Abstract:
A disabled truck recovery unit is detachably mountable on the back of a standard truck tractor to permit the standard truck tractor to be operable to tow a disabled truck tractor over the highway in a safe and effective manner. The disabled truck recovery unit includes an anchoring frame assembly connected to the standard truck tractor and an attaching frame assembly that can be connected to a disabled truck tractor to permit the towing thereof. The two frame assemblies are pivotally connected and powered by a single hydraulic actuator to convert the frame mechanism from a compact transport configuration to an operative position to engage the disabled truck tractor. A scissors linkage mechanism interconnects the hydraulic cylinder and the frame assemblies to effect proper movement thereof. An engine is mounted on the anchoring frame assembly to provide an independent source of operative power for the hydraulic cylinder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims domestic priority on U.S. Provisional Patent Application Ser. No. 60/381,357, filed May 17, 2002, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to transporting disabled vehicles and, more particularly, to a recovery unit for hitching a disabled truck tractor to a towing truck tractor. 
     Due to intense usage of truck tractor and trailer rigs in transporting the bulk of goods and freight over the nation&#39;s highways, it is to be expected that tractor breakdown will be a frequent occurrence. Typically, a disabled tractor has to be removed from the highway to a service facility in order for repairs to be made. Removal normally requires towing the disabled tractor by using a large tow truck specially equipped and dedicated for that purpose. However, such tow trucks are expensive and so in many areas of the country there are either none available or there will usually be considerable delay in obtaining the services of one when a breakdown occurs. 
     Over the years, several attempts have been made to temporarily adapt an ordinary truck tractor to perform such towing tasks in addition to its normal use as part of a tractor and trailer rig. The objective is to eliminate the need to locate a dedicated tow truck in order to remove a disabled tractor from the highway to a service facility. The advantage in being able to use another tractor is that such tractors are found with much greater frequency in all parts of the country than are dedicated tow trucks and thus one would surely be quickly and conveniently available about anywhere the need might arise. Representative of the hoist and towing mechanisms devised in the prior art for this purpose is the recovery unit shown and described in U.S. Pat. No. 4,708,358 (Gehman). Specialized tow trucks for retrieving disabled truck tractors are limited in turning capability when towing a disabled truck tractor. The recovery unit as shown and described in U.S. Pat. No. 4,708,358 simulates a trailer in that the articulated frame locked into the operative position turns like a truck trailer about the pivotal connection between the recovery unit and the fifth wheel of the towing truck. 
     This recovery unit of U.S. Pat. No. 4,708,358 utilizes at least three hydraulic cylinders coupled to two control valves to effect an unfolding and operative connection to a disabled truck tractor. A major problem in operating the recovery unit constructed as described in U.S. Pat. No. 4,708,358 is the coordination required between the operation of the two control valves operating the respective hydraulic cylinders. Improper coordination would result in the recovery unit binding due to the respective hydraulic cylinders urging pivotal movement about two or more axes. U.S. Pat. Nos. 5,988,664 and 5,845,920, issued to Hill teach that the recovery apparatus can be operated through the use of a single hydraulic cylinder; however, the frame mechanism cannot be compactly folded when being transported from one job site to another. These mechanisms take advantage of the fifth wheel on the towing tractor to convert it for towing a disabled tractor instead of a trailer. 
     It would be desirable to provide a disabled truck recovery unit that can be utilized with a standard truck tractor to tow a disabled truck tractor over the highway in a safe and effective manner using a single hydraulic actuator to convert the frame mechanism from a compact transport configuration to an operative position to engage the disabled truck tractor. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to overcome the disadvantages of the prior art by providing a disabled truck recovery unit utilizing a single hydraulic cylinder to operate the unit. 
     It is a feature of this invention that the disabled truck recovery unit incorporates a single hydraulic cylinder cooperable with linkage to convert the frame mechanism from a compact transport configuration to an operative configuration. 
     It is an advantage of this invention that the construction of the disabled truck recovery unit can be accomplished at less cost than has been previously known. 
     It is another object of this invention to configure a single hydraulic cylinder and associated linkage to provide the operation formerly accomplished by a truck recovery unit having three hydraulic cylinders. 
     It is another feature of this invention that the disabled truck recovery unit can be transported in a compact configuration. 
     It is another advantage of this invention that the hydraulic operation of the disabled truck recovery unit can be effected through manipulation of a single hydraulic control lever. 
     It is still another advantage of this invention that the disabled truck recovery unit can be constructed with fewer moving parts than has heretofore been known in the art. 
     It is still another feature of this invention that coordination between multiple hydraulic control valves to effect proper operation of a disabled truck recovery unit has been eliminated through the utilization of a single hydraulic control valve to effect operation of the unit. 
     It is still another object of this invention to provide a power unit as an integral part of the disabled truck recovery unit to provide operative power for the hydraulic cylinder effecting pivotal movement of the frame to operate the unit. 
     It is still another feature of this invention that the power unit can be in the form of an electric motor, a gasoline engine, or a diesel engine. 
