Abstract:
A vertically storable trailer embodying a flat, triangular frame has mounted thereon a container bottom for receiving a load and a container top that is sealingly and lockably engageable with the bottom for securely enclosing the load. The top and bottom have outwardly sloping forward and side walls to permit nestably storing the top in an inverted position within the bottom to reduce trailer storage space and a rearwardly facing flat end wall of the bottom is normal to the frame to facilitate tilting the trailer thereon to reduce floor storage area requirements. Wheel suspension assemblies include a pair of tubes, one end of each tube being pendulously attached to the frame adjacent either side of the container bottom. A wheel is rotatably journalled to an axle affixed to each tube adjacent its free end and within the free end is mounted a shock-absorbing resilient load sustaining unit. A suspension support is pivotally attached to the frame on either side of the container bottom in releasably engageable relation with a bearing of each load sustaining unit for locking same in an operable position to provide ground engagement of the wheel with a predetermined road clearance and releasing the locked load sustaining unit automatically by means of a ground contacting pushrod when the trailer is tilted onto the end wall. When released, the suspension assemblies swing inwardly of the frame to minimize trailer storage space.

Description:
This application is a continuation-in-part application of Ser. No. 739,050 filed May 29, 1985. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to a two-wheeled trailer and more particularly to a small, lightweight trailer that serves as an auxiliary trunk for an automobile and that is storable in a small space when not in use. 
     An expansion of the trunk space of an automobile requires a sealable and lockable container to protect a load therein from the elements and from damage or loss caused by vandalism. While trailers with such containers are generally available, the demand for them is low due to the fact that it is difficult to store them when not in use. 
     Trailers that can be folded to minimize storage space are disclosed in Canadian Pat. No. 447,088 issued on Mar. 9, 1948 to E. Koller and in U.S. Pat. No. 2,469,506 issued on May 10, 1949 to K. Kerr et al. However, these trailers cannot serve as automobile auxiliary trunks since they do not provide the load with protection from the elements and vandalism. In addition, the absence of shockabsorbing springs results in the load being subjected to road shock which is unacceptable to loads of the type generally stored in automobile trunks. 
     A combination trunk and trailer is disclosed in U.S. Pat. No. 2,110,944 issued on Mar. 15, 1938 to F. C. Schultz. While this invention provides a sealable automobile trunk that can be converted to a trailer, it is clearly not intended to serve as a trunk in its trailer configuration. Nor is it intended to be stored separately from the automobile when not in use. In addition, the absence of shock-absorbing springs makes the trailer configuration unacceptable for loads of the type generally stored in automobile trunks. 
     The trailers disclosed in U.S. Pat. Nos. 2,809,046 issued on Oct. 8, 1957 to B. A. Anderson and 3,367,675 issued on Feb. 6, 1968 to D. C. Gearin relate to foldable, single wheel trailers, although they are not intended to be stored separately from the automobile when not in use. Neither do they protect the load from the elements nor from vandalism. 
     Adjustable wheels on trailers as disclosed in U.S. Pat. Nos. 2,806,710 issued on Sept. 17, 1957 to D. C. Mascaro, 2,864,626 issued on Dec. 16, 1958 to S. J. Schantz, 2,869,887 issued on Jan. 20, 1959 to H. A. Westberg, and 2,885,216 issued on May 5, 1959 to J. W. Drowning provide the capability of retracting the suspension means. This is done, however, with power from external sources via cables, levers and hydraulics and is solely for the purpose of lifting and lowering the trailer and its load. While these inventions disclose collapsing wheel suspension means, they are generally complicated and do not provide freely moving and self-collapsing means for minimizing trailer storage space requirements. 
     Load lifting and lowering features are coupled with suspension springs and release mechanisms in trailers disclosed in U.S. Pat. Nos. 2,485,448 issued on Jan. 24, 1950 to G. C. Francis, 2,610,865 issued on Sept. 16, 1952 to O. L. Cantrell, 2,774,606 issued on Dec. 18, 1956 to L. Burweger et al, and 2,809,048 issued on Oct. 8, 1957 to L. V. Kytola. Since the purpose of the suspension springs and release mechanisms is solely to facilitate the lifting and lowering of loads, features for minimizing storage space are not disclosed. In particular, the sizes of suspension mechanisms and the volumes swept by them during retraction are large. This is prevalent because wheels and frames are large and the free ends of the springs move to a position above the top of the wheels. Moreover, shackles, hooks and crankarms, that normally hold the free ends of the springs, are pivoted below the bottom of the springs. While these deficiencies are not generally relevant to lifting and lowering mechanisms, they are very important in collapsible trailers for which minimal storage space is a prime requirement. 
