Abstract:
A wheel restraint for restraining a vehicle at a loading dock includes various features such as, a wheel chock supported by a spring loaded articulated arm with a spring that can be selectively tightened or released, a sensor that detects whether the chock is solidly against a base plate or floor, a bi-directional pivotal joint between the articulated arm and the wheel chock to ensure that the chock can sit squarely on a mating base plate, a wheel chock that meshes with a hydraulically actuated base plate, pivotal or otherwise movable backstops that prevent a wheel chock from sliding out of position, and a base plate cleaning system. The cleaning system might include a vehicle-actuated brush, fluid spray nozzles, electric heater and removable cover plates.

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure generally pertains to restraining a vehicle at a loading dock and more specifically to a wheel chock system. 
     BACKGROUND OF RELATED ART 
     When a truck, trailer or some other vehicle is parked at a loading dock, often some sort of vehicle restraint is used to keep the truck from inadvertently moving away from an elevated platform of the dock. This allows a forklift truck to safely drive between the dock platform and the truck for the purpose of loading or unloading the cargo inside the truck. 
     There are a variety of vehicle restraints available that can be installed at a loading dock for engaging the truck&#39;s RIG (Rear Impact Guard), also known as an ICC bar. An ICC bar is a beam that extends horizontally across the rear of a truck, just below the truck bed. Its primary purpose is to prevent an automobile from under-riding the truck in a rear-end collision. However, not all trucks have an ICC bar that can be readily engaged by an ICC-style restraint. Moreover, ICC bars are not prevalent outside the United States, so in those cases a wheel restraint can be used for blocking one or more of the truck&#39;s wheels. 
     Perhaps the most common wheel restraint is simply a wheel chock that wedges between the driveway and the underside of the wheel. However, wheel chocks often slip out of position on driveways that are slippery due to oil, rain, ice, sand, gravel or dirt. Moreover, wheel chocks usually are loose items that do not permanently attach to the loading dock area, so they often get misplaced. 
     One solution to these problems is disclosed in U.S. Pat. No. 7,032,720, which shows a wheel chock that is coupled to the loading dock by way of an articulated arm. To help prevent the chock from slipping out of its wheel-blocking position, the chock can be placed in mating engagement upon a serrated base plate that is anchored to the driveway. Although such a system can be effective, it does have some drawbacks. 
     First, a counterweight spring on the arm tends to prevent the wheel chock from resting its full weight upon the base plate. Second, the length to which the arm must extend to reach the wheel can adversely affect the angular relationship (about a vertical axis) between the mating surfaces of the chock and base plate. Third, although the &#39;720 device includes a sensor for detecting the presence of a wheel, the sensor does not indicate whether the chock is fully engaged with the serrations of the base plate. And fourth, dirt, ice and other contaminants could hinder the engagement between the chock and the base plate, thus reducing the effectiveness of the chock. 
     Consequently, a need exists for a wheel chock system that overcomes the limitations and drawbacks of current systems. 
     SUMMARY 
     In some embodiments, a wheel chock for restraining a vehicle at a loading dock is supported by a spring loaded articulated arm, wherein the spring force can be released. 
     In some embodiments, a wheel chock is supported by an articulated arm that includes a pivotal joint where the arm connects to the chock, wherein the joint permits the chock to rotate relative to the arm about a vertical axis. 
     In some embodiments, a wheel chock includes a sensor that detects whether the chock is fully engaged with a lower support surface. 
     In some embodiments, a manually manipulated wheel chock is coupled to a hydraulic cylinder that can forcibly draw the chock against a vehicle&#39;s wheel. 
     In some embodiments, a wheel chock can be manually placed upon a mating base plate, and a hydraulic cylinder can move the plate to force the chock against a vehicle&#39;s wheel. 
     In some embodiments, a set of hooks or latches selectively engage and release a wheel chock from a lower support surface that is anchored to the ground. In some embodiments, a manually operated wheel chock includes a cleaning system that inhibits debris, ice and other contaminants from accumulating on a surface upon which the chock is placed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view a wheel restraint in a holding position. 
         FIG. 2  is a perspective view of the wheel restraint of  FIG. 1  but showing the restraint in a release position. 
