Patent Publication Number: US-2015083914-A1

Title: Railway reference machine having a collapsible projector assembly

Description:
CROSS-REFERENCE 
     This application claims priority under 35 USC 119(e) from U.S. Provisional Application Ser. No. 61/882,137 filed Sep. 25, 2013. 
    
    
     BACKGROUND 
     The present disclosure generally relates to railroad right-of-way maintenance machinery, and more particularly relates to machinery used for surveying and aligning a railroad track using a high frequency beam such as an infrared signal. 
     During construction of a railroad, a bed of gravel or ballast is constructed and formed typically between one and three feet thick. Railroad ties are embedded in the ballast and rails are attached to the ties via tie plates. In the case of wooden railroad ties, the rails are nailed to the ties with spikes, but in the case of concrete ties, clips connect the rails and the ties. All rails and ties must be set at a specific height and alignment. For example, the rails must be disposed at a certain height above the ballast and stay within pre-set tolerances with respect to the alignment. 
     A tamping machine known as a ballast tamper is generally equipped with a railway reference machine for surveying the track, and the tamper is used to lift the rails and ties based on the survey such that the ties can be set at the specific height and properly aligned vertically and laterally. Reference or survey points established during the design phase of the railroad track are used to determine what the proper position and depth of the rail and ties should be. Through extended use, the rails become misaligned as the gravel and ballast sink into the ground. Such sinking is not consistent through the length of the railroad. Accordingly, the reference machine is periodically used to realign the rails based on the reference points. 
     For accuracies of the reference points, a buggy having infrared projectors is moved to about 100 feet away from the reference machine, and positioned on reliable reference rails for projecting infrared beams to sensors or receivers mounted to the reference machine A shadow board on the reference machine is provided in operational relationship to the projectors and the receivers for establishing proper alignment and position of the rails and tracks. 
     However, the projector buggy is a separate unit from the reference machine and must be placed far away from the reference machine. An operator of the machine periodically needs to reposition the projector buggy to a proper position. This requires manual adjustment of the projector buggy to a desired point. In some cases, the projector buggy is positioned at the end of a tunnel or on top of a bridge. Not only is this frequent repositioning of the projector buggy time consuming and laborious, but also is very inconvenient and costly. Therefore, there is a need for an improved projector buggy that can travel with the reference machine and is automatically deployed when necessary without much manual intervention of the operator. 
     SUMMARY 
     The present disclosure is directed to a railway reference machine having a collapsible projector assembly and a tamping machine, which is used for surveying and aligning a railroad track. Specifically, the collapsible projector assembly can be stored on a frame of the reference machine when not in use. More specifically, a foldable pusher buggy assembly is provided that rests within a space defined by the frame during transportation of the machine on a highway or a railroad track. Transporting the projector assembly both on the highway and the track is possible by utilizing a roadworthy tamper apparatus. An exemplary transportation of the tamping machine is shown in our co-pending U.S. patent application Ser. No. ______ filed on ______ (Attorney Docket 1425.114261), which is incorporated by reference. 
     One aspect of the reference machine is that, as described in further detail below, the projector assembly includes the pusher buggy assembly having extendable and retractable linkage sections such that the linkage sections of the pusher buggy assembly are stackable and nestable within a confined area on the frame. A projector cart is attached to one end of the pusher buggy assembly, and a lifting device, such as a fork lift, is attached to the other end of the pusher buggy assembly for pivotally raising the buggy assembly onto the frame for storage. 
     Another important aspect is that the linkage sections are connected to each other via a linkage lock assembly. Included in the lock assembly are a locking mechanism and a cushioning mechanism interposed between adjacent ends of the linkage sections. Automatic locking of the adjacent linkage sections is achieved when the linkage sections are fully extended, but the locking mechanism can be released manually when the surveying and aligning of the rails are completed and the pusher buggy assembly needs to be folded and stowed away. For allowing the pusher buggy assembly to travel through curves and/or spirals on the railroad track, the cushioning mechanism is provided with a compliant joint to accommodate vibrations or movements caused by the geometry of the track during operation. 
