Abstract:
A tonneau system for a cargo box of a vehicle having a support frame connectable to the cargo box. A cover spans the support frame and is positionable between a tensioned position and an untensioned position. A pivot block is mounted to the support frame, while the cover is coupled to a rear bracket member. The rear bracket member carries the cover and pivotally engages the pivot block such that the rear bracket member rotates between a raised position and a lowered position. The rear bracket member can be automatically locked in the lowered position. A bow member couples the cover along a cross vehicle direction. The bow member or other member can operate to tension the cover in the cross vehicle direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 11/262,988 filed on Oct. 31, 2005, which is a continuation-in-part of U.S. patent application Ser. No. 11/227,019 filed on Sep. 15, 2005, now U.S. Pat. No. 7,025,403, which is a continuation of U.S. patent application Ser. No. 10/826,079 filed on Apr. 16, 2004, now U.S. Pat. No. 6,976,724. The disclosures of the above applications are incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention generally relates to coverings for pickup trucks and, more particularly, relates to a roll up tonneau cover system. 
   BACKGROUND OF THE INVENTION 
   Tonneau covers have been used for a number of years to cover the cargo box of pickup trucks against dirt, debris, and other environmental contaminants and to improve the aesthetic quality thereof. Current tonneau covers often employ a VELCRO® hook-and-loop fastening system operably coupled between a soft tarp of the tonneau cover and the sidewalls of the cargo box of the pickup truck. This arrangement permits the tarp to be coupled to the cargo box to conceal the contents thereof or, alternatively, to be rolled up to reveal the contents of the cargo box of the pickup truck. The VELCRO® has disadvantages of wearing over time, pulling, and not allowing the fabric to move freely, which may result in a puckered and wrinkled appearance. 
   A series of bows are typically coupled to the tarp and span the width of the cargo box. These bows serve to support and minimize accumulation of dirt, debris, and other environmental contaminants from collecting on top of the tarp. When the tarp is rolled up, these bows are often enclosed within the tarp bundle. 
   Typically, these bows are cylindrical in cross-section and the ends thereof rest upon rails fixed to longitudinal sidewalls of the cargo box of the pickup truck. However, often times these bows fail to minimize the lifting action caused by aerodynamic forces during vehicle travel. That is, conventional soft or roll-up type tonneau covers often suffer from flapping at highway speeds, which can lead to premature failure. 
   Accordingly, there exists a need in the relevant art to provide a tonneau cover system capable of overcoming the aerodynamic lifting forces caused during vehicle travel. Additionally, there exists a need in the relevant art to provide a tonneau cover system capable of reliably coupling the tonneau cover to the vehicle at various longitudinal locations. Still further, there exists a need in the relevant art to provide a tonneau cover system capable of overcoming the disadvantages of the prior art. 
   SUMMARY OF THE INVENTION 
   According to the principles of the present invention, a tonneau system for a cargo box of a vehicle having an advantageous construction is provided. The tonneau cover system a support frame connectable to the cargo box. A cover spans the support frame and is positionable between a tensioned position and an untensioned position. A pivot block is mounted to the support frame, while the cover is coupled to a rear bracket member. The rear bracket member carries the cover and pivotally engages the pivot block such that the rear bracket member rotates between a raised position and a lowered position. The rear bracket member can be automatically locked in the lowered position. A bow member couples the cover along a cross vehicle direction. The bow member or other member can operate to tension the cover in the cross vehicle direction. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a perspective view illustrating a pickup truck having a tonneau cover system according to the principles of the present invention; 
       FIG. 2  is a perspective view illustrating the pickup truck having the tonneau cover system according to the principles of the present invention with portions removed for clarity; 
       FIG. 3  is a cross sectional view illustrating the head rail assembly taken along line  3 - 3  of  FIG. 1 ; 
       FIG. 4  is an enlarged perspective view illustrating the adjustment beam mechanism; 
       FIG. 5  is an enlarge perspective view illustrating the rear frame rail assembly; 
       FIG. 6  is a perspective view illustrating the pickup truck having the tonneau cover system with portions removed for clarity and the rear frame rail assembly in a raised position; 
       FIG. 7  is an enlarged perspective view illustrating the bow member and retaining bracket; 
       FIG. 8  is a side view illustrating the bow member and retaining block member in a released position; 
       FIG. 9  is a side view illustrating the bow member and retaining block member in a retained position; 
       FIG. 10  is an enlarged perspective view illustrating the retaining block member; 
       FIG. 11  is an enlarged perspective view illustrating the bow member in the retained position; 
