Abstract:
A vertically movable loading dock bumper device to be attached to a loading dock and interposed between the loading dock and a vehicle during the loading/unloading process, in which the vertical movement of the bumper is in concert with the vertical movement of the vehicle as the vehicle moves vertically during the loading/unloading process. The dock bumper device consists of a mount component, a bumper component, and a slide component, whereby the mount component is fixedly attached to a loading dock, the bumper component accommodates a bumper, and the slide component connects the bumper component to the mount component in a manner permitting the bumper component to move along the mount component in a vertical direction.

Description:
TECHNICAL FIELD 
     The invention claimed herein relates generally to loading dock bumper devices used to protect loading docks and/or vehicles from damage resulting during the loading/unloading process and, more particularly, to a vertically movable loading dock bumper device. 
     BACKGROUND 
     Loading dock bumper devices are well known in the art. They are used to protect loading docks and vehicles from damage resulting from the vehicles contacting the loading dock during loading and/or unloading activity. Damage to the loading dock and/or the vehicle would otherwise occur because a typical loading/unloading activity is initiated by the vehicle backing towards the loading dock until the rear of the vehicle is very close to the loading dock. Because too great a gap between the vehicle and the loading dock would make loading/unloading difficult, drivers typically err on the side of bringing the vehicle too close to the loading dock, often resulting in contact therewith. Having a loading dock bumper disposed between the vehicle and the loading dock allows the vehicle to back towards the loading dock without fear of contact, as the dock bumper disperses the force of a low speed contact without damage to either the vehicle or the loading dock. 
     Most loading dock bumper devices are immovably fixed to loading docks. Swessel, et al., U.S. Pat. No. 4,744,121 (May 17, 1988), discloses such immovably fixed dock bumpers. Other configurations use dock bumpers which are affixed to moveable portions of the loading dock, but in such configurations the bumper is essentially immovable once the loading dock has been correctly positioned for the specific vehicle and loading/unloading begins. Hahn, U.S. Pat. No. 6,360,394 (Mar. 26, 2002) discloses dock bumpers fixedly attached to a movable dock leveler, and van de Wiel, et al., U.S. Pat. No. 6,497,076 (Dec. 24, 2002) discloses a bumper affixed to a device which moves between an operative position and a stored position. However, in both these devices once the dock bumper is positioned for the loading/unloading activity, it remains in that position and effectively becomes an immovable bumper for the duration of the activity. 
     The disadvantage of such devices is evident from observations of their use with vehicles employing air suspension technology. The cargo box or trailer of a vehicle so equipped moves vertically on its air suspension mechanism to accommodate different cargo weights. A lighter load causes the cargo box or trailer to ride higher, and a heavier load causes it to ride lower. During the loading/unloading process, however, the weight of the cargo necessarily changes. Moreover, machines that may be used in the loading/unloading process, such as forklifts, can substantially (if only temporarily) alter the weight of the vehicle when they are driven onto and off of the vehicle. As a result, during the loading/unloading process the vehicle is often caused to move vertically, often in both directions and often with many movements, corresponding to the changing weight within the cargo box or trailer. 
     When a vehicle is backed against a dock bumper, lateral forces continue to be exerted against the bumper by the vehicle as long as contact continues. When a vehicle having an air suspension mechanism moves vertically during the loading/unloading process, as described above, the lateral forces against the bumper (or even friction between the rear of the vehicle and the bumper) may be sufficient to overcome any slipping between the rear of the vehicle and the bumper, the bumper is physically moved along with the vehicle. When such movements exceed the deforming properties of the bumper, the bumper is either ripped, torn, or otherwise damaged, or detached from the loading dock, or both. 
     A dock bumper device which permits the dock bumper to move in concert with the rear of the vehicle during the loading/unloading process significantly reduces the damage that would occur to the dock bumper and/or the loading dock, as described above. As such, replacement, repair, and maintenance of the dock bumper is greatly reduced, at significant cost and time savings. 
