Abstract:
A frame configuration that is particularly adaptable for use on a trailer such that the frame configuration is operable in both a tilt mode of operation and a dump mode of operation. An actuating mechanism includes a linear actuator that is supported on the frame by a bracket and a yoke that connects to a load bed to power the vertical movement of the load bed in both tilt and dump functions. The linear actuator is pivotally mounted to permit a re-positioning of the actuator into an inoperative position. The frame configuration is provided with an articulated tilt frame in which the tongue is pivoted thereto allowing the load bed to pivot about a tilt axis which can coincide with the wheel axis of the trailer. The bed frame can be locked to the tilt frame for tilting upon articulation with the tongue, while a disconnection of the bed frame from the tilt frame enables the bed frame to pivot about the dump axis to provide a dump function in addition to the tilt function. The actuator can pivot about the connection thereof to the bed frame to position the actuator into a lowered inoperative transport position generally parallel to the trailer tongue. A modified screw jack can be part of a kit that can be utilized to provide the powered operations of the tilt function for existing gravity-based tilt trailers.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims domestic priority on U.S. Provisional Patent Application Serial No. 60/268,448, filed Feb. 13, 2001, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to a trailer attachable to a vehicle and, more particularly, to a trailer configured to provide selectively an operation of tilting about its tire axis and an operation of dumping about a dump axis positioned rearwardly of the tire axis. 
     Trailers have been designed to provide the ability to tilt or to provide the ability to dump. A trailer that tilts generally has an articulated tongue that, when released to articulate about a generally transversely extending horizontal axis, allows the trailer to pivot about an axis corresponding to the center of the trailer tires, which if mounted coaxially on the trailer axle would correspond to the trailer axle, thus allowing the rearward end of the trailer to lower to the surface of the ground and permit convenient access to the trailer bed. Tilting is typically used to load other wheeled devices onto the trailer bed. Since the rearward end of the trailer bed is positionable adjacent the surface of the ground, a wheeled device such as a wheeled utility vehicle, a motorcycle, or a wheeled hand cart, can easily roll onto the trailer bed. Movement of the tilt function of such trailers is typically accomplished manually by releasing a locking device fixing the bed frame to the trailer tongue to permit the tongue to pivot relative to the bed frame and allow the bed frame to pivot about the tire center. Returning the trailer bed to a transport position with the bed frame fixed to the trailer tongue is typically a matter of balancing the load on the trailer bed relative to the tires to permit the bed frame to be pivoted back into position to be locked to the trailer tongue. 
     A dump trailer is also known in the art. Dump trailers are configured to pivot the trailer bed about a dump axis carried by the dump frame with the dump axis being located near or at the rearward end of the trailer bed. When the trailer bed is moved into a dump position, the rearward end of the trailer remains elevated above the ground while the forward end of the trailer bed is raised to urge any load on the trailer bed to slide off the bed onto the ground. The dump function is usually not accomplished manually. The movement of the bed frame carrying the trailer bed relative to the dump frame is typically accomplished through a dump actuator that is sufficiently powerful to raise the trailer bed and load thereon. This dump actuator is normally positioned underneath the trailer and is effective to cause a vertical movement of the trailer bed about the rearwardly positioned dump axis. To provide this known dump actuator configuration for a small towed trailer would require that the actuator be remotely powered and that the trailer structure provide sufficient depth to house and protect the dump actuator. 
     It would be desirable to provide a trailer capable of being towed behind a conventional vehicle, such as a truck or a car, that would be operable to provide both a tilt function and a dump function. It would also be desirable to provide a compact actuator mounting that would be effective to provide the dump function in a manner that would overcome the disadvantages of known dump actuators. It would also be desirable to provide a trailer and actuator configuration that would be conducive to being manually operated without requiring a remote power source. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to overcome the disadvantages of the prior art by providing a trailer having both dump and tilt functions. 
     It is another object of this invention to provide a trailer having an actuator operable to effect a tilting and dumping operations for the trailer. 
     It is a feature of this invention that the trailer is provided with a frame configuration that is connected to the tongue of the trailer and supports a bed frame to provide a dump frame configuration. 
     It is another feature of this invention that the trailer bed is selectively pivotable about a transverse axis corresponding to the axis of rotation of the wheels to provide a tilt feature for the trailer and about a transverse axis located at the rear portion of the trailer to provide a dump feature for the trailer. 
     It is an advantage of this invention that the same actuator can provide both tilt and dump functions for the trailer. 