         FIG. 3  is a perspective view of a wheel chock being lowered upon a mating base. 
         FIG. 4  is an end view looking toward the dock face and showing a wheel chock being lowered upon a base. 
         FIG. 5  is a perspective view similar to  FIG. 1  but showing another embodiment. 
         FIG. 6  is a side view of a wheel chock in a release position. 
         FIG. 7  is a side view similar to  FIG. 6  but showing the chock in a holding position. 
         FIG. 8  is an end view similar to  FIG. 4  but showing another embodiment. 
         FIG. 9  is a side view similar to  FIG. 7  but showing the wheel chock of  FIG. 8 . 
         FIG. 10  is a top view of a cleaning system for the base of a wheel restraint system. 
         FIG. 11  is a top view similar to  FIG. 10  but showing a brush sweeping across the base. 
         FIG. 12  is a top view similar to  FIGS. 10 and 11  but showing the wheel restraint system in a holding position. 
         FIG. 13  is a top view similar to  FIG. 10  but showing an alternate embodiment of a cleaning system. 
         FIG. 14  is a top view similar to  FIG. 13  but showing yet another embodiment. 
         FIG. 15  is a top view similar to  FIG. 14  but showing the wheel restraint system in a holding position. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show a wheel restraint system  10  for restraining at least one wheel  12  of a vehicle  14  at a loading dock  16 . Restraint  10  is shown in a holding position in  FIG. 1  and is shown in a release position in  FIG. 2 . In the holding position, restraint  10  helps hold vehicle  14  adjacent to a dock face  18  so that cargo can be safely conveyed on and off of vehicle  14 . In some cases, a conventional dock leveler  20  can be used to facilitate the loading and unloading operations. An upper section of vehicle  14  is shown in phantom lines to more clearly show the subject invention. 
     Wheel restraint  10  includes a wheel chock  22  that may, for example, rest upon a base  24  (lower support surface) when restraint  10  is in the holding position of  FIG. 1 . To limit the wheel chock&#39;s horizontal movement (particularly in a forward direction away from dock face  18 ) base  24  and/or chock  22  may include an interlocking feature such as a tooth  26  or  28  that engages a mating feature in the opposing surface, as shown in  FIGS. 3 and 4 . The various shapes, sizes, quantities and positions of tooth  26  and  28  are too numerous to mention, and it will be appreciated by those of ordinary skill in the art that the number of possible designs is unlimited. 
     To assist the repositioning of chock  22  between the holding and release positions, an elevated articulated arm  30  couples chock  22  to an anchor  32  that is attached to dock  16 . Various joints of arm  30 , anchor  32  and/or chock  22  enable chock  22  to be moved in three-dimensional space. To ensure that chock  22  can rest flat upon base  24 , a joint  34  coupling arm  30  to chock  22 , as shown in  FIG. 4 , permits chock  22  to rotate about a substantially horizontal axis  36  that is substantially parallel to dock face  18 . To ensure the horizontal footprint of chock  22  can lie square to base  24  regardless of the chock&#39;s distance from dock face  18 , joint  34  also allows chock  22  to rotate about a second axis  38  that is perpendicular to or at least traverses an imaginary horizontal plane  40 . Joint  34  could be any multi-axis joint including, but not limited to, a universal ball joint. 
     To further assist the manual repositioning of chock  22 , a spring  42  coupled to arm  30  helps offset the weight of chock  22  and arm  30 . Counteracting the weight of arm  30  and chock  22  can be helpful while positioning chock  22 ; however, counteracting that weight is not always desired. The weight of arm  30  and chock  22 , for instance, can actually be useful in holding chock  22  solidly against base  24 . Thus, a spring release device  44  might be added so that spring  42  can be selectively stressed ( FIG. 2 ) and released ( FIG. 1 ). In the relaxed position of  FIG. 1 , the stress in spring  42  is reduced but does not necessarily have to be reduced to zero. In some examples, device  44  is a lever that can be toggled over center by rotating the lever about a pivot point  46 . To limit the rotation of the lever, an end stop  48  on device  44  engages arm  30 . 