       FIG. 12  is an enlarged perspective view illustrating the bow member in the released position; 
       FIG. 13  is a cross section view illustrating the tonneau cover system of the present invention in the retained position employing a retaining bracket; 
       FIG. 14  is a cross section view illustrating the tonneau cover system of the present invention in the released position employing a retaining block member; 
       FIG. 15  is a perspective view illustrating a rear frame assembly according to another embodiment; 
       FIG. 16  is a perspective view illustrating a latching assembly; 
       FIG. 17  is a side view illustrating the latching assembly; 
       FIG. 18  is a side view illustrating a rear bracket member and a pivot block in an initial position; 
       FIG. 19  is a side view illustrating the rear bracket member and the pivot block in a down and locked position; 
       FIG. 20  is an exploded perspective view illustrating the rear frame assembly of  FIG. 15 ; 
       FIG. 21  is a side view illustrating the rear bracket member, pivot block, and locking pawl system in a down and locked position; 
       FIG. 22  is a side view illustrating a rear bracket member and a pivot block according to another embodiment in an initial position; 
       FIG. 23  is a side view illustrating the rear bracket member and the pivot block in a down and locked position; 
       FIG. 24  is a bottom view of a portion of the rear bracket member and side frame assembly in the down and locked position; 
       FIG. 25  is a side view illustrating a latching assembly according to another embodiment; 
       FIG. 26  is an exploded perspective view illustrating a vehicle bow member according to another embodiment; 
       FIG. 27  is a partially exploded perspective view illustrating the bow member; 
       FIG. 28  is a perspective view illustrating a portion of the bow member with the plunger in an inward position; 
       FIG. 29  is a perspective view illustrating the bow member assembled together; 
       FIG. 30  is a perspective view illustrating the bow member engaged with the fabric cover of the tonneau cover system of the present invention; 
       FIG. 31A  is a side view illustrating the bow member and a retaining block member according to another embodiment in a released position; 
       FIG. 31B  is a side view illustrating the bow member and a retaining block member according to another embodiment in an engaged position; 
       FIG. 32  is another side view illustrating the bow member and the retaining block member; and 
       FIG. 33  is another side view illustrating the bow member and the retaining block member. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   With reference to  FIGS. 1 and 2 , a pickup truck  10  is shown having a roll up tonneau system  12  which is attached to a cargo box  13  according to the present invention. Cargo box  13  has a front wall  14 , a left sidewall  16 , a right sidewall  18 , and a rear wall or tailgate  20 . Roll up tonneau system  12  includes a flexible, stretchable fabric cover  22  that is drawn tightly over a substantially rigid rail support system  24  and removably attached to rail support system  24 . Rail support system  24  is comprised of a number of frame rails that are attached to one another to form a rectangular frame. The frame rails included are a front frame rail or head rail assembly  26 , a left side frame rail assembly  28 , a right side frame rail assembly  30 , and a rear frame rail assembly  32 . Rail support system  24  is aligned with and coupled to the top of sidewalls  16  and  18  of cargo box  13  as well as the top of front wall  14  and tailgate  20 , according to one of many methods. A clamping system or fastening system may be used to fasten the rail assemblies  26 ,  28 ,  30 , and  32  to the sidewalls  16  and  18  of pickup truck  10 . An example of a clamping system can be found in commonly-assigned U.S. patent application Ser. No. 10/331,711, entitled “Roll Up Tonneau Cover System.” The disclosure of this application is incorporated herein by reference. Stretchable fabric cover  22  is support cross-vehicle via a plurality of cross bows  301 , which each selectively engage corresponding retaining members coupled to left side frame rail assembly  28  and right side frame rail assembly  30 , which will be discussed in detail below. 
   It should be understood that right sidewall  18  and left sidewall  16  of pickup truck  10  and the corresponding right side frame rail assembly  30  and left side frame rail assembly  28  are identical in construction, yet arranged in mirrored symmetry. Accordingly, in the interest of brevity, only one side will be discussed in detail below unless noted otherwise. 
   Still referring to  FIGS. 1 and 2 , right side frame rail assembly  30  is coupled to right sidewall  18  of cargo box  13  of pickup truck  10 . As can be seen, sidewall  18  of cargo box  13  includes a generally horizontal top surface  34  and a downwardly extending inside wall  36 . However, it should be appreciated that generally horizontal top surface  34  and downwardly extending inside wall  36  may have any one of a number of configurations, which are dependent upon styling and functionality determined by the vehicle manufacturer. Hence, it should be understood that the particular shape of these surfaces/walls may vary, along with the specific shape of those corresponding components of frame rail assembly  30 . 
