Abstract:
The boat trailer ( 3 ) includes pivotal support beams ( 5 ) that are pivoted intermediate their ends. Pairs of boat hull support rollers ( 13 ) are mounted on the ends of the roller mounting arms ( 7 ) and are slidably supported by the mounting blocks ( 9 ). The overhanging shoulders ( 30  and  31 ) of the opposed halves of the mounting block rest on the parallel support edges ( 47 ) of the notches ( 40 ) at the ends of each pivotal support beam ( 5 ). The shallow U-shaped arch ( 15 ) of the pivotal roller mounting arm ( 7 ) slides along its length through the compatibly shaped channel ( 20 ) of the mounting block ( 9 ) so that the rollers ( 13 ) at the opposite ends of the roller mounting arm can move with respect to each other upwardly or downwardly so as to maintain constant contact with the changing shape of the boat hull of a boat trailer as the boat is rolled onto or off of the trailer.

Description:
FIELD OF THE INVENTION 
     This invention relates to a boat trailer having roller mounts that are adjustable when the boat support rollers are engaged by the hull of a boat being mounted on the trailer, to reposition the boat support rollers of the trailer so that they conform to the progressively changing shape of the boat hull as the boat is rolled onto the trailer. 
     BACKGROUND OF THE INVENTION 
     Traditional boat trailers for transporting boats have roller assemblies mounted thereon for rolling boats onto and rolling the boats off of the trailer, and for firmly supporting a boat during transport while on the trailer. Almost all boat hulls have a compound curvature from stem to stem, so that the roller assemblies of most trailers are adaptable to the changing curvature of the boat as it is moved along the roller assemblies during loading and unloading of the boat with respect to the trailer. 
     Prior art roller mounts that support the rollers can include pairs of rollers on the ends of pivotal support beams, and the pivotal support beams usually are pivoted intermediate their ends about a centrally disposed axis. As a boat is loaded onto or unloaded from a trailer that uses conventional roller assemblies, the roller assemblies cross the strakes on the hull, and the compound curvature of the boat hull tends to urge some of the rollers to pivot out of contact with the hull. As a result, more of the weight of the boat is applied to the remaining rollers and the boat tends to assume a higher position on the trailer, thereby becoming more unwieldy and less stable. 
     A further problem caused by conventional roller mounts is that when the rollers cross the strakes on the boat hull, further instability and difficulty in loading or unloading the boat is created. 
     One method of dealing with these problems is to supply the trailer with a large number of rollers that are adjustable in their positions in response the changing shape of the hull of the boat as the boat is moved on or off the trailer. This increases the cost of the parts of the boat trailer and the assembly of the boat trailer, as well as increasing the cost of maintenance of the trailer. Also, this type of prior art roller support can be adequate for adjusting the heights of the rollers during the loading and unloading procedures, however, the angle of the hull of the boat also changes at the positions of the rollers and this is not accommodated by some prior art roller support designs. 
     A solution to some of the above noted problems is taught by my U.S. Pat. No. 5,316,329, which is incorporated herein by reference. The &#39;329 patent teaches pairs of rollers mounted on the ends of U-shaped pivotal roller mounting arms and the roller mounting arms are each tiltably supported intermediate their ends at the curve of the U-shape on saddles. When the shape of the boat hull changes at the positions of the pairs of rollers, the U-shaped roller mounting arms slide along their lengths in their saddles to adjust the relative height of the pairs of rollers. This maintains both rollers of each pair of rollers in constant load bearing contact with the changing shape of the boat hull at the position of the rollers. This construction has provided a means by which the rollers of the trailer can conform to the changing shape of the boat hull as it is drawn onto or rolled off of the trailer. However, the visual image of this structure is not particularly pleasing, the time for assembly of this structure is excessive and the assembly must be carefully accomplished in order for the structure to provide the desired alignment of the boat rollers with the boat hull and to avoid premature wear and damage of the parts. Also, it would be desirable to have a structure that is more stable and durable than the prior art. It is to these problems and desires that this invention is directed. 
     SUMMARY OF THE INVENTION 
     Briefly described, the present invention comprises a boat trailer having sliding boat trailer roller mounts for supporting the hulls of boats on the trailer that are adjustable to conform to the changing shape of the boat hull as the boat is rolled on or rolled off the boat trailer. Each sliding boat trailer roller mount includes a pivotal support beam that is supported intermediate its ends on the frame of the trailer so that it can tilt in response to the changing shape of the boat drawn onto the trailer. Notches are formed at the ends of the pivotal support beam for receiving the mounting blocks and the mounting blocks are mounted in the notches at the ends of the pivotal support beams. A roller mounting arm having at its opposite ends rollers rotatably mounted thereon is supported by each mounting block. The mounting block defines a shallow U-shaped channel and the intermediate portion of the roller mounting arm has a similar U-shaped configuration that is slidably mounted along its length in the U-shaped channel. This sliding relationship allows for the tilting of the roller mounting arm and its rollers so that when the shape of the boat hull drawn onto the trailer changes, requiring the rollers to change in relative elevation, the roller mounting arm slides longitudinally through the channel to accommodate this function. 
     The mounting block is formed in two identical segments that mate with each other to form the shallow U-shaped channel that supports the roller mounting arm. The notches of the pivotal support beam are sized so that the mounting block, assembled with its segments placed together about a pivotal support beam, slides into the notch. Once the mounting block is seated in a notch, it becomes perfectly aligned and firmly supported in its place, in full control of the pivotal support beam while allowing the relative sliding motion as described. 
     Thus, it is an object of this invention to provide an improved sliding boat trailer roller mount for supporting the hulls of boats on a trailer. 
     Another object of this invention is to provide the combination of a boat trailer with a sliding boat trailer roller mount for accommodating boats with hulls of various designs while providing adequate support for the boat hulls as the boats are drawn onto or discharged from a boat trailer. 
     Another object of this invention is to provide a durable, easily assembled, supportive, stable sliding boat trailer roller mount that adjusts to the changing shapes of boat hulls at the positions of the rollers as a boat is drawn onto or discharged from a boat trailer. 
    
    
     Other objects, features and advantages of this invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a boat trailer with a plurality of sliding boat trailer roller mounts. 
     FIG. 2 is an exploded view of the boat trailer roller mount. 
     FIG. 3 is an expanded perspective illustration of the mounting block, showing a portion of the pivotal support beam and a portion of the roller mounting arm. 
     FIG. 4 is a close-up perspective view of the plurality of boat trailer roller mounts in use with a boat. 
     FIG. 5 is an elevation of the roller mounting arm and the mounting block, showing the lateral and pivotal displacement of the rollers during loading of a boat onto the boat trailer. 
     FIG. 6 is a side view of the pivotal support beam, showing the pivoting action during loading of a boat. 
    
    
     DETAILED DESCRIPTION 
     Referring now in more detail to the drawings in which like numerals indicate like parts throughout the several views, FIG. 1 shows the general structure of a sliding boat trailer roller mount  1  in use with a boat trailer  3  that is used to transport boats  2 . The roller mounts preferably are mounted in pairs on the ends of pivotal support beams  5 . Preferably, the pivotal support beams  5  are mounted in two opposing pairs, with a forward pair that would extend beneath the boat hull near the bow of a boat, and a rearward pair that would extend beneath the boat hull at the stem of a boat. 
     FIG. 2 shows the sliding boat trailer roller mount  1  on an end of a pivotal support beam  5 . The sliding boat trailer roller mount, in accordance with the present invention, includes a roller mounting arm  7 , a mounting block  9 , a fastener  11 , and a pair of rollers  13  (only one shown in FIG.  2 ). The roller mounting arm  7  is a bar with an intermediate arch  15  and with opposed ends  17  of the arch elongated horizontally. It is important that the roller mounting arm  7  is not rotatable with respect to the mounting block  9  so that the shallow U-shape of the roller mounting arm always stays upright. Accordingly, the roller mounting arm and the correspondingly shaped shallow U-shaped channel  20  of the mounting block are shown in a rectangular cross-sectional configuration. However, other non-circular shapes of these parts can be used as long as the shallow U-shaped arch of the roller mounting arm remains upright. 
     The mounting block shown in FIGS. 2,  3  and  5  is formed in two identical halves  18  and  19  and the halves fit together to form the completed mounting block. As shown in FIG. 3, each half  18  and  19  includes one half of an internal, shallow U-shaped channel  20  that is closed along its length and open at its ends for receiving the roller mounting arm  7 . As can be see from FIG. 2, the roller mounting arm  7  includes the shallow U-shaped arch  15 , and the U-shaped channel  20  is of a corresponding, compatible shape, which is also a shallow U-shape. Each half  18  and  19  of the mounting block includes laterally facing engagement surfaces  21 ,  22  and  23 , with the shallow U-shaped channel  20  extending between engagement surfaces  22  and  23 , and with a connector opening  25  extending between engagement surfaces  21  and  22 . Stabilizing tab  26  extends laterally beneath engagement surface  21  from one of the halves of the mounting block to a position beneath the other half of the mounting block. This provides a lock between the halves of the mounting block so that they can be released from each other only with lateral relative movement. 
     The two meeting halves  18  and  19  of the mounting block include a lower portion  28  and an upper portion  29 , with the upper portion being of larger lateral breadth than the lower portion and including overhanging shoulders  30  and  31 . The shoulders define downwardly facing support surfaces  32  and  33  that will be described in more detail hereinafter. 
     Each pivotal support beam  5  includes a support notch  40  at each of its ends. The pivotal support beams are pivotally mounted on bolts  39  that extend through a clevis  37 , with the clevis being mounted on a lateral beam  35  of the trailer framework. The pivotal support beams  5  are box beams, in that they include opposed parallel sidewalls  42  and  43 , and opposed parallel bottom and top walls  44  and  45 . The notches  40  are formed through the top wall  45  and extend downwardly partially through the opposed sidewalls  42  and  43 , and the notches are of a length along the pivotal support beams  5  that corresponds to the width of the mounting block  9  when the halves of the mounting block are positioned in abutting, facing relationship, as shown in FIG.  2 . The notches  40  include a pair of parallel extending horizontal support edges  47  and  48 , opposed vertical bearing surfaces  49  and  50  at each end of the notches, and upper lateral bearing surface  51 . When the halves  18  and  19  of the mounting block  9  are assembled, by placing the shallow U-shaped channel  20  of each half of the mounting block about the arch  15  of the mounting arm  7  and urging the halves together until their laterally facing engagement surfaces  21 ,  22  and  23  are in abutment with one another, the assembled mounting block and roller mounting arm  7  are then inserted into the support notch  40 . The downwardly facing support surfaces  32  and  33  of the overhanging shoulders  30  and  31  are placed in engagement with the parallel support edges  47  and  48  of the notch, and with the vertical bearing surfaces  49  and  50  and the upper bearing surface  51  at the ends of the notch in abutment with the opposed front and rear surfaces of the overhanging shoulders  30  and  31 . This securely holds the mounting block  9  in the notch of the pivotal support beam  5 , and the shallow U-shaped arch  15  of the roller mounting arm  7  is slidably positioned in the shallow U-shaped channel  20  of the mounting block. 
     The curvature of the shallow U-shaped arch  15  is compatible with the curvature of the shallow U-shaped channel  20  of the mounting block, so that there can be longitudinal movement of the roller mounting arm  7  in the channel  20 . This is best illustrated in FIG. 5, where both of the shallow U-shaped configurations of the arch  15  and the channel  20  find a common center of curvature  54  so that the parallel opposed ends  17  of the roller mounting arm  7  can move up or down, as indicated by direction arrow  55 , as shown in FIG.  5 . This causes the rollers  13  to move up and down so that the upward movement of one roller corresponds to the downward movement of its opposed roller. 
     Once the mounting block  9  and its roller mounting arm  7  are securely placed in a notch  40  at the end of a pivotal support beam  5 , the connector opening  25  of the assembled mounting block registers with opposed aligned side openings  58  of the pivotal support beam  5 , and fastener  11  is inserted through the aligned openings. Fastener  11 , typically a bolt, keeps the mounting block  9  from moving upwardly and out of the notch  40 . 
     As best shown in FIGS. 4 and 6, the pivotal support beams  5  are supported intermediate their ends on clevis  37 , so that the rollers  13  can move up and down in response to the curved hull of a boat engaging the rollers. In addition, the pairs of rollers (FIGS. 4 and 5) can move up and down to accommodate the changing shape of the hull at the position of the rollers, so that when one roller moves up, its companion roller moves downwardly, and vice-versa. 
     The mounting block  9  is fabricated of nylon or other structural material that is of sufficient strength to bear the forces applied thereto and so that sufficient lubricity is provided to allow the arched portion  15  of the roller mounting arm  7  to move longitudinally through the shallow U-shaped channel  20  of the mounting block. A preferred material for the mounting block  9  is glass-reinforced thermal plastic acetyl resin. A suitable material is commercially available from Dow Chemical Company of Midland, Mich., under the trade name “Delrin.” 
     It will be noted that the simple construction of the halves  18  and  19  of the mounting block, and the manner in which the mounting block halves fit together to form the mounting block  9 , together with the simple shape and construction of the support notch  40  that supports the mounting block, results in extremely simple and easy assembly of the mounting block about the arched intermediate portion  15  of the roller mounting arm, and the insertion of the assembly downward into the notch. The fastener  11  is used simply to keep the assembly from moving upwardly out of the notch of the pivotal support beam  5 . 
     A feature of the invention is that both the shallow U-shaped channel  20  of the mounting block  9  and the arch  15  of the roller mounting arm  7  are positioned at a level that extends into the notch  40  of the pivotal support beam  5 . This design causes the surfaces of the notch to reinforce the mounting block so that it is able to resist being pried open by the forces applied by the roller mounting arm. 
     The rollers  13  typically will be made of a soft material, such as rubber, and usually will be conventional 4″ to 5″ diameter rubber rollers with sleeve bearings. The rollers are retained on the parallel opposed ends of the arch by means of a retaining pin or other conventional connector. 
     Although a preferred embodiment of the invention has been disclosed in detail herein, it will be obvious to those skilled in the art that variations and modifications of the disclosed embodiment can be made without departing from the spirit and scope of the invention as set forth in the following claims.