middle deck  14  to be raised as much as about 4 feet to an inclined position above the horizontal support beams  48 . Raising the hinged end portion  20  of the middle deck  14  while it is empty allows automobiles  18  to be moved over the trucks  52  and the body bolsters  54  of the car body  10  and into or out of the cargo well  12  during loading and unloading of the freight car  2 . 
         [0032]    Referring to  FIG. 2 , the counterbalance apparatus  22  is used to support most of the weight of the hinged end portion  20  so that it may easily be raised and lowered manually. The counterbalance apparatus  22  applies a lifting force from the force-generating element to the outer end  50  of the hinged end portion  20  through a tension-carrying member, which may be, for example, a flexible 5/16″ diameter steel cable  28 . The cable  28  operatively connects the hinged end portion  20  to the force-generating element and extends upward and around sheaves  44  which may be mounted in fixed locations, such as between the corner post  38  and the side post  40  that is next to the corner post  38  along the side wall  46  in the direction toward the mid-length of the car body  10 . 
         [0033]    Referring again to  FIG. 2 , the generally helical compression spring  32  or another force-generating element may be held in a protective housing such as a guide tube  56 , securely mounted in the car body  10 , where the compression spring  32  is free to extend and be compressed, or a counterweight is free to move up or down. The compression spring  32  and the guide tube  56  may also be located in an interior space that lies between the corner post  38  and the adjacent side post  40 . In this way, the counterbalance apparatus  22  is situated in what is otherwise unused space inside the railroad car body  10  and does not interfere with any other structure or cargo inside the car. 
         [0034]    The guide tube  56  comprises an interior liner sleeve  58  (shown in  FIGS. 5-6 ), and an upper end fitting  60  that is securely connected to the guide tube  56 , retains the upper end of the spring  32  and opposes the force of the cable  28  in order to compress the spring  32  and thus provides a force supporting part of the weight of the movable deck part  20 . The sleeve  58  may be made from, or at least lined with, a layer of polymeric resin such as UHMW polyethylene so that friction and wear may be minimized as the compression spring  32  moves within the guide tube  56 . 
         [0035]    The upper fitting  60  defines an opening  62 . The cable  28  extends through the opening  62  and through the compression spring  32 , and is secured to a cable end fitting  64 , as by being looped around a crosspin of the end fitting  64  and held by a swaged or cast cable fastener  66 , shown in  FIGS. 5-6 . 
         [0036]    Referring to  FIGS. 5-6 , the cable end fitting  64  is connected to the end of the spring  32  as by mating with a suitable spring retainer  68 . The spring retainer  68  may, as shown, be in the form of a cup with a suitably sturdy annular bottom plate  70  and an upwardly extending sidewall  72  that surrounds a bottom end of the spring  32 , so that the retainer  68  acts as a piston supporting the lower end of the spring  32  and guides the spring  32  as it moves within the guide tube  56 . The end fitting  64  may have an upwardly projecting part that fits matingly through the central opening  74  in the bottom plate  70  and a radial flange  76 , extending beneath the bottom plate  70 , that is too large to pass through the opening  74 . The sleeve  58  facilitates movement of the retainer  68  within the guide tube  56 . Because of the arrangement of the cable  28 , movement of the hinged end portion  20  up or down causes the retainer  68  to slide oppositely within the sleeve  56 . Movement of the retainer  68 , in turn, compresses the compression spring  32  or allows it to expand downward beneath the upper fitting  60 , depending on the direction in which the retainer  68  is moving. 
         [0037]    The length of the cable  28  and the force of the compressed spring  32  may be such that when the hinged end portion  20  is in the lowered position the compression spring  32  applies a lifting force to the hinged end portion  20  that is slightly less than that which would lift the outer end  50  of the hinged end portion  20 . It will be understood that the compression spring  32  should be long relative to the distance through which given a point on the cable  28  will travel when the hinged end portion  20  of the middle deck  14  is raised or lowered, so that the magnitude of the lifting force supplied by the counterbalance apparatus  22  remains within a small range during raising and lowering of the hinged end portion  20 . The hinged end portion  20  of the middle deck  14  can thus be raised easily during loading of automobiles  18  into the cargo well  12  to provide ample overhead clearance above the body bolster  54  as automobiles pass over the wheeled truck  52  at each end of the multi-unit freight car or over a shared truck between car units. 
         [0038]      FIGS. 2-6  show the energy-absorbing device  24  that is used to absorb the energy from a spring  32  or other force-generating element released by a failure in the counterbalance apparatus  22  such as a failure of the cable  28 . Such a released spring  32  would result in an impact of the retainer  68  against the energy-absorbing device  24 . If the cable  28  should fail, the spring  32  would rapidly expand from a compressed condition between the upper fitting  60  and the retainer  68 , launching itself, the spring retainer  68 , the end fitting  64 , and any attached portion of the cable  28  downward through the guide tube  56  toward the energy-absorbing device  24 . The energy-absorbing device  24  helps to prevent substantial damage from occurring to the guide tube  56  and helps to prevent injury from occurring to an operator who may be manually lifting the hinged end portion  20  of the middle deck  14 . The energy-absorbing device  24  may be constructed as shown, to include energy-absorbing parts that are easily replaced after an impact occurs. The construction of the energy-absorbing device  24  also allows for ready access to the interior of the guide tube  56  so that repairs may be made to the spring  32  or cable  28 . 
         [0039]    Referring now to  FIGS. 3 and 4 , as depicted, the energy-absorbing device  24  is attached to the lower end of the guide tube  56  and includes a base that may be in the form of a collar  82 , which may be welded to the guide tube  56 , and a plurality of attachment bars  84 , each securely attached as by being welded to or formed as an integral part of the collar  82 . In one embodiment, the collar  82  is welded or otherwise fixedly attached to the guide tube  56 ; however, it will be understood that the collar  82  may be detachable so long as it is capable of withstanding the maximum anticipated amount of energy from a potential impact of a released part of a counterbalance mechanism without separating from the guide tube  56 . 
         [0040]    A first, or outer, end of a deformable support member  86  is detachably connected to each attachment bar  84  as by a fastener such as a bolt and nut combination  88 . Each deformable support member  86  is a metal strap bent into a “U” shape, with the second end  90  of the strap, which may be wider than the first or outer end, being attached to an impact receiving, or blocking member  92  that fits within or is aligned with the lower end of the guide tube  56  to block, or close, that end of the guide tube  56  and thus safely contain the spring  32 , the spring retainer  68 , and the end fitting  64  in the case of a cable failure. 
         [0041]    The impact receiving member  92  and the guide tube  56  are similarly shaped, and the impact receiving member  92  has a slightly smaller size than the interior of the guide tube  56 , so that it fits within the guide tube  56 . For example, the guide tube  56  and impact receiving member  92  may be of a cylindrical shape, in which case the diameter  93  of the impact receiving member  92  is slightly smaller than the internal diameter of the guide tube  56 , and the impact receiving member  92  may fit within the interior of the guide tube  56 , loosely enough not to jam in the collar  82  when struck by a released part of the counterbalance mechanism, as shown in  FIGS. 5 and 6 . 
         [0042]    The impact receiving member  92  may be of flat plate steel in the form of an annular ring that defines a central hole  94 , as shown in  FIG. 4 . The impact receiving member  92  has an upper, or first face  96  and a lower, second face  98 . The radial distance between the central hole  94  and the exterior margin is designed to provide room for attachment of the upper end  90  of each deformable support member  86 . The upper ends  90  of the deformable support members  86  may be attached as by being welded, to the second face  98  in uniformly spaced-apart positions about the central hole  94 . A pair of mounting ears  100  are attached to the second face  98  of the impact receiving member  92 , aligned with each other on opposite sides of the central hole  94  along an imaginary diametric line across the annular plate  92 , as shown in  FIGS. 3 and 4 . Each mounting ear  100  is located between two deformable support members  86  in one embodiment. 
         [0043]    A stopper bar  102  is attached to the ears  100 , extending along the diameter of the impact receiving member  92  and between the ears  100 , attached, for example, by bolt and nut combination  101 . The stopper bar  102  thus extends across the hole  94  as shown in  FIG. 3 , at a location spaced a small distance beneath the lower face  98 , leaving room for the cable end fitting  64  to protrude through the central hole  94  when the bottom plate  70  of the retainer  68  contacts the annular impact receiving plate member  92 . The length of the stopper bar  102  is slightly less than the diameter of the interior of the guide tube  56  so that the stopper bar  102  fits within the guide tube  56 , as shown in  FIG. 3 . 
         [0044]    The deformable support members  86  may be of any configuration that is capable of bending in response to an impact against the impact receiving plate  92  and thus absorbing energy from the moving spring  32  or a counterweight from a counterbalance mechanism. As shown in  FIGS. 3 and 4 , the deformable support members  86  may be of steel plate cut to a slender flat bar shape and bent to be generally “U” shaped, so that each deformable support member  86  includes an attached or upper end  90 , a U-shaped central portion  104 , and the detachable end  106 . The U-shaped central portion  104  of the deformable support member  86  extends away from the second or lower face  98  of the annular blocking member  92 . The detachable end  106  of the deformable support member  86  extends parallel with the attached end  90  generally toward the second face  98  of the impact receiving element  92  at a location radially further outward from the central hole in the annular impact receiving member  92 , but it does not extend the entire distance back to the second face  98 . The detachable end  106  of the deformable support member  86  defines a hole  108  that is aligned with a hole  110  defined in the lower portion of the attachment bar  84  when the annular impact receiving member  92  is fitted within the collar  82 . The nut and bolt combinations  88  thus detachably attach the disposable and replaceable part of the energy-absorbing assembly  24  to the collar  82 . 
         [0045]      FIGS. 3 and 4  show that four deformable support members  86  are used, although it will be understood that any convenient number of deformable support members  86  suitable to absorb the anticipated amount of energy from the counterbalance mechanism may be used with an equal number of attachment bars  84 . The embodiment shown in  FIGS. 3 and 4  has deformable support members  86  evenly spaced apart around the interior perimeter  100  of the annular ring  96  so that each deformable support member  86  is located to absorb a substantially equal amount of energy if an impact occurs. 
         [0046]    Referring again to  FIGS. 5 and 6 , the energy-absorbing device  24  is attached to one end of the guide tube  56  as by welding the collar  82  to the guide tube  56  adjacent its lower end, where the energy absorbing device can block a released portion such as the spring  32  and cable  28  of a counterbalance mechanism, and receive the impact of a released part in the event that a failure occurs in the counterbalance apparatus  22 . The force-generating element fits within the spring retainer  68  and drives the retainer  68  through the guide tube  56 . The end fitting  64  may be smaller than the central opening  94  in the annular impact receiving plate member  92  and fits through the central opening  94  if the spring  32  is released by failure of the cable  28  and drives the retainer  68  against the annular impact receiving member  92 . The end fitting  64  can then strike and perhaps be contained by the stopper bar  102 . 
         [0047]    Referring to  FIG. 6 , in the event of a failure, the retainer  68 , driven by the spring  32 , impacts the annular impact receiving plate element  92  and the end fitting  64  passes through the central hole  94  defined in the annular impact receiving plate member  92 . In response to the impact, the deformable support members  86  flex and are plastically deformed to absorb much of the energy transferred from the spring  32  by the impact. The material of which the deformable support members are made is malleable enough to absorb the maximum energy caused by such an impact by bending, rolling the “U” bend along the straplike deformable members  86 , rather than fracturing. Any parts, such as the end fitting  64 , that pass through the central opening  94  in the impact receiving member  92  will contact the stopper bar  102  and thus be kept from simply passing freely out from the guide tube  56 . 
         [0048]    Referring now to  FIGS. 7A and 7B , the interior surface  114  of the lower portion of each attachment bar  84  may be beveled. The beveled end  114  creates additional space into which for the deformable support members  86  can deform in the event an impact occurs, as shown in  FIG. 7B . In a pre-impact condition, as shown in  FIG. 7A , a portion of the detachable end  106  of the deformable support member  86  is not in contact with the beveled end  114 . When an impact occurs, the deformable support member  86  may flex to deform a greater distance in a radial direction as compared to a deformable member  86  supported by an attachment bar  84  with a non-beveled end. 
         [0049]    The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.