     In one embodiment, a railway reference machine is provided for surveying and aligning a railroad track, and includes a collapsible projector assembly having a pusher buggy assembly, and a lifting device. A plurality of projectors is mounted to a projector cart. The pusher buggy assembly has extendable and retractable linkage sections such that the linkage sections are stackable and nestable within a space defined by the lifting device and the projector cart. At one end, the pusher buggy assembly is connected to the projector cart and at an opposite end is connected to the lifting device such that the projector cart pivots upwardly about a pivot point to rest the projector assembly in a space defined by a chassis being dimensional for supporting the reference machine, and pivots downwardly about the pivot point to lower the projector assembly on the railroad track. 
     In another embodiment, a railway reference machine is provided for surveying and aligning a railroad track, and includes a collapsible projector assembly including a projector cart having at least one projector, a pusher buggy assembly, and a lifting device. The pusher buggy assembly transitions between a retracted mode and an extended mode. The retracted mode refers to a condition where the pusher buggy assembly is folded and securely stored on a base plate of the projector cart, and the extended mode refers to a condition where the pusher buggy assembly is unfolded on the railroad track. At one end, the pusher buggy assembly is connected to the projector cart and at an opposite end is connected to the lifting device such that the projector cart pivots upwardly about a pivot point to rest the projector assembly in a space defined by a chassis being dimensional for supporting the reference machine, and pivots downwardly about the pivot point to lower the projector assembly on the railroad track. 
     In still another embodiment, a railway reference machine is provided for surveying and aligning a railroad track, and includes a collapsible projector assembly including a projector cart having at least one projector, a pusher buggy assembly, and a lifting device. The pusher buggy assembly is folded and securely stored on a base plate of the projector cart for storage or transportation, and is unfolded on the railroad track for operation. At one end, the pusher buggy assembly is connected to the projector cart and at an opposite end is connected to the lifting device such that the projector cart pivots upwardly about a pivot point to rest the projector assembly in a space defined by a chassis being dimensional for supporting the reference machine, and pivots downwardly about the pivot point to lower the projector assembly on the railroad track. A shadow board buggy has an adjustable shadow board being located between the projector assembly and a rearwardly located receiver buggy having at least one receiver for detecting misalignment of the track. A pair of surfacing receiver is provided for detecting vertical misalignments of rails, and a pair of lining receivers is provided for detecting horizontal misalignments of the rails. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a fragmentary perspective view of the present railway reference machine when a projector assembly is in a retracted mode upon a railway tamper machine; 
         FIG. 2  is a fragmentary perspective view of the railway reference machine of  FIG. 1  when the projector assembly is in an extended mode; 
         FIG. 3  is a fragmentary side view of the projector assembly in a road travel mode; 
         FIG. 4  is a fragmentary side view of the projector assembly in a track travel mode; 
         FIG. 5  is a top perspective view of a pusher buggy assembly in a locked position; 
         FIG. 6  is an enlarged perspective view of a portion of the pusher buggy assembly of  FIG. 5  in an unlocked position; 
         FIG. 7  is a perspective view of the present travel lock; 
         FIG. 8  is an enlarged fragmentary perspective view of the present locking pin of the travel lock of  FIG. 7 ; 
         FIG. 9  is a perspective view of the present linkage lock assembly; 
         FIG. 10  is an enlarged view of a compliant joint of the linkage lock assembly of  FIG. 9 ; 
         FIG. 11  is a perspective view of the compliant joint of  FIG. 10 ; 
         FIG. 12  is a fragmentary perspective view of the present shadow board buggy; 
         FIG. 13  is a fragmentary enlarged view of the present shadow board in a work position; 
         FIG. 14  is a fragmentary enlarged view of the shadow board of  FIG. 13  in a travel position; 
         FIG. 15  is a fragmentary enlarged view of the present biasing wheels assembly; 
         FIG. 16  is a fragmentary perspective view of the present receiver buggy; 
         FIG. 17  is a fragmentary perspective view of the receiver buggy of  FIG. 16  in a retracted position; 
         FIG. 18  is a fragmentary perspective view of the receiver buggy of  FIG. 16  in an extended position; 
         FIG. 19  is a top perspective view of a lining receiver with a quick-release assembly; 
         FIG. 20  is an enlarged view of the quick-release assembly of  FIG. 19 ; and 
         FIG. 21  is a cross-sectional view of the quick-release assembly of  FIG. 20  taken along the line A-A and in the direction generally indicated. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 1-2 , the present railway reference machine is generally designated  10 , and is constructed to survey and align a railroad track using a collapsible projector assembly, generally designated  12 . As is well known in the art, the reference machine  10  is designed to be self-propelled or towed as a separate unit along the railroad track. While it is preferred that the reference machine  10  is self-propelled, a towed reference machine is also contemplated. It is also contemplated that the present reference machine  10  is incorporated into a rail tamper apparatus, as described in our co-pending U.S. patent application Ser. No. ______ filed on ______ (Attorney Docket 1425.114261), which is incorporated by reference. 
