Abstract:
A trailer has a load carrying bed to which a carriage frame and a coupling are slideably attached to opposite sides. Actuators are provided to move the bed with respect to both the carriage frame and the coupling. At least one wheel is attached to the carriage frame to support the utility trailer on the ground. When the coupling is connected to a hitch on a motor vehicle, operating the actuators lowers the bed against the ground to facilitate loading and unloading and raises the bed to enable the trailer to travel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not Applicable  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not Applicable  
       BACKGROUND OF THE INVENTION  
       [0003]     1. Field of the Invention  
         [0004]     The present invention relates to on-road trailers for towing behind a motor vehicle, and more particularly to utility trailers that have a single wheel.  
         [0005]     2. Description of the Related Art  
         [0006]     Utility trailers are commonly towed behind motor vehicles, such as pick-up trucks and automobiles, to transport relatively various kinds of loads. Most utility trailer trailers are designed for a specific application: for example, boat trailers, camping trailers, trailers with pods, and flat bed trailers. It is also known to utilize single-wheel utility trailer trailers for relatively light weight loads to reduce the cost of the device. The single wheel generally is displaced rearward of the trailer kingpin by which the trailer is coupled to the motor vehicle and that positioning enables the wheel to follow turns. To allow a motor vehicle with a single-wheel trailer to be driven backwards easily, it is common to use a double hitch which provides a non-articulated coupling.  
         [0007]     A typical single wheel utility trailer has a fixed rectangular bed and removable side walls. The single wheel is fixedly mounted beneath a longitudinal frame of the bed and cannot caster. Thus the wheel tends to skid laterally during a turn. Alternatively, a caster mounted wheel, as described in U.S. Pat. No. 4,645,230, can be used to follow the towing vehicle through turns.  
         [0008]     Although the bed of a utility trailer usually is only a foot or two above the ground the load being carried must be lifted onto and off of the trailer. One frequent use of a utility trailer is to transport a garden tractor, snowmobile or other article with wheels. Such transport requires the attachment of ramps to enable the article to be driven on and off the trailer. The ramps then must be carried on the utility trailer during the transport and stored when not required. Therefore, it is desirable to facilitate the loading and unloading of utility trailers, especially in a manner that does not require ramps.  
       SUMMARY OF THE INVENTION  
       [0009]     A utility trailer for towing by a motor vehicle comprises a bed with a platform for supporting a load that is carried by the utility trailer while traveling on a road. A coupling is moveably connected to the platform for mating with a hitch on the motor vehicle and a carriage frame also is moveably connected to the platform. At least one wheel is attached to the carriage frame to support the utility trailer on the road. An actuator assembly moves the platform with respect to the coupling and the carriage frame to raise and lower the platform with respect to the road.  
         [0010]     The actuator assembly enables the platform to be lowered against the road for loading and unloading the trailer. This allows articles with wheels, such as garden tractors and snowmobiles to be driven on and off the trailer platform. The actuator assembly raises the platform to enable the trailer to travel on the road when towed behind a motor vehicle.  
         [0011]     In one embodiment of the trailer, the carriage frame is slideably attached to the rear of the trailer platform and a first linear actuator produces motion there between. The coupling is similarly slideably attached to the front of the platform and a second linear actuator produces motion between those components. Operating the second linear actuator, while the platform is on the road, adjusts the height of the coupling to mate with a hitch on a motor vehicle. After that connection has been made, operating both linear actuators in unison raises the platform off the rod.  
         [0012]     A two wheeled trailer incorporating this novel platform elevating mechanism also is described. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a top view of a single-wheeled utility trailer according to the present invention;  
         [0014]      FIG. 2  is a side elevational view of the utility trailer with its bed lowered to the ground for loading and unloading;  
         [0015]      FIG. 3  is a rear elevational view of the utility trailer in  FIG. 2 ;  
         [0016]      FIG. 4  is a front elevational view of the utility trailer in  FIG. 2 ;  
         [0017]      FIG. 5  illustrates the hitch by which the utility trailer is attached to a motor vehicle;  
         [0018]      FIG. 6  depicts the utility trailer with its bed raised from the ground for travel; and  
         [0019]      FIG. 7  is a top view of a two-wheeled utility trailer according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     With initial reference to  FIGS. 1 and 2 , a utility trailer  10  for towing behind an automobile or a small truck, such as a pick-up truck, has a bed  12  having a front side connected to a vehicle coupling  14  and a rear side connected to a carriage frame  15 . The bed  12  comprises a rectangular under frame  16  with a number of cross members to provide internal support. For example, the under frame may be fabricated of square, tubular metal stock. A rectangular plate  20  of steel or similar material is attached to the upper side of the under frame  16  thereby providing a platform  21  on which to place a load for carrying by the utility trailer. In one embodiment, the platform  21  is formed by a center section  17 , to which the vehicle coupling  14  and the carriage frame  15  are connected, and a pair of side sections  18  and  19  removably fastened to opposite lateral sides of the center section. This embodiment enables the width of the utility trailer  10  to be adjusted to fit the load being carried.  
         [0021]     The rear side of the bed  12  has a pair of vertical posts  22  extending upward from the under frame  16 , spaced apart and centered about the middle of that rear side. The rear posts  22  form a first frame  23 . One or more cross members may extend between the two vertical rear posts  22  for strength. The carriage frame  15  is coupled to these rear posts in a manner that allows vertical motion there between. With additional reference to  FIG. 3 , a four of L-shaped guides  24  are attached to the outer lateral side of each rear post  22  and bend around the rear of the post. Space is provided between the read surface of each vertical rear post  22  and guides  24  to receive vertical legs  26  of the carriage frame  15  so that those legs can slide up and down along the rear posts  22 . A lower horizontal member  28  is welded between the two carriage frame legs  26 . A triangular wheel mount  30  projects outward from the top sections of each carriage frame leg  26  and is welded thereto. The wheel mount  30  has an aperture adjacent its remote apex. An inverted U-shaped wheel bracket  34  has a pivot shaft  32  extending upward through the aperture in the wheel mount  30  in a manner that allows the wheel bracket  34  to rotate horizontally. A wheel  36  is mounted on an axel  38  that extends through bearings at the remote ends of each leg of the wheel bracket  34 . The term “wheel” is generically used herein to include wheels with different types of tires and other wheels that allow an object to roll on a roadway.  
         [0022]     A first actuator  40 , such as a motor driven, ball-screw linear actuator, is connected between the carriage frame  15  and the bed  12  of the trailer. The actuator  40  has a DC motor  42  that is electrically powered from the motor vehicle that tows the trailer  10 , however hydraulically powered motors or a cylinder/piston assembly can be used as the actuator. A hand operated actuator, similar to those conventionally used on trailer hitches, also may be employed. In the illustrated embodiment, the motor  42  of the actuator  40  is secured to the carriage frame  15  with the actuator screw shaft  44  extending downward from the motor and having a remote end connected to a bracket  46  on the rear side of the under frame  16 . As will be described, the actuator  40  produces bidirectional, vertical motion between the trailer bed  12  and the carriage frame  15 . Depending upon the polarity of the electricity applied to the motor  42 , the screw shaft  44  is retracted into or extended from the motor, thereby producing up or down motion.  
         [0023]     With reference to  FIGS. 1, 2  and  4 , the front side of the bed  12  has another pair of vertically extending front posts  50  that are spaced apart by an amount that is centered on the mid-point of that side. The front posts  50  form a second frame  51 . Suitable cross members may be attached between the two vertical post  50  additional structural support. Four L-shaped guides  52  are located on the sides of the front posts  50 , in the same manner as guides  24  are attached to the rear posts  22 . The coupling  14  has frame  53  formed by a pair of vertical legs  54  and a pair of cross members  56  and  58  welded between upper and lower ends of the coupling legs  54 . The vertical legs  54  are received within the L-shaped guides  52  which direct the movement of those legs vertically along the front posts  50 . A coupling bracket  60  projects forward from the coupling  14 .  
