Abstract:
An attaching system for a lift-roof cover pivoting substantially about a fixed forward wall upper edge via application of rear hatch technology of the prior art for conventional cab high covers together with attachment means in the form of linkages. The attaching system for mounting to a load bed supports multiple functions providing convenience in distribution and installation processes; in particular facilitating use of processes employed for conventional caps with respect to shipping and storage. The system includes lift-roof to forward wall stop and side retainer means supporting improved functional integrity and security. Also included are draw latches supporting levels of operating convenience demanded for lift-roof applications. Simplified manufacturing adaptation of a conventional cap is supported by pre-assembly of key subassemblies. Capability for completing all functional adjustments before shipping supports installation simplified to levels suited to needs of multiple location installers experienced only with conventional covers of the prior art.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This invention defines improvements to the concepts described under U.S. Pat. No. 5,102,185 which is a continuation-in-part of Ser. No. 216,140, Jul. 7, 1988, abandoned, which is a continuation-in-part of Ser. No. 52,906, May 22, 1987, U.S. Pat. No. 4,756,571. 
   © STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   REFERENCE TO A MICROFICHE APPENDIX 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   (1) Technical Field 
   The invention pertains to lift-roof covers for use with load beds of light trucks, providing improved access to the load bed and extending functions to other uses, with major focus upon achieving these benefits in a manner best accommodating manufacturing and distribution processes broadly in use relative to conventional fixed mount cab high covers (caps) of the prior art. Applicable US classifications include 296/100.1, 100.6 hinged load covers, 296/165 expansible or collapsible vehicle body, 296/176 expansible/collapsible from a first to a second configuration for camping. The disclosure describes key improvements beyond the concept described by U.S. Pat. No. 5,102,185, these improvements providing simplification in manufacturing processes and improvements in convenience of installation and operation to levels approaching those for conventional fixed mount caps (cab high covers) of the prior art. These improvements also increase the functional reliability of the complete lift-roof cover system and make possible enhanced aesthetic appeal by eliminating obvious appearance differences from conventional fixed mount caps of the prior art which have demonstrated highest user acceptance levels. In particular, objection has been made to separation lines between the forward wall and the lift-roof/cap shell when these are visible in side view. The application to a new use of existing technology for hinging and weather sealing rear hatch assemblies for fixed mount caps of the prior art overcomes this deficiency, while supporting functional and economic benefits associated with use of technology which is familiar to practitioners of the art to which the invention pertains. 
   (2) Description of Related Art 
   Through review of the prior art defined in patents relating to pickup truck load bed covers issued subsequent to Lake, U.S. Pat. No. 5,102,185, it can be seen that much effort has been focused on inventing alternate means to provide improved access for loading/unloading and facilitating adaptation to uses beyond cargo protection while also making available a roof height equal to or greater than that of the vehicle cab. Examples include the following: 
   Ekonen et al, U.S. Pat. No. 5,104,175, and Herndon, U.S. Pat. No. 5,951,095, describe transformable cover assemblies which unfold from a low profile on the load bed to provide full enclosure with a roof level equivalent to that of a cab high, fixed mount cap of the prior art. However, they add complexity while giving up significant degrees of security and integrity of appearance with the vehicle when in the cab high operating mode. 
   Plamondon, U.S. Pat. No. 6,149,217, Alexa, U.S. Pat. No. 6,000,745, Moberly, U.S. Pat. No. 5,443,295, and Hanning, U.S. Pat. No. 6,471,282, describe retractible flexible covers of cab height which fail to provide the security and integrated (with vehicle) appearance provided by most fixed mount, molded caps. 
   Aragon et al, U.S. Pat. No. 5,516,182, Herzberg et al, U.S. Pat. No. 5,203,603, and Hutchinson, U.S. Pat. No. 5,655,809, describe telescoping cab high covers having rigid outer paneling. These concepts provide better cargo security, but add significant complexity and also fail to provide the fully integrated appearance provided by most conventional, fixed mount, molded caps. 
   Fowler, U.S. Pat. No. 6,471,280, describes a cover with hard molded shell but, in order to provide improved loading access, requires removal of the shell, an obvious inconvenience. 
   Baldwin, U.S. Pat. No. 6,439,647, Dence, U.S. Pat. No. 6,394,532, and Lambden, U.S. Pat. No. 6,007,137, describe cab high rigid covers pivoting from one or both sides in a manner providing increased interior volume as desirable for adaptation to camping or improved side loading access. However they fail to provide improved access from the rear suitable for loading popular wheeled equipment. 
   Harkins, U.S. Pat. No. 5,209,543, describes an apparatus for enclosures such as pickup bed tops, including a pair of folding top panels longitudinally hinged for closing along the top centerline. In order to achieve the benefits of lift-roof improved access loading from the rear, considerable and costly complexity is added. 
   Medlin, U.S. Pat. No. 5,595,418, and Enninga, U.S. Pat. No. 5,104,175, describe means for mounting a cap to a load bed in ways accommodating pivotal rotation of the complete camper shell about a forward axis by lifting from the rear. However, significant complexity appears to be added in hardware and processes necessary for installation and acceptable function. Furthermore, sealing at the forward wall to load bed interface is not addressed. 
   Moore et al., U.S. Pat. No. 5,421,633, describes a camper shell intended for mounting directly to a truck frame on a vehicle assembly line, adaptable to having its roof pivotally raised from the rear and having flexible walls for camping attached and/or removed. Moore et al appears focused on application of lift-roof functional benefits via a high production volume vehicle assembly process requiring high levels of manufacturing tooling investment and does not appear to address needs of manufacturing and distribution systems in place within the conventional cap industry. 