     Included in the projector assembly  12  is a projector cart, generally designated  14 , having a cart frame  16  supported by a plurality of cart wheels  18  for traveling on the track. At least one high frequency beam transmitter or projector  20  is carried by the projector cart  14  and mounted to the cart frame  16  for projecting an infrared signal to a rearwardly located receiver buggy, generally designated  22 . A shadow board buggy, generally designated  24 , is located between the projector assembly  12  and the receiver buggy  22 . An adjustable shadow board  26  is mounted to the shadow board buggy  24  and is provided in operational relationship to the projector assembly  12  and the receiver buggy  22  to indicate whether the track is out of alignment vertically and/or horizontally. 
     Also included in the projector assembly  12  is a pusher buggy assembly, generally designated  28 , having a first linkage section  30  and a second linkage section  32 . At one end, the pusher buggy assembly  28  is connected to the projector cart  14  and at an opposite end is connected to a lifting device  34 . Both linkage sections  30 ,  32  are connected to each other and cause them to pivotally fold about pivot points  36 . For example, the first linkage section  30  is pulled toward the second linkage section  32 , thereby shortening the distance between the two sections  30 ,  32 . This folding action causes the first and second sections  30 ,  32  to move inwardly toward each other, and as a result the sections are movably or slidably collapsed for storage. Each second linkage section  32  has a pair of pusher wheels  38  for traveling on the railroad track. 
     A chassis  40  supporting the reference machine  10  is attached to the lifting device  34  and is also dimensional for supporting the projector assembly  12 , the receiver buggy  22 , and the shadow board buggy  24 . A plurality of chassis wheels  42  are provided for traveling on the railroad track. A cab  44  accessible by an operator  46  includes various control mechanisms for the reference machine  10 , and is located between the receiver buggy  22  and the shadow board buggy  24 . 
     To perform an accurate survey of the alignment of the rails, the projector cart  14  is typically positioned more than 100 feet in front of the receiver buggy  22 . Positioning of the projector cart  14  is achieved by unfolding and stretching the pusher buggy assembly  28  along the railroad track. As described in further detail below, the pusher buggy assembly  28  is extendable and retractable such that multiple first and second linkage sections  30 ,  32  are stackable upon and nestable within the lifting device  34 . 
     Once the pusher buggy assembly  28  is fully extended, reaching a predetermined position from the receiver buggy  22 , an infrared light is transmitted from the projector  20  towards at least one receiver  48  mounted to the receiver buggy  22 . Three elements, namely the projector  20 , the shadow board  26 , and the receiver  48 , communicate with one another to establish a reference line, and the elements act as a detection system to correct the track alignment relative to the reference line. 
     A built-in error may exist in the correction to the rails. For example, when the projector cart  14  is positioned approximately 120 feet from the receiver buggy  22 , assuming that there is approximately a 14.5 feet spacing between the shadow board buggy  24  and the receiver buggy  22 , there is a 7:1 error correction ratio. Thus, if the projector  20  is within a seven inch depth of track of the reference machine  10 , a tamper machine  50  (shown in phantom) installed within a work area  52  defined by the chassis  40  creates a one-inch depth from a desired height. 
     In other words, the tamper machine  50  lifts the rails until the rails are at a specific height so that the projector  20  can communicate with the receiver  48  before the shadow board  26  comes into alignment and indicates that the rails are set at the proper error tolerance level. Once the tamper machine  50  has lifted and aligned the rails to the desired position, the tamper unit in the machine moves the ballast to support the rails in the now-aligned position as is well known in the art. Then, the projector cart  14  is repositioned on the track for subsequent alignments. 
     Referring now to  FIGS. 1-4 , an important feature of the projector assembly  12  is that it can be collapsed and stowed away for transportation and/or storage. Specifically,  FIG. 1  shows the projector assembly  12  in a retracted mode. As shown in  FIGS. 3-4 , the retracted mode refers to a condition where the pusher buggy assembly  28  is folded and securely stored on a base plate  54  of the projector cart  14  for traveling on a highway or on a railroad track. For example, when in the retracted mode, the projector assembly  12  can either be stowed away for storage and/or transportation on a road, such as a state highway, or on the railroad track using the cart wheels  18 . Additionally,  FIG. 2  shows the projector assembly  12  in an extended mode. The extended mode refers to a condition where the pusher buggy assembly  28  is unfolded and the first and second linkage sections  30 ,  32  are securely locked so that the projector cart  14  reaches a predetermined position from the receiver buggy  22 . 
