Abstract:
A trailer for use in transporting a load from one area to another area has a frame and a bed operatively mounted to the frame which is capable of being moved from a first or lowered position to a second or elevated position in a substantially vertical manner or nontilting manner. At least one lifting mechanism is operatively connected to the bed, which applies the greatest force for lifting the bed from the lowered position to the elevated position at the beginning of the lift, rather than at an end or midpoint of the lift. At least one over-center latching mechanism secures the bed to the frame when the bed is in the elevated position.

Description:
This application claims benefit of Provisional Ser. No. 60/118,885, filed Feb. 5, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is directed to a trailer which is especially useful in lifting and transporting pieces of equipment. The present invention is an improvement over a prior art trailer sold by bil-jax, Inc. of Archbold, Ohio including the Escalate Trailer Workforce® models ET 1500 and ET 2000. The prior art trailer is designed allow a piece of equipment to be transported from one place to another by being hitched to a vehicle. The prior art trailer has a bed which is lowered to the ground using a winch operation such that the bed does not tilt when being raised or lowered. When using the prior art trailer, a piece of equipment is positioned or moved onto the lowered bed. The bed is then raised by a winch into an elevated position so that the bed clears the ground. Operation of this prior art trailer included the raising or lowering by using a hand or automatic winch and cable which pulled the bed into a raised position. The prior art trailer required a great amount of power to raise the bed and the equipment thereon to the raised position. Accordingly, the person operating the trailer must exert extreme amount of effort to raise or lower the trailer. 
     The prior art trailer also was held in position by a standard type of toggle retaining latch to secure the bed to the frame once the bed was in the raised position. It is very important that the bed be very securely held in the raised position such that the equipment being hauled or transported is not damaged and that no injury occurs to the trailer operator. Such equipment often includes heavy and expensive equipment such as personnel lifts, trenchers, compactors, generators, appliances, tillers, welding equipment, lawn mowers, and the like. These pieces of equipment must be able to be securely held on the bed and not inadvertently become detached when the trailer is in use. 
     The primary object of the present invention is to provide an improved trailer where a bed can be raised and lowered in a non-tilting manner and can be used to transport heavy pieces of equipment. The trailer of the present invention includes a lifting mechanism and a passive locking mechanism which provide the operator with a great mechanical advantage thus reducing the amount of force required to raise and lower the bed. 
     In addition, the lifting mechanism and the locking mechanism together provide a trailer system having safety and energy conserving features. 
     SUMMARY OF THE INVENTION 
     The present invention is a trailer that can be operated by one person to move heavy and awkward loads or equipment and to transport or tow the load or equipment behind a vehicle. 
     The improved trailer of the present invention has a frame and at least one wheel and axle assembly on opposing sides of the frame. The wheel and axle assemblies allow the trailer to be readily moved from one location to a different location. The trailer also has a hitching mechanism so that the trailer can be towed by a suitable vehicle. 
     The trailer also has a moveable bed operatively attached to the frame. The bed has a bottom surface or deck and opposing sides which extend in a vertical direction from the deck. The sides of the moveable bed include at least one, and preferably a plurality of, cam follower tracks which extend at an angle from the deck to a top railing. The cam follower tracks matingly engage opposing cams mounted on the frame. The moveable bed is operatively connected to a lifting mechanism which raises and lowers the bed in a non-tilting manner. In a preferred embodiment, the lifting mechanism is operatively connected such that there is approximately a 2 to 1 mechanical disadvantage which advantageously harnesses the power potential of the lifting mechanism. The lifting mechanism which utilizes a small stroke and can be of a small size and still have sufficient power to raise and lower heavy loads. 
     The lifting mechanism is attached to the bed with a lever and a connecting bar. The connecting bar is pivotally attached at a first end to the bed and pivotally attached at a second end to a first end of the lever. The lever is pivotally connected at a midpoint to the lifting mechanism. The connecting bar attaches the lever to the bed in such a manner that the greatest force is exerted at the beginning of the lift, rather than at the end or midpoint of the lift. This feature reduces the risk of overloading the trailer. According to the present invention, it is not reasonably possible to partially raise any loads in excess of the rating of the lifting mechanism since the greatest force is exerted at the beginning of the lift. 
