Abstract:
Example manual wheel restraint systems and methods for restraining a vehicle at a loading dock include are disclosed herein. An example wheel restraint disclosed herein includes a retractable wheel-blocking barrier mounted to a carrier that can be repositioned along a track, where the track is anchored to a driveway of a loading dock. The track runs generally parallel to a vehicle path that a wheel of a vehicle travels along as the vehicle backs into the dock. To block a rear wheel of the vehicle parked at the dock, the barrier extends laterally into the wheel path, adjacent or in front of the wheel. To release the vehicle, the barrier retracts out from within the wheel path. In some examples, to ensure that the vehicle is secured, the barrier and/or the carrier include barrier or carrier catches to help hold the barrier and carrier in a fixed position. In some examples, one or more sensors determine or sense whether the catches are secured or released and generate signals accordingly. The signals, in some examples, alert dock personnel of the condition of the catches.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    This patent generally pertains to wheel restraints and, more specifically, to track-mounted wheel restraint systems. 
       BACKGROUND 
       [0002]    A typical loading dock of a building includes an exterior doorway with an elevated platform for loading and unloading vehicles, such as trucks and trailers. When cargo is being transferred between the vehicle and the platform, it is generally safe practice to restrain the vehicle by some means to prevent the vehicle from accidentally departing the dock prematurely. 
         [0003]    Perhaps the simplest vehicle restraint is a portable wheel chock that is manually wedged in front of a vehicle&#39;s wheel to obstruct the vehicle&#39;s forward movement. Examples of portable wheel chocks are disclosed in U.S. Pat. Nos. 6,390,245; 7,000,740; 7,040,461 and 7,226,265. 
         [0004]    Some example vehicle restraints are permanently mounted to the dock and have a hook that engages the front edge of a truck or trailer&#39;s rear impact guard (also known as an ICC bar). Examples of such vehicle restraints are disclosed in U.S. Pat. Nos. 5,882,167; 6,116,839; 6,190,109 and 7,841,823. 
         [0005]    Other vehicle restraints, such as those that are sometimes referred to as “wheel restraints,” are mounted to the loading dock&#39;s driveway and have an arm or wheel-blocking barrier that moves in front of a rear wheel of the vehicle to create an obstruction that inhibits the vehicle from departing from the dock prematurely. Examples of such wheel restraints are disclosed in U.S. Pat. Nos. 5,762,459; 5,582,498; 6,092,970; 6,676,360; 8,006,811 and 8,307,956 and in US patent publications 2011/0162916 and 2009/0194376. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an end view of an example wheel restraint system constructed according to the teachings disclosed herein. 
           [0007]      FIG. 2  is a top view of  FIG. 1 . 
           [0008]      FIG. 3  is a front side view of  FIG. 1 . 
           [0009]      FIG. 4  is a top view similar to  FIG. 2 , but showing a carrier catch of an example wheel restraint in a release position and a barrier catch of the example wheel restraint in a second position. 
           [0010]      FIG. 5  is a front view of  FIG. 4 . 
           [0011]      FIG. 6  is a top view similar to  FIGS. 2 and 4 , but showing the barrier of the example wheel restraint in a retracted position. 
           [0012]      FIG. 7  is a top view similar to  FIG. 2 , but illustrating another example wheel restraint constructed according to the teachings disclosed herein. 
           [0013]      FIG. 8  is a front view of  FIG. 7 . 
           [0014]      FIG. 9  is a top view similar to  FIG. 7 , but showing a carrier catch of the example wheel restraint of  FIGS. 7 and 8  in a release position and a barrier catch of the example the wheel restraint. 
           [0015]      FIG. 10  is a front side view of  FIG. 9 . 
           [0016]      FIG. 11  is a top view similar to  FIGS. 7 and 9 , but showing the barrier of the example wheel restraint of  FIGS. 7-9  in a retracted position. 
           [0017]      FIG. 12  is a top view similar to  FIG. 2 , but showing another example wheel restraint constructed according to the teachings disclosed herein. 
           [0018]      FIG. 13  is a front view of  FIG. 12 . 
           [0019]      FIG. 14  is a top view similar to  FIG. 12 , but showing a carrier catch of the example wheel restraint of  FIGS. 12 and 13  in a release position and a barrier catch of the example wheel restraint in a second position. 
           [0020]      FIG. 15  is a front view of  FIG. 14 . 
           [0021]      FIG. 16  is a top view similar to  FIGS. 12 and 14 , but showing the barrier in a retracted position. 
           [0022]      FIG. 17  is an end view of another example wheel restraint system constructed according to the teachings disclosed herein. 
           [0023]      FIG. 18  is a top view of  FIG. 17 . 
           [0024]      FIG. 19  is a front view of  FIG. 18 . 
           [0025]      FIG. 20  is a top view similar to  FIG. 18 , but showing a carrier catch of the example wheel restraint of  FIGS. 17-19  in a release position and a barrier catch of the example wheel restraint in a second position. 
           [0026]      FIG. 21  is a front view of  FIG. 20 . 
           [0027]      FIG. 22  is a top view similar to  FIG. 20 , but showing the barrier in a retracted position. 
           [0028]      FIG. 23  is an end view of another example wheel restraint system constructed according to the teachings disclosed herein. 
           [0029]      FIG. 24  is a right side view of  FIG. 23 . 
           [0030]      FIG. 25  is a top view of  FIG. 24 . 
           [0031]      FIG. 26  is a top view similar to  FIG. 25 , but showing a barrier catch of the example wheel restraint of  FIGS. 23-25  in a second position. 
           [0032]      FIG. 27  is a top view similar to  FIG. 26 , but showing the barrier of the example wheel restraint of  FIGS. 23-26  in a retracted position. 
           [0033]      FIG. 28  is an end view of  FIG. 27 . 
       
    
    
     DETAILED DESCRIPTION 
       [0034]      FIGS. 1-6  show an example wheel restraint system  10  constructed in accordance with the teachings disclosed herein. The wheel restraint system  10  of the illustrated example secures a vehicle  12  (e.g., truck, trailer, etc.) being loaded or unloaded of cargo at a loading dock  14 . In the illustrated example, a dock  16  comprises a driveway  18  that leads to a doorway  20  and an elevated platform  22  of a building  24 . When cargo is being transferred between the platform  22  and the vehicle  12 , the wheel restraint system  10  helps prevent the vehicle  12  from accidentally departing prematurely. 
         [0035]    In some examples, the wheel restraint system  10  comprises a retractable wheel-blocking barrier  26  mounted to a carrier  28 . The carrier  28  can travel in a first direction  30  (e.g., a forward direction) and a second direction  32  (e.g., a rearward direction) ( FIG. 4 ) in a longitudinal direction  34  along a track  36  to position the barrier  26  adjacent or near (e.g., just ahead of) a rear wheel  38  of the vehicle  12 . Once the barrier  26  is positioned, the carrier  28  is latched onto the track  36  to substantially inhibit movement of the carrier  28  in the first direction  30 . To secure or release the wheel  38 , the barrier  26  is selectively moved in a lateral direction  40  between a blocking position ( FIGS. 1 and 2 ) and a release position ( FIG. 6 ). In the blocking position, the barrier  26  extends laterally into a wheel path  42  of the wheel  38  such that the wheel  38  is trapped, positioned or captured between the barrier  26  and the platform  22  as shown, for example, in  FIGS. 1-3 . To release the vehicle  12 , the barrier  26  is withdrawn from within a wheel path  42 , as shown in  FIG. 6 . 
         [0036]    Although the details of the wheel restraint system  10  may vary in some examples, the track  36  of the illustrated example includes a lower section  36   a  anchored to the driveway  18  and an upper section  36   b  that has a plurality of discontinuities  44 . The purpose of the discontinuities  44 , which will be explained later in greater detail, are to help hold the carrier  28  to a chosen or selected position along the track  36 . Examples of the discontinuities  44  include, but are not limited to, notches, teeth, holes, pegs, pins and/or detents. 
         [0037]    The carrier  28 , in some examples, comprises a front end  28   a,  a back end  28   b,  and a base  28   c  extending between the front and back ends  28   a  and  28   b.  In the illustrated example, the base  28   c  rests upon and translates along the upper section  36   b.  In some examples, the front end  28   a  and the back end  28   b  include guides  46  for holding the carrier  28  in sliding engagement with the track  36 . In some examples, the guides  46  include rollers to reduce friction between the carrier  28  and the track  36 . 
         [0038]    The barrier  26  of the illustrated example is generally L-shaped and has a wheel-blocking section  26   a  which is elongate in the lateral direction  40 , an arm section  26   b  which is elongate in the longitudinal direction  34 , and a heel section  26 c between the wheel-blocking section  26   a  and the arm section  26   b.  In the illustrated example, the barrier  26  is rotatable about a pin  48  that connects the arm section  26   b  of the barrier  26  to the base  28   c  of the carrier  28 . This allows the barrier  26  to pivot about a rotational axis  50  between the blocking and retracted positions of the barrier  26 . 
         [0039]    To help hold the barrier  26  at the blocking position, the wheel restraint system  10  of the illustrated example includes a barrier catch  52  attached to at least one of the barrier  26  and/or the carrier  28 . In the example illustrated of  FIGS. 1-6 , a pin  54  connects the barrier catch  52  to the base  28   c  of the carrier  28 . The barrier catch  52 , in this example, is rotatable about the pin  54  between a first position ( FIG. 2 ) and a second position ( FIG. 4 ). In the first position, a front end  52   a  of the barrier catch  52  is elevated, as shown in  FIG. 3 , to obstruct the barrier  26  and prevent the barrier  26  from moving from the blocking position to the retracted position. In the second position, the front end  52   a  of the barrier catch  52  is below barrier  26 , as shown in  FIG. 5 , to allow the barrier  26  to rotate from the blocking position to the release position. 
         [0040]    When the barrier  26  is in the blocking position restraining the vehicle  12 , a carrier catch  56  attached to at least one of the carrier  28  or the barrier  26  helps hold the carrier  28  and/or the barrier  26  at a position or location along the track  36 . In the example illustrated in  FIGS. 1-6 , a pin  58  connects the carrier catch  56  to a projection  60  of the barrier  26 . The carrier catch  56 , in this example, is rotatable about the pin  58  between a holding position ( FIG. 2 ) and a release position ( FIG. 4 ). In the holding position, the carrier catch  56  engages one or more of the track discontinuities  44  to restrict movement of the carrier  28  along track  36 , for example, the carrier catch  56  restricts the movement of the carrier  28  in the first direction  30 . In the release position, the carrier catch  56  effectively releases the track discontinuities  44  to allow the carrier  28  to move back and forth along track  36  (e.g., in the first and second directions  30 ,  32 ), thereby allowing the carrier  28  and the barrier  26  to be repositioned to another location or position along the track  36 . 
         [0041]    The movements of the barrier and carrier catches  52 ,  56  can be driven by any suitable means. Examples of such means include, but are not limited to, manual force, spring force, gravity, an electromagnetic solenoid, electromotive (e.g., an electric motor), magnetic force, vehicular force (e.g., wheel  38  pressing against a portion of the wheel restraint), hydraulic force, pneumatic force, and/or various combinations thereof. In some examples, the means for moving a catch in a first direction is different than the means for moving the catch in the second direction opposite the first direction. In some examples the means for moving a catch in the first and second directions is the same. In some examples, the means for moving the barrier catch  52  is different than the means for moving the carrier catch  56 . In some examples, the barrier catch  52  and the carrier catch  56  are moved by similar means. In some examples, the barrier and carrier catches  52 ,  56  move in various modes, examples of which include, but are not limited to, rotational, translational, laterally, vertically, horizontally and/or various combinations thereof. 
         [0042]    Additionally or alternatively, the movements of the barrier  26  and the carrier  28  can be driven by any suitable means. Examples of such means include, but are not limited to, manual force, spring force, gravity, an electromagnetic solenoid, electromotive (e.g., an electric motor), magnetic force, vehicular force (e.g., the wheel  38  pressing against a portion of the wheel restraint  10 ), hydraulic force, pneumatic force, and/or various combinations thereof. In some examples, the means for moving the barrier  26  or the carrier  28  in a first direction is different than the means for moving the barrier  26  or the carrier  28  in a second direction opposite the first direction. In some examples, the means for moving the barrier  26  and the carrier  28  in the first and second directions is the same. In some examples, the means for moving the barrier  26  is different than the means for moving the carrier  28 . In some examples, the barrier  26  and the carrier  28  are moved by similar means. In some examples, the barrier  26  and the carrier  28  move in various modes, examples of which include, but are not limited to, rotational, translational, laterally, vertically, horizontally and/or various combinations thereof. 
         [0043]    In some examples, the operating sequence of the wheel restraint system  10  is as follows. First, the wheel restraint system  10  is in a stored position, as shown in  FIG. 6 , where the barrier  26  is in the retracted position, the barrier catch  52  is in the second position ( FIG. 5 ), and the vehicle  12  backs into the dock  16  to place a rear edge  62  of the vehicle  12  adjacent the platform  22 . Upon backing  64  into the dock  16 , the wheel  38  travels (e.g., backward) along the wheel path  42  that is generally parallel to the track  36 . Next, the carrier  28  is slid or otherwise moved along the track  36  to position the barrier  26  adjacent (e.g., just ahead) of the wheel  38 . The barrier  26  is then rotated from the retracted position ( FIG. 6 ) to the blocking position ( FIGS. 1-5 ). To hold the carrier  28  at the position along track  36 , the carrier catch  56  is rotated to the holding position to engage one or more of the discontinuities  44 , as shown in  FIGS. 1-3 . To hold the barrier  26  at the blocking position, the barrier catch  52  is rotated to the first position, as shown in  FIGS. 1-3 . With the barrier  26  in the blocking position, the barrier catch  52  in the first position, the carrier  28  positioned to place wheel-blocking section  26   a  in front of the wheel  38 , and the carrier catch  56  in the holding position, the wheel restraint system  10  restrains the vehicle  12  by capturing the wheel  38  between the barrier  26  and the platform  22 . To release vehicle  12 , the barrier catch  52  is moved from the first position ( FIG. 3 ) to the second position ( FIG. 5 ), and the barrier  26  is moved from the blocking position ( FIG. 4 ) to the retracted position ( FIG. 6 ). 
         [0044]    To improve safety and proper use, some examples of the wheel restraint system  10  include one or more catch sensors  64  (e.g., a carrier catch sensor  64   b,  a carrier catch sensor  64   d,  a barrier catch sensor  64   a  and/or a barrier catch sensor  64   c ) and a signal indicator  66  for providing a visual signal  68  (e.g., a light such as a red visual signal  68   a,  a green visual signal  68   b,  a red visual signal  68   c  and/or a green visual signal  68   d ) that indicates the position of the carrier catch  56  and/or the barrier catch  52 . The catch sensors  64  are schematically illustrated to represent any device for detecting the position of the barrier catch  52  or the carrier catch  56 . Examples of the catch sensors  64  include, but are not limited to, a proximity switch, a Hall effect sensor, a magnetic resonance sensor, a photoelectric eye, an electromechanical limit switch, etc. 
         [0045]    In some examples, the catch sensors  64  change state and provide a corresponding change in a catch signal (e.g., a barrier catch signal  70   a,  a barrier catch signal  70   c,  a carrier catch signal  70   b,  and a carrier catch signal  70   d ) upon sensing the respective barrier catch  52  or carrier catch  56  having changed position. The term, “state” refers to a sensor&#39;s character or condition that changes in response to sensing a change in the position of a catch, such as the barrier or carrier catches  52  or  56 . Some examples of a sensor&#39;s change in state include, but are not limited to, electrical contacts opening, electrical contacts closing, an output voltage rising, an output current rising, an output voltage falling, an output current falling, electrical resistance rising, electrical resistance falling, electrical inductance rising, electrical inductance falling, etc. 
         [0046]    In some examples, the barrier catch sensor  64   a  changes from a first state to a second state in response to the barrier catch  52  moving from a first position to a second position. In some examples, the barrier catch sensor  64   a  changes from the second state to the first state in response to the barrier catch  52  moving from the second position to the first position. 
         [0047]    In some examples, the barrier catch sensor  64   c  changes from a first state to a second state in response to the barrier catch  52  moving from a first position to a second position. In some examples, the barrier catch sensor  64   a  changes from the second state to the first state in response to the barrier catch  52  moving from the second position to the first position. 
         [0048]    In some examples, the carrier catch sensor  64   b  changes from a holding state to a release state in response to the carrier catch  56  moving from a holding position to a release position. In some examples, the carrier catch sensor  64   b  changes from the release state to the holding state in response to the carrier catch  56  moving from the release position to the holding position. 
         [0049]    In some examples, the carrier catch sensor  64   d  changes from a holding state to a release state in response to the carrier catch  56  moving from a holding position to a release position. In some examples, the carrier catch sensor  64   b  changes from the release state to the holding state in response to the carrier catch  56  moving from the release position to the holding position. 
         [0050]    In some examples, the wheel restraint system  10  includes the barrier catch sensor  64   a  and the carrier catch sensor  64   b,  where the barrier catch sensor  64   a  provides a barrier catch signal  70   a  that indicates whether the barrier catch  52  is in the first position shown in  FIG. 2 , and the carrier catch sensor  64   b  provides a carrier catch signal  70   b  that indicates whether the carrier catch  56  is in the holding position shown in  FIG. 3 . In some examples, a signal indicator  66  is operatively connected (e.g., via hard-wiring or via a wireless communication link  67 ) to the barrier catch sensor  64   a  and the carrier catch sensor  64   b  to receive the barrier catch signal  70   a  and the carrier catch signal  70   b.  Examples of the wireless communication link  67  include, but are not limited to, electromagnetic or radio waves, infrared, ultrasound, laser, etc. Wireless communication, in some examples, employ one or more communication protocols or standards, examples of which include, but are not limited to, Bluetooth, Wi-Fi, ZigBee, etc. In some examples, in response to receiving signals  70   a  and  70   b  indicating that both the barrier catch  52  is in the first position and the carrier catch  56  is in the holding position, the signal indicator  66  provides visual signals  68   a  and  68   d,  where the visual signal  68   a  provides, for example, a red light to personnel outside of a building at loading dock  16  (e.g., outdoor personnel) to indicate that the vehicle  12  is restrained, and the signal  68   d  provides, for example, a green light to personnel inside of the building at the loading dock  16  (e.g., indoor personnel) that the vehicle  12  is restrained, as shown in  FIG. 2 . 
         [0051]    In addition or alternatively, in some examples, the wheel restraint system  10  includes the barrier catch sensor  64   c  and the carrier catch sensor  64   d,  where the barrier catch sensor  64   c  provides a barrier catch signal  70   c  that indicates whether the barrier catch  52  is in the second position shown in  FIG. 5 , and the carrier catch sensor  64   d  provides a carrier catch signal  70   d  that indicates whether the carrier catch  56  is in the release position shown in  FIG. 4 . The signal indicator  66 , in this example, is operatively connected (e.g., via hard-wiring or wireless communication) to the barrier catch sensor  64   c  and the carrier sensor  64   d  to receive the barrier catch signal  70   c  and the carrier catch signal  70   d.  In some examples, in response to receiving the barrier catch signal  70   c  or the carrier catch signal  70   d  indicating that the barrier catch  52  is in the second position or the carrier catch  56  is in the release position, the signal indicator  66  provides visual signals  68   b  and  68   c,  where the visual signal  68   b  provides, for example, a green light to outdoor personnel that the vehicle  12  is not restrained, and the visual signal  68   c  provides, for example, a red light to indoor personnel that the vehicle  12  is not restrained, as shown in  FIG. 6 . 
         [0052]      FIGS. 7-11  show an example vehicle restraint system  72  similar to the example vehicle restraint system  10  of  FIGS. 1-6 . However, with the vehicle restraint system  72 , a carrier catch  74  is solidly or integrally attached to a projection  60  of the barrier  26 , and the carrier catch  56  and the carrier catch sensors  64   b  and  64   d  are omitted. In this example, the carrier catch  74  is movable from a holding position ( FIGS. 7 and 9 ) to a release position ( FIG. 11 ) by moving the barrier catch  52  from a first position ( FIG. 8 ) to a second position ( FIG. 10 ) and then moving the barrier  26  from a blocking position ( FIGS. 7 and 9 ) to a retracted position ( FIG. 11 ). 
         [0053]    In some examples, the wheel restraint system  72  includes the barrier catch sensor  64   a  and/or the barrier catch sensor  64   c.  In response to one or more signals from the barrier catch sensors  64   a  or  64   c  indicating that the barrier catch  52  is in the first position ( FIG. 8 ), the signal indicator  66  provides visual signals  64   a  and  64   d,  where the visual signal  64   a  provides a red light to communicate to outdoor personnel that the vehicle  12  is restrained, and the signal  64   d  provides a green light to communicate to indoor personnel that the vehicle  12  is restrained, as shown in  FIG. 7 . In response to one or more signals from the visual sensors  64   a  or  64   c  indicating that the barrier catch  52  is in the second position ( FIG. 10 ), the signal indicator  66  provides visual signals  68   b  and  68   c,  where the visual signal  68   b  provides a green light to communicate to outdoor personnel that the vehicle  12  is not restrained, and the visual signal  68   c  provides a red light to communicate to indoor personnel that vehicle  12  is not restrained, as shown in  FIGS. 9-11 . 
         [0054]      FIGS. 12-16  show an example vehicle restraint system  76  similar to the example vehicle restraint system  10  of FIGS.  1 - 6 .However, with the vehicle restraint system  76 , a barrier catch  78  and corresponding barrier catch sensors  64   a  and/or  64   c  are mounted to a barrier  80 , rather than to the carrier  28 . Also, the carrier catch  56  and corresponding carrier catch sensors  64   b  and  64   d  are mounted to a carrier  82 , instead of to the barriers  26  or  80 . 
         [0055]    In this example, a pin  84  pivotally connects the barrier catch  78  to the barrier  80  such that the barrier catch  78  is pivotal between a first position ( FIGS. 12 and 13 ) and a second position ( FIGS. 14-16 ). In the first position, the barrier catch  78  engages a lateral edge  86  of the carrier  28  to prevent the barrier  80  from freely swinging from a blocking position ( FIGS. 12 and 13 ) to a retracted position ( FIG. 16 ). In the second position, the barrier catch  56  disengages the lateral edge  86  to allow the barrier  80  to rotate from the blocking position to the retracted position. 
         [0056]    Also in this example, a pin  88  pivotally connects the carrier catch  56  to a projection  90  of the carrier  82  such that the carrier catch  56  is pivotal between a holding position ( FIG. 12 ) and a release position ( FIG. 14 ). In the holding position, the carrier catch  56  engages one or more of the discontinuities  44  of the track  36  to prevent the carrier  82  from moving in the first direction  30 . In the release position, the carrier catch  56  effectively disengages the plurality of discontinuities  44  to allow repositioning of the carrier  82  and the barrier  80  along the track  36 . In some examples, the signal indicator  66  works in conjunction with the catch sensors  64   a,    64   b,    64   c  and/or  64   d  in a manner similar to that of the example wheel restraint systems  10 . 
         [0057]    In another example, shown in  FIGS. 17-22 , a wheel restraint system  92  includes a wheel-blocking barrier  94  that slides within guide members  96  of a carrier  98 . Instead of rotating, the barrier  94  translates laterally between a blocking position ( FIGS. 17 and 18 ) and a retracted position ( FIG. 22 ). To prevent the barrier  94  from being moved unintentionally to a retracted position, the barrier catch  78  is mounted to the barrier  94  in a mounting arrangement similar to that of the barrier  80  in  FIG. 12 , where the barrier catch  78  is movable between a first position ( FIG. 18 ) and a second position ( FIGS. 20 and 22 ). In the first position, the barrier catch  78  engages a lateral edge  100  of the carrier  98  to prevent the barrier  94  from moving from a blocking position ( FIGS. 17 and 18 ) to a retracted position ( FIG. 22 ). In the second position, the barrier catch  78  disengages the lateral edge  100  to allow the barrier  94  to translate from the blocking position to the retracted position. 
         [0058]    The carrier catch  56 , the carrier catch sensors  64   b  and  64   d,  and the protrusion  60  are similar in structure and function as their corresponding parts of the example wheel restraint system  10  shown in  FIGS. 1-6 . To position the barrier  94  relative to the wheel  38 , the carrier catch  56  is moved from a holding position ( FIG. 18 ) to a release position ( FIG. 20 ), which allows the carrier  98  to translate along track  36  in a manner similar to the carrier  28  shown in  FIGS. 1-11 . 
         [0059]    In some examples of the wheel restraint system  92 , a vertical brace  102  extends downward from a distal end  104  of the barrier  94 . In some examples, a lower end  106  of the brace  102  is normally or generally held slightly above or elevated relative to the driveway  18 . However, if the wheel  38  exerts a significant downward force  107  against the distal end  104  of the barrier  94 , the lower end  106  of the brace  102  abuts or engages driveway  18  so that the brace  102  then provides the barrier  94  with vertical support. In some examples, a vertical brace similar to the brace  102  is added to the tip or distal end of the other example barriers disclosed herein. 
         [0060]      FIGS. 23-28  show a wheel restraint system  108  similar to the restraint  92  of  FIGS. 17-22 . However, there are a couple of differences. Instead of the pivotal carrier catch  56  ( FIGS. 17-22 ), the wheel restraint system  108  of the illustrated example has a carrier catch  110  solidly or integrally attached to a projection  112  of a wheel-blocking barrier  114 . The carrier catch  110  is similar in structure and functions similarly to the carrier catch  74  of  FIGS. 7-11 , whereby moving barrier  114  from a blocking position ( FIGS. 23 and 25 ) to a retracted position ( FIGS. 27 and 28 ) automatically moves the carrier catch  110  from a holding position ( FIG. 25 ) to a release position ( FIGS. 27 and 28 ). 
         [0061]    In addition or as an alternative to the vertical brace  102  of  FIGS. 17-22 , the wheel restraint system  108  of the illustrated example includes an example vertical retainer  116 , which helps provide the barrier  114  with vertical support when the barrier  114  is in the blocking position ( FIGS. 23-25 ). Various examples of vertical retainers disclosed herein include, for example, a downward facing surface and an upward facing surface, where the downward facing surface is disposed on at least one of the track or the carrier, and the upward facing surface is disposed on the wheel-blocking barrier such that the upward facing surface faces the downward facing surface at least when the barrier is in the blocking position. 
         [0062]    In the example of wheel restraint system  108 , shown in  FIGS. 23-28 , the vertical retainer  116  comprises a downward facing surface  116   a  on the track  36  and an upward facing surface  116   b  on the barrier  114 . In this example, the upward and downward facing surfaces  116   a  and  116   b  face and engage each other when the barrier  114  is in the blocking position ( FIG. 23 ), and the two surfaces  116   a,    116   b  are spaced apart when the barrier  114  is in the retracted position ( FIG. 28 ). 
         [0063]    In addition or alternatively, the wheel restraint system  108  includes a vertical retainer  118  comprising a downward facing surface  118   a  on a carrier  120  and an upward facing surface  118   b  on the barrier  114 . In this example, the surfaces  118   a  and  118   b  face and engage each other regardless of whether the barrier  114  is in the blocking or retracted position. Other example wheel restraint systems disclosed herein include vertical retainers similar or identical to vertical retainers  118  and/or  120 .  FIGS. 3 ,  8  and  15 , for instance, show an example vertical retainer  122 , and  FIG. 21  shows an example vertical retainer  124 . 
         [0064]    As for an example wheel restraint method associated with one or more of the wheel restraints systems disclosed herein, arrow  126  in  FIG. 6  represents manually moving the carrier  28  along the track  36 . The arrow  128  in  FIG. 2  represents moving the carrier catch  56  from a release position to a holding position. Symbol  130  in  FIG. 2  represents the carrier catch  56  restricting movement of the carrier  28  along the track  36  when the carrier catch  56  is in the holding position. The sensor  64   b  being shown proximate to the carrier catch  56  represents sensing that the carrier catch  56  is in the holding position. In  FIG. 2 , arrow  70   b  by dashed line  132  represents electrically providing a carrier catch signal to indicate that the carrier catch  56  is in the holding position. In  FIG. 2 , dashed line  132  being next to arrow  70   b  represents transmitting a carrier catch signal to the signal indicator  66 . In  FIG. 2 , lines  68   a  and  68   d,  in some examples, represent the signal indicator  66  providing a visual signal indicative of whether the carrier catch  56  is in the holding position. In  FIG. 3 , arrow  136  represents moving the barrier catch  52  from a second position to a first position. In  FIG. 2 , the symbol  138  represents the barrier catch  52  limiting movement of the wheel-blocking barrier  26  when the barrier catch  52  is in the first position. In  FIG. 3 , the sensor  64   a  being shown proximate to barrier catch  52  represents sensing that the barrier catch  52  is in the first position. In  FIG. 2 , the arrow  70   a  by dashed line  134  represents electrically providing a barrier catch signal that indicates that the barrier catch  52  is in the holding position. In  FIG. 2 , dashed line  134  being next to arrow  70   a  and dashed line  132  being next to arrow  70   b  represents transmitting a carrier catch signal and a barrier catch signal to the signal indicator  66 . In  FIG. 2 , lines  68   a  and  68   d,  in some examples, represent the signal indicator  66  providing a visual signal indicative of whether both the carrier catch  56  is in the holding position and the barrier catch  52  is in the first position. 
         [0065]    Additional points worth noting include the following. The term, “track” refers to the overall structure along which the carrier travels. Some portions of the track are untouched by the carrier, for example, the carrier does not necessarily touch the track&#39;s plurality of discontinuities. The expression, “the carrier catch in the release position effectively releasing the track discontinuity” means that the carrier&#39;s movement is no longer significantly restricted or limited by the carrier catch even though the carrier catch, in some examples, might still be touching a track discontinuity. The expression, “the carrier and the barrier are manually moved as opposed to being power driven,” means that the carrier and the barrier are moved by human power alone without mechanical assistance (i.e., are not moved by a hydraulic cylinder, a pneumatic cylinder, a motor nor other powered means). The expression, “the carrier catch restricting movement of the carrier along the track when the carrier catch is in the holding position,” means that the carrier&#39;s movement is limited in some manner or in some direction, but does not necessarily mean that all movement is prevented. The term, “pin” refers to a connector that facilitates one part rotating relative to another part. Some pins include an enlarged head, shoulder or key that helps hold the two parts together in an axial direction with respect to the pin. Example pins include, but are not limited to, a screw, a threaded rod with a nut, a shaft, a rod, etc. 
         [0066]    Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of the coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent either literally or under the doctrine of equivalents.