     It is still another feature of this invention that the selection between the tilt and dump operations of the trailer can be selected by disconnecting or unlatching the articulated tilt frame from the tongue or by disconnecting or unlatching the bed frame from the articulated tilt frame. 
     It is still another object of this invention to provide a mounting for the actuator that will enable the actuator to perform both tilt and dump operations for the same trailer while being capable of being stowed into an inoperative transport position. 
     It is still another feature of this invention that the actuator can be pivoted about the connections thereof with the bed frame and the tongue of the trailer to be lowered into an inoperative transport position substantially parallel with the tongue of the trailer. 
     It is still another advantage of this invention that the actuator can be pivoted to a position that lies entirely below the plane of the surface of the trailer bed. 
     It is yet another object of this invention to provide an actuator that can be manually powered or may be driven by a remote power source. 
     It is yet another object of this invention to provide an actuator that can be installed as a kit for existing dump or tilt trailers to provide a power apparatus for accomplishing the pivotal movement of the trailer. 
     It is still another advantage of this invention that the actuator can be selectively configured for operation in a power mode or in a free mode in which the actuator does not interfere with the gravity operation of the trailer to tilt. 
     It is yet another feature of this invention that a latch mechanism is provided to control the pivotal movement of the actuator between a raised operative position and a lowered inoperative transport position. 
     It is yet another object of this invention to provide a trailer operable to provide both tilt and dump functions which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
     It is a further object of this invention to provide an actuator that can provide powered tilt and dump operations for a trailer and be convertible between a raised operative position and a lowered inoperative transport position generally parallel to the trailer tongue. 
     These and other objects, features and advantages are accomplished according to the instant invention by providing a frame configuration that is particularly adaptable for use on a trailer such that the frame configuration is operable in both a tilt mode of operation and a dump mode of operation. An actuating mechanism includes a linear actuator that is supported on the frame by a bracket and a yoke that connects to a load bed to power the vertical movement of the load bed in both tilt and dump functions. The linear actuator is pivotally mounted to permit a re-positioning of the actuator into an inoperative position. The frame configuration is provided with an articulated tilt frame in which the tongue is pivoted thereto allowing the load bed to pivot about a tilt axis which can coincide with the wheel axis of the trailer. The bed frame can be locked to the tilt frame for tilting upon articulation with the tongue, while a disconnection of the bed frame from the tilt frame enables the bed frame to pivot about the dump axis to provide a dump function in addition to the tilt function. The actuator can pivot about the connection thereof to the bed frame to position the actuator into a lowered inoperative transport position generally parallel to the trailer tongue. A modified screw jack can be part of a kit that can be utilized to provide the powered operations of the tilt function for existing gravity-based tilt trailers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is a schematic right front perspective view of the articulated tilt frame and tongue of a trailer incorporating the principles of the instant invention; 
     FIG. 2 is a schematic right front perspective view of a trailer bed frame to be mounted on the articulated tilt frame and tongue of the trailer depicted in FIG. 1; 
     FIG. 3 is a schematic right front perspective view of a trailer frame assembly incorporating the principles of the instant invention to provide both a tilt function and a dump function for the trailer; 
     FIG. 4 is a cross-sectional view corresponding to lines  4 — 4  of FIG. 3 to depict an elevational view of one side of the trailer frame; 
     FIG. 5 is a schematic right front perspective view of the trailer frame of FIG. 3 with a bottle jack added to provide an actuator for the dump and tilt functions of the trailer frame; 
     FIG. 6 is a schematic right front perspective view of the trailer frame of FIG. 5 with an optional winch added to the tilt frame forwardly of the bottle jack; 
     FIG. 7 is an enlarged side elevational detail view of the bottle jack; 
     FIG. 8 is a front elevational view of the bottle jack depicted in FIG. 7 with a remote power option being depicted; 
     FIG. 9 is an enlarged front elevational view of the bottle jack shown in FIG. 5, the trailer bed frame being represented by the mounting members, the remainder of the trailer frame being deleted for purposes of clarity; 