     These and other objects, features and advantages are accomplished according to the instant invention by providing a disabled truck recovery unit that is mountable on the back of a standard truck tractor to permit the standard truck tractor to be operable to tow a disabled truck tractor over the highway in a safe and effective manner. The disabled truck recovery unit includes an anchoring frame assembly connected to the standard truck tractor and an attaching frame assembly that can be connected to a disabled truck tractor to permit the towing thereof. The two frame assemblies are pivotally connected and powered by a single hydraulic actuator to convert the frame mechanism from a compact transport configuration to an operative position to engage the disabled truck tractor. A linkage apparatus interconnects the hydraulic cylinder and the frame assemblies to effect proper movement thereof. An engine is mounted on the anchoring frame assembly to provide an independent source of operative power for the hydraulic cylinder. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is an elevational view of the disabled truck recovery unit unfolded into the operative configuration for engagement with a disabled truck tractor; 
     FIG. 2 is a top plan view of the disabled truck recovery unit shown in FIG. 1; 
     FIG. 3 is a perspective view of the disabled truck recovery unit shown in FIGS. 1 and 2; 
     FIG. 4 is a perspective view of the disabled truck recovery unit at a mid-position between the transport configuration and the operative configuration; 
     FIG. 5 is a perspective view of the disabled truck recovery unit folded into a position very close to the transport configuration; 
     FIG. 6 is a schematic representation of the disabled truck recovery unit disposed on a truck tractor and unfolded into the operative position and engaged with a disabled truck; and 
     FIG. 7 is a schematic representation of the disabled truck recovery unit in the full operative position with the rear drive wheels of the disabled truck tractor raised for transport over the highway. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1-5, a disabled truck recovery unit  10  incorporating the principles of the instant invention can be seen. This disabled truck recovery unit  10  is similar to the embodiment depicted in U.S. Pat. No. 4,708,358 granted to Roland P. Gehman, et al, on Nov. 24, 1987. The descriptive portions of U.S. Pat. No. 4,708,358 are incorporated herein by reference. This disabled truck recovery unit  10  improves on the device shown and described in U.S. Pat. No. 4,708,358 (Gehman) in that only a single hydraulic cylinder  42  and control valve  43  are required to operate the disabled truck recovery unit  10 , as will be described in greater detail below. Any references herein to such terms as “forward”, “rearward”, “left”, “right”, “upwardly”, “downwardly”, and the like are words of convenience and are not to be construed as limiting terms. Such terms are to be determined by standing at the rear of the towing truck tractor  20 , on which the recovery unit  10  would be mounted, and facing toward the towing truck tractor  20  into the normal direction of travel. 
     The disabled truck recovery unit  10  is primarily formed with an anchoring frame assembly  12  and an attaching frame assembly  14  composed of respective longitudinal beams  16  and cross beams  18  rigidly interconnected to form rectangular-shaped open structures, with the attaching frame assembly  14  preferably being slightly longer than the anchoring frame assembly  12 . As depicted in U.S. Pat. No. 4,708,358, support legs (not shown) and arms (not shown) can be utilized to support the disabled truck recovery unit in a free-standing condition on the ground under which an appropriate truck tractor can back underneath the disabled truck recovery unit to permit a detachable mounting thereon. Once the disabled truck recovery unit  10  has been mounted on the towing truck  20 , the support legs and arms are released and removed from the anchoring frame assembly  12 . Alternatively, the recovery unit  10  can be lifted into place by a fork lift (not shown) or other lifting device to be mounted on the towing truck  20 . 
     The anchoring frame assembly  12  has a plate  30  mounting a downwardly extending king pin  31  and being attached across its longitudinal beams  16  at the front portion of the anchoring frame assembly  12 . Similarly, the attaching frame assembly  14  has a plate  32  mounting a downwardly extending king pin  33  and being attached between a pair of the cross beams  18  at the rear portion thereof. The king pin  31  of the anchoring frame assembly  12  adapts it to be coupled to a fifth wheel  24  of the towing tractor  20 , whereas the king pin  33  of the attaching assembly frame  14  adapts it to be coupled to a fifth wheel  29  of a disabled tractor  25  (as seen in FIGS. 6-7) to be towed using the recovery unit  10 . 
     Also, the anchoring frame assembly  12  has pivot plates  34  mounted at the rearward end of the anchoring frame assembly  12  in which are formed upper and lower pivotal mounting holes  35 ,  35   a . The pivot plates  34  are attached to the anchoring frame assembly  12  at opposite sides of the rear portion thereof. Further, the attaching frame assembly  14  is provided with pivot plates  36  defining upper and lower complementary pivotal mounting holes  37 ,  37   a . The pivot plates  36  are attached to the attaching frame assembly  14  at opposite sides of the forward portion thereof to register with the pivot plates  34  on the anchoring frame assembly  12 . The pivot plates  36  of the attaching frame assembly  14  are pivotally mounted on the pivot plates  34  of the anchoring frame assembly  12  by pins  38  positioned through the corresponding upper holes  35 ,  37  to define a pivot axis  15  about which the attaching frame assembly  14  pivotally moves relative to the anchoring frame assembly  12 . 
