Abstract:
A hard cover assembly for the open bed of a pickup truck is provided comprising a rigid cover and a rail kit. A rigid cover, with a crowned central body portion, constructed out of thermoplastic having a relatively high coefficient of linear thermal movement is used for operation within an outdoor environment having a wide range of temperature variation. A rail kit comprising molded thermoplastic members configured to closely conform to and protect the truck bed rails is combined with the rigid cover to provide a complete hard cover assembly. The molded thermoplastic members of the rail kit include a channel receiving a depending perimeter lip of the rigid cover. The channel is developed to accommodate the linear thermal movement of the rigid cover and may be further adapted to limit the full linear thermal expansion of the rigid cover thereby causing the crowned central body portion to deflect upwards. A lock assembly is provided to lock the rigid cover in a closed position under the full range of temperature variation. The hard cover assembly is installed onto the bed rails by means of hand adjustable fasteners. In particular, the rail kit is mounted directly to the bed rails by a plurality of hand clamps that can be inspected and adjusted by the vehicle owner to ensure safe operation. The rigid cover is hinge mounted to the rail kit using hand knobs so that the vehicle owner can conveniently install and remove the rigid cover for different cargo carrying needs.

Description:
[0001]    The present application claims priority under 35 U.S.C § 119(e) based on U.S. Provisional Application No. 60/185,852 filed Feb. 29, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention is generally directed toward a top for a land vehicle. More particularly, this invention is directed to a hard cover for a pickup truck cargo bed.  
         BACKGROUND OF THE INVENTION  
         [0003]    Pickup truck vehicles are used for both work-related activities and personal transportation. The pickup truck bed provides carrying space for both work-related and personal cargo. In order to prevent cargo carried inside the truck bed from being damaged by weather or stolen by thieves, it has become common to install a protective cover over the truck bed.  
           [0004]    One particularly successful type of cover is referred to as a tonneau cover. There are three categories of tonneau cover in use. These include hard covers, soft covers, and retractable, folding or “specialty” covers. A large number of prior art devices including all three categories have been proposed, and are disclosed under U.S. Patent Classification 296/100. Many advancements in the soft and “specialty” cover categories have been translated in one way or another to hard cover devises. Therefore, advancements in soft covers can be referenced by U.S. Pat. No. 4,838,602 to Nett, U.S. Pat. No. 4,941,705 to Wurtz, U.S. Pat. No. 5,058,652 to Wheatley et al, U.S. Pat. No. 5,186,514 to Ronai, U.S. Pat. No. 5,480,206 to Hathaway et al, U.S. Pat. No. 5,553,652 to Rushford, U.S. Pat. No. 5,655,808 to Wheatley, U.S. Pat. No. 5,984,400 to Miller et al., U.S. Pat. Nos. 6,024,401 and 6,024,402 both to Wheatley. Advancements in “Specialty” covers, including retractable, folding and multi-part covers can be referenced by U.S. Pat. No. 4,479,677 to Gulette et al., U.S. Pat. No. 4,550,945 to Englehardt, U.S. Pat. No. 4,776,629 to Cross, U.S. Pat. No. 4,832,394 to Macomber, U.S. Pat. No. 4,861,092 to Bogard, U.S. Pat. No. 5,636,893 to Wheatley et al., U.S. Pat. No. 4,946,217 to Steffen et al., and U.S. Pat. Nos. 5,931,521 and 6,000,744 both to Kooiker.  
           [0005]    The hard cover category of product is very popular, and represents the largest dollar volume in annual sales for cover manufacturers. Within this category of product, the most popular hard covers by a wide margin are the rigid fiberglass tonneau covers of a unitary construction. Hard covers that are not rigid fiberglass tonneau covers will be known by referring to U.S. Pat. No. 4,273,377 to Alexander, U.S. Pat. No. 4,762,360 to Huber, U.S. Pat. No. 5,743,586 to Nett and U.S. Pat. No. 5,795,011 to Flentge.  
           [0006]    The Truck Cap &amp; Accessory Association (TCM) compiles statistics on rigid fiberglass tonneau cover product sales. A group of twenty-seven (27) rigid fiberglass tonneau cover manufacturing companies participate in a TCAA product sales reporting program. This group of manufacturers report sales of approximately 220,000 units into the North American market each year. A prior art devise that is representative of the product sales referenced by TCM is exemplified by U.S. Pat. No. 5,688,017 to Bennett.  
           [0007]    As known by those familiar with rigid fiberglass tonneau covers, the art of a lay-up construction of thermosetting resins and glass fiber reinforcement is well understood and has been practiced virtually unchanged for generations. With the exception of the cited reference U.S. Pat. No. 4,824,162 to Geisler et al, it is a strait forward matter to produce fiberglass shells adapted to cover land vehicles.  