         [0024]     With specific reference to  FIG. 5 , the coupling bracket  60  preferably is a T-shaped bar  61  with a square cross section that is sized to fit within the square receptacle  62  of a conventional motor vehicle hitch  63 . This type of receptacle  62  commonly receives a member with a ball that provides an articulated trailer coupling. Although a ball is not used with the present single wheeled trailer  10 , one may be provided on the coupling bracket  60  to accommodate conventional trailers as well as the novel traveler  10 . The hitch  63  is attached to the bumper  64  and the undercarriage of a motor vehicle. The receptacle  62  has a square opening  65  within which the forward end of the trailer coupling bracket  60  fits and a flange  66  extends around the opening. A hitch pin  70  is slid into aligned apertures  68  and  69  that extend horizontally through both the receptacle  62  and the coupling bracket  60  thereby securing the trailer to the motor vehicle hitch  63 . A pair of clamps  71  are pivotally attached above and below the bar  61 . When the coupling bracket  60  is slid into the hitch receptacle  62 , the clamps  71  are bolted together which grips the flange  66  on the end of the hitch  63  between the clamps further fastening the coupling bracket  60  to the vehicle.  
         [0025]     Hook plates  72  are welded to the ends of a cross member  73  of the coupling bar  61 . The opening of each hook plate  72  receives an upper pin  74  that is inserted into one of a series of vertically spaced apertures  75  in one of the vertical legs  54  of the trailer coupling  14 . Upon that engagement, a lower pin  76  is inserted in another one of the apertures  75  beneath the hook plate  72 . The spacing between adjacent apertures  75  is such that with the pins  74  and  76  in place, the hook plates  72 , and thus the coupling bracket  60 , can not the removed from the vertical legs  54 . This secures the components of the trailer coupling  14  together in a manner that allows the height of the coupling bracket  60  to be adjusted to accommodate variation in height of the hitch receptacle  62  on different vehicles.  
         [0026]     The adjustment is made by inserting a detached coupling bracket  60  into the hitch receptacle  62  on a motor vehicle. The vehicle is moved backward until the hook plates  72  are between the vertical legs  54  of the trailer coupling  14 . The upper pins  74  then are inserted into the vertical leg apertures  75  that are immediately above the hook plates  72  and the vertical legs  54  are lowered, as will be described, until those pins rest in the openings in the hook plates. The lower pins  76  are then inserted into the leg apertures  75  that are immediately below the hook plates  72 .  
         [0027]     Referring again to  FIGS. 1, 2  and  4 , a second actuator  77  produces vertical motion between the coupling  14  and the trailer bed  12 . This second actuator  77  preferably is identical to the first actuator  40 . For example, the second actuator  77  includes an electrically powered motor  78  attached to the coupling  14  with a drive screw  79  extending downward there from with a remote end attached to the under frame  16  of the bed  12 . Activation of the second actuator  77  extends or retracts the screw shaft from the motor  78 , thereby raising or lowering the coupling  14  along the bed posts  50 . The coupling  14  and in particular the coupling bracket  60  are illustrated raised upward along the front posts  50  of the bed  12 .  
         [0028]      FIG. 2  illustrates the trailer  10  with the bed  12  resting on the ground so that a load can be easily loaded or unloaded from the bed. This position facilitates loads with wheels, such as garden tractors and snowmobiles, to be easily driven onto and off of the platform  21 . In this position, activation of only the second actuator  77  raises and lowers the vertical legs  54  to a height at which they can be connected to the coupling bracket  60  on a motor vehicle. After the trailer  10  has been connected to the motor vehicle hitch, both of the actuators  40  and  77  are operated simultaneously to raise the bed  12  off the ground to a height at which the trailer can be pulled over a road as illustrated in  FIG. 6 .  
         [0029]     The present mechanism for raising an lowering the bed of a trailer also can be used on two-wheeled trailer, such as trailer  80  in  FIG. 7 . The bed  12  of the trailer  80  is the same as described previously for the single-wheeled trailer  10 . A carriage frame  82  is slideably coupled to the rear posts  22  of the bed  12  in the same manner as well. However, a T-shaped wheel mount  84  is welded to the legs  83  of the carriage frame  82 . An axel extends across the wheel mount  84  and a wheel  86  is attached to each end of that axel. Operating an actuator  88  raises and lowers the trailer bed  12  with respect to the carriage frame  82 .  
         [0030]     The coupling  90  at the front of the bed  12  is able to slide vertically along the front posts  50  when driven by another actuator  92 . The coupling  90  has a bracket  94  with a conventional socket  96  that is adapted to receive the ball of a standard trailer hitch. Because the trailer  80  in  FIG. 7  has two wheels  86 , a conventional pivoting, or articulated, coupling can be used to attach the trailer to a motor vehicle.  
         [0031]     The foregoing description was primarily directed to a preferred embodiment of the invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.