     FIG. 10 is a side elevational view of the mounting of the bottle jack depicted in FIG. 9, the bottle jack being shown in an upright operative position; 
     FIG. 11 is a side elevational view similar to that of FIG. 10 but with the bottle jack being lowered into a horizontal inoperative position on top of the tongue; 
     FIG. 12 is a top plan view of the bottle jack, tongue and front portion of the trailer frame shown in FIG. 11; 
     FIG. 13 is a schematic side elevational view of the trailer incorporating the principles of the instant invention and depicting both the tilt function and the alternate dump function of the trailer relative to a normal transport position; 
     FIG. 14 is a side elevational view similar to that of FIG. 10, but depicting an alternative trailer bed lift jack arrangement utilizing a cable lift system; 
     FIG. 15 is a schematic side elevational view of the trailer moved into a dump position by the alternative trailer bed lift jack and cable lift system of FIG. 14; 
     FIG. 16 is front elevational view of a screw jack actuator operable to provide an assist to the tilt function of existing gravity-based tilt trailers, the trailer bed frame being represented by the mounting members, the remainder of the trailer frame being deleted for purposes of clarity; 
     FIG. 17 is a side elevational view of the latch mechanism for the screw jack actuator corresponding to lines  17 — 17  of FIG. 16; and 
     FIG. 18 is a cross-sectional view of the screw jack actuator corresponding to lines  18 — 18  of FIG. 17 to depict a top plan view of the latch mechanism. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1-6 the details of a trailer frame incorporating the principles of the instant invention can best be seen. Any references to left and right are used as a matter of convenience and are determined by standing at the rear of the trailer and facing the hitch to be connected to a vehicle, which would be the normal direction of travel of the trailer. The trailer  10  has a tongue  12  provided with a hitch  13  located at the forward terminus of the tongue  12  to connect in a known manner to a vehicle, such as a truck or a car to provide motive power for the movement of the trailer  10  over the surface of the ground G. The forward end of the tongue  12  can also be provided with a conventional support jack (not shown) to keep the hitch  13  at a convenient height when disconnected from any vehicle. The trailer  10  also includes an axle  15  on which tires  16  can be directly mounted on or, as is depicted in the drawings, to which tires  16  can be mounted through a pair of laterally opposed suspension arms  18 . The tires  16  are rotatable about the spindles  17  allowing the trailer  10  to be movable over the ground G in a conventional manner. The transversely extending spindles  17  also defines a tilt axis  19 , as will be described in greater detail below. 
     The tilt frame  20  can best be seen in FIG.  1 . The tilt frame  20  is preferably formed in an “A-frame” configuration and is rigidly connected to the axle  15  by mounting flanges  21 . A rear transverse support member  23  defines a dump axis  29 , to be described in greater detail below, and carries support brackets  24  pivotable about the dump axis  29  for attachment of the trailer bed frame  30 . A front transverse member  25  carries a pivot bracket  26  for pivotally connecting the tongue  12  for articulation about a horizontal articulation axis defined by the pivot bracket  26 . The side rails  22  of the tilt frame  20  converge to meet at a lock bracket  27  that is positioned in register with the tongue  12  so that a removable fastener  27   a  (best seen in FIGS. 1,  3 ,  5 ,  6 ,  11  and  12 ) can fix the apex of the tilt frame  20  to the tongue  12  and prevent any articulation of the tongue  12  relative to the tilt frame  20  about the pivot bracket  26 . Diagonally oriented support struts  28 , interconnecting the laterally spaced ends of side rails  22  and the center of the front transverse member  25 , provide rigidity for the tilt frame  20 . The converging side rails  22  each have a locking tab  22   a  welded on the inside. The locking tabs  22   a  are alignable with the mounting members  36  on the trailer bed frame  30 , for reasons to be described in greater detail below. 
     The trailer bed frame  30  can be seen best in FIG. 2 depicted as an independent structure. The trailer bed frame  30  has a pair of laterally spaced side rails  32  that are positionable above the side rails  22  of the tilt frame  20 . The side rails  32  of the bed frame  30  are formed with holes  33  for detachable connection by fasteners (not shown) to the support brackets  24 . As a result, the trailer bed frame  30  is pivotable about the dump axis  29 . The rearwardmost transverse frame member  34  is, therefore, positioned rearwardly of the rearward transverse frame member  23  of the tilt frame  20 . Accordingly, any pivotal movement of the trailer bed frame  30  about the dump axis  29  will result in the rearwardmost transverse frame member  34  of the trailer bed frame  30  dropping closer to the ground, while the rearward transverse frame member  23  of the tilt frame  20  maintains its normal elevation above the ground. 
     The trailer bed frame  30  further includes a forwardmost transverse frame member  35  provided with forwardly projecting mounting members  36  for connecting to the bottle jack  40 , as will be described in greater detail below. The mounting members  36  are positioned for alignment with the locking tabs  22   a  to permit the trailer bed frame  30  to be selectively locked to the tilt frame  20 . A tongue bracket  38  is fixed to the forwardmost transverse frame member  35  and to the second transverse frame member  37  and is positioned to surround the tongue  12  when the trailer bed frame  30  is positioned on top of the tilt frame  20  in its normal operating configuration. Central traverse frame members  31  are positioned between the second traverse frame member  37  and the rearmost traverse frame member  34  so that the trailer bed frame  30  will support planking or the like (not shown) to provide a trailer bed in a manner known in the art. 
     Referring now to FIG. 3, the trailer frame  11  can best be seen. The trailer bed frame  30  is mounted on top of the tilt frame  20  with the side rails  32  connected to the support brackets  24  for pivotal movement about the dump axis  29 . Removable pins (not shown) interengage the locking tabs  22   a  and the mounting members  36  to keep the trailer bed frame  30  locked to the tilt frame  20 . Alternatively, the locking tabs  22   a  can be formed with upwardly extending locking pins (not shown) that align with holes through the mounting members  36  which can then be locked into place by click pins, cotter pins, hair pins or the like. The bottle jack mounting brackets  57  are also shown in FIG. 3 connected to the tongue  12  forwardly of the tongue bracket  38  and rearwardly of the lock bracket  27 . The details of the bottle jack mounting brackets  57  are better seen in FIGS. 9-12 and are described below. The configuration shown in FIG. 3 is the normal operating position in which the trailer  10  can be towed along the public highway carrying a load without the capability of either tilting or dumping unless reconfigured as described in greater detail below. 
     The elevational details of the trailer frame  11  can best be seen in the cross-sectional view of FIG.  4 . The trailer bed frame  30  is positioned on top of the tilt frame  20 . The transverse bed frame members  31 ,  34 ,  35  and  37  have different thicknesses, as are represented by the lines shown in FIG.  4 . All of the transverse frame members  31 ,  34 ,  35 ,  37  of the trailer bed frame  30  terminate in a common plane forming the top surface of the trailer bed frame  30  so as to provide a planar surface  39  on which to mount the planking forming the bed (not shown) of the trailer  10 . The forwardmost transverse frame member  35  and the second transverse frame member  37  have a thickness that terminates just above the side rails  22  of the tilt frame  20 . The central traverse frame members  31  have smaller cross-sections and greater clearance above side rails  22 . The rearwardmost transverse frame member  34  has the largest cross-sectional configuration as there is no primary frame component immediately beneath the frame member  34 . The mounting flanges  21  are depicted as interconnecting the side rails  22  of the tilt frame  20  and the axle  15 . The side rails  32  of the trailer bed frame  30  nest over top of the mounting flanges  21  just outboard of the side rails  22  of the tilt frame  20 . 
     FIG. 5 depicts the mounted location of the bottle jack  40 , connected to the bottle jack mounting brackets  57  affixed to the tongue  12 . The details of the bottle jack  40  and the relationship thereof to the trailer frame  11  will be described in connection with FIGS. 7-12 below. One skilled in the art will recognize that the bottle jack  40  is depicted in FIG. 5 in a normal operating position, capable of lifting the trailer bed frame  30  relative to the tilt frame  20  about the dump axis  29 . While the bottle jack  40  is preferred because of its simplicity and economy, other hydraulic or electric actuators could also be substituted equally for the bottle jack  40 . In FIG. 6, an optional winch  14  is depicted as being mounted on the tilt frame  20  forwardly of the bottle jack  40 , preferably mounted on the lock bracket  27 . Preferably, the winch  14  is formed with bolts or connectors (not shown) depending downwardly therefrom to engage slots (not shown) formed in the lock bracket  27  that can receive the bolts (not shown) to provide a quick-attach system for the winch  14 . The winch  14  must be detachable to permit the bottle jack  40  to be reclined into an inoperative horizontal position, as will be described in greater detail below. The winch  14  can be operable with the bottle jack  40  in the upright position as the cable can pass between the bottle jack  40  and the legs  52  of the yoke  50 . 
     An extended stroke bottle jack  40  is depicted in FIGS. 7 and 8, with modifications to provide a more convenient pressure release valve  42 , an integral pump handle  45  and an optional fitting  44  for connection to a remote power source. The bottle jack  40  includes a handle  45  for pumping hydraulic fluid from an internal reservoir into the conventional operative internal chambers of the bottle jack  40 , causing the tip  46  at the distal end of the bottle jack  40  to extend upwardly. Manipulation of the pressure release valve  42  will allow the hydraulic fluid to return to the internal reservoir and permit the tip  46  to contract back to the housing  41 . The base  47  of the bottle jack  40  includes a clevis  48  adapted for pivotal connection to a support member, which in this configuration would be the tongue  12  in a manner described below. Preferably, the bottle jack  40  will be equipped with an optional fitting  44  that will allow the bottle jack  40  to be connected to a remote hydraulic system, such as on a tractor or the like (not shown), for operation thereof in lieu of the manipulation of the pump handle  45  and pressure release valve  42 . The release valve  42  will preferably be adapted to extend to a greater height above the base  47  to permit a convenient operation without requiring the operator to place his hands into the area of moving frame components. 
     The mounting of the bottle jack  40  is best seen in FIGS. 9-12. The clevis  48  is mounted by a pivot bolt  49  to a pair of upright links  58  pivotably supported on hubs  58   a  mounted in the bottle jack mounting brackets  57  and positioned on opposing sides of the tongue  12 . The upright links  58  transfer the load exerted on the bottle jack  40  through the hubs  58   a  to the bottle jack mounting brackets  57  and, therefore, to the tongue  12 . A pivot control quadrant  55  fixed to the base  47  of the bottle jack  40  on each side of the tongue  12  is also mounted on the pivot bolt  49  for pivotal movement in concert with the base  47  of the bottle jack  40 . The quadrants  55  extend vertically below the tongue  12  and restrain the bottle jack  40  in pivotal relationship with upright links  58  by a restraining pin  56  interengaging the quadrants  55 , the upright links  58  and the bottle jack mounting brackets  57  beneath the tongue  12 . As shown in FIGS. 9 and 10, the axes of the pivot bolt  49 , restraining pin  56  and bottle jack  40  are secured in a common plane. 
     A yoke  50  has an elevated bight portion  51  connected to the tip  46  by a fastener (not shown). A pair of legs  52  extend downwardly from the bight portion  51  for pivotal connection to the mounting members  36  projecting forwardly from the forwardmost transverse frame member  35  of the trailer bed frame  30 . The pivot axis  53  passes through the pivotal connection between the legs  52  of the yoke  50  and the mounting members  36 , the axis of bottle jack  40  and approximately concentrically through the pivot bolt  49  fastening the clevis  48  of the bottle jack  40  to the upright links  58 . The upright alignment of the bottle jack  40  follows the upward movement of the trailer bed reflecting the upward movement of the pivot axis  53  passing through the pivotal connection between the legs  52  and mounting members  36 . The upright links  58  are pivotable with the quadrants  55  about the restraining pin  56  defining the pivot axis carried by the bottle jack mounting brackets  57 . The bight portion  51  is rigidly fastened to the tip  46  of the bottle jack  40  so the extension of the tip  46  from the bottle jack  40  raises the yoke  50  and the connected trailer bed frame  30 . 
     Particularly since the bottle jack  40  is of a construction that extends upwardly a substantial distance above the tongue  12 , the bottle jack  40  in the upright operative position can be in the way of the loading some materials onto the trailer bed (not shown). Accordingly, it would be desirable to provide a mechanism for allowing the bottle jack  40  to be moved into a non-intruding inoperative position in such circumstances. The mounting apparatus described above provides such a mechanism. When the bottle jack  40  is desired to be moved into a lowered inoperative position, the restraining pin  56  is removed from engagement with the pivot control quadrants  55 , upright links  58  and the bottle jack mounting brackets  57  to allow the bottle jack  40  and the affixed pivot control quadrants  55  to pivot about the pivot bolt  49 . The connected yoke  50  will also pivot on its respective connection to the mounting members  36  about the concentric pivot axis  53  to allow the entire bottle jack  40  and connected yoke  50  to be lowered to a horizontal position on top of the tongue  12 , as is depicted in FIGS. 11 and 12. 
     While lowering bottle jack  40  and the connected yoke  50 , a limited amount of misalignment between pivot bolt  49  and pivot axis  53  can be accommodated as the upright links  58  can pivot relative to the bottle jack mounting brackets  57 . Furthermore, strain within the legs  52  will allow the axis of bottle jack  40  to slightly misalign with the pivot axis  53 . A reinstallation of the restraining pin  56  into aligned quadrant holes  59  and through the upright links  58  and the bottle jack mounting brackets  57  will retain the bottle jack  40  and attached yoke  50  in the lowered position. One skilled in the art will readily recognize that the optional winch  14 , if installed on the tongue  12 , would have to be removed before the bottle jack  40  and yoke  50  could be lowered to the inoperative transport position. 
     Referring now to all the drawings, but particularly the schematic multi-positional drawing of FIG. 13, the operation of the trailer  10  in both the tilt and dump functions can be seen. Referring first to the tilt position  60  of the trailer  10 , the operator must remove the fastener device  27   a  (best seen in FIGS. 1,  3 ,  5 ,  6 ,  11  and  12 ) interengaging the lock bracket  27  and the tongue  12  to permit the tongue  12  to articulate about its pivotal connection with the pivot bracket  26 . Since the trailer bed frame  30  is still fixed to the tilt frame  20  by virtue of the pins connecting the locking tabs  22   a  to the mounting members  36 , the trailer bed frame  30  will tilt with the tilt frame  20  about the tilt axis  19  defined by the spindles  17 . The tip  46  of the bottle jack  40  is free to extend from the housing  41 , thereby allowing the yoke  50  to move upwardly with the mounting members  36  to which it is attached. The bottle jack  40  is pivotable on the hubs  58   a  supporting the upright links  58  on the bottle jack mounting brackets  57 , allowing the bottle jack  40  to rotate rearwardly to accommodate the upward and rearward movement of the mounting members  36 . Once the trailer  10  is returned to the normal home position, the fastener  27   a  can be re-engaged between the lock bracket  27  and the tongue  12 . 
     Re-configuring the trailer  10  to permit the dump function to operate requires the removal of the pins (not shown) interconnecting the locking tabs  22   a  and the mounting members  36 , thereby releasing the trailer bed frame  30  for pivotal movement relative to the tilt frame  20  about the dump axis  29  for the positioning thereof in a dump position  61 , shown in FIG.  13 . To force the raising of the trailer bed frame  30 , the bottle jack  40  can be pressurized by stroking the pump handle  45 , or by connecting the optional fitting  44  to a remote source of hydraulic power, resulting in an extension of the tip  46  from the housing  41 . The attached yoke  50 , the legs  52  of which extend downwardly for connection to the mounting members  36 , then rises with the tip  46  and draws the forwardmost transverse frame member  35  of the trailer bed frame  30  upwardly, rotating about the dump axis  29  carried by the rear transverse frame member  23  of the tilt frame  20 . As with the tilt function above, the bottle jack  40  is pivotable about the hub connection  58   a  between upright links  58  and the bottle jack mounting brackets  57  to allow the bottle jack to rotate rearwardly to accommodate the upward and rearward motion of the forwardmost transverse frame member  35  as it pivots about the dump axis  29 . 
     Referring now to FIGS. 14 and 15, an alternative trailer bed lift jack assembly  70  can best be seen. A jack support  71  is fixed to the top of the tongue  12 , preferably by welding. The assembly  70  includes a jack post  72  fixed to the base  47  of the hydraulic jack  75  to elevate the base  47  of the hydraulic jack  75  above the tongue  12  a sufficient distance to locate a lower pulley  73  rotatably mounted on the jack post  72  at a position forwardly of the centerline of the lift jack assembly  70 . The jack post  72  is pivotally connected to the jack support  71  by a pivot pin  74 . A rod extension  76  is fixed to the tip  46  of the hydraulic jack  75  to rotatably mount an upper pulley  77  at a position spaced above the tip  46 . The rod extension  76  also provides a cable mount  78  to which is affixed the end of a cable  79  that is entrained around the lower pulley  73 , then entrained around the upper pulley  77  and connected to the trailer bed frame  30 . 
     The front wall of the trailer  10  is provided with a cam track  80  that is centrally mounted above the tongue  12  in register with the upper pulley  77 . The cam track  80  is preferably formed as a reinforced leg channel configured in a “C-shape” so as to allow the cable  79  to pass into the cam track  80 , but not the upper pulley  77  which rides on top of the cam track  80 . The base of the cam track  80  is supported by the trailer bed frame  30  and provides the connection point for the distal end of the cable  79  for lifting the trailer bed in a manner to be described in greater detail below. Both the lower and upper pulleys  73 ,  77  and the pivot pin  74  between the jack post  72  and the jack support  71  are offset from the centerline of the lift jack assembly  70 , the pulleys  73 ,  77  being offset forwardly of the centerline and the pivot pin  74  being rearwardly of the centerline, to reduce the bending moment on the piston of the hydraulic jack  75  and the moment urging the lift jack assembly  70  against the cam track  80  since two strands of the cable  79  are rearward of the hydraulic jack  75  and one strand is forward thereof. 
     The cam track  80  provides a track against which the upper pulley  77  rides as the trailer bed is being raised by the action of the lift jack assembly  70 . The cam track  80  prevents the lift jack assembly  70  and the third strand  83  of the cable  79  from rubbing against the bottom corner of the trailer bed. Preferably, the cam track  80  is detachable and is supported on a cam support  85  by a pin  84  that also attaches the cable  79  to the trailer bed frame  30 . Removal of the connecting pin  84  and the pivot pin  74  enables the entire lift assembly  70  and cam track  80  to be removed from the trailer  10 . 
     Operation of the lift assembly  70  effects a multiplication of the stroke of the hydraulic jack  75  through the three strands  81 ,  82 ,  83  of the cable  79 . As is best seen in the schematic view of FIG. 15, a 22.5 inch stroke of the hydraulic jack  75  will lift a standard trailer bed 67.5 inches to provide a 47 degree dump angle for the trailer bed. The upper pulley  77  maintains constant contact with the cam track  80  throughout the lifting operation, primarily due to the forces exerted by the first and third strands  81 ,  83  of the cable on the rearward side of the hydraulic jack  75 , which is offset only by the force exerted on the second strand  82  forwardly of the hydraulic jack  75 . The arrangement depicted in FIG. 15 provides substantially the same moment arm for the lift force exerted on the cable  79  about the dump axis  29  at the top of the stroke of the hydraulic jack  75  with the trailer bed at the maximum dump angle as at the bottom of the stroke with the trailer bed in a transport position. 
     While the intent of the alternate lift jack assembly  70  described above is to substitute for the bottle jack  40 , the trailer  10  would still be able to provide both the tilt and dump functions due to the frame arrangements  20 ,  30  described above. Removal of the alternate lift jack assembly  70  is preferred if the hydraulic jack  75  would be in the way of hauling a long load on the trailer bed, as opposed to the function of lowering the bottle jack  40  described above. However, lowering the alternative lift jack assembly  70  can also be accomplished if sufficient slack is provided for the cable  79 , as the alternative lift jack assembly  70  can be pivoted about the pivot pin  74 . It will be noted by one skilled in the art, however, that the height of the pulleys  73 ,  77  could still present a clearance problem for a long load, which is why a removal of the assembly  70  is preferred. 
     Referring now to FIGS. 16-18, a screw jack actuator  90  that can be utilized to provide a mechanical assist to the tilt function of a conventional gravity-based tilt trailer is best seen. The screw jack actuator  90  is an inexpensive extensible actuator that, with the other parts defined below, can be marketed as an after-market kit for use with previously existing tilt trailers. The screw jack actuator  90  is extensible and contractible in a conventional manner through operation of a crank handle  91  positioned at the top of the actuator  90 . Manual rotation of the crank handle  91  telescopically extends the bottom tip  92  of the actuator  90  which is fastened via a pivot pin  93  to the mounting brackets  57  affixed to the opposing sides of the trailer tongue  12 . As a result, the outer casing  94  of the screw jack  90  raises vertically. Since the yoke  50  is attached to a collar  95  fixed to the outer casing  94 , and since the legs  52  of the yoke  50  are connected to the mounting members  36 , the trailer bed pivots about the tilt axis as defined above to provide the tilt operation for the trailer  10 . 
     The bottom tip  92  is pinned to the telescopic section  96  that extends from the outer casing upon appropriate rotation of the crank handle  91  by a connecting pin  97 . When pinned, the bottom tip  92  fixes the telescopic section  96  to the mounting brackets  57  for extension and contraction in a normal manner. Removal of the pin  97  enables the bottom tip  92  to slide relative to the telescopic section  96  irrespective of the operation of the crank handle  91 . As a result, the removal of the pin  97  allows the outer casing  94  to freely move relative to the bottom tip  92  which has a substantial length extending into the telescopic section  96 . Thus, the trailer bed is free to move with the force of gravity or other external force to effect pivotal movement about the tilt axis. Accordingly, removal of the connecting pin  97  allows the conventional tilt trailer to operate in the conventional manner as though the screw jack  90  were not attached. 
     The bottom tip  92  is beveled, as is best seen in FIG. 17, to form a cam surface for interaction with the latching mechanism  100 . The latching mechanism  100 , which can be utilized with the bottle jack actuator  40  described above, is required because the actuator  90  is not stabilized by spaced apart pivots  49 ,  56  as is described above with respect to the bottle jack  40 . The latching mechanism  100  serves as a forward stop apparatus to control or restrict the forward pivotal movement of the actuator  90  and includes a latch plate  101  pivotally supported on the mounting brackets  57  and defining actuating levers  102  that project outwardly and forwardly through slots  103  formed in the mounting brackets  57 . The latch plate  101  is formed with a concave cutout  104  that conforms to the size and shape of the bottom tip  92  for engagement therewith to restrict pivotal movement of the screw jack  90  toward the lowered transport position, as is described above with respect to the bottle jack  40 . A pair of springs  105  interconnect the opposing ends of the pivot pin  93  with the corresponding actuation levers  102  to bias the levers  102  toward a raised position that interferes with the pivotal movement of the screw jack  90 . 
     A pair of stops  54  limit the rearward movement of the yoke  50  and connected screw jack  90  to prevent the screw jack  90  from tipping rearwardly too far. Accordingly, the screw jack  90  is trapped in the upright operative position between the stops  54  which restrict rearward pivotal movement of the actuator  90  and the latching mechanism  100  which restricts and controls the forward pivotal movement of the actuator  90 . Preferably the stops  54  are affixed, such as by welding, to the mounting members  36  and include adjustable heads  54   a , such as a carriage bolt, threaded into the stop  54  to engage the legs  52  of the yoke  50 . The adjustable heads  54   a  permit the stop to be reoriented for proper effectiveness. The latch mechanism  100  serves as a forward stop apparatus to limit the forward position of the screw jack  90  when placed in the upright operative position, thus trapping the screw jack  90  between the latch plate  101  and the stops  54 . 
     In operation, the screw jack  90  (or bottle jack  40 ) can be lowered to the inoperative transport position by depressing one of the actuation levers  102  to overcome the biasing force exerted by the springs  105 . The resulting pivotal movement of the latch plate  101  disengages the cutout  104  from the bottom tip  92  and allows the screw jack  90  to pivotally move about the axis  53  defined by the pivotal connection between the yoke legs  52  and the mounting members  36 . Returning the screw jack actuator  90  to the upright operative position is simply a matter of manually raising the screw jack  90 . The beveled cam surface of the bottom tip  92  engages the latch plate  101  to cause the latch plate  101  to deflect downwardly against the biasing force exerted by the springs  105  until the screw jack  90  reaches the upright position at which point the bottom tip  92  falls within the concave cutout  104  allowing the latch plate  101  to snap back into engaging position by the biasing force exerted by the springs  105 , trapping the screw jack  90  between the latch plate  101  and the stops  54 . 
     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiments of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. 
     In the way of example, one skilled in the art will recognize that the principles of the invention described above can be utilized on substantially any vehicle or apparatus having a load bed or other member that is pivoted relative to a frame. More specifically, these principles can be used to provide a dump bed on a pick-up or dump truck (not shown). The actuator  40  or  90  would be trapped between the bed of the pickup truck and the cab with the yoke  50  pivotally connected to the bed. Furthermore, by inserting an articulating tilt frame between the bed and the chassis of the truck, both tilt and dump functions could be selectively provided for the truck. 
     Also, the actuator could be in the form of a bottle jack  40 , which has its own internal reservoir of hydraulic fluid, a mechanically operated screw jack  90 , or other actuators such as a conventional hydraulic cylinder with an external port adapted for connection to a remote source of hydraulic power. Furthermore, the hydraulic cylinder could be mounted upside down, as compared to the depiction of the actuators  40  and  75  in the drawings, with the rod extending downwardly. In such a configuration, the hydraulic cylinder could have the hydraulic fluid supplied through a hydraulic connector associated with a hollow rod so that the port and associated hoses do not have to move vertically with the barrel of the hydraulic cylinder. 
     Still further, the yoke does not have to mount to the top of the actuator rod, but can be connected to the bottom of the hydraulic component moving vertically, particularly where the hydraulic cylinder is mounted upside down as described above. A similar configuration is shown and described above with respect to the screw jack  90 . A low profile configuration with the yoke mounted to the bottom of the vertically movable barrel would be particularly desirable with respect to the adaptation of the principles of the invention disclosed above in conjunction with a pick-up or dump truck.