     SUMMARY OF THE INVENTION 
     A principal objective of the present invention is to overcome the problems and shortcomings of the prior art by providing a trailer which can serve as an automobile auxiliary trunk that protects its load from the elements, vandalism and road shock encountered by the wheels. 
     Another objective of the invention is the provision of a trailer that is readily collapsible, easily storable and which requires but a small storage space. Such a trailer meets present needs in that expansion of automobile trunk space becomes necessary with the advent of small, compact automobiles and in that storage of such a trailer, together with an automobile, within the confines of a common home garage becomes mandatory in high density housing developments. 
     Yet another objective of the invention is the provision of a trailer that is simple in design and construction and which is easy to manufacture. 
     Still another objective of the invention is the provision of a trailer that requires no tools or special skills to operate and store. 
     The problems associated with the prior art may be substantially overcome and the aforenoted objectives achieved by recourse to the present invention which comprises, in combination, frame means for supportably carrying a load, including attachment means connectable to a trailer hitch of a towing vehicle, container means having a bottom portion mounted on the frame means for receiving the load and a top portion sealingly and lockably engageable with the bottom portion for securely enclosing the load, the bottom portion having an end wall adapted to vertically support the trailer in a stored position and both portions being nestable to reduce trailer storage space, wheel suspension means pendulously attached to the frame means adjacent the bottom portion, wheel means rotatably journalled to the suspension means and suspension support means movably attached to the frame means adjacent the bottom portion in releasably engageable relation with the suspension means for locking same in an operable position to provide ground engagement of the wheel means with a predetermined road clearance and releasing the locked suspension means in the vertically supported position, whereby the wheel means swing inwardly of the frame means to minimize trailer storage space. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be more particularly described with reference to embodiments thereof shown, by way of example, in the accompanying drawings in which: 
     FIG. 1 is a bottom perspective view of a trailer in accordance with the present invention showing an exploded and cut-away view of a suspension assembly and wheel; 
     FIG. 2 is a side elevation view of the trailer of FIG. 1 in a horizontal or operating position; 
     FIG. 3 is a side elevation view of the trailer of FIG. 1 in a vertical or storing position; 
     FIG. 4 is a side sectional view of the suspension assembly of FIG. 1 in a stored configuration; 
     FIG. 5 is a fragmentary sectional view of the suspension assembly of FIG. 4 taken along the lines A--A showing a load sustaining unit which is based on a cylindrical resilient rubber bushing material; 
     FIG. 6 is a fragmentary sectional view of the suspension assembly of FIG. 4 taken along the lines A--A showing a load sustaining unit based on conically shaped torsion plates as attachment surfaces for the bushing material; 
     FIG. 7, appearing with FIG. 3, is a side elevation view of the suspension assembly of FIG. 1 in its stored position; 
     FIG. 8 is a partial view of the suspension assembly of FIG. 4 shown operatively engaging a suspension support in both a loaded and unloaded operating position; 
     FIG. 9, appearing with FIG. 3, is an end view of the suspension assembly of FIG. 3 and a fragmentary end view of a container bottom of the trailer; 
     FIG. 10 is a fragmentary bottom perspective view of a second embodiment of the suspension support of the present invention; 
     FIG. 11 is a bottom perspective view of a disconnecting hinge; 
     FIG. 12, appearing with FIG. 8, is a side sectional view of another embodiment of the suspension assembly showing a hybrid load sustaining device; 
     FIG. 13 is a side sectional view of yet another embodiment of the suspension assembly showing a multileaf cantilever spring; 
     FIG. 14 is a fragmentary bottom perspective view of a disassembled suspension assembly pivot shaft support; 
     FIG. 15 is a disassembled, fragmentary bottom perspective view of another embodiment of the suspension support; 
     FIG. 16, appearing with FIG. 6, is a side elevation view of another embodiment of a load sustaining unit based on conically shaped torsion plates as attachment surfaces for the bushing material; 
     FIG. 17 is a fragmentary sectional view of the embodiment of a load sustaining unit in FIG. 16 based on conically shaped torsion plates as attachment surfaces for the bushing material; 
     FIG. 18 is a sectional view of apparatus for practicing a method of manufacturing an improved load sustaining unit based on conically shaped torsion plates as attachment surfaces for the bushing material; 
     FIG. 19, appearing with FIG. 2, is a fragmentary sectional view of another embodiment of an interface between the suspension support and the free end of a suspension arm shown in FIG. 8; and 
     FIG. 20 is a bottom perspective view of the trailer with a leaf sPring suspension assembly; 
     FIG. 21 is a side elevation view of the trailer of FIG. 20 in a horizontal or operating position; 
     FIG. 22 is a side elevation view of the trailer of FIG. 20 in a vertical or storing position; 
     FIG. 23 is a fragmentary bottom perspective view of a third embodiment of the suspension support of the trailer with the leaf spring suspension assembly; and 
     FIG. 24 is a top perspective view of the trailer with inserts for use as a portable kitchen or other work facility. 