     The improved trailer of the present invention also includes a passive securing mechanism which is designed to lock the bed in place when the bed is in a fully raised position. The securing mechanism has a camming latch mechanism which engages a portion of the frame. The securing mechanism is held in place with a restraining mechanism, such as a spring, when the securing mechanism is in a latched position, thus reducing the risk of the securing mechanism becoming unlatched without an outside force being applied to the securing mechanism. When the bed is in a raised position, the bed is resting on level portions of cam follower tracks of the bed. The operator applies a force on the securing mechanism to release the securing mechanism from the bed. The bed is pushed back into angled portions of the cam follower tracks, thereby allowing gravity to lower the bed. The securing mechanism gives the operator a mechanical advantage, thus reducing the force required to lower the bed. 
     During operation of the trailer, a bed is lowered to the ground in a non-tilting manner and the load or equipment is easily positioned on the bed. The bed is raised in a non-titling manner to an elevated position so that the trailer can be attached to any suitable vehicle for towing. 
     The improved trailer of the present invention thereby provides a lifting and securing system which has additional safety and energy conserving features. One safety feature is a two-handed requirement in order to lower the bed. One hand of the operator is on the securing mechanism while the other hand is operating a power switch. Another safety feature is that the bed is triplely secured when in a raised position by, first, having the level portions of the cam follower tracks hold the bed in an engaged position; second, the over-center securing mechanism holds the bed in a locked position on the frame; and, third, the lifting mechanism is in a “bottomed out” or fully engaged position such that the lifting mechanism can not move any further, thereby holding the bed in a raised position. 
     Still another safety feature is the lifting mechanism which is operated in a unidirectional manner such that the lifting mechanism is only powered in one position; i.e., when raising the bed. The unidirectional power safety feature eliminates the risk of the operator powering down the bed without unlatching the securing mechanism, thus preventing any damage to the securing mechanism and/or the operator. 
     The main energy conserving feature is the unidirectional lifting mechanism which uses power in the up position, while allowing gravity to lower the bed. In a preferred embodiment, the lifting mechanism has a flow restrictor type device on a hydraulic cylinder to control the downward speed of the bed. The unidirectional lifting mechanism uses approximately one-half of the total energy of a power up/power down hydraulic cylinder. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of a trailer frame including a bed in a first or elevated position; 
     FIG. 2 is a side elevation view of a trailer frame including a bed in a partially lowered position; 
     FIG. 3 is a side elevation view of a trailer in a second or lowered position; 
     FIG. 4 is a plan view of a trailer frame; 
     FIG. 5 is a side elevation view of one side of a trailer bed; 
     FIG. 6 is a plan view of a trailer bed; 
     FIG. 7 is a side elevation view of another side of a trailer bed; 
     FIG. 8 is a side elevation schematic view of a locking mechanism in a first or locked position; 
     FIG. 9 is a side elevation schematic of a lock mechanism in a second or mid position; and 
     FIG. 10 is a side elevation schematic view of a lock mechanism in a third or unlocked position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A trailer, according to the present invention, is generally indicated in the drawings by the reference numeral  10 . The trailer includes a frame  11  having first and second longitudinally extending frame members  12 , rails  14 , and a support bar or end  16 . In the embodiment shown, the frame members  12  are in opposed parallel relationship. One end of each of the frame members  12  is operatively connected to longitudinally extending rails  14  which converge as the rails extend from the frame members  12 . The rails  14  terminate at an apex, or first end,  16 . The frame members  12  include a plurality of cam members  18  positioned in a spaced apart relationship along the longitudinal frame members  12 . Mounted on the frame members  12  is a bed  20  which includes a deck  22 , angled support portions  24  and cam follower tracks  26 . Individual cam follower tracks  26  matingly engage corresponding cam members  18  on the frame members  12 . Each cam follower track  26  defines a horizontal section  27  which is adjacent the deck  22 , as best seen in phantom in FIG.  1 . The bed portion  20  of the invention is found in the bil-jax, Inc. Escalate Trailer 1500 and 200 Models. Since a standard and commercially available bed is utilized, features of this bed will not be described in detail. 
     At least one wheel and axle assembly  30  comprising a wheel  32  and axles  34  is operatively mounted to each longitudinally extending frame member  12 . FIGS. 1-3 show the wheel  32  in phantom. 
     The trailer  10  further includes at least one lifting mechanism  40  which is operatively and pivotally mounted on the first end  16  of the frame members  14 . The hydraulic cylinder lift mechanism  40  comprises a source of power such as a cylinder  42  having a rod or first end  44  that is connected to a lever  50  at a midpoint  51 . The hydraulic cylinder lift mechanism  40  is operatively connected to a source of hydraulic fluid under pressure. The hydraulic fluid causes the rod  44  to advance and retract. The cylinder  42  is pivotally attached at a second or opposed end,  46  to the frame  11 . 
     The lever  50  is operatively connected at a first end  52  to one of the frame members  14  by means of a pivot means  54 . A second end  56  of the lever  50  is in a spaced apart relationship to the first end  52  and has a pivot means  58 . A connecting bar  60  is operatively connected to the second end  56  of the lever  50 . A first end  62  of the bar  60  is operatively mounted to the second end  56  by the pivot means  58 . The connecting bar  60  has an opposed or second end  64  which is pivotally mounted by a pivot means  66  to an upright portion  68  of the bed  20 . 
     Referring now to FIG. 3, the trailer  10  is shown in a down position. The rod  44  of the cylinder  42  is in an extended position. The lever  50  is rotated in a direction away from the cylinder means  40 . The connecting bar  60  is in an extended position such that an interior angle A° which is defined between the lever  50  and the connecting bar  60  is at its greatest point, and in a preferred embodiment is greater than about 90°. The cam members  18  are positioned at a top portion of the cam follower tracks  26 . 
     Referring now to FIGS. 1,  2  and  3 , when the trailer bed  20  is to be moved to an elevated position, the hydraulic cylinder lift mechanism  40  is activated. The rod  44  retracts in a direction toward the cylinder  42  such that the lever  50  pivots about the pivot point  54  in a direction toward the hydraulic cylinder lift mechanism  40 . The lever  50  and the connecting bar  60  pivot about the opposing pivot point  58 , thereby decreasing the angle A° between the lever  50  and the connecting bar  60 . The connecting bar  60  is attached to the bed  20  such that the greatest pressure is exerted at the beginning of the lift or elevation, rather than at the end or midpoint of the lift. This feature reduces the risk of overloading the trailer bed  20 . It is not reasonably possible to partially raise loads in excess of the power ratings of the hydraulic cylinder lift mechanism  40 . 
     As the cylinder rod  44  retracts and the lever  50  and the connecting bar  60  pivot, the bed  20  is pulled in an upward and forward direction toward the front or apex  16  of the trailer  10 . As the bed  20  moves upwardly, the cam follower tracks  26  slide along the corresponding cam members  18 . When the bed  20  is in a raised position, as shown in FIG. 1, the cylinder  42  has bottomed out, or is at the end of its stroke, and there is no more room to move. This acts as a safety feature to ensure that the bed  20  remains securely locked onto the frame  11 . 
     Another safety feature is a securing mechanism  80 , as best seen in FIGS. 8-10, which is positioned on a front supporting frame portion  82  of the frame  11 . The securing mechanism  80  provides an “over-center” securing of the bed to the frame such that, in order to detach the securing mechanism, the securing mechanism must be rotated or pivoted through an angle greater than 90°. The front frame member  82  is substantially perpendicular to the longitudinally extending frame members  12 . The securing mechanism  80  comprises a latch mechanism  84  having a slanted or cammed leading edge  86  and a rear engaging portion  88 . The cammed surface  86  and the rear engaging portion  88  define an engaging notch  90 . The latch  84  has a second end  94  which extends in an opposed direction from the cammed surface  86 . The second end  94  has an extending portion  96  which extends in a parallel direction to the rear engaging surface  88  and defines a first pivot point  98 . 
     The securing mechanism  80  includes a first pivot means  100  having a generally L-shape is operatively connected to a midpoint to the pivot point  98 . The first pivot means  100  is also operatively connected at a first end  102  to the frame  82  by a second pivot point  104 . The L-shaped pivot means  100  has a second end  106  which is in an opposed relationship to the pivot point  98  and the first end  102 . A handle  130  is operatively connected to the second end  106  of the L-shaped pivot means  100 . 
     The securing mechanism  80  also includes a second pivot means  110  having a first end  112  which is operatively connected by a pivot means  114  to the frame portion  82 . The second pivot means  110  is in a spaced apart relationship to the first pivot means  100  and from the pivot point  104  which connects the first or L-shaped pivot means  100  to the frame portion  82 . The pivot point  114  operatively connects the second pivot means  110  to the frame portion  82  such that the second pivot means  110  rotates about the pivot point  114 . The second pivot means  110  has a second end  120  which defines a slot  122 . The slot  122  operatively engages a pin or extending member  124  on the latch  84 . The pin member  124  is adjacent the second end  94  of the latch  84 . 
     The securing mechanism  80  further includes a spring or restraining mechanism  140  which is operatively connected at a first end  142  to the rear engaging portion  88  of the latch  84  and is operatively connected at a second end  144  to a lower portion  146  of the frame portion  82 . 
     When the securing mechanism  80  is in a locked position, as shown in FIGS. 1 and 8, the engaging notch  90  engages a portion or bar  150  of the bed  20  which is mounted in a parallel relationship to the frame portion  82 , as best seen in FIG.  1 . The engaging bar  150  extends between the raised bed portions  68  in a generally perpendicular direction. 
     The securing mechanism  80  provides an “over-center” locking position such that the forces applied to the securing mechanism  80  must pivot the locking mechanism through greater than 90°. The “over-center” locking position ensures that the locking mechanism is securely held in place. In addition, as the latch  84  is moved to the locking position, the camming surface  86  slideably moves along the engaging bar  150  until the engaging bar  150  is in alignment with the engaging notch  90 . The engaging bar  150  contacts the rear engaging portion  88  of the latch  84  and an audible “clicking” or “latching” sound is heard. 
     To operate the trailer  10  in a safe manner, the operator rotates the handle  130  in an upward direction such that the handle  130  and L-shaped pivot means  100  rotate about pivot points  98  and  104 . The latch  84  also rotates about and slides along the slot  122  and the pivot point  114 . The latch  84  rotates such that the engaging notch  90  is moved in a direction away from the engaging bar  150 . The spring  140  is stretched such that the latch  84  is held in a taut but engaged position. The operator continues to rotate the handle  130  in an upward direction, as now shown in FIGS. 2 and 9 and when the locking mechanism  80  is in a fully unlocked position, as shown in FIGS. 3 and 10, the L-shaped pivot means  100  has further rotated about pivot points  104  and  98  while the second pivot means  102  has further rotated about pivot point  114 . The pin member  124  has moved along the slot  120  to engage a lower portion  125  of the slot  122 . The latch  84  is completely free of the engaging bar  150  and the spring  140  is in a further extended position. 
     In order to operate the trailer a master power switch (not shown) is turned on in order to supply power to a battery  160 , schematically shown in FIG.  4 . The operator uses one hand to constantly hold an “up/down” switch  162  in a desired position. While using the other hand, the operator begins to rotate the handle  130  of the locking mechanism  80  in an upward direction, as described above. The operator keeps the first hand on the “up/down” switch  162 , holding it in either an “up” or “down” position to engage the lift mechanism  40 . In a preferred embodiment, the switch  162  must be held in position the entire time the bed  20  is in motion such that the operator&#39;s hands are safely out of any harms&#39; way. 
     It should be understood that changes can be made with respect to the number and sizes of lift mechanisms and/or securing mechanisms without departing from the scope of this invention or from the following claims.