     More specifically,  FIGS. 3 and 4  illustrate the projector assembly  12  in road and track travel modes, respectively. As shown in  FIG. 3 , the road travel mode refers to a condition where the folded pusher buggy assembly  28  is stored in a space defined by the lifting device  34 , the base plate  54  and the projector cart  14  while being transported on the highway. To secure clearance from the track, the lifting device  34  holding the folded pusher buggy assembly  28  and the projector cart  14  pivots upwardly about a pivot bar  56  at an angle of about 90 degrees toward the cab  44  ( FIGS. 1-2 ), and rests in a space defined by the chassis  40 . As a result, when the projector assembly  12  is being transported on the highway by the roadworthy tamper apparatus, e.g., as taught in the U.S. application Ser. No. ______ (Attorney Docket 1425.114261), the first and second linkage sections  30 ,  32  lie substantially in parallel relative to the rails. 
     A lifting cylinder  58 , preferably a hydraulic actuator, is used for the pivoting movement, and is connected at one end to the lifting device  34  and at an opposite end to the chassis  40 . During the pivoting movement, the folded pusher buggy assembly  28  is secured by at least one holding bar  60  and/or at least one travel lock  62 . While the holding bar  60  is connected at one end to the lifting device  34  and at an opposite end to the projector cart  14 , the travel lock  62  is connected at one end to a stand structure  64  of the projector cart  14  and at an opposite end to the cart frame  16 . 
     As shown in  FIG. 4 , the track travel mode refers to a condition where the folded pusher buggy assembly  28  is still stored on the base plate  54  as in the road travel mode, but the projector cart  14  is lowered and movable on the track for transportation. Specifically, the lifting device  34  pivots downwardly about the pivot bar  56  at an angle of about 90 degrees toward the railroad track so that the cart wheels  18  engage the rail heads for traveling on the track. When the reference machine  10  reaches a desired work site on the track, the pusher buggy assembly  28  is lowered by the lifting device  34  on the rails for deployment. 
     Referring now to  FIGS. 5-8 , all pusher wheels  38  located on the same side, either right or left, are releasably collectively locked by the travel lock  62  to prevent movement during transportation and/or storage. A plurality of indentations  66  are defined on a lower edge  68  of the travel lock  62 , and each indentation  66  matingly biases an axle  70  connected to a pair of pusher wheels  38  of each second linkage section  32 . To place the pusher buggy assembly  28  in a locked position, the travel lock  62  pivots downwardly about a lock pivot pin  72 , capturing a locking pin  74  mounted to the cart frame  16  with a protrusion portion  76  of the travel lock  62  to secure the position. Conversely, to place the pusher buggy assembly  28  in an unlocked position, the travel lock  62  pivots upwardly about the lock pivot pin  72 , thereby releasing the locking pin  74 . When the travel lock  62  releases the pusher wheels  38 , the projector cart  14  is also released and subsequently the pusher buggy assembly  28  can be unfolded. 
     As best shown in  FIG. 7 , a plurality of shock absorbing pads  78 , such as neoprene pads, is provided to dampen shocks occurring at various mating sites  80 , namely between the axles  70  and corresponding indentations  66 , and also between the cart frame  16  and the travel lock  62 . As a result, the shock absorbing pads  78  provides consistent contact between the travel lock  62  and the axles  70  to prevent unnecessary movement during transportation of the projector assembly  12 . While only the mating sites  80  between the axles  70  and the indentations  66  are shown, other similarly situated sites causing abrasions or movements are also contemplated. 
     Referring now to  FIGS. 2 and 9 , an exemplary linkage lock assembly, generally designated  82  ( FIG. 9 ), is shown. The linkage lock assembly  82  firmly secures the first and second linkage sections  30 ,  32  to ensure and maintain a constant distance between the linkage sections from one end of the first linkage section  30  to the other opposite end of the second linkage section  32  when fully extended. In the preferred embodiment, the first linkage section  30  has an elongated portion  84  and an angled portion  86 . An upper end  88  of the elongated portion  84  is attached to a generally “C”-shaped bracket  90  in cross-section transverse to a longitudinal axis of the elongated portion  84  for pivotally connecting to an end member  92  disposed at an upper end  94  of the second linkage section  32 . A pair of bracket apertures  96  disposed on both sides of the bracket  90  is configured for receiving a transverse threaded fastener  98 , such as a bolt. 
     A stiffener  100  is attached to the upper end  88  of the elongated portion  84  and the angled portion  86 , and the stiffener is extending outwardly vertically from an outer surface  102  of the upper end of the elongated portion  84  and the angled portion  86 . Preferably, the stiffener  100  continues from the upper end  88  of the elongated portion  84  to an entire length of the angled portion  86  to help resisting the compressive and bending loads of gravity when the first and second linkage sections  30 ,  32  are unfolded and extended. 
     A biasing member  104  is attached to the angled portion  86  such that the biasing member biases upon a spring  106  that is attached to the upper end  94  of the second linkage section  32 . In a preferred embodiment, a polyurethane spring material is used as the spring  106  to provide a shock absorbing property. Also attached to the biasing member  104  are a linkage lock  108  and a pair of hook stops  110 . One end of the biasing member  104  biases against the spring  106 , and the other end of the biasing member is connected to the linkage lock  108 . 
     As the linkage lock  108  bears down near the upper end  94  of the second linkage section  32  when the first and second sections  30 ,  32  are fully unfolded, the pair of hook stops  110  disposed on opposite sides of the biasing member  104  correspondingly snap over a pair of posts  112  extending laterally on opposite sides of the upper end  94  of the second linkage section  32 . As shown in  FIG. 2 , when all first and second linkage sections  30 ,  32  are securely locked, the linkage lock assembly  82  stops movement of the projector cart  14  and consistently maintains the distance between the projector  20  and the receiver  48 . 
     Referring now to FIGS.  2  and  9 - 11 , an exemplary compliant joint, generally designated  114 , is provided for allowing the pusher buggy assembly  28  to travel through curves and/or spirals on the railroad track and simultaneously limiting movement of the pivot joints  36  within a predetermined tolerance level. Specifically, the end member  92  of the second linkage section  32  has a bore  116  configured for receiving the compliant joint  114  that controllably minimizes pivotal and/or lateral movements caused by the geometry of the railroad track. 
     In the preferred embodiment, the compliant joint  114  includes an outer sleeve  118  surrounding an inner sleeve  120 , both of which preferably have a cylindrical shape. An elastic material  122 , such as a rubber, is disposed between the outer and inner sleeves  118 ,  120  for controlled movement. A center opening  124  configured for receiving the fastener  96  is defined by the inner sleeve  120 . 
     As an example, the compliant joint  114  is slidably inserted into the bore  116  of the end member  92 , and then the “C”-shaped bracket  90  of the first linkage section  30  fits over the end member. Connection of the compliant joint  114 , the end member  92 , and the “C”-shaped bracket  92  is achieved by fastening the fastener  98  through the bracket apertures  96  and the center opening  124 . Accordingly, the compliant joint  114  provides the first linkage section  30  with not only radial pivoting movement but also lateral pivoting movement relative to the second linkage section  32 . While only a specific type of compliant joint is described, other suitable compliant joints, such as various spherical bushings and slots, are also contemplated. 
     Referring now to FIGS.  2  and  12 - 15 , the shadow board  26  is adjustable in multiple ways. When the rails have vertical or horizontal curves or dips, the shadow board  26  must be positioned accordingly to compensate for variations of the railroad track. For example, when calibrated, the shadow board  26  is moved until it occludes or blocks an infrared signal from the projector  20  such that the signal is not received by the receiver  48 . When the track deviates laterally or vertically, the receiver  48  detects the infrared signal from the projector  20 , and the tamper machine  50  corrects the rails to the desired position. 
     A positional adjustment of the shadow board  26  is achieved by a cage mount  126 , which is connected at one end to the shadow board  26  and at an opposite end to a biasing wheels assembly, generally designated  128 . Multiple cylinders  129 , preferably hydraulic, are provided for actuating the cage mount  126  horizontally (left or right), vertically (up or down), and diagonally relative to the chassis  40 . Notably, however, the cage mount  126  is not adjustable forwardly or rearwardly. 