   The concepts cited above provide various benefits beyond those provided by conventional fixed mount caps of the prior art. In most cases compromises are introduced which are evidently unacceptable to most purchasers of fixed mount, molded caps (historically comprising the primary market for pickup truck covers), who demand an appearance well integrated with styling of the vehicle, together with secure, weatherproof enclosure of the load bed to a height matching that of the vehicle cab. It would appear that Enninga and Medlin are able to retain all key functional and aesthetic benefits provided by conventional caps as long as they are used in the closed condition. When in the open condition cargo space is compromised, due to intrusion of the cap forward wall, which moves rearward as the cap shell is raised and introduces issues with respect to sealing to the load bed forward wall. Also, complexity introduced in the components and associated processes necessary for installation become of particular concern where installation may be completed at multiple locations by individuals with limited experience relative to the product. Therefore, objects of my invention include to provide the benefits of improved access for loading and easy adaptation to alternate uses while minimizing complexity in the installation process and/or costs in added hardware and avoiding compromises relative to benefits already provided by conventional fixed caps of the prior art. 
   Grise, U.S. Pat. No. 4,452,482, and McGaughey et al, U.S. Pat. No. 4,461,185, describe hatch frame construction for pickup truck caps including an integral hinge for supporting a hatch door in a weatherproof manner with location close to the cap roof edge. These patents are of referent interest in describing adaptation of radius door technology to lift-roof cover application 
   Ely et al, U.S. Pat. No. 6,179,350, describes a draw latch and various means for providing resistance to keep the members of a latch assembly in a variety of given positions and addresses need for manually raising a catch in order to effect disengagement. 
   Gromotka, U.S. Pat. No. 5,478,125, describes a draw latch in which rotation of the lever initially disengages the catch and positive contact between the lever and latch arm at a distance from the latch pivot causes the hook arm to kick out. Objects include to provide these functions with parts which are few, durable and reliable in all functions. 
   P. R. Gley et al, U.S. Pat. No. 3,519,298, describes a positive lock for toggle catch, or draw latch, permitting concomitant release of the catch and movement of the handle to an open position. 
   The above draw latch patents address need for one-handed convenience in operation. Various methods are described as used in the prior art for positioning handles and latch arms to support convenient operation. Plastic inserts have been employed where corrosion from exposure to the elements could otherwise impair function. Metal-to-metal frictional methods are commonly employed in order to support low cost. However, it would appear that, in practice, most friction or interference methods tend to result in high efforts and/or variation in effort due to wear and/or manufacturing variability. Such methods may be adequate to temporarily retain latch handles to an open position, because full hand strength may be conveniently applied to effect release. However, the control effort with respect to a latch arm pivoting from a latch handle needs to be relatively low in order to support convenient operation, which requires moving the latch arm independently of the handle either immediately before moving the handle, or simultaneously with handle operation, but in any case as a fluid one-handed movement. Accordingly it is an object to provide a draw latch which supports convenient positioning of component parts in operation by applying reliable methods to draw latches having other characteristics suited to lift-roof cover application. This may be best achieved with concepts depending on zero resistance beyond that of a free pivot and force of gravity, or otherwise with a more reliable method of providing frictional resistance than generally employed in the prior art. 
   SUMMARY OF THE INVENTION 
   To meet expectations with respect to product attributes broadly demanded within the primary market containing the majority of potential lift-roof cover users, these attributes must not be significantly compromised. Of particular importance for meeting needs of customers through the total delivery chain are convenience in manufacturing, distribution and installation as well as in end use. Accordingly, objects include to provide a forward wall and attaching system which may be conveniently pre-assembled and stored ready for assembly with minimal rework to a molded reinforced plastic cover of the prior art (generally limited to removal of material as needed to attach added hardware), together with an attaching system simplifying the process of installation to a vehicle load bed while supporting shipping, handling, storage methods employed for conventional caps of the prior art. Subassemblies incorporating draw latches and lift assist struts (plus rigid support struts and rigid support strut engagement means) are also used supporting these objectives. Draw latches have been uniquely developed for lift-roof application to provide reliable operating convenience. 
   To satisfy users, opening and closing operations must be conveniently completed by one person. Available draw latches of the prior art have been found lacking in functions necessary for such convenience. Latches on each side of the cover need to be simultaneously operated with simple movement of one hand, both in closing/latching and releasing/raising the cover. This requires reliable friction means and operating geometry ensuring that, when the lift-roof cover has been lowered on the load bed and the latch handle is operated to effect engagement, the engaging latch arm can be conveniently positioned to complete engagement and, after operation to effect release, remain in a position allowing unimpeded lift-roof raising or lowering. 
   A preferred forward wall is adapted from technology applied to rear hatch doors for conventional fixed caps of the prior art, generally referred to as radius doors in the trade to which the invention pertains. Adaptation of extruded-frame-hinged-within-extruded-frame pivotal attachment allows the forward wall to lift-roof structure interface joint to be inboard of the lift-roof side walls and hidden as viewed from outside of the vehicle, a valuable aesthetic benefit. Related benefits of applying this proven technology to a new use include simplified systems for lift-roof to forward wall hinging/sealing and orientation/position adjustment of the forward wall relative to load bed. 
   A novel forward wall to load bed attaching system is in the form of a linkage which supports multiple functions, including providing (a) means for adjusting location of the forward wall on the load bed and orientation of the forward wall to achieve effective sealing in closed condition between forward wall, lift-roof and load bed; (b) means of conveniently completing installation or removal from the vehicle load bed without fully removing attaching fasteners (c) in conjunction with lift assist struts, means to hold the forward wall to a closed position relative to the lift-roof with all components secured above a plane across lower edges of the molded lift-roof, so that the complete lift-roof cover may be shipped, handled and stored prior to installation using the same methods employed for a conventional fixed mount cap of the prior art. 