     Examples of vertically movable dock bumpers are disclosed in the following references: 
     Drawing “Adjustable Bottom Pad (692-0029)”; dated Oct. 17, 1985 (showing a vertically adjustable pad mounted to the dock face); 
     Spec Sheet “Loading Systems Mobile Dock Bumper RB 250M”; dated circa 1993 (showing a vertically-adjustable spring-loaded dock bumper); and 
     Drawing “Hohenbeweglicher Anfahrpuffer 5146.0102”; dated November 1995 (showing a vertically-adjustable, spring-loaded dock bumper). 
     While each of these references discloses a vertically movable dock bumper, the devices disclosed therein are of complicated and inferior design. As such, the cost of manufacture and/or installation of these devices would be high, as would be the likelihood of failure during operation. The invention claimed herein seeks to address these design flaws with its simple yet rugged design and utilization of a movement mechanism which reduces the potential for lateral binding present in the devices disclosed in the prior art, thereby resulting in a reduction of the deficiencies inherent in the prior art devices. 
     SUMMARY 
     In one aspect, the invention is directed to a loading dock bumper device adapted to allow for the vertical movement of a bumper. This aspect may include one or more of the following features: 
     a mount component, a bumper component, and a slide component, whereby the mount component is suitably adapted to fixedly attach to a loading dock, the bumper component is suitably adapted to accommodate a bumper, and the slide component is suitably adapted to connect the bumper component to the mount component in a manner permitting the bumper component to move along the mount component in a vertical direction in concert with the vertical movement of a vehicle; the mount component may be constructed of channel iron having a substantially flat back panel and two lateral flanges, a top plate constructed of sheet steel or bar stock, and an attachment plate constructed of angle iron; the bumper component may be constructed of channel iron having a substantially flat front panel and two flanges oriented along the top and bottom, with the bumper component suitably adapted to fit within the flanges of the mounting component and against the inner surface thereof, and suitably adapted to carry a bumper on its outer surface; and the slide component may be constructed of a pair of steel rods with a pair of springs disposed thereon, with the pair of rods disposed through apertures formed into the mount component and the bumper component such that the rods are fixedly attached to the mount component and retain the bumper component within the mount component, and the springs support the bumper component and facilitate its movement in a vertical direction. 
     Other features and advantages of the invention are described below. 
    
    
     DESCRIPTION OF DRAWINGS 
     FIG. 1 is a front cut-away view of the dock bumper device. 
     FIG. 2 is a side cut-away view of the dock bumper device. 
     FIG. 3 is a side view of the dock bumper device installed for use on a loading dock, with a vehicle backed against it. 
     FIG. 4 is a perspective, exploded view of the mount component of the dock bumper device, with its three subcomponents depicted separately for clarity of detail, and with dotted lines depicting the relationship of the subcomponents to each other. 
     FIG. 5 is a perspective, exploded view of the bumper component of the dock bumper device, with its two subcomponents depicted separately for clarity of detail, and with dotted lines depicting the relationship of the subcomponents to each other. 
     FIG. 6 is a front view of the slide component of the dock bumper device, with ghost lines depicting the relationship of the mount component and the bumper component to the slide component. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a front cut-away view of one embodiment of the claimed inventive device, a vertically movable dock bumper  1 . The dock bumper  1  is intended to be affixed to a loading dock  8  in a manner such that the bumper component  4  of the dock bumper  1  is positioned between the loading dock  8  and a vehicle  9 , such as a truck, which uses the loading dock  8  to load and/or unload goods, for the purpose of protecting both the loading dock  8  and the vehicle  9  from damage in the event of contact between the vehicle  9  and the loading dock  8 . (FIG. 3 depicts the relationship of the dock bumper  1 , the loading dock  8 , and a vehicle  9 .) Moreover, the dock bumper  1  is adapted to allow the bumper component  4  to move in a vertical direction in concert with any vertical motion of the loading/unloading vehicle  9  in contact therewith, thereby effectively providing protection to both the loading dock  8  and the vehicle  9  while addressing the problem of potential damage to the bumper component  4  caused by the vertical movement of the vehicle  9 . 
     The dock bumper  1  includes three primary components: a mount component  2  (shown in detail in FIG.  4 ), a bumper component  4  (shown in detail in FIG.  5 ), and a slide component  6  (shown in detail in FIG.  6 ). The mount component  2  is suitably adapted to be fixedly attached to a loading dock  8 . The bumper component  4  is suitably adapted to accommodate a bumper  14 . The slide component  6  is suitably adapted to connect the bumper component  4  to the mount component  2 , in a manner permitting the bumper component  4  to move along the mount component  2  in a vertical direction. 
     FIG. 2 shows a side view of the mount component  2 . The mount component  2  is comprised of three subcomponents: a back plate  15 , an attachment plate  48 , and a top plate  62 . FIG. 4 is an exploded perspective view of the mount component showing these three subcomponents. These three subcomponents are fixedly attached to each other and are all constructed of a rigid metal, such as steel or iron. In one embodiment, the back plate  15  is constructed of channel iron, the attachment plate  48  is constructed of angle iron, and the top plate  62  is constructed of plate steel. In another embodiment the top plate  62  may be constructed of steel bar stock. 
     The back plate  15  is comprised of a back panel  34 , a first side flange  22 , and a second side flange  28 , and has a top edge  18  and a bottom edge  20 . 
     The back panel  34  is substantially flat and substantially rectangular in shape, with a width  36  less than its height  38 . The first side  40  of the back panel  34  and the second side  42  of the back panel  34  are opposite and lateral when the back panel  34  is in its intended vertical orientation. Extending from the first side  40  of the back panel  34  is the first side flange  22 , and extending from the second side  42  of the back panel  34  is the second side flange  28 . Both the first side flange  22  and the second side flange  28  extend in the same direction from the plane of the back panel  34  and are both oriented substantially perpendicular to the back panel  34  and are parallel to each other. The surface of the back panel  34  on the same side as the first side flange  22  and the second side flange  28  is designated the front surface  44  of the back panel  34 ; the opposite surface is designated the back surface  46  of the back panel  34 . 
     The first side flange  22  is substantially rectangular, with a length  24  substantially the same as the height  38  of the back panel  34  and a width  26  substantially less than the length  24  of the first side flange  22 . The second side flange  28  is substantially the same size and shape as the first side flange  22 . The first side flange  22 , the second side flange  28 , and the back panel  34  are integrated as a single piece of metal forming the “u” shape common to channel iron. 
     In one preferred embodiment, the back panel  34  is between eight inches and sixteen inches in width  36  and between sixteen inches and twenty-four inches in height  38 , and has a thickness of between one-eighth inch and one-half inch; the first side flange  22  and the second side flange  28  are each between two and three inches in width  26 , 32  and have substantially the same length  24 , 30  and thickness as the back panel  34 . In the most preferred embodiment, the back panel  34  is twelve inches in width  36  and eighteen inches in height  38 , and has a thickness of one-quarter inch; the first side flange  22  and the second side flange  28  are each two and one-half inches in width  26 , 32  and have the same length  24 , 30  and thickness as the back panel  34 . 
     The attachment plate  48  is comprised of a top flange  52  and a back flange  54 . The top flange  52  and the back flange  54  are both substantially rectangular in shape and substantially equivalent in dimension, and are positioned adjacent to each other along one of the long sides of each of the flanges  52 , 54 , thereby forming an angle. The top flange  52  and the back flange  54  are oriented substantially perpendicular to each other. The top flange  52  and the back flange  54  are integrated as a single piece of metal forming the shape common to angle iron. The attachment plate  48  has a length  50  substantially the same as the width  16  of the back plate  15 . In the preferred embodiment, the top flange  52  has a width  53  substantially the same as the width  26  of the first side flange  22 , and the back flange  54  has a width  55  between two and three inches, with both flanges having a thickness substantially the same as the thickness of the back panel  34 . 
     The top plate  62  is substantially flat and substantially rectangular in shape, with a width  64  substantially the same as the width  16  of the back plate  15 . In the preferred embodiment, the top plate  62  is between twelve inches and sixteen inches in length  65 , and has a thickness of between one-eighth inch and one-half inch, with a most preferred thickness of one-quarter inch. 
     The three subcomponents of the mount component  2  are fixedly, attached to each other as follows: The top flange  52  of the attachment plate  48  is fixedly attached to the bottom edge  20  of the back plate  15  and to the bottoms of the first side flange  22  and the second side flange  28 . A preferred manner of attachment is by welding. The top flange  52  is oriented substantially perpendicular to the back panel  34  and oriented such that it extends forward from the front surface  44  of the back panel  34  in the same direction as the first side flange  22  and the second side flange  28 , resulting in the back flange  54  of the attachment plate  48  being oriented substantially coplanar with the back panel  34 . The top plate  62  is fixedly attached to the top edge  18  of the back plate  15  and to the tops of the first side flange  22  and the second side flange  28 . A preferred manner of attachment is by welding. The top plate  62  is oriented such that the first edge  70  of the top plate  62  is aligned flush with the first side flange  22  and the second edge  72  of the top plate  62  is aligned flush with the second side flange  28 . The front edge  66  of the top plate  62  extends from the front surface  44  of the back panel  34  in the same direction as the first side flange  22  and the second side flange  28  in an amount substantially equal to the width  26  of the first side flange  22 , with the remaining portion of the top panel extending rearward from the back surface  46  of the back panel  34 , forming a lip  68 . The top plate  62  is oriented substantially perpendicular to the back panel  34 . The result is that the mount component  2  is configured as a five sided shallow container opened at the front, with the top side  108  extending rearward (the top plate lip  68 ) and the back side extending downward (the back flange  54  of the attachment plate  48 ) beyond the sides of the container. 
     FIG. 5 shows an exploded perspective view of the bumper component  4 . The bumper component  4  is comprised of two subcomponents: a front plate  84  and a bumper  14 . The front plate  84  is constructed of a rigid metal, such as steel or iron. In one embodiment, the front plate  84  is constructed of channel iron. The bumper  14  is a standard bumper known in the art and characterized by the quality of being able to receive and dissipate a force from an object striking the bumper  14 , such as a vehicle  9 . In one embodiment the bumper  14  is constructed of rubber. The bumper  14  is fixedly attached to the front plate  84 . 
     The front plate  84  is comprised of a front panel  102 , an upper flange  90 , and a lower flange  96 , and has a first edge  86  and a second edge  88 . 
     The front panel  102  is substantially flat and substantially rectangular in shape, with a width  104  less than the width  36  of the back panel  34  and a height  106  less than the height  17  of the back plate  15 . The top side  108  of the front panel  102  and the bottom side  110  of the front panel  102  are located opposite each other. The intended orientation of the front panel  102  is vertical. Extending from the top side  108  of the front panel  102  is the upper flange  90 , and extending from the bottom side  110  of the front panel  102  is the lower flange  96 . Both the upper flange  90  and the lower flange  96  extend in the same direction from the plane of the front panel  102  and are both oriented substantially perpendicular to the front panel  102  and are parallel to each other. The surface of the front panel  102  on the same side as the upper flange  90  and the lower flange  96  is designated the back surface  114  of the front panel  102 ; the opposite surface is designated the front surface  112  of the front panel  102 . 
     The upper flange  90  is substantially rectangular, with a length  92  substantially the same as the width  104  of the front panel  102  and a width  93  substantially less than the length  92  of the upper flange  90 . The lower flange  96  is substantially the same shape and size as the upper flange  90 . The upper flange  90 , the lower flange  96 , and the front panel  102  of the front plate  84  are integrated as a single piece of metal forming the “u” shape common to channel iron. 
     In one preferred embodiment, the front panel  102  is between eight inches and sixteen inches in width  104  and between eight inches and sixteen inches in height  106 , and has a thickness of between one-quarter inch and three-quarter inch; the upper flange  90  and the lower flange  96  are each between two and three inches in width  93 , 99  and have substantially the same length  92 , 98  and thickness as the front panel  102 . In the most preferred embodiment, the front panel  102  is slightly less than twelve inches in width  104  such that when positioned vertically within the cavity of the mount component  2  the front plate  84  fits between the first side flange  22  and the second side flange  28 ; and the front panel  102  is twelve inches in height  106  and has a thickness of one-half inch; the upper flange  90  of the front plate  84  and the lower flange  96  of the front plate  84  are each two and one-half inches in width  93 , 99  and have the same length  92 , 98  and thickness as the front panel  102 . In this embodiment, one or more reinforcement bars  116  constructed of a rigid metal, preferably steel bar stock, are welded to the back surface  114  of the front panel  102 , providing reinforcement to the front plate  84  and minimizing the instance of the front plate  84  buckling when the bumper  14  is contacted by a vehicle  9 . 
     The bumper  14  is fixedly attached to the front surface  112  of the front panel  102 . 
     In one embodiment, the front panel  102  further comprises a plurality of apertures  118  dispersed along the front panel  102  and suitably adapted to accommodate a plurality of fastening devices  120  suitably adapted to attach the bumper  14  to the front panel  102 . 
     FIG. 6 shows a front view of the slide component  6 . The slide component  6  is comprised of a first slide pin  122 , a second slide pin  136 , a first spring  150 , and a second spring  158 , and a first nut  166  and a second nut  168  to secure the slide component  6  to the mount component  2 . 
     The first slide pin  122  is a rigid metal rod having a circular cross section and a uniform diameter  124 . In one embodiment the first slide pin  122  is constructed of round stock steel. The length  126  of the first slide pin  122  is slightly greater than the height  17  of the back plate  15 . The first slide pin  122  has a top end  128  and a threaded bottom end  130 . Fixedly attached to the top end  128  of the first slide pin  122  is a first top cap  132 . The first top cap  132  is a rigid, flat metal disk, being substantially circular, having a diameter  134  greater than the diameter  124  of the first slide pin  122 . The first top cap  132  is oriented perpendicular to the top end  128  of the first slide pin  122 . 
     The second slide pin  136  is a rigid metal rod having a circular cross section and a uniform diameter  138 . In one embodiment the first slide pin  122  is constructed of round stock steel. The diameter  138  of the second slide pin  136  is substantially the same as the diameter  124  of the first slide pin  122  and the length  140  of the second slide pin  136  is substantially the same as the length  126  of the first slide pin  122 . The second slide pin  136  has a top end  142  and a threaded bottom end  144 . Fixedly attached to the top end  142  of the second slide pin  136  is a second top cap  146 . The second top cap  146  is a rigid, flat metal disk, being substantially circular, having a diameter  148  greater than the diameter  138  of the second slide pin  136 . The second top cap  146  is oriented perpendicular to the top end  142  of the second slide pin  136 . 
     In one preferred embodiment, the first slide pin  122  has a length  126  of between seventeen inches and twenty-five inches, and a diameter  124  of between three-quarter inch and one and one-half inches, and the second slide pin  136  has substantially the same dimensions. In the most preferred embodiment, the first slide pin  122  has a length  126  of nineteen inches and a diameter  124  of one inch, and the second slide pin  136  has substantially the same dimensions. 
     The first spring  150  is constructed of a flexible metal and coiled such that it has a substantially uniform outside diameter  152  and a substantially uniform inside diameter  154 . The inside diameter  154  of the first spring  150  is slightly greater than the diameter  124  of the first slide pin  122 . The first spring  150  has a length  156  less than the length  126  of the first slide pin  122 . The first spring  150  is suitably adapted to support the weight of the bumper component  4 . 
     The second spring  158  is constructed of a flexible metal and coiled such that it has a substantially uniform outside diameter  160  and a substantially uniform inside diameter  162 . The inside diameter  162  of the second spring  158  is slightly greater than the diameter  138  of the second slide pin  136 . The second spring  158  has a length  164  less than the length  140  of the second slide pin  136  and substantially the same as the length  156  of the first spring  150 . The second spring  158  is suitably adapted to support the weight of the bumper component  4 . The first nut  166  is suitably adapted to be placed onto and secured to the threaded bottom end  130  of the first slide pin  122 . The second nut  168  is suitably adapted to be placed onto and secured to the threaded bottom end  144  of the second slide pin  136 . 
     The first and second slide pins  122 , 136  are positioned within apertures  56 , 58 , 74 ,  76 , 94 , 95 , 100 , 101  located in the mount component  2  and the bumper component  4 . Formed into the top plate  62  of the mount component  2  are a first top plate apertures  74  and a second top plate aperture  76 . Each of these apertures  74 , 76  are substantially circular. The first top plate aperture  74  has a diameter  75  just slightly larger than the diameter  124  of the first slide pin  122  and smaller than the diameter  134  of the first top cap  132 . The second top, plate aperture  76  has a diameter  77  just slightly larger than the diameter  138  of the second slide pin  136  and smaller than the diameter  148  of the second top cap  146 . The first top plate aperture  74  passes completely through the top plate  62  and is located proximate to the front edge  66  of the top plate  62  and proximate to the first side flange  22 . The second top plate aperture  76  passes completely through the top plate  62  and is located proximate to the front edge  66  of the top plate  62  substantially the same distance from the front edge  66  of the top plate  62  as is the first top plate aperture  74  from the front edge  66  of the top plate  62 , and is located proximate to the second side flange  28  substantially the same distance from the second side flange  28  as is the first top plate aperture  74  from the first side flange  22 . 
     Formed into the top flange  52  of the attachment plate  48  are a first attachment plate aperture  56  and a second attachment plate aperture  58 . The first attachment plate aperture  56  is substantially the same size and shape as the first top plate aperture  74  and the second attachment plate aperture  58  is substantially the same size and shape as the second top plate aperture  76 . The first attachment plate aperture  56  passes completely through the top flange  52  of the attachment plate  48  proximate to the first side flange  22 , and the second attachment plate aperture  58  passes completely through the top flange  52  of the attachment plate  48  proximate to the second side flange  28 , such that the first attachment plate aperture  56  is aligned directly below the first top plate aperture  74  and the second attachment plate aperture  58  is aligned directly below the second top plate aperture  76 . 
     Formed into the upper flange  90  of the front plate  84  of the bumper component  4  are a first upper flange aperture  94  and a second upper flange aperture  95 . The first upper flange aperture  94  is substantially the same size and shape as the first top plate aperture  74  and the second upper flange aperture  95  is substantially the same size and shape as the second top plate aperture  76 . The first upper flange aperture  94  passes completely through the upper flange  90  of the front plate  84  proximate to the first edge  86  of the front plate  84 , and the second upper flange aperture  95  passing through the upper flange  90  of the front plate  84  proximate to the second edge  88  of the front plate  84 , such that the first upper flange aperture  94  is aligned directly below the first top plate aperture  74  and the second upper flange aperture  95  is aligned directly below the second top plate aperture  76  when the front plate  84  is positioned vertically within the cavity of the mount component  2 . 
     Formed into the lower flange  96  of the front plate  84  of the bumper component  4  are a first lower flange aperture  100  and a second lower flange aperture  101 . The first lower flange aperture  100  is substantially the same size and shape as the first top plate aperture  74  and the second lower flange aperture  101  is substantially the same size and shape as the second top plate aperture  76 . The first lower flange aperture  100  passes completely through the lower flange  96  of the front plate  84  proximate to the first edge  86  of the front plate  84 , and the second lower flange aperture  101  passes completely through the lower flange  96  of the front plate  84  proximate to the second edge  88  of the front plate  84 , such that the first lower flange aperture  100  is aligned directly below the first top plate aperture  74  and the first upper flange aperture  94 , and the second upper flange aperture  95  is aligned directly below the second top plate aperture  76  and the second upper flange aperture  95 , when the front plate  84  is positioned vertically within the cavity of the mount component  2 . 
     To complete the assembly of the dock bumper device  1 , the front plate  84  is positioned vertically within the cavity of the mount component  2  and against the back plate  15 , such that the upper flange  90  of the front plate  84  contacts the front surface  44  of the back panel  34  and the lower flange  96  of the front plate  84  contacts the front surface  44  of the back panel  34 . In this configuration the front panel  102  is positioned between the first side flange  22  and the second side flange  28  and the front panel  102  is oriented substantially parallel to the back panel  34 . In this configuration the first top plate aperture  74  is aligned with the first upper flange aperture  94  and with the first lower flange aperture  100  and with the first attachment plate aperture  56 , and the second top plate aperture  76  is aligned with the second upper flange aperture  95  and with the second lower flange aperture  101  and with the second attachment plate aperture  58 . The first slide pin  122  is positioned through the first top plate aperture  74 , first upper flange aperture  94 , first lower flange aperture  100 , and first attachment plate aperture  56  such that the first top cap  132  rests on the top plate  62  and the threaded bottom end  130  of the first slide pin  122  extends below the top flange  52  of the attachment plate  48 . The second slide pin  136  is positioned through the second top plate aperture  76 , second upper flange aperture  95 , second lower flange aperture  101 , and second attachment plate aperture  58  such that the second top cap  146  rests on the top plate  62  and the threaded bottom end  144  of the second slide pin  136  extends below the top flange  52  of the attachment plate  48 . The first spring  150  is disposed over the first slide pin  122  and positioned between the lower flange  96  of the front plate  84  and the top flange  52  of the attachment plate  48 . The second spring  158  is disposed over the second slide pin  136  and positioned between the lower flange  96  of the front plate  84  and the top flange  52  of the attachment plate  48 . Finally, the first nut  166  is placed onto the threaded bottom end  130  of the first slide pin  122 , thereby securing the first slide pin  122  to the top flange  52  of the attachment plate  48 , and the second nut  168  is placed onto the threaded bottom end  144  of the second slide pin  136 , thereby securing the second slide pin  136  to the top flange  52  of the attachment plate  48 . 
     Assembled as such, movement of the bumper component  4  in a downward direction compresses the first spring  150  and the second spring  158 , and movement of the bumper component  4  in an upward direction releases the first spring  150  and the second spring  158 . If no force is applied to move the bumper component  4  (or to prevent such movement), the first spring  150  and the second spring  158  will together tend to move the bumper component  4  in an upward direction. The use of two springs  150 , 158  disposed over two slide pins  124 , 136  disperses the lateral forces present on the bumper component  4  and minimizes the likelihood of the bumper component  4  binding on one or both of the slide pins  124 , 136 . 
     The dock bumper device  1  is mounted to a loading dock  8  as follows: the mount component  2  is oriented vertically and placed against the loading dock  8  and fixedly attached thereto. The back surface  46  of the back panel  34  and the back flange  54  of the attachment plate  48  are positioned such that they are adjacent to the vertical front wall  10  of the loading dock  8 . The lip  68  of the top plate  62  is positioned such that it is adjacent to the upper surface  12  of the loading dock  8 , thereby bearing a substantial portion of the weight of the device  1 . 
     In one embodiment, the lip  68  of the top plate  62  is welded to the upper surface  12  of the loading dock  8 , and the back flange  54  of the attachment plate  48  is welded to the vertical front wall  10  of the loading dock  8 . In another embodiment, a plurality of top apertures  78  are dispersed along the lip  68  of the top plate  62 , passing completely through the lip  68 , and a plurality of side apertures  60  are dispersed along the back flange  54  of the attachment plate  48 , passing completely through the back flange  54 . In this embodiment, a plurality of bolts  80  suitably adapted to pass through the top apertures  78  and the side apertures  60  and into the loading dock  8  are used to fixedly attach the mounting component to the loading dock  8 . Anchor sleeves  82  may be used to further secure the bolts  80  into the loading dock  8 . 
     Among the advantages of the disclosed invention are the following. The inherent rigidity and strength of the metal components  2 , 4 , 6  of the dock bumper device  1  provide excellent durability and minimize the need for maintenance. The simple design makes the device  1  inexpensive to manufacture and adaptable to many different loading dock  8  configurations. The dual slide pin  124 , 136  configuration ensures smooth movement with a minimum of binding due to lateral forces. The vertical movement of the bumper  14  in concert with the vehicle  9  virtually eliminates any destructive rubbing of the bumper  14 , thereby solving the problem of bumpers  14  being damaged or torn off loading docks  8  by the movement of vehicles  9  during loading and unloading. 
     The disclosed invention is not limited to what is described in the foregoing embodiments. Those skilled in the art will be able to contemplate variations consistent with the spirit of the invention. Other embodiments not specifically set forth herein are also within the scope of the following claims.