    
    
     It should be noted that as a convention, when referring to the top, bottom or sides of the trailer, these terms should be construed as the top, bottom or sides of the trailer while in its normal horizontal position with its wheels in contact with the ground. Thus when the trailer is standing on its end, the top of the trailer is in a vertical plane. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now more particularly to the accompanying drawings, where like and corresponding parts are designated by similar reference characters, there is illustrated an embodiment of the invention, generally designated as a trailer 10 having a forward end 11 and a rearward end 12. The main components of the trailer are a triangular frame 13, a cross-member 14 with a pair of pivot housings 15, a pair of independent suspension assemblies, generally designated 16, pivotally attached to the cross-member 14 by means of the pivot housings 15, a pair of wheels 17 journalled to the suspension assemblies 16, a pair of suspension supports 18 pivotally attached to the frame 13, a container bottom 19 fixedly attached to the frame 13 and a container top 20 sealingly and removably attached to the container bottom 19. 
     The frame 13 extends forwardly of the container bottom 19 to the forward end 11 and has at its apex, attachment means 21 for hitching the trailer 10 to a conventional ball hitching element (not shown) mounted at the rearof a towing vehicle such as an automobile. Lifting means comprising a rod 22, suitably connected to the forward end 11 as by arc welding, provides apair of handles at the forward apex of the frame 13 to facilitate manual lifting of the forward end 11 of the trailer 10 from its horizontal, or operating position, (FIG. 2) to its vertical, or storing position,(FIG. 3) 
     Storing supports 23 and 24, consisting of hard rubber like material, are mounted on the container bottom 19 at the rearward end 12. These supports provide means for maintaining the trailer 10 in its vertical position, as shown in FIG. 3. 
     Referring next to FIG. 4, a suspension assembly 16 is shown to comprise a rectangular cross-section suspension tube 25 which contains a shock-absorbing resilient load sustaining unit 26 comprising a fixed cylindrical steel shaft 27, welded at both ends, to a pair of mounting plates 28 which, in turn, are riveted or bolted to the tube 25. It will beunderstood from FIG. 4 and FIG. 5 that the shaft 27 has fixedly and concentrically attached to its external cylindrical surface a thick-walledbushing 29 consisting of resilient material, such as rubber, which in turn is fixedly and concentrically attached at its external cylindrical surface29&#39; to a corresponding internal cylindrical surface 30&#39; of the suspension arm 30. A free end 33 of the suspension arm 30 protrudes beyond the end ofthe suspension tube 25 and is restrained from rotating freely about the shaft 27 by torsional resistive forces within the bushing 29. 
     A second embodiment of the load sustaining unit 26 is shown in FIG. 6. Two identical conically shaped torsion plates, 34 and 35, formed from sheet steel, are riveted or bolted to interior side wall surfaces of the tube 25. A second set of identical conically shaped torsion plates 36 and 37 are riveted or bolted to the arm 30 while a pivot shaft 38 maintains the conically shaped plates concentric. Intermediate the pairs of plates 34, 36 and 35, 37, a pair of torsion washers39 and 40, fabricated from a resilient material such as rubber, are fixedly attached to the facing surfaces thersof. Torsional forces generated by the suspension arm 30 are transmitted via the plates 36 and 37 to the washers 38 and 40 creating evenly distributed internal strain and stress. This provides the torsionalforces that resist rotation of the arm 30 about the shaft 38. 
     The location of the unit 26 inside the tube 25 produces a slender suspension assembly, as shown in FIGS. 7 and 9, thereby minimizing the space between the wheel 17 and the container bottom 19. As shown in FIG. 4, the free end 33 of the arm 30 does not extend laterally beyond the longitudinal extension of the envelope of the tube 25 in its unloaded storing configuration, thereby allowing collapsing of the assembly 16 to avertical position as shown in FIG. 3. This configuration of the assembly 16is achieved by having a long suspension tube 25 which maintains a relatively small angle of incline in the operating position of the traileras shown in FIG. 2 and FIG. 8 thereby maintaining the required road clearance of the free end 33 in its loaded operating position shown in FIG. 8 in broken line form. 
     The significance of the slender feature of the assembly 16 is shown in FIG.9 which depicts the location of the assembly relative to the outwardly sloped will of the container bottom 19. Any protrusion of the unit 26 beyond the longitudinal envelope of the suspension tube 25 would directly increase the storage space required for the trailer. 
     The slender suspension tube 25 provides the following functions: 
     a crank to allow movement of the wheel due to changes in load and due to road obstructions; 
     a crank to allow movement for collapsing the suspension assembly; 
     a housing for the load sustaining unit; and 
     a thin-walled structural box member for efficiently resisting longitudinal torsional forces created by the absence of a full wheel to wheel axle. 
     A shaft 31, being fixedly attached to a side wall of the tube 25 near the forward most end thereof and projecting inwardly, mates with the outwardlyprojecting pivot housing 15 to produce a compact pivotal connection for theassembly 16, without the pivotal connection protruding significantly into the inner space of the container bottom 19. A horizontally disposed axle 32 projecting outwardly from the outer wall of the tube 25, near the rearward most end, provides a journalled connection for the wheel 17. 
     When the trailer 10 is in the horizontal operating position, the free end 33 of the arm 30, protruding from the tube 25 at its rearward most end, isheld from rotational displacement about the shaft 31 by a supporting end 41of the support 18 at the top and by a retaining support 42 at the bottom. Longitudinal or lengthwise movement of the free end 33 resulting from loadchanges on the assembly 16 is allowed by pivotal movements of the support 18 about a pivot shaft 43 which is fixedly attached to the frame 13. 
     The supporting end 41 consists of a cylindrically shaped steel bearing shaft 41&#39; welded along an edge of an L-shaped forward extension of the support 18. The end 41 couples with a curvilinear lining of a bearing 44 located at the free end 33. The lining is fabricated of nylon or other, similar, low friction, low wearing material. As shown in FIG. 4, one side of the bearing 44 is cut away to provide an opening for decoupling of the end 41. This novel method for coupling and decoupling the arm 30 protects the bearing surfaces from road dirt by positioning the opening to the bearing 44 so that it opens towards the rearward end 12 of the trailer. Dirt being thrown into the air by the bottom half section of the wheel 17 will have one component of its relative velocity vector directed rearward,thereby preventing entry of dirt into the bearing opening, it being locatedat a level below the centre of the wheel 17. 
     As shown in FIG. 8, the length of the support 18 from the shaft 43 to the supporting end 41 is such that the angle of rotational displacement of thesupport 18 about the shaft 43, caused by longitudinal or lengthwise movement of the free end 33, is similar to the angle of change in incline of the arm 30, thereby minimizing rotational movement, and friction between the supporting end 41 and the bearing 44. As shown in FIG. 8, thisnovel mechanism also ensures that the angle between the support 18 and the arm 30 is always greater than 90 degrees, thereby maintaining a stable condition in which the supporting end 41 of the support 18 stays coupled to the free end 33 and requires no external holding mechanism. 
     This arrangement of the support 18 also eliminates the requirement for pivoting the support 18 below the level of the suspension arm 30. This increases ground clearance of the trailer in the operating position and decreases the horizontal storage space of the trailer in the storing position. 