   In use, the lift assist struts are mounted between the load bed and lift-roof structure in a manner (a) facilitating sealing at the forward wall to lift-roof interface by loading the lift-roof forward against the forward wall and (b) adding lateral constraint in location of the lift-roof relative to load bed, providing protection from damage which might otherwise result, for example, from severe wind gusting immediately on raising the lift-roof. 
   A durability concern for conventional caps of the prior art has related to effects of severe shake, as associated with some modes of heavy duty model pickup operation on rough road surfaces. Without countermeasures, lift-roof structure side wall forward lower edges have increased sensitivity to lateral vibration compared with a conventional cap, in which the side walls are integral with the forward wall. Such vibration is prevented by incorporation of side wall retainer means between the lift-roof structure and the forward wall structure. To accommodate dimensional variability, these units incorporate means for adjustment of relative lateral position. 
   The use of frame-hinged-within-frame radius door fabrication technology in a forward wall to lift-roof attachment system results in forward loads imposed by the lift assist struts being transferred to the forward wall by the hinge interface when the lift-roof is in a raised position. Rigidity of the hinge interface protects the seal from excessive compression in upper locations, so that with the lift-roof closed and without countermeasures, forward loading is transferred primarily to the lower edges of the inverted U shaped lift-roof side wall to forward wall interface. This results in the seal and inner and outer frames deforming toward the lower edges to a degree eventually impairing both sealing and positioning of the lift-roof on the load bed. To avoid these conditions and provide precise control of closed location of the lift-roof relative to the forward wall, means of adjustable forward wall closure stop are needed. This is achieved cost effectively by integrating such means of adjustable stop with the adjustable lift-roof side wall retainers at each side of the lift-roof cover. These integrated units allow closure position to be set simultaneously with side wall retainer engagement during assembly, protecting sealing function between the lift-roof and the forward wall and preventing vibration of lift-roof side walls relative to the forward wall, as well as increasing security from unauthorized forced entry. 
   Designing for flex under severe operating conditions has become broadly recognized as necessary for structures such as tall buildings and bridges in order to achieve reliability with acceptable cost. This concept may have been less broadly recognized in automotive accessory applications and, perhaps as a result, fracturing of early molded cap shells was not uncommon, particularly in cold climates. Therefore, manufacturers have developed caps which better absorb flex. Severe operation results in significant torsional flexing of most pickup truck frames, much of which is transmitted to the load bed. If ignored, the effects add cost in reliability and other functional respects. Flex may be less of a concern with low frequency twist, as induced by normal off-road operation. However, pickups, particularly heavy duty models, may induce severe lateral shake due to high rate suspension systems which, under some light load operating modes on rough road surfaces, instead of fully absorbing irregularities, cause high frequency shake to be transmitted to the load box. Accordingly, it is an object of the invention to address issues of structural flex under operating conditions in lift-roof cover application. 
   In summary, the object of my invention is to add novel improvements with respect to convenience, cost and reliability affecting assembly, distribution, installation and use while providing a combination of advantages relative to fixed mount covers of the prior art as described in the parent U.S. Pat. No. 5,102,185 and fully maintaining the benefits already provided by conventional bed covers of the prior art. Further objects and advantages will become readily apparent to those skilled in the art to which the invention pertain upon reference to the following detailed description of a preferred embodiment. 

   
     DESCRIPTION OF THE DRAWINGS 
     The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views. Much of what is described in the disclosure refers to one side of a lift-roof cover. The other side may be assumed to be of like or mirror image form. 
       FIG. 1  is a perspective view looking forward of an improved lift-roof cover installed on a light truck load bed with the lift-roof structure (cap shell) in a raised condition. 
       FIG. 2  is a fragmentary sectional view from inside an installed lift-roof cover, looking toward its right side, showing a preferred forward wall attaching and adjusting means in form of linkages for attaching a lift-roof cover to a light truck load bed. The position of components with the lift-roof cover installed for use is shown in solid line and other positions are shown in broken line. 
       FIG. 3  is a fragmentary perspective view of a latch and strut pivot mount assembly as installed to the right side rail of a lift-roof structure in closed condition. 
       FIG. 4  is a fragmentary sectional view looking forward along arrows  4 — 4  of  FIG. 5 , showing a lift-roof to forward wall adjustable side retention/stop means. 
       FIG. 5  is fragmentary sectional view downward along arrows  5 — 5  of  FIG. 4 , showing forward wall sealing means and also a lift-roof to forward wall adjustable side retention/stop means. 
       FIG. 6  is a fragmentary sectional view along arrows  6 — 6  of  FIG. 5 . 
       FIG. 7  is a fragmentary sectional view similar to  FIG. 5  of an alternate side retention/stop means. 
       FIG. 8  is a fragmentary side elevation of an alternate forward wall attaching linkage means. 
       FIG. 9  is a fragmentary sectional plan view along arrows  9 — 9  of  FIG. 8  of an alternate forward wall attaching linkage. 
       FIG. 10  is a fragmentary sectional view along arrows  10 — 10  of  FIG. 9 . 
       FIG. 11  is a sketch depicting the lift-roof cover as initially placed on a load bed with latches engaged to hold desired location. 
       FIG. 12  is a sketch depicting the forward attaching linkage engaged with the load bed. 
       FIG. 13  is a sketch depicting the lift-roof raised for attachment of lift assist strut lower pivots. 
       FIG. 14  is a sketch depicting the lift-roof lowered to levels at and near (broken line) full closure. 
       FIG. 15  is a fragmentary view looking forward of a first draw latch of the prior art mounted to the left side of a lift-roof structure. The fully latched condition is shown in broken line and an initial released condition is shown in solid line. 
       FIG. 16  is a view looking forward of a first draw latch of the prior art as in  FIG. 15 , showing a desired operating condition following release. 
       FIG. 17  is a fragmentary view looking forward of a first improved draw latch similar to the draw latch shown in  FIGS. 17 and 18  except as described for use in a lift-roof cover, mounted to the left side of a lift-roof structure. 
       FIG. 18  is a fragmentary view along arrows  18 — 18  of  FIG. 17 . 
       FIG. 19  is a fragmentary view looking forward of a second draw latch of the prior art mounted to the left side of a lift-roof structure, in a latched condition. 
       FIG. 20  is a fragmentary view looking forward of a second draw latch of the prior art mounted to the left side of a lift-roof structure, in a released condition. 
       FIG. 21  is a fragmentary view along arrows  21 — 21  of  FIG. 20  of a second draw latch of the prior art mounted to the left side of a lift-roof structure, in a released condition. 
       FIG. 22  is a fragmentary sectional view along arrows  22 — 22  of  FIG. 23  of a second improved draw latch similar to the draw latch shown in  FIGS. 19 ,  20  and  21  except as described, for use in a lift-roof cover, mounted to the left side of a lift-roof structure. 
       FIG. 23  is a fragmentary view along arrows  23 — 23  of  FIG. 22  of a second improved draw latch for use in a lift-roof cover, mounted to the left side of a lift-roof structure. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 : The lift-roof cover  10  is mounted on a load bed  11  including side walls  12  fabricated so that the outside vertical surface  13  of the load bed wall  12  is continuous with the upper, substantially horizontal surface  15  of the wall  12  and the surface  15  likewise is continuous with an inside vertical flange  16  formed approximately at 90 degrees where it joins the upper surface  15 , the flange  16  serving to add rigidity to the upper surface  15 , as needed under vertical loading, and extending downward typically one to two inches. The flange  16  is fully accessible along most of the length of the load bed  11  between the load bed forward wall  17  and rear end  18 . Side walls  19  at left and right sides  20 ,  21  respectively of a lift-roof structure  22  incorporate windows  14  and are joined at their lower edges  23  to substantially horizontal structural rails  24  which terminate along their length at an inner edge  25  almost directly above the load bed flanges  16 . The rails  24  and side wall lower edges  23  match contours of the upper surfaces  15  of the load bed side walls  12 . Sealing means  26  are mounted along the lower surface of the lift-roof cover rails  24  to provide weather sealing between the load bed upper surfaces  15  and lift-roof structure  22  when closed. 
   Referring to  FIGS. 1 ,  2  and  4 : In a preferred embodiment the lift-roof structure  22  is pivotally attached to a forward wall structure  28  extending upward from the load bed wall  17  behind the cab  30 , by means of an inverted U shape outer frame  31  hinged to an inner frame  32  of matching shape with sealing means  33  at side interfaces  34  between the outer and inner frames  31 ,  32 . The outer frame  31  is attached to a forward opening surround  36  in the lift-roof structure  22  and the inner frame  32  contains glass  38  retained by a horizontal closure member  40 . The outer and inner frames  31 ,  32  are attached to each other at an upper lateral hinge interface  41  by telescopically assembled interlocking extruded male and female hinge halves  42 ,  44 , respectively, of a sectional form similar to those illustrated by McGaughey et al, U.S. Pat. No. 4,496,185 ( FIG. 1   a ) and Grise, U.S. Pat. No. 4,452,482 ( FIG. 2 ). 
   Vertical adjustability of the forward wall  28  relative to lift-roof  22  is needed to ensure correct relationship of the forward wall lower edge  46  relative to side wall rails  24  and the interfacing load bed  11 , in closed condition. This adjustment may be made when the forward wall  28  is first installed to the lift roof structure  22  during the assembly process by control of a range of overlap  47  between the lift-roof  22  and the outer frame  31  to which the lift-roof  22  is attached. If adjustment is later needed relative to a load bed  11  with which the lift-roof cover  10  is to be used, increased convenience is desirable. Therefore, in a preferred embodiment, the forward wall  28  may include a lower member  48  adjustably attached via accessible attachment means  50 . Relative rigidity of the hinge interface  41  protects the upper seal interfaces from excessive compression. However, in a closed condition forward loading is transferred disproportionately toward the lower edge  52  of the seal interface  34  by the lift-roof side walls  19 . This results in a tendency for the sealing means  33  and interfacing radius door frames  31 ,  32  to be distorted toward the lower edge  52 , eventually impairing both sealing and positioning of the lift-roof  22  on the load bed  11 . To prevent these conditions and provide improved control of closed location of the lift-roof  22  on the load bed  11  and relative to the forward wall  28 , forward wall to lift-roof structure adjustable stop and side retainer means  54  are employed at each side. 
   Referring to  FIGS. 1 ,  2 ,  5  and  6 : Reliable weather sealing between the forward wall  28  and lift-roof structure  22  below the hinge interface  41  is achieved on each side of the forward wall  28  with auxiliary sealing means  60  mounted to the inner frame outer surface  62  and seating against the facing inner surface  64  of outer frame  31 . At lower levels substantially vertical surface continuation  66  below the inner frame outer surface  62  faces a matching surface continuation  68  below and preferably coplanar with the outer frame surface  64  and inside edge  25  of rail  24 , so that seal  70  mounted to said lower surface continuation  66  seats against the matching outer surface continuation  68  when the lift-roof  22  is closed. The lower seal  70  extends forward from below the auxiliary seal  60 , so that rain water running down the forward edge of seal  60  drops onto seal  70  and is carried over the load bed forward wall  17 . 
   Referring to  FIG. 1  and  FIG. 3 : Further improvement results from the use of draw latches  72  uniquely developed for convenience in operation of the lift-roof cover  20 . Improved draw latches  72  are mounted to latch and strut pivot mount brackets  73  attached to each lift-roof rail  24  to form a part of the lift-roof structure  22 . In the manufacturing process, the draw latches  72  and lift assist struts  74  together with rigid struts  75  are pre-assembled to the brackets  73  to form latch and strut pivot mount subassemblies  76 , which are then held for installation to the lift-roof structure  22 , thus simplifying the final assembly process. Lifting force exerted by the lift strut  74  tends to distort the lower edge  23  of the side wall  19 . Because such force is absent in a conventional fixed cover installation to a load bed, stiffness is typically insufficient to avoid visible distortion in a lift-roof adaptation, particularly under reflected light conditions. Visible distortion can be eliminated by increasing bending and torsional stiffness along the side wall structural rail  24 . However, a less costly method in adapting a cover of the prior art to lift-roof function without degrading appearance has been found to be by transferring strut lift force to an upper area of the side wall  19  as a side force. Accordingly, latch and strut pivot mount bracket  73  incorporates side wall structural reinforcing means  79  projecting upward from a level close to the lower edge  63  of the window  14  against the lift-roof side wall  19  and hidden from external view behind window frame structure  65  typically present in a conventional cab high cover of the prior art. 
   Some caps of the prior art are molded with an inside downward oriented lip  67 , so that the lip  67  overlaps the flange  16 , thereby providing control of lateral location when sitting on a load bed  11 . In a lift-cap application such a lip is removed in locations adjacent to components where interference may otherwise result, as at forward wall attaching linkages  80  and latches  72 . For lift-roof adaptation of molded caps not having such a lip, brackets  73  mounted to the rails  24 , each with an inboard surface  68  substantially coplanar with the load bed flange  16  provide a convenient option of adding a lateral locating means  69 , optionally attached by rigid strut attachment means  78 , the locating means  69  having a ramped leading edge  71  suitable for providing precise lateral location on the load bed  11  when the lift-roof  22  is closed. 
   Referring to  FIG. 1  and  FIG. 2 : A preferred forward wall to load bed attaching system is in the form of a linkage  80  at both sides  19  of the lift-roof cover  10 , incorporating pivot links  81 , attached via fastening means  82  to a lower part  83  attached to, or forming part of, the forward wall  28  at a pivot link upper slotted end  84 , and via fastening means  85  to a load bed inner flange forward attaching clamp means  86  at the pivot link lower end  87 . 
   In a preferred embodiment the load bed forward attaching clamp means  86  is rigidly attached to a rearward attaching clamp means  88  via a bar  89 , so forming a clamp link  90 . Said rearward clamp means  88  is attached via fastening means  91  to a lower end  92  of a forward wall orientation link  93 . An upper end  94  of the orientation link  93  is attached via fastening means  95  at an upper location  96  to each side of the forward wall structure  28 . In a preferred embodiment the upper location  96  is attached to, or forms a part of, inner frame  32 , thus facilitating pre-assembly. Thus, the forward wall structure  28 , together with four fastening means  82 ,  85 ,  91 ,  95 , pivot link  81 , clamp link  90  and orientation link  93  forms a linkage  80  at left and right sides of the forward wall  28 . When fastening means  82 ,  85 ,  91 ,  95  are loosened, linkage  80  provides freedom of movement of component links  81 ,  90 ,  93 , enabling adjustments in position of the links relative to forward wall structure  28  and the vehicle load bed  11 . 
   Multiple functions are accomplished with use of attaching linkage  80 : with fastening means  82 ,  85 ,  91 ,  95  tightened to provide rigid joints, support is provided to control orientation of the forward wall  28  relative to the load bed  11 , plus means are provided for adjusting longitudinal location of the lift-roof cover  10  on the load bed  11  and adjusting orientation of the forward wall  28  relative to load bed  11  to achieve effective sealing between the forward wall  28 , lift-roof  22  and load bed  11  in a closed condition; means are also provided to complete installation or removal from the vehicle load bed  11  without need to fully remove attaching fastening means  82 ,  85 ,  91 ,  95 ; in conjunction with other components, means are provided to hold the forward wall  28  to a closed position relative to the lift-roof  22  with all components secured above a plane across lower edges  23  of the molded lift-roof  22 , so that the lift-roof cover  10  may be shipped, handled and stored using the same methods employed for a conventional cap of the prior art. 
   Preferred fastening means  82 ,  85 ,  91 ,  95  for the attaching linkage  80  include friction lock-nuts  107 , so that fastening means  82 ,  85 ,  91 ,  95  may be set with zero clamp load and yet maintain reliable attachment (as needed to facilitate shipping). The friction lock-nuts  107  are used in combination with bolts  97  suitable for force-fitting to structural components so that tightening of fastening means  82 ,  85 ,  91 ,  95  is largely reduced to a one handed operation. Dimensions may be set so that, in event of looseness at one location, as due to error, linkage engagement is still retained with the load bed side wall flange  16 . The lift-roof cover  10  is prepared for shipping with the forward wall  28  held to a closed position as described above. This is accomplished by installing the latch and strut pivot mount bracket sub-assemblies  76  to the lift-roof structure  22  with lift-assist struts  74  and strut lower pivot brackets  98  positioned along the rail  24 , forward of the latch and strut pivot bracket  73  with the brackets  98  held in the linkage rear clamps  88 , and with clamp links  90  and pivot links  81  in an upper, approximately horizontal position shown by the upper broken outline in  FIG. 2 . 
   Referring to  FIGS. 8 ,  9 , and  10 : Where access between the load bed side wall inner flange  16  and outer surface  13  is blocked or limited, as by load bed wall structure  100 , toward the forward wall  17 , a modified form  101  of the preferred linkage  80  may be employed. An extension member  102  of relatively rigid form such as having an angle cross section and of high strength material, may be attached under clamp fasteners  103 ,  104  inboard of the flange  16 . The extension member  102  allows use of a forward clamp means  103  at a position where adequate access is available between the flange  16  and the side wall outer surface  13  rearward of attachment of the extension member  102  to pivot link  105 . The desired lateral, vertical and longitudinal control of forward wall positioning on the load bed  11  is thereby provided. A retaining angle bracket  106  with adjustable means of attachment  108  to a horizontal face  109  on the extension member  102  may be used to engage the side wall flange  16  where clearance between the flange  16  and blocking structure  100  is limited. Where no clearance is available, adjustments may be made to ensure linkage contact is maintained at the forward end  111  with the flanges  16  at both sides of the load bed  11 , so providing control of lateral positioning at the forward wall  28  relative to the load bed  11 . 
   Referring to  FIG. 1  and  FIG. 2 : Following installation of the latch and strut pivot bracket assemblies  76  to the rails  24  with the lift assist struts  74  lying forward along the rails  24 , the forward wall  28 , complete with attaching linkages  80  at each side, is installed and clamped into position in the same manner as for a conventional cap rear hatch  113  of similar construction. The forward wall  28  is then held to a closed orientation relative to the lift-roof structure  22  and the linkage rear clamp means  88  are clamped to the strut lower pivot brackets  98  to maintain the forward wall closed relationship to lift-roof  22 . The forward wall lower members  48  are then checked and, if necessary, adjusted for relationship to the lift roof lower edges  23 . Side retainer/forward stop means  54  are, at this stage, installed to the rails  24  at metal-to-metal interfacing component positions and should require no further adjustment when the lift-roof cover  10  is installed to a load bed  11 . 
   Referring to  FIGS. 1 ,  2 ,  13  and  14 : Functional improvements also include rearward mounting of lift assist struts  74  between the vehicle load bed  11  and the lift-roof rails  24  in a manner facilitating full closure at the forward wall to lift-roof seal interface  34  when the lift-roof  22  is lowered by forcing the lift-roof  22  forward against the forward wall  28 , and also adding lateral constraint in location of the lift-roof  22  relative to load bed  11 . Geometry of the lift assist strut action is such that, with the lift-roof  22  in a lower, closed position, vertical loading of the lift-roof  22  on the lift assist struts  74  exceeds vertical force provided by the lift assist struts  74 , so that the lift-roof  22  will remain in a lower, closed position unless manually raised. The lift assist struts  74  are located close to the rail inner edges  25  and the load bed flanges  16  so that, if the lift-roof structure  22  remained unlatched in error, the struts  74  constrain its lateral location. When the lift-roof structure  22  is raised above the fully lowered position, the forward force provided by the lift assist struts  74  pushes the lift-roof  22  against the forward wall structure  28  at the hinge interface  41 . As the lift-roof  22  is lowered toward closed, an increasing forward component of loading in the lift assist struts  74  causes an increase in forward deflection of the forward wall  28  at the hinge interface  41  relative to the forward wall lower edge  46  due to combined effect of flex in the forward wall structure  28  and flex in the load bed side walls  12  in the vicinity of the flanges  16  under tensile force transferred through orientation links  93 , until a lift-roof position  114  (shown in broken line in  FIG. 14 ) is reached where full closure has occurred at the forward wall to lift-roof seal interface  34 . Due to the forward deflection of the forward wall  28  at the hinge interface  41 , relative to the forward wall lower edge  46 , position  114  occurs prior to full closure with the load bed  11 , generally when the lift-roof  22  is at least a half inch clear of the load bed rear end  18 . 
   Referring to  FIG. 11 : Installation is first a process of installing low friction/low stiction load bed interfacing seals  26  and positioning the lift-roof cover  10  on the load bed  11 , in the same way as for conventional caps. After checking and, if necessary, adjusting function, the draw latches  72  are engaged with the flanges  16  to hold the lift-roof cover firmly in position. 
   Referring to  FIG. 12  and  FIG. 2 : The forward wall adjusting linkage rear clamp fasteners  91  are then loosened to release the strut lower pivot brackets  98 , and the linkage  80  is rotated downward in direction of arrow B so that clamp means  86 ,  88  may be swung down clear of the load bed flange  16 , then moved laterally inboard under the flange  16 . The clamp link  89  is then swung upward in direction of arrow C to engage the flange  16 . If necessary, orientation link lower end  92  is at this time adjusted to a position where the forward wall  28  is oriented with a closed relation to the lift-roof  22 . Forward clamp means  86  is moved upward, as accommodated by slot adjusting means  84  of pivot link  81 , so that flange  16  is engaged by forward clamp means  86 . Clamp fasteners  85 ,  91  are then tightened to appropriate torque levels, followed by tightening of fasteners  82  and  95 . 
   Referring to  FIGS. 2 ,  13  and  14 : The latches  72  are next released and a set height installation strut  120  is attached by temporary attachment means, (such as adhesive backed Velcro),  122  at one end to the lift roof structure ceiling  123  adjacent to the lift-roof rear hatch  113 . The lift-roof structure  22  is then carefully raised until the installation strut lower end  125  falls forward to the rear edge  126  of the load bed  11  and is allowed to sit on the tailgate  128 . Lift assist strut lower pivot bracket  98 , having been released when forward adjusting linkage fasteners  91  were first loosened, may now be rotated in direction of arrow D to a location such as rear tie-down mountings where the lower pivot bracket  98  can be bolted to the load bed  11 . (Referring now to  FIG. 2  and  FIG. 14 ): After removing the set height installation strut  120  and lowering the lift-roof  22 , operating relationships for lift-roof side retainer/stop units  54  are checked and latches  72  again engaged for closed mode operation. 
   Referring to  FIGS. 1 ,  4 ,  5  and  6 : Without countermeasures the lift-roof side wall forward lower edges  132  have increased potential for lateral vibration as compared with a conventional load bed cover, in which the side walls are integral to the forward wall. Such vibration is prevented cost effectively with stop and side wall retainer means  54  attached to the lift-roof  22  at left and right sides  20 ,  21 . To accommodate variability in manufacture, stop and side wall retainer means  54  incorporate means for adjustment of lateral relative position  134 . 
   A preferred lift-roof adjustable side wall retainer and forward stop means  54  includes a first part or bracket  135  attached to a mount  136  attached to and/or forming a part of the lift-roof structure  22 , the bracket  135  having a face  137  on a substantially vertical and longitudinal plane with a ramped leading edge  138  to guide engagement and prevent blocking due to minor misalignment of interfacing parts  135 ,  83 , the face  137  being substantially coplanar with a mating face  139  on flange  83 , attached to or forming a part of the forward wall  28 . The bracket  135  and flange  83  each also have interfacing stop surfaces  140 ,  141  so that, as the lift-roof  22  is lowered to a closed condition, the stop surfaces  140 ,  141  make positive contact. The bracket  135  is attached to the mount  136  via fastening means  142 , comprising a bolt  143  passing through slotted and/or oversize holes  134  in the mount  136  or bracket  135 , the bolt  143  being retained by a friction lock-nut  145 . The bolt is constrained from rotation by interference or force fitting to one part, while an adjustment slot is provided in the other, thus allowing the friction lock-nut  145  to be torqued to provide clamping, or loosening of the bracket  135  relative to the mount  136  using one hand and one tool. The use of slotted and/or oversize holes  134  accommodates relative lateral position adjustment between the first part  135  and the mount  136 . By varying the thickness of spacing means  146  between the mount  136  and part  135 , longitudinal position adjustment of the part  135  relative to the mount  136  may also be provided. With the lift-roof  22  in a closed, lower position, the bracket  135  is set to bear forward against flange  83  attached to or forming a part of forward wall structure  28 . With the side retainer and closure stop adjustment means  54 , closure of the lift-roof structure  22  relative to the forward wall  28  may be set during the manufacturing assembly process as needed to ensure satisfactory sealing between the lift-roof structure  22  and the forward wall  28  and also to ensure that the possibilities of vibration of lift-roof structure side walls  19  relative to the forward wall  28  or of unauthorized forced entry are eliminated. It will be recognized by one skilled in the art to which the invention pertains that with simple rearrangement of components, the various described functions may be reversed between components attached to the forward wall  28  and those attached to the lift-roof  22  without departing from the scope of the invention. (Referring to  FIG. 7 ): It will be also be recognized that an alternate bracket  147  may be easily fabricated to capture flange  83  on both sides and by similar means vertical capture may also be achieved. 
   Referring to  FIG. 15  and  FIG. 16 : Draw latches are used to draw and hold two structures together. The following describes limitations of two draw latches of the prior art and how they are improved to meet functional needs for lift-roof operation. A first over-center draw latch of the prior art  150  comprises a latch hook  152 , a latch handle  154  and a latch base  156 ; the latch hook  152  being pivotally attached to the latch handle  154  at pivot means  155 , the latch handle  154  being pivotally attached to the latch base  156  at pivot means  157 . The latch base  156  is attached to a vertical surface  158  fixedly attached to, or forming part of, a first structure  22  and the latch hook  152  is used to engage a suitable engagement means  16  on the second structure  11 . In latched condition (shown in broken outline in  FIG. 15 ), tension force passing through the latch hook engagement point  159  with the second structure  11  and through the latch hook pivot  155 , holds the latch hook  152  to the latched position until latch handle  154  is manually rotated away from the latch base  156  in direction of arrow L. Rotation of the handle  154  per arrow L away and down from the latch base  156  brings the tension force line “over center” across the latch handle pivot  157  toward a released condition (shown in solid line in  FIG. 15 ), first lowering the latch hook  152  from engagement with the load bed flange  16 . To complete full release (referring now to  FIG. 16 ), with upward rotation of the latch handle  154  in direction of arrow M, the latch hook  152  should be moved clear of the load bed flange  16  per arrow N. In reverse, with the cap shell  22  in the lowered position, downward rotation of the latch handle  154  per arrow  0  first moves the latch hook  152  per arrow P against the flange  16 . With relatively low rotational friction levels, the latch hook  152  can be conveniently held in the position shown in solid line in  FIG. 15 . using a thumb while, with the same hand, the handle  154  is rotated upward in direction of arrow Q, pulling the latch hook  152  into engagement with the load bed flange  16 . As the handle  154  is rotated further upward, the structures  11 ,  22  are drawn and held to a latched condition. 
   The first draw latch of the prior art  150 , as available, is built with axial clamp friction between components  152 ,  154 ,  156  at pivot interfaces  155 ,  157  so that, without force beyond gravity, components  152 ,  154  tend to remain in whatever relative position they are placed. However it has been found that initial operating efforts are too high for convenience and the friction declines with use to levels where, with weight of the latch handle  154  bearing against the latch hook  152 , the latch hook  152  tends to fall under the flange  16  following initial disengagement, resulting in interference with the side walls  15  when lowering the lift-roof  22  from open, and/or re-engagement with the inner flange  16  when the lift-roof  22  is raised from closed. 
   Referring to  FIGS. 1 ,  17  and  18 : In a preferred embodiment, first alternate improved draw latches  72  are mounted to the rails  24  and have latch handles  164  which, when rotated to a fully latched/closed position, pull latch hooks  166  into engagement with the load bed inner flanges  16 , thereby drawing the lift-roof  22  down to the load bed  11 . With appropriate vertical adjustment, this causes compression of sealing means  26  between the rails  24  and load bed side wall upper surfaces  15  and prevents significant movement relative to the load bed  11 . In the first improved draw latch  72  for use with a lift-roof cover, the latch handle  164 , in rotating downward, is positively limited at a lower position where the latch hook  166  hangs clear of engagement or interference with the flange  16  when the lift-roof  22  is raised or lowered. The latch base  167  is mounted against a vertical surface  158  forming a part of, or attached to, lift-roof side wall rail  24 , with the latch handle  164  pivoting from the latch base  167  and in a vertically upward orientation when in fully latched mode. As modified for the lift-cap application, the latch base  167  is formed at a lower end  168  to create a positive stop  170  for the latch handle  164  at a position where said latch handle is oriented down from its near vertical latched position and the latch hook pivot  172  is substantially inboard of the latch handle pivot  174 , following release of the latch hook  166  from the load bed flange  16 . The first improved draw latch  72  is substantially free of rotational friction drag at the latch hook pivot attachment  172  and the latch hook  166  is modified from the first draw latch of the prior art  150  as by removal of material  176  so that, when the handle  164  is rotated downward against the stop  170 , the latch hook  166  can hang freely and remain clear of the load bed wall upper surface  15 . This allows the lift-roof structure  22  to be freely lowered toward a closed position before, with easy one-handed operation, moving and holding the latch hook  166  under the flange  16 , while rotating the handle  164  toward vertical to engage the latch hook  166  with the flange  16  and pull the lift-roof structure  22  to a fully latched position. 
   Referring to  FIGS. 19 ,  20  and  21 : A second over-center draw latch of the prior art  178  includes a base  179 , a latch handle  184  pivotally attached to the base  179  at a pivot  185 , and a latch hook  180  pivotally attached to the handle  184  at a hook pivot  183 . Retention means  181  temporarily retain the latch handle  184  in an upward vertical orientation with the hook pivot  183  in a lower released position (shown in  FIG. 20 ). However, the latch hook  180 , following disengagement, remains in a position determined by relation of its center of gravity  182  to its pivot  183 , about which it freely rotates. This position may be such as either to interfere with the load bed wall upper surface  15  when the lift roof  22  is lowered and re-engage the load box inside flange  16  when it is raised, or otherwise to fall clear and remain clear of the flange  16  when engagement is desired. The relation of the latch hook  180  to the latch handle  184  is such that its position cannot easily be controlled while also operating the handle  184  with the same hand. 
   Referring to  FIG. 22  and  FIG. 23 : In a second alternate improved latching means  186  suitable for lift-roof cover application, the addition of reliable friction means  188  acting relative to rotation of the latch hook  190  about its pivot  192  facilitates operation of the latching function as a one-handed operation, allowing simultaneous latching at left and right sides  20 ,  21  when the lift roof cover  10  is closed. Reliable rotational friction drag is provided by use of leaf spring  194  bearing against a circumferential surface  196  of the latch hook  190  where the circumferential surface  196  wraps around the pivot pin  192 . It will be recognized by one skilled in the art to which the invention pertains that wear in the friction interface  188  between the leaf spring means  194  and the latch hook circumferential surface  196  will not quickly change normal force at the friction interface  188 . This is because, unlike friction methods commonly employed in over-center draw latches of the prior art, friction drag is controlled by spring deflection, which will be large relative to any change in deflection resulting from wear. Therefore, friction drag can be expected to be adequately maintained over a lift-roof cover functional lifetime. When the latch handle  200  is raised, the latch hook  190  is first lowered and, as the hook  190  clears the flange  16 , added friction drag exceeding the effect of gravitational force, which gravitational force otherwise causes the latch hook  190  to hang substantially vertically below hook pivot  192 , causes the latch hook  190  to be rotated inboard and upward with latch handle  200  in direction of arrow R. This ensures that, with the latch handle  200  retained to an upward vertical orientation, the latch hook  190  will not re-engage the flange  16  when the lift-roof  22  is raised to an open position, nor interfere with the load bed side wall upper surface  15  when the lift-roof  22  is lowered. Also, from this position, with the lift-roof  22  in a lowered position, if the latch hook  190  is first independently manually rotated substantially downward from its resulting position relative to the handle  200  following release, the added friction ensures that the latch hook  190  will move against, and be held against, the load bed inside flange  16  until the latch hook  190  has fully engaged, when the latch handle  200  is then fully rotated downward to draw the latch hook  190  upward. 
   The improvements of the present invention relating to a load bed lift-roof cover are defined by the following claims: