Abstract:
A chain tie down anchor for a vehicle has a chain pivotally anchored to a mounting bracket and passing through a vehicle floor for access from above the vehicle floor and which when retracted hangs in a catenary like manner.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to cargo tie down anchoring devices for use in semi-trailers and other vehicles providing improved wear properties and substantially flush retension when not in use. 
     2. Description of the Prior Art 
     Various U.S. Patents show inventions addressing chain anchoring arrangements moveable from a substantially flushed or stored position to an extended position. None of these arrangements show the instant invention. 
     Wallace Number 3,865,048 shows a chain anchor with two disks on each end of the chain. The top disk permits the chain to hang below the surface or floor of a vehicle, extending downward completely enclosed within a tube. The bottom disk remains within the tube and slides upward as the chain is pulled out to a point where it stops against a reduced diameter at the top of the tube thereby providing all anchoring stress on the tube structure itself. 
     Fermbach Number 4,315,707 shows a vertically telescoping tube contained within a second tube which upon vertical extension provides lateral resistance to a load. A simple cotter is used to limit removal of the telescoping tube but it does not provide any substantial strength to resist a vertical load. 
     Kuhn Number 3,494,587 shows a tube embedded in concrete having a chain anchored at the bottom of the tube through the use of an expanding conical section anchor member. The chain retracts and is wholly contained within the tube. 
     Veasman Number 3,524,413 shows an extensible cylindrical anchor body having a top cap flush with the vehicle floor surface when retracted and an inverted mushroom shaped bottom section providing anchoring when a hook is attached to the anchor member. 
     SUMMARY OF THE INVENTION 
     This invention provides a number of advantages in providing a partially movable anchor in vehicles which are herein described. 
     One advantage of the invention is providing a substantially flush surface with a floor of a vehicle while having a chain anchor accessible from above the floor. 
     Another advantage of the invention is that the line of the axis of the chain passing from under the floor through and above the floor is optimized, improving loading on the chain and reducing wear. 
     Another advantage to the invention is that the chain when retracted is completely suspended from its two ends thereby reducing wear, increasing access for inspection and maintenance. 
     Other advantages of the invention will become apparent upon reading the specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective cut away view of a semi-trailer vehicle with the invention in place. 
     FIG. 2 is a side elevational view of the invention. 
     FIG. 3 is an end elevational view of the invention. 
     FIG. 4 is a sectional view taken substantially on line 4-4 of FIG. 3. 
     FIG. 5 is a sectional view showing the invention under tensile load, and similar to FIG. 4 showing the parts in stowed position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a semi-trailer (10) having a floor (11) supported on frame members (12). The chain tie down anchor assembly (15) may be bolted or affixed to the frame member (12) in a suitable manner. The vertical leg (16) of the anchor assembly is provided with bolt holes (17) for mounting. A horizontal leg (18) meets with the vertical leg (16). A tube (19) which is welded in a corresponding opening in leg (18), provides a passageway (19a) for the anchor chain (20) which has a disk shaped stop element (21) at the top end thereof. The chain (20) may be engaged by a number of suitable devices to extend its length or provide a fixed attachment thereto such as the hook (22) and second chain (23) shown although other suitable arrangements of cable eyes, clevis arrangements or the like may be suitable. 
     FIG. 2 is a side elevational view of the anchor assembly (15) in which the vertical (16) and horizontal (18) legs may be seen. The tube (19) passes through the horizontal leg (18) providing a passageway for the chain (20). In this view tension on the second chain (23) wrapped about cargo 23a (FIG. 1) is transmitted through the hook (22) to the first chain (20) by the engagement of the hook (22) with the half link (24) comprising the base or lower portion of the stop (21) Also apparent in this view is one of the side plates (25) which is mounted perpendicular and welded to each of the respective legs (16 and 18) of a bracket 25a. A bolt (26) holds the bottom link of the chain (20) as will be more fully discussed herein. 
     FIG. 3 is an elevational edge view showing the vertical (16) and horizontal (18) legs with the two side plates (25). The mounting holes (17) are shown in plate (16), may also be seen in this view the chain (20) passing through the tube (19), which is shown broken apart for clarity, as connected with the top disk (21) via half link (24) at the top-most extension of the upper portion 20a chain. The bottom link extension (27) at the distal end of the lower portion 20b of the chain is engaged by bolt (26) in turn held in place by nut (48) or other suitable means. 
     FIG. 4 shows the invention in section with rivets (39) extending through bolt holes (17) in leg 16 and vertical portion 12a of frame 12 affixing a vertical leg (16) to the frame member (12). The horizontal leg (18) has the vertical tube (19) extending therethrough and through the floor providing a passageway for chain (20) to pass from beneath the floor of the trailer to above the floor of the trailer. Hook (22) is shown engaging half link (24) affixed to the disk (21). 
     This sectional view shows bottom link (27) pivoting on bolt (26) to a horizontal position as a lateral extension at which place the link abuts stop plate (28). As is illustrated in this view the pivoting and stop positioning aspects of this arrangement result in the horizontal displacement of second link (29) and a corresponding straightening of the axis of the chain resulting in a more direct run through the pipe (19) lessening side-ward loads on the pipe by holding the chain out of contact with the bottom end of the tube or the vertical portion thereof by effectively centering the self assuming straight length intermediate portion 20c of the chain thus minimizing wear from the rubbing of the chain (20) on the pipe or guide (19) or other parts of the assembly. The distance of this displacement is determined by the distance between the two points (30) and (31) at the ends of the bottom link (27) whereat bolt (26) engages one end of link 27 at (31). The link 29 engages link 27 at (30). 
     FIG. 5 shows the assembly with the chain in its retracted position the disk (21) resting on the top surface of the pipe (19). Also shown in this figure is a portion of the floor board (35) of which provides the seating surface for the semi-trailer or vehicle. This view shows the chain at rest or stowed hanging from the half link (24) at the top, and a bolt (26) at the bottom end of the chain. The lateral displacement of the bottom link (27) discussed in the previous figure no longer occurs, since the weight of the remainder of the chain causes the end link (27) to hang downwardly. The centers (30) and (31) are substantially vertically oriented thereby also resulting in displacement of the second link (29) and other links away from the center line of the pipe (19). This arrangement permits the chain to hang freely suspended from only two points in a catenary loop with minimal friction with other elements of the assembly. In the environment in which the chain tie down is used trailers are frequently removed in an unladen condition or are driven with not all chain tie down assemblies under tension. In this situation, prior art assemblies result in substantial degree of frictional contact of parts and wear to the chains and other parts of the assembly by virtue of the motion of the trailer and unwanted contact between the various parts resulting in constant clatter. 
     The instant invention with the chain forming a catenary like curve limits wear to only those points where the chain may be most easily inspected and the components most easily replaced. In addition the load in the engaged position is distributed on two elements of the mounting assembly, the bolt (26) and the stop plate (28).