     The function of the retaining support 42 is necessary on all trailers traveling at high speed, especially trailers with small wheels. On each side of the trailer 10, the support 42 reduces high amplitude, low frequency oscillation of the load and protects the arm 30 and the support 18 from damage due to continual hammering resulting from returns of the wheel 17 and the arm 30 from large excursions caused by large depressions in the roadway. 
     An actioning end 45 of the support 18 has a rotational relationship with a pushrod 46 by means of a pivot 47. A longitudinal, linear displacement of the pushrod 46 is generated by a force on an extension 48 of the pushrod 46 which extends beyond the rearward end 12, as the trailer 10 is pivoted from the horizontal position to the vertical position by manually lifting and pivoting the rod 22 about the storing supports 23. The linear displacement of the pushrod 46 produces a rotational displacement of the suspension support 18 about the shaft 43 such that the supporting end 41 moves rearward beyond the free end 33, thus allowing the arm 30 and the assembly 16 rotational displacement about the shaft 31. The force for the rotational displacement of the suspension assembly 16 on each side of the trailer 10 is provided by gravity which develops a pendular action on the assembly 16 and wheel 17 about the shaft 31. The final collapsed position of the assembly 16 and the wheel 17 is attained when the trailer 10 is in the vertical position shown in FIG. 3. Similarly, as the trailer 10 is pivoted from the vertical to the horizontal position, the assembly 16 and the wheel 17 are pivoted on the shaft 31 by pendular action until the freeend 33 engages the support 42. The supporting end 41 of the support 18 thenmoves forward on top of the arm 30 to hold the free end 33 from free rotational displacement about the shaft 31. The force for this action is obtained from the pushrod 46 which is displaced rearwardly by a combination of a gravitational force and a returning force developed by a spring 49. The action of restoring the trailer 10 to its operating configuration is now complete and further pivoting of the trailer about the supports 23 transfers the weight of the trailer 10 onto the wheels 17,the assemblies 16, the arms 30 and the suspension supports 18. 
     A stepwise increase in cross-section of the pushrod 46 near its rearward most end 48 provides a locking facility to prevent accidental actuation ofthe pushrod 46 when the trailer 10 is in the horizontal position. The locking action is achieved by the stepwise decrease in cross-section of the rearward most end 48 of the pushrod 46 dropping into a notch 50&#39; of a sliding bearing 50 when the trailer 10 is pivoted to the horizontal position. The force for this downward motion is obtained from a combination of the gravitational force acting on the pushrod 46 and the spring force developed by the spring 49 acting on the rear of the pushrod 46. It should be noted that the spring 49 is positioned angularly to the pushrod 46, thereby providing both longitudinal and lateral forces. 
     When pivoting the trailer 10 about the supports 23 from the operating position to the storing position, the rearward most end 48 of the pushrod 46 is first lifted out of the notch 50&#39; and is then moved with a longitudinal linear sliding displacement through the bearing 50. 
     Referring to FIG. 10, a second embodiment of the suspension support actuation mechanism of this invention comprises an extension to the support 18 to form a lever arm 51 which serves as a handle for manually collapsing the assembly 16. A spring 52 holds the lever arm 51 in the rearward position while the trailer 10 is in the operating position. When the trailer 10 is in the storing position, a force applied manually on thelever arm 51 elongates the spring 52, moves the supporting end 41 rearwardly and releases the arm 30 to allow the assembly 16 to pendulate to a vertical position. 
     To return the trailer 10 to the operating position, it is pivoted about thesupports 23 thereby also inducing a pendular pivoting action on the assemblies 16. The supporting end 41 is pushed rearward by the arm 30 which snaps back into its operating position when the free end 33 engages the support 42. 
     The embodiment of FIG. 10, therefore, provides a simpler but not fully automatic suspension collapsing mechanism. 
     The container top 20 is attached to the container bottom 19 by a pair of disconnectable hinge assemblies, generally designated 53, which are shown in FIG. 11 mounted on one side of the top 20 and bottom 19. A lock (not shown) on the other side of the top 20 and bottom 19 permits sealingly positioning the container top 20 onto the container bottom 19 to form a secure, lockable weathertight enclosure for the load. 
     Referring to FIG. 11, it will be observed that the assembly 53 comprises a hinge pivot shaft 54 that fits into a hinge housing 55 which is open on one side of its generally cylindrical body. By pivoting the container top 20 beyond its normal 90 degrees opening range, the hinge pivot housing 55 can be disconnected from the hinge pivot shaft 54 as shown in FIG. 11. 
     The container bottom 19 and container top 20 have outwardly sloping side walls such that the inverted container top 20 fits into the container bottom 19. The wall at the rearward end 12 of the container bottom 19 is perpendicular to the frame 13 to facilitate standing the trailer 10 on thesupports 23 and 24 in the storing position. The container top 20 has a highsloped forward end to minimize wind resistance when the trailer 10 is towedand to provide clearance for the intrusion of the member 14 and housings 15when the container top 20 is nested with the container bottom 19 as when storing the trailer. These features allow storage of the container top 20 inside the container bottom 19 which halves the total storage space normally required by the assembled container assembly. 
     While the preferred embodiment of the assembly 16 contains a load sustaining unit based on torsional loading of a resilient material such asrubber, other forms of load sustaining devices are shown in FIG. 12 and FIG. 13. The configuration shown in FIG. 12 comprises a hybrid load sustaining device consisting of a flat, single leaf, cantilever spring 56 made of steel or fiberglass reinforced epoxy resin material, fixedly attached to an inner surface of a side wall of the tube 25 by retaining plates 57 and 58, at least one first resilient supporting cushion 59 made of rubber and a second cushion 80 also made of rubber. This is a highly efficient arrangement in which the spring 56 is stressed uniformly from its anchorage at the plates 57 and 58 to its support by the cushion 59. Such uniform stressing of a flat spring is not possible in prior art designs and allows the use of minimal spring material to achieve the required load sustaining forces. The cushion 60, being located closer to the spring free end 33, prevents overloading of the spring 56 by reducing the moment arm through which the force acts on the spring on large excursions. 
     The configuration shown in FIG. 13 comprises a multileaf cantilever spring 62 made of steel or fiberglass reinforced epoxy resin material fixedly attached to the tube 25 by retaining plates 63 and 64. 
     Although the preferred embodiment of this invention has been described withpivotal bearings based on cantilevered pivot shafts that support the assembly 16 and the support 18, these can also comprise pivotal bearings based on simply supported pivot shafts as shown in FIG. 14 and FIG. 15. 
     Plates 65 and 66, shown in FIG. 14, are fixedly attached to an extension ofthe cross-member 14 and provide the bearing surface for a shaft 67 which extends on both sides of the tube 25 through apertures 68. 
     In FIG. 15 the support 18, shown as a channel 18&#39;, is pivoted on the shaft 43 which is supported by a bracket 69. The bracket 69 is fixedly attached to an extension of the rearward member of the frame 13 and performs the additional function of interconnecting the members of the frame 13 and attachment means for the support 42. The support 42 is also based on a structure of a simply supported crossmember. 
     In FIG. 16 and FIG. 17 there is shown another embodiment of the load sustaining unit 26 based on the principle of conical plates shown in FIG. 6. This embodiment avoids the shaft 38 and comprises, in part, a pair of thin, circular rubber torsion washers 72 between which the arm 30 is sandwiched. The washers 72 provide high, linear, evenly distributed shear forces to hold the arm 30 in place without requiring the shaft 38. A simple thrust bolt 71, nut 71&#39; and two washers 71&#34; provide lateral compression of the washers 72 via torsion plates 73 and 74 which are made of sheet steel. The pressure thus generated on the rubber-to-metal interface of thewashers 72 and the plates 73 and 74 improves the anchoringqualities of the bond at each interface. 
     FIG. 18 shows apparatus that may be employed for manufacturing the rubber and torsion plate sandwich of the load sustaining unit of FIG. 17. The method incorporates a tooling plate 75, which holds the preformed, conically shaped torsion plate 73 in its preformed configuration and a tooling plate 76 which distorts the flat torsion plate 74 to decrease the thickness of the washer 72 cavity at a central section 70 in inverse proportion to the basic thickness of the cavity. The maximum thickness of the cavity is defined by a removable cylindrical cavity wall 77 which spaces the plates 73 and 74 apart. The required force for distorting the plate 74 is supplied by a thrust bolt assembly consisting of a bolt 78, a nut 79 and Belleville springs 80. After injection molding of the rubber, two identical rubber and torsion plate sandwiches are assembled onto the arm 30 by bonding two of the plates 74 to the suspension arm 30, using a structural adhesive, and by applying pressure by means of the thrust bolt 71, nut 71&#39; and the two washers 71&#34;. This process flattens the torsion plates 74 thereby providing constant pressure over the whole surface of each section 72 and also compensating for molding shrinkage of the rubber.The completed unit 26 is then riveted or bolted to a pair of facing side walls inside the tube 25. 
     In FIG. 19 there is shown a sectional view of a second embodiment of the interface between the support 18 and the free end 33 of the arm 30. This interface is based on a flexible bearing comprising a resilient L-shaped block 81, made of rubber-like material, which is bonded to the support 18 on one side and to an L-shaped metal striker plate 82 on the other side. The free end 33 meets the plate 82 and maintains full contact with it overthe range of relative angular displacements between the arm 30 and the support 18. This novel bearing arrangement eliminates relative movements and frictional wear between the free end 33 and the support 18. In addition, since there is always full surface to surface contact between the free end 33 and the striker plate 82, collection of road dirt at this interface is minimized. 
     Referring to FIGS. 20, 21 and 22, another embodiment of the invention is illustrated, with a leaf spring suspension assembly. The suspension assembly to the left side of the page is shown exploded for the purpose ofclarity in FIG. 20. 
     A pair of leaf springs 16&#39;, which may be multi-leaf springs, are pinned at one end of each by means of pins 15&#39;. Pins 15&#39; are retained within brackets 15 which are preferably welded to opposite sides of the frame. While the pins 15 may be located below the frame, it is preferred that they should be located outward of both sides of the frame and above the bottom of the frame. Thus the springs, which extend along the trailer in afront to back orientation are located alongside the sides of the trailer. 
     Wheels 17 which are located outside the springs are connected by means of an axle 17&#39;. The axle is clamped to the springs in a conventional manner (not shown). 
     The other ends of the springs 16&#39; are preferably bent downwardly and are held within a locking means. Preferably the locking means are comprised ofpins 42 and 18&#39;, the bent portion 16&#34; of the springs being held between them. The pairs of pins are retained by brackets 18, which are preferably welded to a cross member 14&#39; welded to the frame rearwardly of the axle and wheels. 
     The upper pins 18&#39; are removable from the brackets 18 in order to release the springs. Once they are removed, e.g. when the trailer is in its vertical storage position resting on its rear, the springs 16&#39; may be swivelled about pins 15&#39; , the axle 17&#39; being moved toward and eventually in contact with the bottom of the frame. In this Position the wheels 17 overlap the sides of the frame, presenting a substantially narrowed side profile for the trailer and thus reducing the amount of storage space required. 
     It should be noted that if care is taken to avoid the affects of twisting torque on the springs, such as by using a robust multi-leafed spring and robust anchoring points, the wheels can be fastened to short separated wheel axles connected to the spring, avoiding the requirement for an axle passing under the trailer. In this case the springs and wheels can be swung far over alongside the trailer, further reducing the required storage space. 
     In order to release the pins 18&#39;, cranks comprised of levers 45&#39; and 41&#34; are connected via crankshafts 43&#39; between the ends of each pushrods 46 andthe ends of pins 18&#39;. The pushrods are urged into their extended positions,by which the spring locking pins 18&#39; are located in place within brackets 18, by means of springs 49 which extend between the pushrods 46 and the rear of the frame. 
     When the trailer is placed on its end, pushrods 46 are pushed so as to overcome the spring 49 tension, rotating the cranks and pulling pins 18&#39; out of position, thus releasing the ends of the springs 16&#39;, and allowing the springs and attached wheels to rotate about pins 15&#39; and move alongside the trailer sides. 
     When moving the trailer off its end, the springs 15&#39; are rotated into theirextended positions manually or by means of gravity, and once the trailer weight is released from the pushrods, the spring 49 tension causes rotation of the crank so as to replace the locking pins 18&#39;, into their positions in bracket 18 thus securing the ends of the springs 16&#39;. 
     FIG. 23 illustates another embodiment of the invention. In this embodiment the springs 16&#39; are retained and rotated about pins 15&#39; in a manner similar to that described with reference to FIGS. 20-22. However the spring locking means at the other side of each spring is comprised of a notch in a crank 41, which is pinned to rotate about a horizontal axis. The crank 45&#39; contains an elongated slot 18&#34; through which pushrod 46&#39; extends. The pushrod has a narrowed forward portion, adjoining a wider rear portion at a ledge 46&#34;. The crank is urged to its normal position supporting the end of spring 16&#39;, whereby the wheels are extended, by means of spring 49&#39; which is connected between the upper portion of the crank and the frame. 
     In operation, with the wheels in extended position, the end of spring 16&#39; is retained within the end notch of crank 41. Weight of the trailer is applied via the frame, crank pin and crank to the end of the spring 16&#39;, from which it is transferred to the axle 17&#39; and the wheel 17 (the other side of the trailer having a similar structure and function). 
     When the trailer is up-ended to stand on its end, the pushrod 46&#39; advances by contact with the ground causing the step 46&#34; to engage the bottom of slot 18&#34;. This causes rotation of the crank, releasing the end of spring 16&#39;. Each spring is thus released and may rotate about pin 15&#39;, causing the axle 17&#39; and wheels 17 to move toward the top of the trailer, thus reducing its side profile. Alternatively the end of spring 16&#39; may also move the end 46&#34;&#39; of pushrod 46&#39; to disengage the ledge 46&#34; from the end of slot 18&#34;, thus reducing the tension in spring 49&#39;. 
     As the trailer is moved off the ends of pushrod 46&#39;, the springs 16&#39; rotateabout pins 15&#39;. With spring 16&#39; in its lowermost position and pushrod 46&#39; having lost contact with the ground, crank 41 moves to a position to support spring 16&#39; in the end notch of crank 41&#34;. Alternatively the ends of spring 16&#39; rotate the cranks 41 against the tension of the spring 49&#39; as springs 16&#39; move downward. When springs 16&#39; reach their lowermost position, cranks 41 being forced by springs 49&#39; snap into position such that springs 16&#39; engage with the notch in cranks 41. 
     When the trailer is moved off its end, pushrod 46&#39; loosens. As the trailer is rotated further towards its horizontal position, pushrods 46&#39; are pulled by gravity to engage the ledge 46&#34; with the end of slot 18&#34;. Alternatively once the trailer stands on its wheels, pushrods 46&#39; may be pulled out in order to engage the ledge 46&#34; with the end of the slot 18&#34;. 
     It should be noted that each pushrod 46&#39; contains a stop 48&#39; to limit its rearward movement. It also contains stops 48 which engage the sides of a slot in a panel or in the frame of the trailer, so that it could not move inadvertently forward and cause disengagement of the end of the springs. 
     Turning now to FIG. 24 another embodiment of the invention is shown. In FIG. 24 an insert 86 is illustrated which fits into the trailer container.The insert is preferably a preformed structure which will provide horizontal shelves when the trailer is in its storage location. The shelves may contain a hinged folding work surface 84. Thus the trailer mayform for example a work bench when in its stored position. 
     The insert may also include storage bins which would hold small objects, and form the horizontal shelves when the trailer is in the vertical position. When the trailer is in the horizontal position the bins form divided containers. When travelling with the insert in position it serves to retain objects in position. 
     As indicated earlier the trailer may also include a top unit 20 formed of sides and a roof. Preferably shelves 85 extend between the sides of the top unit and its roof, which are horizontal when the roof is open and the trailer is end down. The shelves may also contain uprights at their front edges which help to secure objects, particularly when travelling. The top unit can be closed at the front by a net. 
     Should the top unit 20 be hinged to the trailer at one side, once the trailer is standing on its end it may be opened into the form shown in FIG. 24, forming a very convenient and useful working and storage arrangement. 
     It will be apparent to those skilled in the art to which this specificationis addressed that the embodiments heretofore described may be varied to meet particular specialized requiremenets without departing from the true spirit and scope of the invention disclosed. For example, the frame 13 mayform an integral part of the container bottom 19. The foregoing embodimentsare therefore not to be taken as indicative of the limits of the invention but rather as exemplary structures of the invention which is described by the claims appended hereto.