Abstract:
A system for converting an ABDW-type control valve to an ABDX-type control valve for use in a braking mechanism for a railway vehicle includes an ABDW-type control valve body in communication with an air supply system of the braking mechanism for controlling an application and release of brakes in response to changes in air pressure within the braking mechanism. A breather plate is mounted on an accelerated application valve interface on the control valve body. The breather plate has an internal stability volume for compensating a function of an accelerated application valve. A modified slide valve bushing is mounted inside the control valve body for establishing fluid communication with at least one passageway within the control valve body. At least one plug mounted is to at least one air passageway within the control valve body for sealing or choking the at least one air passageway.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present disclosure relates generally to railway vehicle brake equipment. More particularly, the present disclosure relates to an apparatus and method for converting an ABDW control valve to an ABDX-R control valve for use in railway vehicle brake equipment. 
         [0003]    2. Description of the Related Art 
         [0004]    Railway vehicle braking systems generally operate by charging and discharging compressed air to and from one or more storage reservoirs located on each railway car. Each storage reservoir is connected to a compressed air source, such as a locomotive air compressor, by a brake pipe. The storage reservoirs are typically separated from the brake pipe by a brake valve which is sensitive to changes in air pressure in the brake pipe. The brake valve senses a pressure drop in the brake pipe and utilizes the compressed air from one or more storage reservoirs to apply the brakes. Because brakes are applied by discharging the air pressure from the storage reservoirs, modern railway vehicle braking systems have a built-in safety feature. In case of a significant air loss, such as during unwanted separation of railway vehicles or a sudden failure of the compressed air source, the brake valve will initiate a full-force, emergency brake application by discharging the compressed air stored in the storage reservoirs. 
         [0005]    Railway vehicle braking systems are typically controlled by an operator using a control stand in the locomotive. As the brake valve is moved to release the compressed air in the brake pipe, the loss in air pressure is sensed by individual brake valves on each railway vehicle. Using the air pressure from the one or more storage reservoirs on the railway vehicle, the brake valve applies force on a brake piston to apply the brakes on the railway vehicle. In order to release the brakes, the air pressure in the brake pipe must be restored to cause the brake valve to exhaust the pressure in the brake piston and thereby release the brakes. The system then recharges the air in the storage reservoirs and maintains the air pressure in the brake pipe until the subsequent brake application. 
         [0006]    Over the years, a number of railway vehicle braking systems have evolved, the AB-based braking system being the most common. In the AB-based braking system, slight brake pipe pressure reductions do not cause unintended service or emergency brake applications and there is less sensitivity to brake pipe leakage compared to previous braking systems. AB-based control valves receive air from the brake pipe through a cross-over pipe and direct the air to various reservoirs on the railway vehicle during the recharging of the braking system. A plurality of different AB-based control valves have been developed throughout the years. 
         [0007]    In one embodiment, an ABD-type control valve includes a pipe bracket and two primary operating portions. Pipe connections from the brake pipe are made to the valve body, which is secured to the frame of a railway vehicle. The two primary operating portions include an emergency portion and a service operating portion. ABD-type control valves include an accelerated release function, where a rapid rise in brake pipe pressure on a first railway vehicle causes a chain reaction on the rest of the vehicles throughout the train and a much quicker release of the brakes. 
         [0008]    An improvement to the ABD-type control valve was introduced in 1974 in the form of an ABDW control valve. Its main advancements over ABD-type control valves are a faster brake application and continuous action though an accelerated application valve. The ABDW control valve exhausts air from the brake pipe locally at each car using the accelerated application valve as long as air is being exhausted at the automatic brake valve in the control stand of the locomotive. This causes an accelerated buildup of brake cylinder pressure during service brake applications. During a brake release, the ABDW valve functions in a similar manner to an ABD valve. These control valves are approved for railway vehicles of up to 75 feet in length. Railway vehicles equipped with an ABDW control valve that exceed the 75-foot length must be equipped with additional or supplemental devices to provide an increase in accelerated application valve activity. 
         [0009]    The latest improvement to AB-type control valves occurred in 1994 with the introduction of an ABDX control valve. The ABDX control valves are designed for operation on conventional trains and modern freight trains that are longer, heavier, and operate at higher speeds. Whereas ABDW control valves rely on an external accelerated application valve to effect a local exhaustion of air from the brake pipe, ABDX valves have a built-in capability that eliminates the need for an external accelerated application valve. The ABDX control valves provide an improved, more efficient accelerated application valve function, as well as increased stability against undesired emergency applications resulting from fluctuations in brake pipe pressure. 
         [0010]    Considering that a plurality of AB-type control valves have been developed throughout the years, railway vehicles traveling on today&#39;s railways may be equipped with any of the above-described control valves. While most new railway vehicles are built with the most modern ABDX-type control valves, many existing railway vehicles utilize older, less-effective AB-type control valves, such as an ABDW-type valve. In order to update the braking system of an older railway car to the newest control valve, it is necessary to completely replace an existing ABDW control valve with a new ABDX control valve. The upgrade from an ABDW-type control valve to an ABDX-type control valve provides an improved accelerated application valve and the stability functionality of the ABDX-type control valve. 
       SUMMARY OF THE INVENTION 
       [0011]    In view of the foregoing, a need exists in the art to convert an existing ABDW-type control valve to have the function of an ABDX-type control valve without replacing the existing control valve. An additional need exists for an apparatus and method for converting the ABDW-type control valve to have the service stability, application speed, and other operating parameters of an ABDX-type control valve. 
         [0012]    Accordingly, a system for converting an ABDW-type control valve to an ABDX-type control valve for use in a braking mechanism for a railway vehicle is needed. In accordance with one embodiment, the system may include an ABDW-type control valve body in communication with an air supply system of the braking mechanism for the railway vehicle. The control valve body is desirably operative for controlling an application and release of brakes in response to changes in air pressure within the braking mechanism for the railway vehicle. The system may further include a breather plate provided on an accelerated application valve interface on the control valve body. The breather plate may have an internal stability volume for compensating a function of an accelerated application valve. A slide valve bushing may be provided inside the control valve body for establishing fluid communication with at least one passageway within the control valve body. Additionally, at least one plug may be provided for sealing at least one air passageway within the control valve body. 
         [0013]    In accordance with another embodiment, the breather plate may further include a body having a first side opposite a second side and an internal stability volume between the first side and the second side. The breather plate may additionally include a first opening and a second opening in communication with the internal stability volume and in alignment with a first passageway and a second passageway on the accelerated application valve interface of the control valve body. A gasket surrounding the first opening and the second opening may be provided for sealing the fluid connection between the first passageway on the control valve body and the first opening on the breather plate and the second passageway on the control valve body and the second opening on the breather plate. A plurality of through holes in alignment with a plurality of bolt holes on the accelerated application valve interface of the ABDW-type control valve body may be provided for connecting the breather plate to the control valve body. 
         [0014]    In accordance with yet another embodiment, the breather plate may further include a breather plate plug connected to the body and in communication with the internal stability volume. In one embodiment, the breather plate plug may extend within the internal stability volume. Additionally, the breather plate plug may include an O-ring seal. In another embodiment, the breather plate may further include a recessed gasket face on the first side of the breather plate. The gasket may be recessed within the recessed gasket face. A choke plug may be provided in one of the first opening or the second opening. The choke plug may have a central passage extending through a longitudinal length thereof. The breather plate may further include a drive stud provided on the first side for engaging a corresponding opening provided on the control valve body. 
         [0015]    In a further embodiment, the slide valve bushing may include a plurality of recessed passageways extending around at least a part of an external perimeter of the bushing. The plurality of recessed passageways is desirably separated axially along a longitudinal extent of the bushing. Additionally, the slide valve bushing may include a plurality of through passages extending radially through at least one side of the bushing, wherein the plurality of through passages may be separated axially along a longitudinal extent of the bushing. In one embodiment, one of the plurality of plugs may be an accelerated application valve choke plug provided in an accelerated application valve choke on the valve body. The accelerated application valve choke plug may include a mesh filter to filter impurities in air passing through the accelerated application valve choke. In another embodiment, the accelerated application valve choke plug may be inserted into an accelerated application valve bushing that is pressed inside the accelerated application valve opening. In a further embodiment, a slot may be provided between accelerated application valve opening and an air chamber to establish a fluid connection between the accelerated application valve opening and the air chamber. 
         [0016]    In another embodiment, a breather plate for connecting and mounting to an accelerated application valve interface of an ABDW-type control valve body for converting an ABDW-type control valve to an ABDX-type control valve may include a body having a first side opposite a second side and an internal stability volume between the first side and the second side. 
         [0000]    The breather plate may additionally include a first opening and a second opening in communication with the internal stability volume and in alignment with a first passageway and a second passageway on the accelerated application valve interface of the control valve body. A gasket surrounding the first opening and the second opening may be provided for sealing the fluid connection between the first passageway on the control valve body and the first opening on the breather plate and the second passageway on the control valve body and the second opening on the breather plate. A plurality of through holes in alignment with a plurality of bolt holes on the accelerated application valve interface of the ABDW-type control valve body may be provided for connecting the breather plate to the control valve body. 
         [0017]    In accordance with yet another embodiment, the breather plate may further include a breather plate plug connected to the body and in communication with the internal stability volume. In one embodiment, the breather plate plug may be set within the internal stability volume. Additionally, the breather plate plug may include an O-ring seal. In another embodiment, the breather plate may further include a recessed gasket face on the first side of the breather plate. The gasket may be recessed within the recessed gasket face. A choke plug may be provided in one of the first opening or the second opening. The choke plug may have a central passage extending through a longitudinal length thereof. The breather plate may further include a drive stud provided on the first side for engaging a corresponding opening provided on the control valve body. 
         [0018]    In yet another embodiment, a method for converting an ABDW-type control valve to an ABDX-type control valve for use in a braking mechanism for a railway vehicle may include the steps of removing an accelerated application valve from an ABDW-type control valve body to expose an accelerated application valve interface and mounting a breather plate on the accelerated application valve interface. The breather plate may have an internal stability volume for compensating the function of the accelerated application valve. The method may further include the steps of mounting a slide valve bushing inside the control valve body for establishing fluid communication with at least one passageway within the control valve body. In another embodiment, the method may include the step of mounting at least one plug for sealing at least one air passageway within the control valve body. In a further embodiment, the method may include the steps of expanding an accelerated application valve opening for pressing an accelerated valve bushing and providing a slot between the accelerated application valve opening and an air chamber on the valve body for establishing a fluid communication between the accelerated application valve opening and the air chamber. 
         [0019]    These and other features and characteristics of the apparatus and method for ABDW to ABDX control valve conversion, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1A  is a front view of an ABDW control valve body modified in accordance with one embodiment of the present disclosure; 
           [0021]      FIG. 1B  is rear view of the ABDW control valve body shown in  FIG. 1A ; 
           [0022]      FIG. 1C  is a left side view of the ABDW control valve body shown in  FIG. 1A ; 
           [0023]      FIG. 1D  is a right side view of the ABDW control valve body shown in  FIG. 1A ; 
           [0024]      FIG. 1E  is a top view of the ABDW control valve body shown in  FIG. 1A ; 
           [0025]      FIG. 2  is a perspective view of an ABDW control valve modified in accordance with one embodiment of the present disclosure; 
           [0026]      FIG. 3A  is a perspective view of an assembled breather plate for use on an emergency portion of an ABDW control valve modified in accordance with one embodiment of the present disclosure; 
           [0027]      FIG. 3B  is an exploded perspective view of the breather plate shown in  FIG. 3A ; 
           [0028]      FIG. 3C  is a front view of the breather plate shown in  FIG. 3A ; 
           [0029]      FIG. 3D  is a cross-sectional view of the breather plate shown in  FIG. 3C , taken along the line A 1 -A 1 ; 
           [0030]      FIG. 3E  is a cross-sectional view of the breather plate shown in  FIG. 3C , taken along the line B 1 -B 1 ; 
           [0031]      FIG. 4A  is a right side view of a slide valve bushing for use with an ABDW control valve modified in accordance with one embodiment of the present disclosure; 
           [0032]      FIG. 4B  is a bottom view of the slide valve bushing shown in  FIG. 4A ; 
           [0033]      FIG. 4C  is a front view of the slide valve bushing shown in  FIG. 4A ; 
           [0034]      FIG. 4D  is a side cross-sectional view of the slide valve bushing shown in  FIG. 4C , taken along the line A 1 -A 1 ; 
           [0035]      FIG. 4E  is a front cross-sectional view of the slide valve bushing shown in  FIG. 4D , taken along the line C-C; 
           [0036]      FIG. 4F  is a front cross-sectional view of the slide valve bushing shown in  FIG. 4D , taken along the line D-D; 
           [0037]      FIG. 4G  is a front cross-sectional view of the slide valve bushing shown in  FIG. 4D , taken along the line E-E; 
           [0038]      FIG. 4H  is a front cross-sectional view of the slide valve bushing shown in  FIG. 4D , taken along the line F-F; 
           [0039]      FIG. 4I  is a front cross-sectional view of the slide valve bushing shown in  FIG. 4D , taken along the line G-G; 
           [0040]      FIG. 4J  is a front cross-sectional view of the slide valve bushing shown in  FIG. 4D , taken along the line H-H; 
           [0041]      FIG. 5  is a top cross-sectional view of the ABDW control valve body shown in  FIG. 1B ; 
           [0042]      FIG. 6  is a top cross-sectional view of the ABDW control valve body shown in  FIG. 1D ; and 
           [0043]      FIG. 7  is a partial cross-sectional view of the ABDW control valve body shown in  FIG. 1E . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]    For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal”, and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting. 
         [0045]    Referring to  FIGS. 1A-1E , a body of an emergency portion of an ABDW control valve  10  is illustrated (hereinafter referred to as “valve body”). Valve body  10  is shown separate from the pipe bracket and service portion, which are omitted for the clarity of the disclosure. One of ordinary skill in the art will understand that valve body  10  can be coupled to conventional pipe bracket and service portion in a complete control valve assembly. Valve body  10  includes a front side  12  opposite a rear side  14 . A pair of opposing sides  16 ,  18  extends between front side  12  and rear side  14  to define an external contour of valve body  10 . A top side  20  and bottom side  22  extend across upper and lower portions of valve body  10 . 
         [0046]    With particular reference to  FIG. 1B , rear side  14  of valve body  10  includes an interface  24  for connecting an accelerated application valve (not shown). Interface  24  includes a substantially planar face  26  having a plurality of first air passages  28  for directing air to and from the accelerated application valve. A plurality of bolt holes  30  are disposed around the plurality of air passages  28  for connecting the accelerated application valve to valve body  10 . Bolt holes  30  are adapted for engagement with conventional fasteners (not shown) to removably secure the accelerated application valve to valve body  10 . 
         [0047]    Referring to  FIG. 1E , a plurality of air connections  32  are provided on a top side  20  of valve body  10 . A slide valve opening  34  is provided in a central portion of top side  20  and is adapted for engaging a slide valve (not shown). The slide valve engages the conforming seat in a slide valve bushing  70 . The slide valve is housed within the slide valve opening and move axially with the emergency piston (not shown). As will be described hereafter, slide valve bushing  70  has a plurality of keyed passageways positionable for fluid communication with a corresponding plurality of air passageways within valve body  10 . Depending on the orientation of the slide valve within slide valve bushing  70 , fluid pressure communication between various passageways within valve body  10  can be established or interrupted. Quick action passageway chamber  38  is provided adjacent to slide valve opening  34  on top side  20  of valve body  10 . 
         [0048]    In order to convert a function of an ABDW control valve to that of an ABDX control valve, several modifications and additions must be made to valve body  10 . Because ABDX control valves have an internal compensation for the stability volume provided by the accelerated application valve, an ABDW valve body is modified to include a corresponding stability volume in place of an accelerated application valve. Removal of the accelerated application valve from an ABDW valve body requires the addition of a stability volume incorporating the quick action chamber breather choke. With reference to  FIG. 2 , an ABDW-type valve body  10  is shown with a breather plate  40  provided to compensate for the removal of an accelerated application valve. Breather plate  40  is connected to rear side  14  of valve body  10  by fastening breather plate  40  to planar face  26  using a plurality of fasteners  42  engaging bolt holes  30  (shown in  FIG. 1B ). 
         [0049]    With reference to  FIGS. 3A-3B , breather plate  40  has a generally block-shaped body  44  having an internal volume  46 . Body  44  includes a plurality of through holes  48  corresponding to the plurality of bolt holes  30  on valve body  10  (shown in  FIG. 1B ). Each through hole  48  accepts a fastener  42  (shown in  FIG. 2 ) to fasten breather plate  40  to valve body  10 . A first side  50  of body  44  includes a recessed gasket face  52  adapted for retaining a gasket  54  therein. Gasket face  52  is dimensioned to encompass the plurality of first air passages  28  provided on rear side  14  of valve body  10  (see  FIG. 1B ). Gasket  54  provides a seal at the interface between first side  50  of breather plate  40  and planar face  26  of valve body  10 . Gasket  54  is desirably seated within gasket face  52 . 
         [0050]    With continuing reference to  FIGS. 3A-3B , a choke plug  56  is provided to reduce the area one of the plurality of first air passages  28 . As shown in  FIG. 3D , choke plug  56  may be threaded into a first opening  58  extending through the first side  50  of body  44 . A central passage  60  extends through choke plug  56  to provide fluid communication between air passage  28  on valve body  10  and internal volume  46  of breather plate  40 . In one embodiment, central passage  60  is bored to have a diameter corresponding to a diameter of a #46 drill (0.081 in). Choke plug  56  is in communication with the quick action chamber of valve body  10 . A second opening  62  is provided adjacent to first opening  58  and provides a direct fluid communication with the second air passage  28  on valve body  10 . 
         [0051]    With reference to  FIGS. 3C-3E , and with continuing reference to  FIGS. 3A-3B , internal volume  46  of breather plate  40  extends within the interior of body  44 . Because internal volume  46  must be closely controlled, a breather plate plug  64  is provided on a side of body  44 . 
         [0052]    As best shown in  FIG. 3B , breather plate  40  is provided with a stud  68  to prevent inappropriate interchange of an accelerated application valve with an otherwise unmodified ABDW-type emergency portion. As will be described in greater detail hereafter, several other modifications are necessary to an existing ABDW-type emergency portion before breather plate can be installed and the completed valve assembly be put into service. Drive stud  68  protrudes outward from first side  50  of body  44 . Drive stud  68  is received within a corresponding opening provided on a rear side  14  of valve body  10 . Such opening is created in an existing ABDW-type emergency portion after the appropriate internal modifications have been made to the emergency portion to assure the proper functioning of breather plate  40 . In an event where an installation of a breather plate  40  is attempted on an unmodified ABDW-type emergency portion, drive stud  68  will prevent a proper mating between first side  50  of body  44  and planar face  26  of valve body  10 . One of ordinary skill in the art will understand that the arrangement of the drive stud  68  and the corresponding opening may be reversed such that the drive stud  68  is provided on the valve body  10  and a corresponding opening on the breather plate  44 . 
         [0053]    Breather plate  40  replaces the accelerated application valve found on existing ABDW-type control valves and serves to route the air from the quick action chamber port (i.e., one of the plurality of air passages  28  provided on planar face  26 ) to internal volume  46 . The air is then routed from internal volume  46  into the exhaust port (i.e. the other of the plurality of air passages  28  provided on planar face) on rear side of valve body  10  to which the accelerated application valve was previously mounted. 
         [0054]    Due to differences between internal components of an ABDW-type control valve and an ABDX-type control valve, additional modifications are made to an emergency portion of an existing ABDW-type valve body to convert it to an ABDX-type body. The function of the accelerated application valve from an ABDW-type control valve is carried out internally within the valve body  10  modified in accordance with one embodiment of the present disclosure. In order to eliminate the need for an accelerated application valve, the activity carried out by accelerated application valve is incorporated into the slide valve function. With reference to  FIGS. 4A-4J , a slide valve bushing  70  replaces an existing ABDW-type bushing. Bushing  70  is installed in valve body  10  such that the slide valve seat faces the mounting face of the accelerated application valve. As best illustrated in  FIG. 4D , bushing  70  includes a plurality of recessed passages  72  extending around at least a part of the external perimeter of bushing  70 . The plurality of recessed passageways  72  are separated axially along a longitudinal extent of the bushing  70 . Plurality of recessed passages  72  is adapted for providing fluid communication between various air passageways within valve body  10 . Depending on the orientation of the slide valve, the plurality of recessed passageways  72  of bushing  70  route the air to the appropriate air passageway. Additionally, as further illustrated in  FIG. 4D , bushing  70  includes a plurality of through passages  74  extending radially through at least one side of bushing  70 . The plurality of through passages  74  are separated axially along a longitudinal extent of the bushing  70 . Several slots  76  are provided along the longitudinal length of bushing  70  for providing fluid communication with the vent valve, the brake pipe, and the exhaust valve.  FIG. 5  shows bushing  70  inserted into slide valve opening  34  on top side  20  of valve body  10 . 
         [0055]    With reference to  FIGS. 1D and 6 , several modifications are made to an existing accelerated application valve (AAV) opening  78  on valve body  10 . A tapered hole  80  is drilled in AAV opening  78  to accept AAV bushing  82 . As shown in  FIG. 1D , AAV bushing  82  is pressed into tapered hole  80 . An AAV choke plug  84  is provided inside AAV bushing  82 . AAV choke plug  84  has a central through passage having a reduced diameter compared to a diameter of AAV opening  78 . A mesh filter  86  is provided on AAV choke plug  84  to filter impurities in the air passing through AAV choke plug  84 . With continuing reference to  FIG. 1D , a slot  88  is milled between AAV opening  78  and an air chamber  90 . Slot  88  establishes a fluid communication between AAV opening  78  and air chamber  90 . With reference to  FIGS. 1E and 7 , a plurality of plugs  92  are provided to seal two of the plurality of air connections  32  provided on top side of valve body  10 . The plugs  92  may be threaded to the valve body  10 , press fit to the valve body  10 , or certain plugs  92  may be threaded to the valve body  10  while other plugs  92  are press fit to the valve body  10 . 
         [0056]    By replacing the accelerated application valve on an ABDW-type control valve, and by modifying the internal components of the ABDW-type control valve in accordance with the teachings described above, a conventional ABDW-type control valve is modified to have the function of a modern ABDX-type control valve. This eliminates the need to scrap an existing ABDW-type control valve body when updating the braking system of a railway vehicle to utilize the modern ABDX-type equipment. Performance characteristics of a new ABDX-type control valve are achieved by modifying an existing ABDW-type valve body and replacing the necessary components in accordance with the embodiments described herein. 
         [0057]    While various embodiments of the apparatus and method for ABDW to ABDX control valve conversion were provided in the foregoing description, those skilled in the art may make modifications and alterations to these embodiments without departing from the scope and spirit of the invention. For example, it is to be understood that this disclosure contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment. Accordingly, the foregoing description is intended to be illustrative rather than restrictive. The invention described hereinabove is defined by the appended claims and all changes to the invention that fall within the meaning and the range of equivalency of the claims are to be embraced within their scope.