   Turning now to  FIG. 3 , head rail assembly  26  will now be described in detail. As can be seen in the figure, head rail assembly  26  generally includes an extruded front bracket member  40 . Extruded front bracket member  40  is preferably made of a light-weight, corrosion resistant material, such as aluminum. Extruded front bracket member  40  includes a gasket channel  42  extending longitudinally along a forward portion  44  of extruded front bracket member  40 . Gasket channel  42  is sized to receive a corresponding channel feature  46  of a flexible gasket member  48  such that flexible gasket member  48  is coupled with and supported by extruded front bracket member  40 . Gasket member  48  is positionable such that it engages and forms a fluid seal between a nose portion  50  of gasket member  48  and front wall  14  of pickup truck  10 . In this regard, water and other environmental contaminants are prevented from entering cargo box  13  of pickup truck  10 . During assembly, channel feature  46  of flexible gasket member  48  is slid into gasket channel  42 . 
   Extruded front bracket member  40  further includes cover retaining slot  52  extending longitudinally along forward portion  44  of extruded front bracket member  40 . Cover retaining slot  52  is sized to receive a corresponding rod member  54 . Preferably, rod member  54  is received within a channel  56  sewn or otherwise formed in stretchable fabric cover  22 . In this regard, stretchable fabric cover  22  is reliably retained in connection with extruded front bracket member  40 . During assembly, rod member  54  is first slid into channel  56  of stretchable fabric cover  22  and the two are slid into cover retaining slot  52 . 
   Still referring to  FIG. 3 , extruded front bracket member  40  further includes a tip support  60  extending along forward portion  44 . Tip support  60  is adapted to be received between a fold-back portion  62  of stretchable fabric cover  22  and provides support to stretchable fabric cover  22 . Tip support  60  permits stretchable fabric cover  22  to extend forward from extruded front bracket member  40  to bridge a gap between extruded front bracket member  40  and front wall  14  and to further conceal gasket member  48 . Tip support  60  may be received within a support channel  64  formed in extruded front bracket member  40 . However, it should also be understood that tip support  60  may be integrally formed with extruded front bracket member  40  or may be part of a separate polymer extrusion to which the stretchable fabric cover  22  is sewn. This extrusion would be slidably engaged with bracket member  40 . 
   Referring now to  FIGS. 3 and 4 , tonneau system  12  further includes an adjustment beam mechanism  100  engagable with extruded front bracket member  40 . Adjustment beam mechanism  100  is provided for maintaining a constant tensional force on stretchable fabric cover  22  to a desired tightness. Adjustment beam mechanism  100  includes a cantilever beam member  102  having a first end  104  and a second end  106 . First end  104  of cantilever beam member  102  is fixedly mounted to extruded front bracket member  40  via conventional fasteners  109  and a mounting bracket  110 . Mounting bracket  110  is slidably engaged in slot  112  of extruded front bracket member  40 . Mounting bracket  110  is preferably sized to permit simple positioning of mounting bracket  110  and cantilever beam member  102  relative to extruded front bracket member  40  when the fasteners are loosened. However, on the other hand, mounting bracket  110  should preferably frictionally engage flanges  114  when the fasteners are tightened. 
   As best seen in  FIGS. 2-4 , adjustment beam mechanism  100  further includes a finger member  120 , which is operably coupled to frame rail assembly  30 . Finger member  120  is sized to extend upward from frame assembly  30  in a generally L-shaped configuration. An end  122  of finger member  120  is engagable with second end  106  of cantilever beam member  102 . Such engagement of finger member  120  against the biasing force of cantilever beam member  102  cause extruded front bracket member  40  to be urged forward (relative to the vehicle) to draw stretchable fabric cover  22  tightly over rail support system  24 . 
   It should be understood that cantilever beam member  102  may be pre-bent to tailor a desired biasing force. It is generally desired that adjustment beam mechanism  100  is disposed on each side of the vehicle bed to provide equal tensioning thereabout. Specifically, it is desired that adjustment beam mechanism  100  is arranged to provide about 15 to 10 pounds of tensioning force on each side. 
   Turning now to  FIG. 5 , rear frame rail assembly  32  will be described in detail. Rear frame rail assembly  32  generally includes an extruded rear bracket member  200 . Rear bracket member  200  is similar in construction to front bracket member  40 ; however, rear bracket member  200  includes a rounded bull nose portion  202 . Rear bracket member  200  further includes a receiving channel  56 ′ for receiving rod member  54  coupled to fabric cover  22  similarly as mentioned above. Rear frame rail assembly  32  still further includes a latching system, such as that described in commonly-assigned U.S. patent application Ser. No. 10/331,711, entitled “Roll Up Tonneau Cover System.” 
   With continued reference to  FIG. 5 , rounded bull nose portion  202  of rear bracket member  200  is sized to be pivotally received within a concave portion  204  of a corresponding rear pivot block  206 . In this regard, rear frame rail assembly  32  may pivot upward about the interface between rounded bull nose portion  202  and concave portion  204  into a raised position (see  FIG. 6 ). In this raised position, the tension in fabric cover  22  is released. However, in a lowered position, the tension is then again exerted upon fabric cover  22  according to the biasing force of adjustment beam mechanism  100 . Rear pivot block  206  is fixedly coupled to frame rail assembly  30  via conventional means, such as fasteners. It should be appreciated that as rear bracket member  200  is lowered into a down position, fabric cover  22  is drawn rearward against the biasing force of adjustment beam mechanism  100 . During this operation, fabric cover  22  is translated rearward a predetermined distance. This translation distance will be used to affect additional retaining features that will be described in detail below. During an opposing operation, the raising or pivoting of rear bracket member  200  causes the tension in fabric cover  22  to be released, which causes fabric cover  22  to translate forward in response to the biasing forces of adjustment beam mechanism  100 . 
   Still referring to  FIG. 5 , rear bracket member  200  further includes a strip member  212  extending along rearward portion  210 . Strip member  212  is adapted to be sewn into fabric cover  22  and provides support to stretchable fabric cover  22 . Strip member  212  may be received within a support channel  214  formed in rear bracket member  200 . However, it should also be understood that strip member  212  may be integrally formed with rear bracket member  200 . 
   With reference to  FIGS. 22-24 , rear bracket member  200  may optionally include a stop member  700  extending outwardly from a bottom portion thereof. Stop member  700  may be in the form of a pin or post having a generally circular cross section. Furthermore, frame rail assembly  30  may have an elongated slot  702  formed therein which extends lengthwise in the cross vehicle direction. Slot  702  is positioned complementary to stop member  700  and adapted to receive stop member  700  when rear bracket member  200  is lowered to the down position. It should be appreciated that the interconnection of stop member  700  and slot  702  when rear bracket member  200  is lowered to the down position provides a positive and fixed position between rear bracket member  200  and pivot block  206  in a fore-aft direction of pickup truck  10 , yet permits lateral movement of rear bracket member  200  relative to pivot block  206  in the cross-vehicle direction along the length of slot  702 . This encourages proper alignment of tonneau system  12 . 
   With reference to  FIGS. 15-22 , an alternative rear frame assembly and latch system  500  will be described in detail. Rear frame rail and latch system  500  generally comprises an extruded rear bracket member  510 , a latching assembly  512 , and frame rail assembly  30 . Rear bracket member  510  is similar in construction to rear bracket member  200  and front bracket member  400  except for the features that will be described herein. Rear bracket member  510  and latching assembly  512  work together to define a system that captures and retains rear bracket member  510  relative to latching assembly  512 , yet permits lateral movement of rear bracket member  510  relative to latching assembly  512 . 
   With particular reference to FIGS.  15  and  17 - 20 , rear bracket member  510  is illustrated being made of a light-weight, corrosion resistant material, such as aluminum. Rear bracket member  510  generally comprises a top face  514 , a bottom face  516 , an interconnecting inclined face  518  disposed between top face  514  and bottom face  516 , and a latching face  520 . Top face  514  is generally disposed in planar relationship with a top section of latching assembly  512 , which will be described herein. Bottom face  516  is disposed parallel to, but spaced offset from, a top portion of tailgate  20 . It is anticipated that stretchable fabric cover  22  will extend along top face  514 , down inclined face  518 , and terminate at an intersection of inclined face  518  and bottom face  516 . To this end, a cover retaining slot  522  extends longitudinally along an edge of rear bracket member  510 . Cover retaining slot  522  is sized to receive a corresponding rod member  54 . Preferably, rod member  54  is received within a channel  56  sewn or otherwise formed in stretchable fabric cover  22 . In this regard, stretchable fabric cover  22  is reliably retained in connection with rear bracket member  510 . During assembly, rod member  54  is first slid into channel  56  of stretchable fabric cover  22  and the two are slid into cover retaining slot  522 . 
   A seal groove  524  is disposed adjacent cover retaining slot  522  for receiving a seal member  526  therein. Seal member  526  is adapted to sealingly engage and/or contact a top surface of tailgate  20 . Seal member  526  may have any cross-sectional shape that is conducive to sealingly engage the top surface of tailgate  20 . 
   A slidenut channel  528  is disposed along bottom face  516 . Slidenut channel  528  is provided for coupling additional accessories, such as additional seals and/or coverings to rear bracket member  510  using a conventional fastener and sliding nut arrangement. In other words, a nut (not shown) may be slidably disposed within slidenut channel  528  such that the nut is retained by flanges  530  ( FIG. 20 ) of slidenut channel  528 . A fastener (not shown) can be used to couple an accessory to the nut in a predetermined position. Alternatively, an accessory can be provided having a complimentary engaging feature that can be slid within slidenut channel  528 . Rear bracket member  510  may further comprise an upwardly turned hook member  532  extending from top face  514 , which will be described herein. 
   Referring now to  FIGS. 16-21 , latching assembly  512  comprises a stanchion  534 , a pivot block  536 , and a latch member  538 . Stanchion  534  may be injection molded and may include a pair of upwardly extending leg members  540  extending from a base member  542 . Base member  542  can comprise a flange rail system  544  that is sized to be slidingly engaged within a corresponding channel  546  ( FIG. 20 ) formed in side frame rail assembly  30 . Accordingly, stanchion  534  can be slid within channel  546  to a predetermined position and retained in this predetermined position using a conventional fastener and/or slidenut system. 
   Each leg member  40  of stanchion  534  comprises an aperture  548  formed therethrough coaxially aligned with each other. Apertures  548  are sized to slidably receive a guide member or bolt  550  therethrough. Guide member  550  may include a fastener (not shown) disposed on an end  552  of guide member  550  to permit sliding movement of guide member  550  relative to stanchion  534  but resist disengagement of guide member  550  from stanchion  534 . An opposing end  554  of guide member  550  may be fixedly coupled with pivot block  536 . A spring member  558  may be disposed about a section of guide member  550  between stanchion  534  and pivot block  536 . A first end  560  of spring member  558  may be received within a counter bore  562  formed about aperture  548  within one of the leg members  540  of stanchion  534 . An opposing end  563  of spring member  558  may engage pivot block  536  to urge pivot block  536  away from stanchion  534 . In operation, spring member  558  may, at least in part, urge rear bracket member  510  away from head rail assembly  26 , thereby tightly drawing stretchable fabric cover  22 . 
   As seen in  FIG. 20 , pivot block  536  comprises a flange rail system  564  that is sized to be sligingly engaged within corresponding channel  546  formed inside frame rail assembly  30 . Accordingly, pivot block  536  can be slid within channel  546  in response to the urging force exerted by spring member  558 . In other words, in some embodiments, pivot block  536  can freely slide within channel  546  as needed. In some embodiments, pivot block  536  may comprise a slidenut channel  565  that is sized to receive a nut (not shown) therein such that the nut may be coupled with a fastener (not shown) to fixedly mount pivot block  536  within channel  546 . 
   Pivot block  536  further comprises a downwardly turned hook member  566  extending from a top face  568 . Downwardly turned hook member  566  is sized and shaped to engage and receive upwardly turned hook member  532  of rear bracket member  510 . As can be seen in  FIGS. 18 and 19 , a distal end  570  of upwardly turned hook member  532  can be captured by a distal end  572  of downwardly turned hook member  566  as rear bracket member  510  is rotated into a down and locked position ( FIG. 19 ). Additionally, a bull nose portion  574  of upwardly turned hook member  532  can engage and ride along a concave portion  576  of downwardly turned hook member  566  to provide a smooth transition between the initial insertion position ( FIG. 18 ) and the down and locked position ( FIG. 19 ). It should be appreciated that the interconnection of downwardly turned hook member  566  and upwardly turned hook member  532  provides a positive and fixed position between rear bracket member  510  and pivot block  536  in a fore-aft direction of pickup truck  10 , yet permits lateral movement of rear bracket member  510  relative to pivot block  536  in the cross-vehicle direction. This encourages proper alignment of tonneau system  12 . 
   To retain rear bracket member  510  in the down and latched position, a locking pawl system  578  is provided having a latch pawl  580  selectively engageable with a latch feature  582  ( FIG. 17 ) formed in rear bracket member  510 . As seen in  FIG. 16 , latch pawl  580  comprises a pawl face  584 , a pair of leg members  586  extending from pawl face  584 , latch pawl  580  extending from pawl face  584 , and an extension arm  590  extending from pawl face  584  and terminating at a finger portion  592 . Latch pawl  580  is adapted to be pivoted about an axis  594  extending through leg members  586  and an aperture  596  ( FIG. 20 ) formed in pivot block  536 . Latch pawl  580  may be spring biased into a locked position. Latch pawl  580  is sized to be received within latch feature  582 . In some embodiments, latch feature  582  may comprise a ledge or other cut-out  598  ( FIG. 18 ) operable to engage latch pawl  580  when in a locked position. Alternatively, such arrangement would permit free rotation of rear bracket member  510  relative to pivot block  536  when latch pawl  580  is disengaged from latch feature  582 . 
   In operation, rear bracket member  510 , having stretchable fabric cover  22  disposed thereabout and retained by rod member  54  and cover retaining slot  522 , can be lifted to reveal cargo box  13  of pick-up truck  10 . However, to retain and lock rear bracket member  510  in a down and locked position, rear bracket member  510  is first engaged with pivot block  536  such that upwardly turned hook member  532  of rear bracket member  510  is received with downwardly turned hook member  566  of pivot block  536  ( FIG. 18 ). Rear bracket member  510  is then pivoted downwardly such that top face  514  of rear bracket member  510  is generally planar with top face  568  of pivot block  536 . As rear bracket member  510  pivots about pivot block  536 , latch pawl  580  can engage and ride along a curved portion  600  ( FIG. 18 ) of latching face  520  of rear bracket member  510 . In this regard, latch pawl  580  will cam along curved portion  600  until being received within latch feature  582 , thereby latching rear bracket member  510  relative to pivot block  536 . Alternatively, finger portion  592  may be depressed such that latch feature  582  is rotated about axis  594 , thereby retracting latch pawl  580  from contact with latching face  520  of rear bracket member  510 . In this regard, rear bracket member  510  can be rotated downward into the down position and finger portion  592  can be released to urge latch pawl  580  into locking engagement with latch feature  582 . 
   With reference to  FIG. 25 , rear bracket member  510  may alternatively be configured with an end member  750  in the place of hook member  532 . End member  750  includes a bull nose portion  752  and a stop shoulder  754 . Furthermore, pivot block  536  may alternatively be configured with a protruding member  760  in place of hook member  566 , a concave portion  762  of protruding member  760 , and a catch member  764 . Catch member  764  extends outwardly at an end of concave portion  762  opposite protruding member  760 . Bull nose portion  752  of end member  750  can engage and ride along concave portion  762  of protruding member  760  to provide a smooth transition between various positions of rear bracket member  510 . In a down and locked position as seen in  FIG. 25 , stop shoulder  754  of end member  750  engages catch member  764  of pivot block  536 . It should be appreciated that this engagement of stop shoulder  754  and catch member  764  provides a positive and fixed position between rear bracket member  510  and pivot block  536  in a fore-aft direction of pickup truck  10 , yet permits lateral movement of rear bracket member  510  relative to pivot block  536  in the cross-vehicle direction. This encourages proper alignment of tonneau system  12 . 
   Turning now to  FIGS. 6 and 7 , it can be seen that tonneau system  12  further includes a retaining system  300  for retaining sections of fabric cover  22  located between head rail assembly  26  and rear frame rail assembly  32 . As best seen in  FIG. 6 , retaining system  300  includes a plurality of cross vehicle bow members  301  operably coupled with fabric cover  22  and engaging retaining brackets  302  fixedly coupled to frame rail assembly  28 ,  30 . Retaining brackets  302  may be of any shape or design; however, two possible configurations will be discussed herein. 
   With reference to  FIGS. 6 and 7 , retaining bracket  302  is illustrated as a generally sheet-like member shaped to define a generally planar section  304  and a receiving section  306 . Planar section  304  is disposed adjacent frame rail assembly  28 ,  30  and fastened thereto via conventional means, such as fasteners. Receiving section  306 , however, is shaped to receive a corresponding portion of vehicle bow member  301 . That is, in the embodiment illustrated in  FIGS. 6 and 7 , vehicle bow member  301  is generally cylindrical in cross-section. Accordingly, receiving section  306  is generally cylindrical, concave in shape to readily receive and retaining vehicle bow member  301  therein. Receiving section  306  extends upward to an end  308 , which is positioned relative to vehicle bow member  301  to generally prevent vehicle bow member  301  from disengaging with retaining bracket  302  in a vertical direction. 
   Vehicle bow member  301  is generally cylindrical in cross-section. Vehicle bow member  301  may define an enclosed tubular member or may be constructed of rolled aluminum, or other material. Preferably, vehicle bow member  301  further includes an optional paddle-shaped bow end  310  extending outwardly from vehicle bow member  301 . Paddle-shaped bow end  310  overlaps a portion of frame rail assembly  28 ,  30 . Paddle-shaped bow end  310  serves to push outwardly in a lateral direction (in the cross-vehicle direction) keeping the stretchable fabric cover  22  taunt. Paddle-shaped bow end  310  further biases the periphery of stretchable fabric cover  22  down to seal against frame rail assembly  28 ,  30 . Frame rail assembly  28 ,  30  have alternating high and low sections that act as a labyrinthian seal. 
   Alternatively, as seen in  FIGS. 8-12 , retaining bracket  302  may be made as a block member, generally indicated at  302 ′. Retaining block member  302 ′ is preferably made of a Nylon or other plastic material and is injection molded. Retaining block member  302 ′ is preferably fastened to frame rail assembly  28 ,  30  via a fastener  303  extending through an aperture  350  formed in retaining block member  302 ′. Fastener  303  engages a sliding bracket  305  received within frame rail assembly  28 ,  30 . Retaining block member  302 ′ further includes a tab member  352  that is sized to be slidably received within a channel  354  of frame rail assembly  28 ,  30 . Tab member  352  and channel  354  cooperate to prevent, or at least, minimize rotation of retaining block member  302 ′ to ensure proper positioning of retaining block member  302 ′. Retaining block member  302 ′ further includes a receiving section  356 , which is shaped to receive a corresponding portion of vehicle bow member  301 . That is, in the embodiment illustrated in  FIGS. 8-12 , vehicle bow member  301  is generally cylindrical in cross-section. Accordingly, receiving section  356  is generally cylindrical, concave in shape to readily receive and retaining vehicle bow member  301  therein. Receiving section  356  extends upward to an end  358 , which is positioned relative to vehicle bow member  301  to generally prevent vehicle bow member  301  from disengaging from retaining block member  302 ′ in a vertical direction. More particularly, as seen in  FIG. 10 , end  358  may terminate at a single finger  360 , if desired. 
   Turning now to  FIGS. 13 and 14 , it can be seen that vehicle bow member  301  is engaged and retained within receiving section  356  when rear bracket member  200  is lowered (see  FIG. 13 ), while conversely vehicle bow member  301  is released and free to be raised when bracket member  200  is raised (see  FIG. 14 ). It is worth noting that this operating is illustrated in  FIGS. 13 and 14  in connection with retaining bracket  302  and retaining block member  302 ′. 
   As best seen in  FIG. 8 and 9 , vehicle bow member  301  is coupled to fabric cover  22  through a coupling system  400 . Coupling system  400  includes a rod or cord member  402  slidably received within a bow channel  404  extending longitudinally through vehicle bow member  301 . Cord member  402  captures a portion  406  of fabric cover  22  simply by routing fabric cover  22  around cord member  402 . The shape of bow channel  404  retaining cord member  402  therein, thereby preventing fabric cover  22  from disengaging from vehicle bow member  301 . Most preferably, portion  406  of fabric cover  22  is sewn into fabric cover  22  to prevent migration of fabric cover  22  relative to cord member  402 . It should be understood that this positive coupling of fabric cover  22  to vehicle bow member  301  (and the corresponding coupling of vehicle bow member  301  to either retaining bracket  302  or retaining block member  302 ′) serves to retain and prevent rising of fabric cover  22  during vehicle travel. 
   With reference to  FIGS. 26-33 , alternative cross vehicle bow members  800  and a complementary alternative retaining system  802  will be described in detail. It should be appreciated that vehicle bow members  800  and retaining system  802  may have a similar general configuration across pickup truck  10  and tonneau system  12 , as described above with reference to retaining system  300  and vehicle bow members  301 . 
   Vehicle bow member  800  is illustrated as a generally elongated assembly. Vehicle bow member  800  includes a main housing  810  and a bow end assembly  812  disposed in an end of main housing  810 . As best seen in  FIG. 31 , main housing  810  has a hollow construction with a generally rectangular cross section including sidewalls  814  having tapered portions  816 . Tapered portions  816  facilitate movement of vehicle bow member  800  relative to side frame rail assemblies  28 ,  30  and into engagement with retaining system  802 . Main housing  810  may be constructed of aluminum. 
   With particular reference to  FIGS. 26-30 , bow end assembly  812  includes a bow end housing  820 , a plunger  822 , and a spring  824 . Bow end housing  820  has a clam shell construction including a first component  830  and second component  832 . First and second components  830 ,  832  include complementary pins  834  and holes  836  which engage each other and positively fix the positions first and second components  830 ,  832  relative to each other. When bow end assembly is disposed into main housing  810  ( FIGS. 29-30 ), main housing  810  holds first and second components  830 ,  832  together. Bow end housing  820  further includes an outwardly extending shelf portion  840  adapted to engage with retaining system  802 , as described in further detail below. Bow end housing  820  may be constructed of plastic. 
   Plunger  822  is received and supported by main housing  810  and bow end housing  820 . Plunger  822  includes a main body  850 , a head portion  852  extending outwardly from main body  850 , and a leaf portion  854 . Head portion  852  has a generally flat and rectangular construction and is adapted to directly engage with fabric cover  22  of tonneau system  12  ( FIG. 30 ). Leaf portion supports spring  824  along the length thereof. Plunger  822  may be constructed of steel and, furthermore, may be relatively thin enough so as to be flexible. For example, plunger  822  can be made of ⅛ inch thick steel. 
   When bow end assembly  812  is assembled together, the components of bow end housing  820  are disposed around main body  850  and leaf portion  854  of plunger  822  such that plunger  822  is slidably supported in a slot  860  formed through end surfaces  862 ,  864  of bow end housing  820 . Furthermore, a window  866  is formed in a top surface  868  of bow end housing  820 . Window  866  is configured so that spring  824  can be disposed between first and second components  830 ,  832  of bow end housing  820 . Furthermore, window  866  is configured so that spring  824  can engage and extend between a rear face  870  of window  866  and an inner face  872  of plunger  822 . As seen in  FIG. 28 , when plunger  822  is moved inwardly along slot  860  to an inward position, spring  824  is compressed between rear face  870  of window  866  and inner face  872  of plunger  822 . Therefore, spring  824  biases plunger  822  outwardly relative to bow end housing  820  and main housing  810  towards an extended position ( FIGS. 26-27 ,  29 - 30 ). 
   With particular reference to  FIG. 30 , fabric cover  22  of tonneau system  12  folds over head portion  852  of plunger  822 . A pocket  880  may be sewn or otherwise formed in fabric cover to receive plunger  822 . As plunger is moveable an inward position ( FIG. 28 ), pocket  880  may be formed before fabric cover  22  is disposed on vehicle bow member  800 . Furthermore, as spring  824  biases plunger  822  outwardly, plunger  822  biases fabric cover  22  outwardly in the cross vehicle direction when engaged with fabric cover  22 . Accordingly, vehicle bow member  800  operates to tension fabric cover  22  in the cross vehicle or side to side direction. This tensioning of fabric cover  22  in the cross vehicle direction may improve performance of tonneau system  12 . It should be appreciated that front frame rail assembly  26  and/or rear frame rail assembly  32  can comprise bow end assembly  812 , such that plungers  822  are received in corresponding pockets  880  of fabric cover  22 . In this regard, bow end assembly  812  can bias fabric cover  22  of tonneau system  12  in a cross vehicle direction. 
   With reference to  FIGS. 31-33 , alternate retaining system  802  includes retaining bracket  890 . Retaining bracket  890  is shaped to define a main body  892  having a generally circular cross section and two wing portions  894  extending outwardly from main body  892  in opposing directions. Main body  892  is disposed adjacent one of frame rail assembly  28 ,  30  and fastened thereto via conventional means, such as fasteners. 
   Wing portions  894  of retaining bracket  890  are shaped to capture shelf portion  840  of vehicle bow member  800  between one of wing portions  894  and one of frame rail assemblies  28 ,  30 . That is, wing portions  894  may generally prevent vehicle bow member  800  from disengaging with retaining bracket  890  in a vertical direction. As seen in  FIG. 31 , shelf portion  840  has a cross section including tapered sidewalls  910 ,  912  corresponding to tapered portions  816  of main housing  810 . Furthermore, shelf portion  840  includes a top portion  914  and inclined portions  916 ,  918 . Retaining bracket  890  may be configured so that when top portion of shelf portion  840  is engaged with one of wing portions  894 , vehicle bow member  800  is secured between retaining bracket  890  and one of frame rail assemblies  28 ,  30  and oriented as desired relative to frame rail assemblies  28 ,  30 . As seen in  FIGS. 32-33 , when vehicle bow member  800  is secured relative to retaining bracket  890 , vehicle bow member positions plunger  822  proximate one of sidewalls  16 ,  18  of pickup truck  10 . As plunger  822  may be flexible, plunger  822  may help exert a downward force to help sealingly engage a rubber seal  930  of cover  22  and one of sidewalls  16 ,  18 . It should be appreciated that retaining system  802  can be configured so that one or more components, such as retaining bracket  890 , are movable in a fore-aft direction of pickup truck  10  to engage bow member  800  and lock the position of tonneau system  12 . Retaining system  802  is otherwise similar to retaining system  300  described above. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.