     When chock  22  is in the holding position of  FIG. 1 , a sensor  50  mounted to chock  22  can be used determine whether chock  22  is actually fully engaged with base  24 . Sensor  50  can be any device that can provide a signal  52  in response to proper engagement between chock  22  and base  24 . Examples of sensor  50  include, but are not limited to, a proximity switch (e.g., Hall effect sensor), electromechanical switch, photoelectric eye, etc. Signal  52  can be transmitted via wires through arm  30  or can be transmitted wirelessly to control one or more signal lights  54 . 
       FIG. 5  shows another example wherein a hydraulic cylinder  56  (hydraulic arm) replaces articulated arm  30 . By controlling or stopping the flow of hydraulic fluid using conventional techniques, cylinder  56  can help hold wheel chock  22  at its holding position, as shown in  FIG. 5 . An anchor  58  with a pivotal joint  60  allows repositioning of cylinder  56  and chock  22 . Similar to spring  42  of wheel restraint  10 , a spring  62  can be used to help offset the weight of cylinder  56  and chock  22 . 
       FIGS. 6 and 7  show a wheel chock  64  and a sliding base  66  with an alternate tooth design. This wheel restraint system includes a linear actuator  68  (e.g., a hydraulic cylinder, lead screw, etc.) that is held in place by an anchor  70  fixed to the loading dock. Actuator  68  can draw chock  64  tightly up against wheel  12  by pulling base  66  towards dock face  18 , as indicated by arrow  72 . To release wheel  12 , actuator  68  extends to push base  66  and chock  64  away from dock face  18 . Once chock  64  is no longer tightly up against wheel  12 , chock  64  can be manually lifted from base  66 . The mechanism for maintaining the chock in position shown in  FIGS. 6 and 7  could be used with a manual chock, or one connected to a mechanism for facilitating chock placement such as that shown in  FIGS. 1 and 2 . The same holds true for the remaining examples or concepts described herein. 
       FIGS. 8 and 9  show a wheel chock  72  resting upon a stationary base  74 . To limit the chock&#39;s movement away from dock face  18 , one or more hooks or latches  76  are pivotally connected to chock  72  or base  74 . For the illustrated example, a hinge  78  connects each latch  76  to base  74  such that selected latches  76  can be pivoted upward to limit the movement of chock  72 . Although it is generally more important to limit the chock&#39;s movement away from dock face  18 , latches  76  and their mounting configuration to base  74  or chock  72  could be such that latches  76  restrict the chock&#39;s movement in other directions as well. 
       FIGS. 10 ,  11  and  12  show a wheel chock system  80  that includes a cleaning system  82  for inhibiting contaminants, such as dirt and ice, from accumulating on a base  84 . To prevent ice from accumulating, a heating element  86 , such as electrical resistive wire or some other heat-generating source, is installed in proximity (i.e., in heat exchange relationship) with base  84 . 
     A brush  88  mounted to a movable arm  90  can be used to sweep dirt from base  84 . One end  92  of arm  90  is pivotally coupled to an anchor  94 . An opposite end  96  of arm  90  provides a cam surface  98  against which wheel  12  can push so that as a vehicle backs into the loading dock, the engagement of wheel  12  against cam surface  98  forces brush  88  to sweep across base  84 . When the vehicle departs, a spring  100  can be used to pull arm  90  back to its position of  FIG. 10 . Alternatively, arm  90  could be power actuated. A linearly movable brush is also well within the scope of the invention. 
       FIG. 13  shows an alternative cleaning system  102  that includes one or more nozzles  104  that discharges a fluid  106  (e.g., air, water or an ice-thawing liquid) to clear contaminants from a base  108  or some other lower support surface. Fluid discharge can be triggered manually, or it can be triggered automatically in response to a timer or a sensor responsive to a vehicle or the presence of a contaminant. 
       FIGS. 14 and 15  show a cleaning system  110  wherein one or more covers  112  help shelter unused portions of base  108 . For the illustrated example, covers  112  are moved manually by simply lifting the covers on or off of base  108 . Alternatively, covers  112  can be hinged to base  108  so that covers  112  can be pivoted on and off. 
     Although the invention is described with respect to various examples, modifications thereto will be apparent to those of ordinary skill in the art. Many of the wheel restraint features disclosed herein are interchangeable among the various examples. The scope of the invention, therefore, is to be determined by reference to the following claims: