Abstract:
A lock for a retractable cover which overlies a bed of a pickup truck has a cover-connectable housing and a handle that pivots relative to the housing for clamping a pointed tip of a flexibly mounted fastener into engagement with a nearby member such as a guide rail extending along one side of the bed of a pickup truck to retain a housing-connected retractable cover in a chosen position. A push button trigger pivoted on the handle is depressable to unlatch the handle and thereby release the clamping action of the handle. A torsion spring biases the trigger relative to the handle. A compression spring biases the handle relative to the housing. A leaf spring flexibly mounts the fastener on the handle. A key-operated plug assembly may retain the trigger in a latched position.

Description:
BACKGROUND 
     Retractable covers for overlying rear load carrying compartments or “beds” of pickup trucks are disclosed in a number of patents, and example being U.S. Pat. No. 6,276,735. One form taken by such covers utilizes a plurality of substantially identical, elongate, slat-like members or the equivalent which extend laterally between extruded guide rails of substantially identical and uniform cross-section that extend along upper regions of opposite sides of the bed of a pickup truck. The laterally extending slat-like members are flexibly joined to provide a lengthy cover that can be compactly retracted into a coil in much the same manner as the cover of a rolltop desk. A retractable cover which has gained wide acceptance is sold by Applied Products, Inc. of Grand Forks, N. Dak. 58201 under the trademark RETRAX. RETRAX brand retractable covers may be viewed at www.retrax.com. 
     To retain a RETRAX cover closed or in selected open positions, a lever latch has been used, such as is disclosed in U.S. Pat. No. 5,609,373. The lever latch provides a cover-connectable housing on which a handle pivots toward and away from a closed position where the handle causes a flat head of a cap screw carried by the handle to be clamped against one of the two guide rails that extend along upper regions of opposite sides of the bed of a pickup truck. The lever latch has a depressable push button trigger for releasing the clamping action of the closed and latched handle, and makes double-duty use of a single torsion spring not only to bias the handle toward an open and unlatched position relative to the housing, but also to bias the push button trigger toward a normal and non-depressed position relative to the handle. 
     The cap screw of the lever latch that has its flat head clamped into engagement with a guide rail is threaded through a portion of the handle of the lever latch, and is securely held in place by a lock nut. To maintain proper operation of the lever latch assembly, frequent adjustment of the cap screw often is needed to correct for wear and to accommodate such variations as are encountered along the length of the extruded guide rail as it is jostled and bumped about during the wear and tear of a lengthy service life of the retractable cover. A two-handed, two-tool effort is required to adjust the combination of the cap screw and the locknut. As such, the process of frequently adjusting the cap screw of the lever latch is both tedious and time consuming. 
     Problems of a more serious character may arise when the variations encountered along the length of the guide rail require an adjustment of the cap screw which enables the lever latch assembly to properly grip the guide rail while positioned at one location therealong, but which renders the lever latch assembly incapable of properly gripping the guide rail when the lever latch is at other locations along the length of the guide rail. When this situation is encountered, the retractable cover is only capable of being held securely in some partially open or closed locations, but not when the retractable cover is moved to other partially open or closed locations—which is quite unacceptable. Customers expect the costly retractable covers they have purchased to be capable of being retained and locked anywhere that the customers have chosen to position their covers along the lengths of the guide rails that support opposite sides of the covers. 
     The disclosures of the patents identified above are incorporated herein by reference. 
     SUMMARY 
     The present invention addresses the foregoing and other drawbacks of the prior art by providing improved lockable latch assemblies, or locks, for securely, reliably and releasably retaining retractable covers in closed and in various open positions overlying the load carrying compartments or “beds” of pickup trucks and the like. Although locks embodying features of the present invention are suitable for use in a wide variety of industrial and commercial applications, they are particularly well suited to upgrade and replace the lever latches of U.S. Pat. No. 5,609,373 that have been used on retractable covers for overlying the rear load carrying compartments or beds of pickup trucks. 
     A lockable latch assembly, or lock, that embodies features of the present invention ordinarily can perform quite nicely for extended periods of time without requiring any adjustment at all to perform properly in securely releasably gripping a guide rail along which a retractable cover of the RETRAX type moves to close or partially close the load carrying compartment of a pickup truck or the like. If adjustment of the lockable latch assembly, or lock, is eventually needed, such adjustment is much easier to effect than was the case with lever latches of the type disclosed in U.S. Pat. No. 5,609,373. 
     Some embodiments of the present invention provide a lockable latch assembly, or lock, that clamps a pointed tip of a flexibly supported fastener firmly into engagement with a nearby member such as a guide rail to ensure that the lock (and whatever the lock is connected to, typically a retractable cover) does not move along or relative to the guide rail. Such an arrangement provides a significant improvement when compared to the rigidly supported, flat cap screw head that is clamped against a significant guide rail surface area in accordance with the lever latch that is disclosed in U.S. Pat. No. 5,609,373. 
     Some embodiments of the present invention employ springs of widely differing character that are selected to make best use of their performance characteristics 1) to bias a pivotal handle of the lock toward a closed position where the handle firmly clamps the pointed tip of a set screw fastener against a elongate guide rail, 2) to bias a push button trigger of the lock toward a latched position where the trigger retains the handle in the closed position, and 3) to flexibly mount on the handle the set screw fastener which has the pointed tip that is clamped by the handle into secure engagement with the guide rail. Such an arrangement represents a significant improvement over the single-spring lever-latch of U.S. Pat. No. 5,609,373. 
     In some embodiments, a relatively strong torsion spring is selected for use, but only to bias the handle of the lock toward a closed, latched position relative to the housing of the lock—a position where the handle clamps the hardened, pointed tip of a set screw type fastener securely into engagement with a surface of an elongate guide rail, thereby making optimum use of a strong torsion spring precisely as is needed to perform its one function well during a lengthy service life of the lock. 
     In some embodiments, a relatively gentle compression coil spring is selected for use, but only to bias the push button trigger of the lock toward a normally latched position relative to the handle of the lock—a position where the trigger latches the handle in a closed, non-operated position, thereby making optimum use of a relatively lightweight and gentle-acting compression coil spring precisely as is needed to perform its one function well during a lengthy service life of the lock. 
     In some embodiments, a relatively stiff yet bendable leaf spring is used to flexibly mount a pointed-tip-type fastener on the handle in a way that will cause the pointed tip of the fastener to forcefully engage a surface of a guide rail to retain the lock and a retractable cover on which it is mounted in a customer-selected position. Such an arrangement permits the fastener to move automatically toward and away from the guide rail as may be needed to accommodate variations in the guide rail without any need for physical adjustment of the fastener. However, should any adjustment of the fastener eventually be needed, the set screw that preferably comprises the fastener can be turned by the single-handed use of a simple conventional Allen wrench—which is neither tedious nor time consuming. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       A fuller understanding of the present invention may be had by referring to the description and claims that follow, taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a top plan view of a lock that embodies features of the present invention, with a handle of the lock shown latched in a closed position; 
         FIG. 2  is a sectional view as seen from a plane indicated by a line  2 - 2  in  FIG. 1 , with the view showing a pointed-tip-type set screw fastener that is flexibly supported by a leaf-spring of the lock; 
         FIG. 3  is a rear side elevational view thereof; 
         FIG. 4  is a sectional view as seen from a plane indicated by a line  4 - 4  in  FIG. 3 ; 
         FIG. 5  is a sectional view as seen from the same plane as  FIG. 2 , but with the handle of the lock unlatched and pivoted to an open position; 
         FIG. 6  is a front side elevational view on a reduced scale, with the handle of the lock pivoted to the open position; 
         FIG. 7  is a rear side elevational view thereof; 
         FIG. 8  is a right end elevational view thereof; 
         FIG. 9  is an exploded view showing selected components of the lock in disassembly; 
         FIG. 10  is a sectional view similar to  FIG. 2  showing a push button trigger of the lock in a latched and locked attitude; 
         FIG. 11  is a bottom view of selected components of  FIG. 10 ; 
         FIG. 12  is a sectional view similar to  FIG. 10 , but showing the push button trigger unlocked and depressed; 
         FIG. 13  is a bottom view of selected components of  FIG. 12 ; 
         FIG. 14  is a sectional view which reproduces a selected portion of  FIG. 2 , with the view also showing, in cross-section, an extruded guide rail having a surface that is firmly engaged by the pointed-tip-type fastener of the lock when the handle of the lock is in the closed and latched position shown in  FIGS. 1-4 ; and, 
         FIG. 15  is a sectional view that repeats a selected portion of the sectional view of  FIG. 14 , with the view also showing in a much exaggerated depiction, how a leaf spring that flexibly supports the pointed-tip-type fastener may bend or deflect to move the pointed-tip-type fastener toward and away from the rail to automatically compensate for such minor variations as may be encountered along a length of the guide rail. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a lockable latch assembly or lock  100  embodying features of the present invention is indicated generally by the numeral  100 . Referring to the exploded view of  FIG. 9 , the lock  100  includes a generally rectangular base or housing  110 , a complexly configured handle  150  that is pivotally connected to the base or housing  110  by a pivot pin  140 , and a push button trigger  200  that is pivotally connected to the handle  150  by a roll pin  210 . 
     As will be explained, a feature of the lock  100  resides in the use made by the lock  100  of a pointed-tip-type threaded fastener  250  carried by a leaf spring  275  that is connected to the handle  150 —an arrangement that flexibly mounts the fastener  250  on the handle  150 . As will be explained, the flexible mounting of the fastener  250  enables a pointed tip  255  of the fastener  250  to be securely but resiliently clamped against an elongate guide rail  300  (such as is shown in cross-section in  FIG. 14 ) when the handle  150  of the lock  100  is latched in the closed position that is shown in  FIGS. 1-4  and  14 . 
     The elongate guide rail  300  may assume a wide variety of cross-sectional configurations, one example being shown in  FIG. 14 , and another being indicated by the numerals  16   a  and  16   b  in the aforementioned U.S. Pat. No. 6,276,735, the disclosure of which is incorporated herein by reference. A retractable cover (such as is shown in U.S. Pat. No. 6,276,735, or as is shown at www.retrax.com) that extends between two guide rails (having identical cross sections, for instance of the character shown in  FIG. 14 ) can be opened and closed to provide or restrict access to the rear load carrying compartment or bed of a conventional pickup truck, such as is shown in U.S. Pat. No. 6,276,735. 
     The lock  100  is typically mounted on a retractable cover (portions of which are indicated by the numeral  50  in  FIGS. 5 and 14 ) that is movable along guide rails (such as the guide rail  300  shown in  FIG. 14 ) between a cover-closed position and various cover-open positions. The ability of the leaf spring  275  to deflect or to bend slightly as by flexing away from a lower portion  154  of the handle  150  (in a manner shown with some exaggeration in  FIG. 15 ) provides a flexible mount for the fastener  250 —a flexible mount which ensures that the pointed tip  255  of the fastener  250  will be clamped firmly against a surface  302  of the rail  300  (as is depicted in  FIG. 14 ) even when the surface  302  of the rail  300  varies slightly in position along the length of the elongate guide rail  300  which typically extends for the full length of the load-carrying compartment or bed of a pickup truck or the like. 
     Referring principally to the exploded view of  FIG. 9 , the base or housing  110  of the lock  100  is a generally rectangular, upwardly opening structure that has two spaced, parallel extending, relatively lengthy upstanding side walls  112 ,  114 , and two spaced, parallel extending, relatively short, upstanding end walls  116 ,  118 . A complexly configured bottom wall  120  closes a majority of the bottom of the base or housing  110 . Upper portions of the side walls  112 ,  114  and the end walls  116 ,  118  join with a horizontally projecting flange  122  which extends around the perimeter of an upwardly-opening region  125  located interiorly with respect to the base or housing  110 . 
     The perimetrically extending flange  122  has a continuous, downwardly-facing bottom surface  124  that resides in a single, substantially horizontally extending plane. The bottom surface  124  can rest atop portions  50  ( FIGS. 5 and 14 ) of a structure such as a retractable cover to which the base or housing  110  is connected. The retractable cover (portions of which are indicated by the numeral  50  in  FIGS. 5 and 14 ) typically has a generally rectangular opening  55  ( FIG. 5 ) through which the side walls  112 ,  114  and the end walls  116 ,  118  of the base or housing  110  extend. If desired, a conventional thin and flat, weather resistant gasket (not shown) having the generally rectangular configuration of the bottom surface  124  of the flange  122  may be interposed between the bottom surface  124  and the upwardly-facing surface that extends about the opening  55 . 
     Referring to  FIG. 9 , the perimetrically extending flange  122  of the base or housing  110  has an upwardly facing surface that includes a C-shaped upper surface  126  that extends in an imaginary upper plane  127  (see  FIG. 5 ), and a U-shaped upper surface  128  that extends in an imaginary lower plane  129  (see  FIG. 5 ) that parallels the upper plane  127  at a short distance therefrom. The upper and lower surfaces  126 ,  128  are connected by a shoulder  130  ( FIGS. 5-9 ). As can best be seen in  FIGS. 5 and 9 , the shoulder  130  is located near where a relatively wide and lengthy part  121  of the interior region  125  of the base or housing  110  joins with a relatively narrower and shorter part  123  of the interior region  125  of the base or housing  110 . 
     Referring to  FIG. 9 , aligned holes  132 ,  134  are formed through the upstanding side walls  112 ,  114  to permit the cylindrical body  142  of the pivot pin  140  to extend therethrough. The pivot pin  140  has an enlarged head  144  at one end of the body  142 , and a perimetrically extending groove  146  located near the opposite end thereof. A retaining ring  148  is provided that is configured to engage the groove  146 . Nylon washers  149  are provided for positioning on the cylindrical body  142  of the pivot pin  140 , with one of the washers  149  situated adjacent the head  144 , and the other situated adjacent the retaining ring  148 . 
     The complexly configured handle  150  which is pivotally connected to the base or housing  110  by the pivot pin  140  can pivot between a closed position shown in  FIGS. 1-4  and  14 , and an open position shown in  FIGS. 5-8 . A torsion spring  160  (best shown in the exploded view of  FIG. 9 ) has coils  162  that encircle part of the body  142  of the pivot pin  140 . The torsion spring  160  has one leg  164  that presses against a portion of the handle  150 , and another leg  166  that presses against a portion of the base or housing  110  to bias the handle toward the open position shown in  FIGS. 5-8 . 
     Referring to  FIG. 9 , the handle  150  has an upper portion  152  and a lower portion  154  that are coupled by an intermediate portion  156 . The intermediate portion  156  has two spaced, parallel-extending arms  158  (best illustrated in the sectional view of  FIG. 4 ) through which identical, aligned holes  159  (one of which is shown in  FIG. 9 ) are formed. The body  142  of the pivot pin  140  extends through the holes  159  to mount the handle  150  for pivotal movement on the housing or base  110 . 
     Referring initially to  FIGS. 1 ,  9  and  10 , the upper portion  152  of the handle  150  has a top surface  151  with a raised annular area  153  that surrounds an opening  155  through which a round button  205  of the trigger member  200  normally extends. However, as is shown in  FIG. 12 , the button  205  is depressable to pivot the trigger  200  to an operated position that releases the handle  150  to move from the closed position shown in  FIGS. 1-4  and  14  to an open position such as is shown in  FIGS. 5-8 . 
     Referring to  FIGS. 1 ,  3  and  9 , the top surface  151  is defined by a relatively thin, perimetrically extending region  199  of the upper portion  152 , and by a much thicker region  161  of the upper portion  152 . A major part of the relatively thin region  199  has a thickness that is approximately equal to the short distance that separates the two parallel-extending planes  127 ,  129  that are shown in  FIG. 5 . The thicker region  161  surrounds and defines a generally cylindrical plug-receiving passage  157  that opens through the top surface  151  at location spaced from the trigger button opening  155 . The plug-receiving passage  157  is also open at its lower end (as can be seen in  FIGS. 10-13 ). 
     The plug-receiving passage  157  has an interior configuration (not shown) that is well known to those who are skilled in the art—a configuration that is designed to receive and cooperate with a conventional key-operated plug assembly  170  ( FIGS. 9 ,  10  and  12 ) which has an exterior configuration that also is well known to those who are skilled in the art. The plug assembly  170  includes a plurality of tumblers  173  ( FIG. 2 ) that cooperate in a conventional way with interior formations of the passage  157  to permit the plug  170  to turn only a quarter rotation when a suitably configured key (not shown) is inserted into a keyhole  171  of the plug  170 , and that permit the key to be removed only when the plug  170  is turned to either of the ends of its permitted quarter turn of rotation. 
     Referring to  FIGS. 11 and 13 , a bottom end region of the plug assembly  170  includes a pair of depending abutments  174 ,  175  that are separated by a space  176 . If the plug assembly  170  is turned to a locked position such as is shown in  FIGS. 10 and 11 , the abutment  174  is then positioned so that, if the trigger  200  is depressed, a projection  203  of the trigger will be engaged and blocked by the abutment  174 , thereby preventing depression of the trigger  200 . However, if the plug  170  is turned a quarter turn to an unlocked position such as is shown in  FIGS. 12 and 13 , neither of the depending abutments  174 ,  175  obstructs depression of the trigger  200 , hence the projection  203  moves into the space  176  located between the two depending abutments  174 ,  175 . 
     Referring to  FIGS. 1 ,  2 ,  9  and  10 , the lower portion  154  of the handle  150  defines a generally rectangular projecting part  185  which has two spaced holes  180 ,  181  formed therethrough. The hole  180  has a tapered, countersunk formation at its upper end which receives the tapered head of a conventional Phillips head screw  182  when the screw  182  is inserted to extend through the hole  180 . A nut  183  is provided for being tightened onto a threaded, lower end region of the screw  182 . 
     One purpose for providing the screw  182  and the nut  183  is to securely attach the leaf spring assembly  190  (components of which are shown in the exploded view of  FIG. 9 ) to the underside of the projecting part  185  of the lower portion  154  of the handle  150 . Another purpose, although infrequently utilized, is to provide an easy-torelease-and-reinstall attachment that can be utilized if a leaf spring  275  (or leaf spring assembly  190 ) having a different degree of “bendability” or “flexibility” needs to be installed on the handle  150 . 
     Referring to  FIG. 9  (which shows the three elements of the leaf spring assembly  190  disassembled), the leaf spring assembly  190  includes a generally rectangular leaf spring  275 , an internally threaded stainless steel bushing  192 , and the previously mentioned threaded fastener  250  which has the pointed tip  255 . In preferred practice, the fastener  250  is pointed-tip-type stainless steel set screw. 
     Holes  193 ,  194  are formed through opposite end regions of the rectangular leaf spring  275 . The hole  193  is sized to permit the threaded lower end region of the screw  182  to extend therethrough. The nut  183  may be tightened in place on the screw  182  to securely attach the leaf spring assembly  190  ( FIG. 9 ) in place on the projecting part  185  of the lower portion  154  of the handle  150 . 
     The hole  194  is sized to permit the set screw fastener  250  to extend loosely therethrough. The internally threaded steel bushing  192  is welded to the leaf spring  275  in alignment with the hole  194  so the set screw fastener  250  can extend through the hole  194  and can be threaded into the bushing  192 . The threads on the interior of the bushing  192  are sized to provide a snug or tight fit when the set screw fastener  250  is threaded into the bushing  192 —which permits the set screw fastener  250  to be adjusted, but ordinarily securely retains the set screw fastener  250  in a position to which the set screw fastener  250  has been installed. 
     The hole  181  that is formed through the rectangular projecting part  185  of the lower portion  154  of the handle  150  is of a size that quite loosely receives the bushing  192  that is welded to the rectangular leaf spring  275 . The pointed tip  255  of the set screw fastener  250  extends upwardly a significant distance out of the threaded bushing  192 , and extends upwardly a significant distance out of the hole  181  that is formed through the lower portion  154  of the handle  150 . 
     The stiff but slightly bendable nature of the leaf spring  275  taken together with the relatively large size of the hole  181  and the significant distance that the pointed tip  255  of the fastener extends upwardly out of the bushing  192  and the hole  181  ensure that, even when the leaf spring  275  bends or deforms in the much exaggerated manner shown in  FIG. 15 , the pointed tip  255  will still be pressed by the leaf spring  275  into firm and secure engagement with the guide rail surface  302 . The relatively large size of the hole  181  permits the bushing  192  and the set screw fastener  250  to move freely within the hole  181 , and permits the leaf spring  275  to bend or deflect as is shown in an enormously exaggerated manner in FIG.  15 —so the pointed tip  255  of the set screw fastener  250  can move without obstruction toward and away from the surface  302  of the guide rail  300  shown in  FIG. 14 . 
     By this arrangement, if the downwardly facing surface  302  of the rail  300  should vary slightly in position along the length of the elongate rail  300 , the flexible mounting of the set screw fastener  250  by the leaf spring  275  will automatically accommodate such variation without requiring any adjustment of the set screw fastener  250 . If, however, wear of, or damage to, the guide rail  300  or components of the lock  100  should necessitate some minor adjustment of the set screw fastener  250 , no lock nut needs to be loosened and then retightened to permit adjustment of the set screw fastener  250 . Adjustment of the set screw fastener  250  simply requires the one-handed use of a conventional Allen wrench (not shown) inserted into a hex opening  259  ( FIG. 8 ) at the lower end of the set screw fastener  250 . 
     As will be apparent from the foregoing description, the push button trigger  200  is provided to serve as a latch for retaining the handle  150  in the closed position shown in  FIGS. 1-4  and  14 . Referring to  FIG. 9 , the trigger  200  has a generally L-shaped or right-angle appearance, which also is shown in cross-section in  FIGS. 5 ,  10  and  12 . The round push button  205  forms a substantially horizontally extending leg of the trigger  200 , and a depending portion  206  forms a substantially vertically extending leg of the right-angle, generally L-shaped configuration of the trigger  200 . 
     A hole  204  is formed through the trigger  200  in the vicinity of the junctures of the above-mentioned horizontally and vertically extending legs  205 ,  206  to receive the roll pin  210  which pivotally mounts the trigger  200  on the handle  150 . A recess  207  is defined by the depending leg  206  to receive one end region of a compression spring  220 . An opposite end region of the compression spring  220  engages the thick part  161  of the handle  150  that defines the passage  157  that contains the plug assembly  170 . By this arrangement, the compression spring  220  is caused to bias the trigger toward the normal latched position shown in  FIGS. 1-7 ,  10  and  11 . 
     Referring to  FIG. 5 , a notch  209  formed in the depending leg  206  of the trigger  200  normally engages a projection  215  (as shown in  FIG. 2 ) formed on an interior part of the base or housing  110  normally serves to retain the handle  150  in its closed position shown in  FIGS. 1-4  and  14 . When the button  205  of the trigger  200  is depressed as shown in  FIG. 12 , the notch  209  disengages the projection  215 , permitting the handle  150  to pivot to the open position shown in  FIG. 5  under the influence of the torsion spring  160 . 
     Depression of the push button  205  as shown in  FIG. 12  releases the handle  150  from its closed position by moving the notch  209  out of engagement with the projection  215  defined by the base or housing  110 . When a force depressing the button  205  is released, the depressed trigger  200  will return to its normal position due to the influence of the compression spring  220 . 
     Because the surface  302  of the extruded, elongate guide rail  300  may vary in a minor way—typically by only a few thousands of an inch—in position along the length of the guide rail  300 , the leaf spring  275  is provided to ensure that the pointed tip  255  of the set screw fastener  250  will always be pressed firmly against the surface  302  despite small variations in the position of the guide rail surface  302 . When the lock  100  is initally brought into service, the set screw fastener  250  is adjusted (i.e., is set) so that, when the handle  150  is moved to and latched in the closed position (as shown in  FIGS. 1-4  and  14 ), the leaf spring  275  will always be caused to be slightly bent or very slightly deflected, as is shown with great exaggeration in  FIG. 15 . 
     By adjusting the set screw fastener  250  so that the pointed tip  255  is always caused to project or extend sufficiently far from out of the hole  181  formed through the rectangular part  185  of the lower handle portion  154  to cause the leaf spring  275  (i.e., the leaf spring assembly  190 ) to be deflected or bent slightly (as is depicted in a much exaggerated manner in  FIG. 15 ), the deflected or slightly bent leaf spring  275  will be caused to always press the pointed tip  255  of the set screw fastener  250  firmly and securely into engagement with the guide rail surface  302  whenever the handle  150  is moved to and is latched in the closed position as shown in  FIGS. 1-4  and  14 . This will be true regardless of the presence of minor variations (along the length of the extruded guide rail  300 ) of a few thousands of an inch in the position of the guide rail surface  302  that is engaged by the pointed tip  255  of the set screw fastener  250 . 
     In view of the arrangement just described, a retractable cover  50  (portions of which are shown in  FIGS. 5 and 14 ) to which the base or housing  110  is connected, will be securely retained and held in whatever position a customer positions it along the length of the guide rail  300  because the pointed tip  255  of the fastener  250  will always be pressed firmly and securely into engagement with the surface  302  of the guide rail  300 . If, when the retractable cover  50  is moved to various different positions along the length of the guide rail  300 , the pointed tip  255  of the fastener  250  needs to move a few thousands of an inch toward or away from the surface  302  to accommodate variations in the surface  302  that are encountered along the length of the guide rail  300 , the flexible mounting of the fastener  250  by the leaf spring  275  will automatically attend to any needed movement of the pointed tip  255  toward or away from the surface  302  as the leaf spring  275  flexes automatically to maintain the biasing of the fastener  250  toward and into firm and secure engagement with the surface  302  of the guide rail  300 . 
     Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example, and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed. It is intended to protect whatever features of patentable novelty that exist in the invention disclosed.