           [0008]    The mechanical apparatus of rigid fiberglass tonneau covers has advanced since the earliest prior art patents and devises of the 1940s. However, there are three essential mechanical systems interfacing with a fiberglass cover shell and a pickup truck bed. These include a hinge assembly to open and close the cover for access to cargo; a lock to secure the cover in a closed position; and, a counter balance to support the cover in operative open positions. A fourth rail support assembly has been added in recent years to help interface a rigid heavyweight fiberglass shell to the pickup truck vehicle. An example of such a rail support assembly may be known by referring to U.S. Pat. Nos. 4,079,989 and 5,688,017. In effect, the rail support prevents the rigid fiberglass shell from damaging the metal bed rail surfaces of pickup truck.  
           [0009]    Thus, it may be appreciated that a large number of practitioners of the fiberglass method offer essentially a commodity product. Differentiation among products offered within the market is achieved through relative execution of the fiberglass construction, and the now four mechanical systems used to produce rigid fiberglass tonneau covers. The art is well known, and numerous distinguishing factors determine the relative desirability of one product over a second product.  
           [0010]    A new style of hard tonneau cover has been disclosed by the present inventor in U.S. patent application Ser. No. 09/571,043 filed May 15, 2000, and is herein incorporated in its entirety by such reference. A hard cover composed of two sheets of heat deformable plastic material fused together to produce a unitary construction is disclosed. Thermoformed hard covers have been proposed in the past, but have been difficult to implement, and successful thermoformed hard covers are therefore unknown in the industry. Examples of proposed thermoformed hard covers may be known by referencing U.S. Pat. No. 3,762,762 to Beveridge et al., and U.S. Pat. No. 3,785,698 to Dean et al. The thermoformed hard cover of the referenced patent application has been advanced, in part, to overcome the problems of translating the solutions fiberglass methodologists have used in the past to provide hinges, locks, counterbalances and support frames for thermoformed hard covers of the earlier art.  
           [0011]    Rigid fiberglass tonneau covers are installed onto the truck bed by one of two methods. In the earliest method, fiberglass hard cover installation hardware attaches into the metal structure of the truck bed by means of a plurality of sheet metal screws or other substantially similar fastening devises. The problem with this approach is that the sheet metal forming the truck bed is modified, which reduces the resale value of the vehicle. The first method is now largely a thing of the past. In the second method, the rigid fiberglass cover is attached to a frame assembly, and the frame assembly is attached onto the truck bed. As disclosed by Penner in U.S. Pat. No. 2,989,340, sheet metal fasteners are offered to attach the frame sub-assembly to the truck bed. Early frame devises were advantageous because they deflected/absorbed damaging stress away from the truck bed rails. These systems were later adapted for relatively convenient removal from the truck bed, as in Penner, U.S. Pat. No. 4,124,247. Other attachment methods, as for example U.S. Pat. No. 4,079,989 to Roberston and U.S. Pat. No. 5,228,736 to Dutton, were advanced to eliminate sheet metal deforming fasteners. The frame support method was later advanced further when tool adjusted clamps replaced fasteners. Tool operated clamps have now become the standard mounting methodology in the industry. The frame support was advanced yet again, with a number of different approaches that reduced damage to the truck bed, and facilitated relatively convenient removal, as characterized in FIG. 4 of U.S. Pat. No. 5,860,691 to Thomsen et al. Clamp on frames provide a “no drill” solution, the sheet metal forming the truck bed therefore remains unmodified, and the resale value of the vehicle is thus preserved.  
           [0012]    Accordingly, a number of options are known to those skilled in the fiberglass methodologies to provide means for hinging, balancing, locking and preventing sheet metal damage. In implementing a thermoformed hard cover, the present inventor has learned that the apparent options common to fiberglass hard covers are impractical or not sufficiently advanced to translate from fiberglass construction experience to a thermoformed construction for a hard tonneau cover.  
           [0013]    A problem related to hinge assemblies characteristic of the fiberglass methodology is that the hinge elements attaching to the fiberglass shell are inoperable in a thermoformed plastic shell. Fiberglass materials provide greater localized strength than thermoformed plastic. As shown in U.S. Pat. No. 4,324,429 to Wilson et al., a relatively small hinge element may be securely fastened to fiberglass with a plurality of fasteners with good results. The art of the fiberglass methodology teaches that the focused pressure points may also be reinforced with inserts that absorb hinging stress, such as aluminum plates. A hinge leaf fastening arrangement, as in Goble U.S. Pat. No. 5,340,188 would however distress the thermoformed hard cover to fatigue. Fiberglass hinging methodologies can not be translated to thermoformed plastic, because hinge apparatus stress must be distributed over a comparatively large area of the thermoformed hard cover. The hinge apparatus shown in U.S. Pat. No. 5,632,522 to Gaitan et al. may be adapted for thermoformed hard covers, and to some advantage, but the additional hardware cost of this method is unnecessary when the thermoformed hard cover is appreciated. The problems corrected by the hinge and lift system of Lunney in U.S. Pat. No. 5,971,446 have been solved in the present invention with less sophisticated and expensive apparatus. A different and low cost approach is needed to accomplish hinging action in a thermoformed hard cover.  
           [0014]    A problem with the lock methodology of rigid fiberglass tonneau covers is that a substantially fixed position is used to locate the receiving end of the lock assembly that is attached to the vehicle. This approach is inoperable with thermoformed hard covers because thermoformed plastic materials have a coefficient of thermal movement that is considerably greater than fiberglass. If the operating environment of a full size truck bed hard cover is −40° to +160° F., the rate of thermal movement of a thermoformed cover is greater than +/−0.5 inches from a starting temperature of 60° F. (in/in/° F. ˜4.0−6.0 E−0.05). Therefore a fixed lock-receiving end, such as a rotary lock, is not a satisfactory approach for thermoformed hard covers. A fixed point receiving end lock can be referenced in U.S. Pat. No. 5,688,017 to Bennett.  
           [0015]    The counter balancing methodologies used in rigid fiberglass covers is also problematic. In reference to the patent pending devise of the present inventor, it has already been disclosed that counter balancing apparatus must produce a constant closing force when the thermoformed cover is closed. The constant thrusting force of the counter balance must be directed in a manner operable to close the cover rather than open the cover. Thermoformed hard covers have less high temperature strength than fiberglass covers. Therefore, the lift systems of Penner U.S. Pat. No. 4,124,247 and Wislon et al U.S. Pat. No. 4,324,429 would strain a thermoformed hard cover. The localized counter balance pressure points associated with fiberglass methodologies must also be widely distributed over a wide area to preserve the predetermined shape and desired appearance of a thermoformed hard cover. The lift system proposed by Miller in U.S. Pat. No. 5,503,450 could be developed more readily to thermoformed hard covers, but the additional associated hardware cost is unnecessary when a thermoformed hard cover is appreciated. The lift system of Nesbeth in U.S. Pat. No. 5,909,921 is impractical for the present invention. The lift system of Buchanan in U.S. Pat. No. 5,944,376 could be adapted to the present invention provided the lifting force is distributed through a wide area of the thermoformed hard cover. The lift system of Lund et al. U.S. Pat. No. 5,988,728, could likewise be more readily translated for advantage to a thermoformed hard cover. However, the Lund methodology does not compliment the present invention which is preferred for providing a hard cover that is simple to partially or completely remove and reinstall upon the truck bed.  
           [0016]    Rigid fiberglass tonneau covers are considerably heavier than comparably sized thermoformed hard covers. The specific weight of fiberglass is approximately 35% greater than the thermoformable plastic materials that may be economically used to construct a hard cover. Therefore, another problem is that hand tools are required to clamp the installation hardware of the heavy weight rigid tonneau cover to the pickup truck vehicle. In particular, clamps with threaded elements and bolts are tightened with a wrench or hand tool to hold the frame assembly upon the truck bed. These arrangements sometimes lead to damage, including deformation or abrasion of the metal surfaces of the truck bed rails. The lighter weight construction of a thermoformed hard cover requires less clamping force (and less lifting force) for implementation and is therefor more amenable to less destructive and other tool operated clamping methodologies.  
           [0017]    As pickup truck vehicles are used for a variety of purposes, it is often desirable to remove an installed hard cover for an open truck bed. The two common methods of rigid fiberglass tonneau cover attachment present problems when a vehicle operator wants to remove the hard cover from the truck bed. In the case of derivatives of the first method of installation, it may be necessary to remove some of the fasteners from the sheet metal forming the truck bed. This requirement increases the damage to the sheet metal each time the hardware is removed and reinstalled onto the truck bed. (Fasteners joining rail support members are also problematic.) In the case of the second method of installation, the clamps have to be disengaged so that the hard cover and the cooperative frame assembly can be removed from the truck bed. The rigid fiberglass cover arrangement requires hand tools to disengage the clamps and the lifting efforts of two or more people to remove a comparatively heavy weight fiberglass cover and its associated frame assembly from the truck bed. In both cases, both methods of attachment present the vehicle operator with a number of problems that make it inconvenient to use an open truck bed and return to a closed truck bed when desired. In U.S. Pat. No. 5,688,017, Bennett proposes a rail that maintains a low profile, and a fiberglass cover that is removed from the frame for an open truck bed. Bennett does not disclose an equally simple methodology to remove the frame should the vehicle operator also prefer a completely open truck bed.  