     When the shadow board  26  is not in use or being transported, the board may be folded to comply with a highway height requirement. As shown in  FIGS. 13-14 , the shadow board  26  pivots downwardly or upwardly about a pair of pivot pins  130  under the action of an auxiliary cylinder  132 , which is connected at one end to the shadow board  26  and at an opposite end to the cage mount  126 . Accordingly,  FIG. 13  shows the shadow board  26  in a work position, and  FIG. 14  shows the shadow board in a travel position. 
     In operation, the shadow board buggy  24  is securely positioned relative to the rails for accurate surveys of the railroad track. For example, the biasing wheels assembly  128  includes a pair of biasing wheels  134 . Each biasing wheel  134  has a flange  136  extending radially on an outer periphery of the wheel for biasing against an inner surface of each corresponding rail under the action of a spring-return hydraulic cylinder  138 . While a single acting hydraulic actuator is described here, other types of cylinders, such as a dual acting cylinder, are also contemplated. Thus, the biasing wheels  134  are urged against inside surfaces of the rails to maintain the shadow board buggy  24  in position during track alignment. 
     Referring now to FIGS.  2  and  16 - 18 , a detailed illustration of the receiver buggy  22  is shown. Multiple receivers are typically used for detecting the misalignment of the rails. In the preferred embodiment, a pair of surfacing receiver  140  is provided for detecting vertical misalignments of the rails. Each surfacing receiver  140  is mounted to an upper end  142  of a receiver support bar  144 . A lower end  146  of the support bar  144  is inserted into an outer tube  148  of a sliding mount  150  such that the support bar slidably telescopes upwardly and downwardly within the outer tube. 
     Additionally, a pair of lining receivers  152  is also provided for detecting horizontal misalignments. Each lining receiver  152  is mounted to a lower end  154  of a vertical post  156 . For generating the reference infrared signals, the projector  20  is provided for the pair of surfacing receivers  140 , and similarly additional two side projectors (not shown) are provided for the corresponding lining receivers  152 . In operation, the receivers  140 ,  152  simultaneously receive the infrared signals from the projectors. 
     When the surfacing receivers  140  are not in use or being transported, the sliding mount  150  may be lowered to protect the receivers and/or to comply with the highway height requirement. As shown in  FIGS. 17-18 , for vertical movement of the sliding mount  150 , a telescoping rod  158  is attached to at one end to the sliding mount  150  and at an opposite end to a horizontal support bar  160 . Each end of the support bar  160  is connected to the vertical posts  156 . For example, the sliding mount  150  slides upwardly to position the surfacing receivers  140  for detecting the infrared signals, and slides downwardly for storage during transportation. 
     Referring now to FIGS.  16  and  19 - 21 , a quick-release assembly, generally designated  162 , is shown. As for the lining receivers  152 , a width restriction for the track and/or the highway requires the lining receivers to be removed, folded, or retracted for clearance. In the preferred embodiment, the quick-release assembly  162  is provided for releasably securing the lining receiver  152  into a socket  164  configured for accommodating the lining receiver. Preferably, the socket  164  is fixedly attached to near or adjacent the lower end  154  of the vertical post  156  at a desired height. As best shown in  FIGS. 19 and 21 , a spring  166  is attached to an inner planar surface  168  of a tube  170  having an open end  172  and a closed end  174 . A receiver support bar  176  is connected at one end to the closed end  174  of the tube  170 , and at an opposite end to the lining receiver  152 . 
     To attach the support bar  176  to the socket  164 , the support bar is initially inserted into the socket against the action of the spring  166  guided by a guide pin  178 , thereby depressing a spring plunger  180  while rotating the receiver clockwise at about 45 degree angle to lock the receiver in place with a locking protrusion  182 . Conversely, to remove or release the lining receiver  152  from the socket  164 , the receiver is slightly pushed into the socket, thereby depressing the spring plunger  180  again while rotating the receiver counterclockwise to unlock. As a result, the lining receiver  152  is released from the socket  164  and pulled out of the socket under the action of the spring  166  for storage. 
     Returning now to FIGS.  12  and  15 - 16 , as is the case with the shadow board buggy  24 , the receiver buggy  22  also must be secured on the rails for accurate surveys of the railroad track. Accordingly, an additional biasing wheels assembly  184  similar to the biasing wheels assembly  128  illustrated above is provided and connected near the lower ends  154  of the vertical posts  156 . 
     While a particular embodiment of the present railway reference machine has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the present disclosure in its broader aspects and as set forth in the following claims.