           [0018]    A problem specific to the second method of installation, in which a plurality of clamps are used to engage the frame assembly of the hard cover to the truck bed, is that the clamps become loose during normal vehicle operation. This problem may result from vehicle vibration during normal driving conditions or vehicle flexing during off-road travel. In both events, when the clamps loosen, a number of dangerous conditions can result. Therefore, in order to prevent loose clamps from creating dangerous conditions, it is necessary for the vehicle operator to carry a hand tool that is periodically used to retighten the clamps after a period of driving, or before a road-trip. Although this is an acceptable solution to a problem, regrettably, not all vehicle operators are as pre-cautious as they should be when using a fiberglasshard cover with tool operated clamp-on hardware. All of the prior art referenced by the applicant discloses clamps or fasteners that require the use of hand tools or the like. A clamp body using a tool operated threaded fastener similar to the one disclosed in the present embodiment is referenced in U.S. Pat. No. 5,860,691 to Thomsen et al. Another clamp arrangement, which is disclosed in U.S. Pat. No. 5,904,393 to Yoder, could be adapted to receive a hand-operated fastener for the advantage of inspection and re-tightening. Clamps having a cam action that do not require hand tools are proposed by Love in U.S. Pat. No. 5,765,902 and Rippberger in U.S. Pat. No. 5,975,618. The problem with these clamps is that they are developed to interface with largely proprietary rail extrusions. Therefore, these concepts are not immediately useful for wide scale implementation. Fiberglass onneau cover manufactures have not learned and do not know that a lightweight hard cover can use hand-operated clamps with success.  
           [0019]    What is needed is a “no-drill” and a “no-tool” method of attaching a hard cover to a pickup truck bed. The “no-drill” and “no-tool” method should also be easy to use and convenient to allow the vehicle operator to use an open truck bed and to return to a closed truck bed when desired, The present invention fulfills these needs by successfully adapting the four elementary mechanical systems of tonneau covers to a thermoformed hard cover. The present invention also teaches that a thermoformed hard cover can be disengaged from a rail assembly to simplify removal and reinstallation of a hard cover. Finally, the present invention provides means for the vehicle operator to inspect and ensure installation equipment is secure and properly engaged for safe driving.  
         SUMMARY OF THE INVENTION  
         [0020]    It is a primary object of the present invention to provide a lightweight thermoformed hard cover assembly for the bed of a pickup truck vehicle. The present invention comprises a thermoformed hard cover and a thermoformed rail assembly. According to this aspect, the thermoformed rail assembly engages the truck bed, and the thermoformed hard cover engages the rail assembly of operative use.  
           [0021]    It is an object to provide a thermoformed hard cover that is hinged. According to this aspect, the hinge of the thermoformed hard cover is adapted to distribute hinge stress over a comparably wide area.  
           [0022]    It is another object to provide a thermoformed hard cover with a lock. According to this aspect, the thermoformed hard cover encapsulates locking apparatus that engages a lock-receiving end that accommodates the thermal movement of a thermoformed hard cover.  
           [0023]    It is another object to provide a thermoformed hard cover with a lift system. According to this aspect, the thermoformed hard cover uses a lift system arranged to produce a constant closing force when the thermoformed hard cover is closed. According to yet another aspect, forces of the lift system are deflected over a comparably wide area of the thermoformed hard cover.  
           [0024]    It is another object to provide a frame support for the thermoformed hard cover. According to this aspect, a decorative thermoformed rail cover is provided with the frame support. According to this aspect, the thermoformed rail cover offers protection for the truck bed. According to yet another aspect, the thermoformed rail cover is adapted to channel unwanted matter away from the interior of the truck bed. The thermoformed rail cover is adapted to conceal rigid frame support members.  
           [0025]    It is yet another object to provide a thermoformed hard cover assembly that is removable. According to this aspect, the comparatively lightweight thermoformed hard cover is removed from the rail assembly to provide an open truck bed. According to another aspect, the rail assembly can remain in place or be removed altogether. According to these features, the thermoformed hard cover is removed while the decorative rail assembly remains in place for simplified reinstallation.  
           [0026]    Still according to this object, a detachable hinge element is used to interface between the thermoformed hard cover and the rail assembly. The hinge apparatus uses hand-operated knobs to engage the hinge bracket in the operative conditions for opening and closing of the hard cover relative to the truck bed.  
           [0027]    Still according to this object, the rail assembly is engaged to the truck bed by hand operated clamps for a “no-tool” installation. Hand operated clamps can be used in substitution of tool operated clamps to disengage the rail assembly from the vehicle when a completely open truck bed is required. According to these features of the present invention, a “no-drill”, “no tool”method of installation is proposed.  
           [0028]    According to another aspect of the present invention, hand operated clamps simplify the task of periodically inspecting and re-tightening clamps that become loose due to vehicle vibration and flexing.  
           [0029]    It is another object to provide a hard cover that prevents the unwanted opening and closing of the truck bed tailgate. According to this aspect, a thermoformed member of the rail assembly is affixed to the thermoformed hard cover.  
           [0030]    It is another object to provide a rail assembly that accommodates the thermal movement of the thermoformed hard cover. According to this aspect, the thermoformed rail cover is adapted to receive a moving thermoformed hard cover.  
           [0031]    Briefly, in accordance with this invention, there is provided a hard cover assembly that is easy to install and inspect for safe operation. The hard cover assembly combines a unitary thermoformed hard cover with an attractive rail assembly that is separately engaged to the pickup truck bed by means of hand operated clamps, for a no drill, no tool installation.  
           [0032]    Other objects, aspects, features and advantages of the present embodiment of the invention will become apparent from the following descriptions and appended claims when taken in conjunction with the accompanying drawings. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0033]    [0033]FIG. 1 is a perspective view of the hard cover in an open position upon a pickup truck bed.  
         [0034]    [0034]FIG. 2 is a perspective section view showing the inside structure of the hard cover in the area of the tailgate.  
         [0035]    [0035]FIG. 3 is a partial perspective view showing the prop components of the hard cover assembly.  
         [0036]    [0036]FIG. 4 is an exploded perspective showing the passenger side rail member of the rail kit.  
         [0037]    [0037]FIG. 5 is a sectional view showing the relationship of the hard cover perimeter lip to the channel of the rail kit.  
         [0038]    [0038]FIG. 6 is a perspective view showing how the driver side rail is positioned on the bed rail.  
         [0039]    [0039]FIG. 7 is a perspective view showing the rail kit positioned upon the bed rail.  
         [0040]    [0040]FIG. 8 is a perspective sectional view suggesting how the rail kit is clamped onto the bed rail.  
         [0041]    [0041]FIG. 9 is a perspective view showing how the hinge bar interfaces with the rail kit.  
         [0042]    [0042]FIG. 10 is a perspective view pointing out certain features of the hard cover assembly.  
         [0043]    [0043]FIG. 11 is a side section suggesting how the hinge bar engages the rail kit and fastened to the hard cover with hand knobs. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0044]    According to the present invention disclosed in FIG. 1, a hard cover assembly  2  is seen installed upon the truck bed  4  of a pickup truck vehicle  6 , here shown in phantom. The hard cover assembly  2  comprises a unitary hard cover  8  and a protective rail assembly  10 .  
         [0045]    The hard cover  8 , in the present embodiment, is constructed out of two sheets of heat deformable thermoplastic material. The top sheet  12 , in the present arrangement, is a coextruded construction comprising a suitable weatherable thermoplastic material, such as Bayer Corporation&#39;s Centrex® 485 ASA/AES sheet extrusion grade polymer, and an ABS polymer substrate. In the present example, the Centrex® material is provided with a textured surface, such as a fat line hair cell texture, to provide a scratch resistance finish. The bottom sheet  14  is extruded out of a preferably low impact ABS polymer that provides a more rigid construction. The top sheet  12  and bottom sheet  14  are selectively fused together by known means in areas  16  where the two thermoformed sheets achieve interfacial contact. In other embodiments, hard cover  8  may be made from other heat deformable thermoplastic materials such as polyethylene, or from thermosetting resin materials, including fiberglass, of known nature. The present twin sheet construction of the hard cover  8  may also be modified with the addition of a foam core operable to rigidify a thermoformed hard cover.  
         [0046]    The protective rail assembly  10 , in the present embodiment, comprises four members including a driver side member  18 , a passenger side member  20 , a front wall member  22 , and a tailgate member  24 . The four members unite to provide protective rail assembly  10 . The four members  18 ,  20 ,  22  and  24  are preferably constructed out of the same material as the top sheet  12 , so that the hard cover assembly  2  blends together and has an attractive finish and appearance in different operative conditions.  
         [0047]    As seen in FIG. 1, the hard cover  8  is supported in an open position by opposing props  26 . As may be understood by referring to the latch rods  28 , cover  8  is locked in a closed position by actuating a handle  30  that thrusts the latch rods  28  outward to engage rod brackets  32  attached to the members  18  and  20  in the areas near the tailgate pillars  34 . The hard cover  8  is hingedly engaged by elements of the members  18  and  20 , hidden from view in the present figure adjacent the front wall member  22 . Accordingly, it may be appreciated that hard cover  8  opens and closes to provide the vehicle operator with access to cargo stored within the truck bed  4 .  
         [0048]    It should also be understood, in reference to the present embodiment, that hard cover  8  is of a size that is substantially common to a number of different truck bed makes and models. Accordingly, the one hard cover  8  represented in FIG. 1 will fit a number of different pickup truck makes and models in a similar standardized bed length which have been fitted with a specific make and model dedicated rail assembly  10 . A handful of hard covers  8  are therefore developed to fit the full range of pickup truck models offered. It should also be understood that the protective rail assembly  10  is provided to adapt the hard cover assembly  2  to a specific make and model of pickup truck. A handful of protective rail assemblies  10  are therefore adapted to cooperate with one hard cover  8  to provide a closely fitting truck specific hard cover assembly  2 .  
         [0049]    Turning now to FIG. 2, the rear section  36  of hard cover  8  is seen. In this figure the method for attaching the tailgate member  24  to the back wall  38  of the hard cover  8  may be understood. In the present embodiment, a plurality of predrilled holes  40  are included in the both the tailgate member  24  and back wall  38 . The holes  40  align when the member  24  and wail  38  are brought together for assembly. Tailgate member  24  is attached to wall  38  by threading thumbscrews  42  through thumbnuts  44  in the manner suggested. This methodology is used so that assembly of the vehicle specific tailgate member  24  to a common size hard cover  8  can be accomplished without the need for hand tools. Other fastening or adhering means may be employed in keeping with the objective of providing a no-tool assembly and installation.  
         [0050]    It may also be appreciated that the present arrangement prevents the tailgate of the vehicle from being opened when the hard cover  8  is closed. The tailgate member  24  extends downward from the perimeter margin defining the hard cover  8 , overlaying the tailgate when in a closed position. This arrangement is also preferred in the present embodiment because a tailgate member  24  that mounts upon the top ledge of the tail gate is subjected is damaging cargo handling operations and load bearing conditions. The tailgate member  24  is mounted to the cover  8  so that it is removed from potential damaging conditions when the cover  8  is opened.  
         [0051]    Referring now to FIG. 3, the method for attaching the props  26  to the hard cover assembly  2  may be understood. The props  26  have ball socket ends  46  that engage ball studs  48  supported upon stud brackets  50 . The props  26  attach to the stud brackets  50  that are in turn attached to the hard cover assembly  2  in the manner suggested. Other fastening means may be employed in keeping with the objective of providing a no-tool assembly and installation. In the most preferred method, a threaded aluminum bar  43  is contained within the molded prop support in  41  of the bottom sheet  14 . The threaded aluminum bar  43  receives a threaded stud  47  engaging prop  26 . The bar  43  provides the further benefit of providing deflective strength to the prop support  41 . It may also be convenient to use a clip  138  to retain the free end of the prop  26  when it is disengaged from the rail assembly  10  during times when the hard cover  8  is removed for an open truck bed.  
         [0052]    Turning now to FIG. 4, a closer look at the construction of and passenger side member  20  is provided, it being understood driver side member  18  is a mirror image of said passenger side member. Member  20  includes a molded plastic rail protector  52  and a rigid frame structure  54 . In the present embodiment, rail protector  52  includes a channel  56  that receives the down turning lip  58  of hard cover  8  when closed. Channel  56  also acts as a rain gutter to channel water away from the inside of the truck bed  4 . The channel  56  is open toward the front and rear  60  of the vehicle to enable the run-off of water. The molded rail protector  52  also includes a plurality of clamp positioning pockets  62 , a slot  64  to receive a lock bracket  32 , a fixed prop bracket emboss  66  to accommodate a prop bracket block  68 , and an elevated pocket  70  to receive the opposed ends of the front wall member  22 .  
         [0053]    The rigid frame structure  54  is provided to give the molded plastic rail protector  52  strength and longitudinal stability. The structure  54  is composed of a long angle piece  72 , upon which a rod bracket  32  and a prop bracket block  68  are welded. The structure  54  also includes a short angle piece  74 , which is welded to long piece  72  at a substantially right angle in a position adjacent the truck bed front wall. The short angle piece  74  also includes a hinge bracket  76  having a slot  126 . The portion of the short angle piece  74  with the hinge bracket  76  extends beyond the margin  78  formed by the pocket detail  70  of the plastic rail protector  52 . The rail protector  52  is attached to the aluminum structure  54  in an overlying relationship to provide a unitary construction by means of a plurality of mechanical fasteners in the areas referenced by holes  80 . The top inside surface of structure  54  receives a foam strip  82  including single sided tape. The foam tape  82  prevents the structure  54  from damaging the painted surfaces of the bed rails  84 . The driver side member  18  and passenger side member  20  are positioned onto the truck bed  4 , and the (aluminum) rigid frame structure  54  communicates directly with the truck bed rails  84 .  
         [0054]    In reference to lock bracket  32 , it is desirable to provide a lock receiving end that accommodates the movement of a lock end, which movement is due to the relative expansion and contraction of a central body portion of the thermoformed hard cover. In the embodiment disclosed the brackets  32  engage the rod ends  28  of the lock apparatus when the hard cover  8  is closed. The brackets  32  extend laterally front to back a distance greater than the combined thickness of the rod ends, plus the range of movement characteristic of the hard cover  8  in extreme temperature operating environments. In the present case, the bracket is at least one inch wide, but preferably two inches, to capture the rod ends  28  in a wide range of temperature environments.  
         [0055]    [0055]FIG. 5 provides a cross-section view of pre-assembled passenger side member  20 , taken along lines A-A of FIG. 4, upon the bed rail  84  of truck bed  4 . Plastic rail protector  52  includes an inside lip  86  that extends downward from a compression ledge  88  formed on the inside margin  90  of the channel  56 . The length of lip  86  exceeds the length of the down turn lip  92  of the bed rail  84 . The outside margin  94  of channel  56  joins exterior rail portion  96 , which is molded at its lower margin  98  to closely conform to the outside contours  100  of the bed rails  84 . In this manner, the plastic rail protector  52  has the appearance of being an integral part of the truck bed  4 . As may also be appreciated in reference to the present figure, hard cover  8  includes a down turned lip  58  that is received by channel  56  when the hard cover  8  is closed. When in the closed position, gasket  102 , adhering to bottom plastic sheet  14 , compresses against compression ledge  88  to produce a water resistance seal. As may also be seen, the distance between the inside margin  90  and the outside margin  94  of channel  56  is greater than the width, in cross-section, of the lip portion  58  of hard cover  8 . This arrangement is preferred because the thermoplastic materials used to construct the hard cover  8  expand and contract in response to elevated and low temperature conditions, respectively. Accordingly, channel  56  is equal in width to the thermal movement associated with the operating environments to which the hard cover  8  will be exposed. Therefore, the present figure suggests where the downturn lip  58  of hard cover  8  is positioned within the channel  56  when the medium operating temperature is 60° F. It may also be appreciated that the outside margin  94  of channel  56  may be brought closer to the down turn lip  58 , so that under elevated temperature conditions, the lip  58  expands to the outside margin  94 . When this occurs, additional expansion of hard cover  8  is accommodated by the side-to-side upward deflection of the central body portion of the hard cover  8 . In this arrangement, the hard cover  8  will appear to move in a “crowning” action when the operating temperature reaches elevated extremes.  
         [0056]    Turning now to FIGS. 6, 7,  8  and  9 , the manner in which the protective rail assembly  10  and hard cover  8  are installed without hand tools is suggested. As seen in FIG. 6, driver side member  18  is positioned upon the driver side of the truck bed  4 . In this figure, the relative position of the hinge bracket  76  is seen extending beyond the margin  78  of the pocket  70 . It would also be feasible to capture the hinge bracket  76  within an elongated pocket  70  so that the hinge bracket  76  does not extend beyond the margin  78 . In FIG. 7, the driver side member  18  and passenger side member  20  are positioned on the truck bed  4  along with the front wall member  22 . The front wall member  22  includes opposes ends  104 , which insert into the pockets  70  formed in the plastic rail protectors  52 . As suggested in FIG. 7, pockets  70  receive ends  104  of front wall member  20  in an overlaying arrangement so that only a small seam between the members  18  and  20 , and  22  is visibly apparent. Also seen in FIG. 7 are two slots  106  formed in front wall member  22 . Slots  106  are used in the hinge arrangement that will be discussed below. After the members  18 ,  20  and  22  are positioned upon the truck bed rails  84 , a plurality of hand clamps  108  are provided to secure the members  18  and  20  to the truck bed  4 . As suggested in FIG. 8, clamps  108  are positioned in the clamp positioning pockets  62  formed along the wall  86  of the plastic rail protector  52 . The clamps  108  engage the downturn lip  110  of rigid frame structure  54  and inside lip  92  of bed rail  84 . Engagement is achieved by inserting the thread portion  112  of hand knob  114  through the slotted hole  116  to the threaded hole  118  of the clamp  108  and turning the hand knob  114  to full tension. It should also be stated lock washers are used between the knob  114  and the clamp  108  to maintain tension. When full tension is achieved, the claw teeth  120  of the clamp  108  compress the lip  110  of the rigid frame structure  54  against the lip  92  of the bed rail  84 . A plurality of hand clamps  108  are used to fasten the members  18  and  20  to the truck bed  4  for a no tool installation.  
         [0057]    As will be understood by referring to FIG. 8, the installation of the rail kit  10  to the truck bed  4  is achieved without the use of hand tools. As may also be appreciated, the vehicle operator can periodically inspect the tension of hand knobs  114  to ensure that clamps  108  are properly engaged, and so that the hard cover assembly  2  is properly installed and secured for safe driving and access to the cargo stored within the truck bed  4 . Other arrangements may be used in keeping with the objectives of providing a no-tool installation and a simple and convenient way of inspecting and re-tightening the installation hardware for safe operation.  
         [0058]    Turning now to FIGS. 9 and 10, the manner in which the hard cover  8  is installed onto the protective rail assembly  10  is suggested. After the clamps  108  have secured the members  18  and  20  to the truck bed  4 , the hard cover  8  can next be installed. The first step is to insert two hinge bars  122  into the slots  106  provided on the front wall member  22 . A short bend portion  124  of hinge bar  122  is inserted through slot  106  and corresponding slot  126  of hinge bracket  76 . As suggested in FIG. 9 at the passenger side, after portion  124  is properly inserted, hinge bar  122  is pivoted into a lowered position so that the short bend portion  124  is engaged by slot  126 .  
         [0059]    Next, as shown in FIG. 10, the hard cover  8  is lifted over the truck bed  4  and a front wall  128  of the hard cover  8  is positioned within a channel  130  formed in the front wall member  22 . While the hard cover  8  is manually maintained in an open position as suggested, the hinge bars  122  are manipulated by hand to insert threaded studs  132  projecting from the hard cover  8  through corresponding holes  134  on the extended portion of the hinge bars  122 . After the hinge bars  122  are loosely engaged by the studs  132 , the fixed ends  136  of props  26  are disengaged from the retaining clips  138  and rotated downward to so that the socket ends  46  of the props  26  can be installed onto the prop brackets  50  attached to the rail members  18  and  20 . After the props  26  are in place, and the hard cover  8  is retained in the open position, pass-through hand knobs  140  are threaded over studs  132 . A plurality of hand knobs  140  are thus rotated to full tension to compress the hinge bars  122  into a fixed position against a platform provided to receive the hinge bars. FIG. 3 may also be referred to, to better appreciate the details of this arrangement. As can be seen in this view, the hinge bars  122  reside in a platform  142  molded into bottom sheet  14 , that is adapted to deflect the forces of strain associated with the hinging action upon the hard cover  8 . The platform  142  is further adapted to support the studs  132  of the hinge apparatus. In the present embodiment, a reinforcing plate  146  is welded to the interior surface of the platform  142  preventing interior segments of the threaded stud  132  from movement. Reinforcing plate  146  also strengthens the platform to help prevent deflection upon the rigid cover in a region adjacent the front wall  128 . It should be further explained that the studs  132  are segments of a u-bolt  144  that is contained within the platform  142  formed by bottom sheet  14 . U-bolt  144  is preferred so that studs  132  will not loosen with wear-and-tear and rotate as hand knobs  140  are employed to secure hinge bar  122  to hard cover  8 . This arrangement may be better appreciated in FIG. 11.  
         [0060]    It may also be suggested that the u-bolt  144  arrangement of FIG. 11 may be substituted with two captive threaded inserts (not shown) and the pass through hand knobs  140 . The threaded segments  132  of the u-bolt may be substituted with hand knobs  114  having thread portions  112 .  
         [0061]    Thus, it may be appreciated that the hard cover  8  may be attached to the protective rail assembly  10  by means that do not require hand tools. Furthermore, when the vehicle operator wishes to remove the hard cover  8  for an open truck bed, the reverse procedure is used to remove the hard cover  8 . The hard cover  8  can therefore be disengaged from the rail assembly  10 , which may optionally remain installed on the truck bed while the hard cover  8  is removed. In the present arrangement, the unsightly mechanical apparatus of the rail assembly  10  is concealed by the decorative molded plastic members  52  which provides an attractive appearance. When a completely open truck bed  4  is preferred, the entire hard cover assembly  2  can be conveniently removed without tools by detaching the clamps  108  and lifting the rail assembly  10  away from the bed rails. Other arrangements may be used in keeping with the objectives of providing a no-tool installation and a simple and convenient way of inspecting and re-tightening the installation hardware for safe operation.  
         [0062]    Briefly, in accordance with this invention, a hard cover assembly is provided for installation onto the bed rails of a pickup truck. A rigid cover is combined with a rail assembly to provide a complete assembly. The rail assembly mounts directly to the bed rails with a series of hand clamps, and the rigid cover mounts to the rail kit with a series of hand knobs. The hard cover and rail kit are separately or both removable from the bed rails to provide an open truck bed. Hand clamps and knobs are provided for a “no-drill” and a “no-tool” installation. The hand fasteners can be inspected to insure the hard cover assembly is securely mounted to the truck bed for safe operation and driving. The hard cover and rail assembly is adapted to accommodate the thermal movement of the hard cover in both elevated and low temperature environments. It is to be understood that the drawings and descriptive matter herein are in all cases to be interpreted as merely illustrative of the principles, methods and apparatus of the invention, rather than as limiting in any way, since it is contemplated that various changes may be made in various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.