     Such pivotal connection allows pivotal movement of the attaching frame assembly  14  between its stored and extended conditions relative to the anchoring frame assembly  12 , as seen respectively in FIGS. 3 and 5. When the attaching frame assembly  14  is pivoted to its extended condition, and more specifically to an operative position seen in FIG. 7, relative to the anchoring frame assembly  12 , pins  39  can be extended through the lower ones of their aligned complementary mounting holes  35   a ,  37   a  to rigidly lock the anchoring and attaching frame assemblies  12 ,  14  in fixed relation so as to form a solid towing beam which will interconnect the fifth wheels  24 ,  29  of the tractors  20 ,  25 . It will be noticed that when the attaching frame assembly  14  is at its transport or stored configuration, wherein the attaching frame assembly  14  overlies the anchoring frame assembly  12 , the attaching frame assembly  14  is incapable of being coupled to the disabled tractor fifth wheel  29 , whereas when the attaching frame assembly  14  is at its extended position, in which the attaching frame assembly  14  forms a rearward extension of the anchoring frame assembly  14 , the attaching frame assembly  14  is capable of being aligned with and coupled to the fifth wheel  29 . 
     Another basic component of the recovery unit  10  is an actuating mechanism. The actuating mechanism is formed by the hydraulic cylinder  42  and the actuation linkage mechanism  40  and is selectively operable to move the attaching frame assembly  14  relative to the anchoring frame assembly  12  between the stored or transport and extended or operative positions. Also, once the attaching frame assembly  14  has been moved to its extended condition and coupled to the fifth wheel  29  of the disabled tractor  25  the actuating mechanism is selectively operable to move the attaching frame assembly  14  to and from the towing position relative to the anchoring frame assembly  12  so as to place the frame  26  of the disabled tractor  25  in a raised towing position. 
     The hydraulic cylinder  42  can be powered from a hydraulic system onboard the towing truck  20 , but is preferably supplied by a power unit such as the engine  13  that is mounted directly on the anchoring frame assembly  12  of the recovery unit  10  beneath the hinged engine cover  13   a , which is depicted in the drawings in an elevated position to best depict the engine. Under normal conditions, the engine cover  13   a  is lowered to cover the engine  13 . A five and a half horsepower engine has been found to be sufficient to power the operation of the hydraulic cylinder  42 . Alternatively, the hydraulic system can be powered electrically from the towing truck  20 . Hydraulic hoses running between the hydraulic cylinder  42 , the control valve  43  and the power source for pressurized hydraulic fluid have been removed from the drawings for purposes of clarity, though one skilled in the art will understand that such conventional devices would be required to power the operation of the hydraulic cylinder  42 . 
     Unlike the actuating mechanism of U.S. Pat. No. 4,708,358, the actuating mechanism of the instant disabled vehicle recovery unit  10  is formed of a single hydraulic cylinder  42  coupled to an actuation linkage  40 . The actuation linkage  40  is formed with a pair of first links  44  extending from a pivot mechanism  45  to the anchoring frame assembly  12  and a pair of second links  46  interconnecting between said pivot mechanism  45  and the attaching frame assembly  14 . The linkage  40  works as a scissors linkage in that the respective pairs of links  44 ,  46  pivot about the pivot mechanism  45  as actuated by the hydraulic cylinder  42  to effect pivotal movement of the attaching frame assembly  14  relative to the anchoring frame assembly  12 , as will be described in greater detail below. 
     The general sequence of the pivotal movement of the attaching frame assembly  14  can be seen in FIGS. 3-5. The actuation linkage  40  is collapsed, as depicted in FIG. 5, by the extension of the hydraulic cylinder  42  which serves to push the pivot mechanism  45  away from the pivotal connection at the pivot axis  15  between the anchoring frame assembly  12  and the attaching frame assembly  14 . As one of ordinary skill in the art will recognize, the axis of the hydraulic cylinder  42  cannot pass over center with respect to the pivotal connections  47 ,  48  between the linkages  44 ,  46  and the respective frame assemblies  12 ,  14 . Full extension of the hydraulic cylinder  42 , however, will pull the attaching frame assembly  14  fairly close to the anchoring frame assembly  12  to form a compact transport configuration. 
     A stop plate  49  is provided on the linkage  44  to engage the opposing linkage  46  to prevent the actuation linkage  40  from folding over center with respect to the hydraulic cylinder  42 . Beginning with the transport configuration similar to that depicted in FIG. 5, a manipulation of the control valve  43  for the hydraulic cylinder  42  to cause the hydraulic cylinder  42  to retract, causes the pivot mechanism  45  to be pulled toward the pivot axis  15  and, thereby, spread the actuation linkage  40 . The spreading of the actuation linkage  40  causes the attaching frame assembly  14  to pivot about the pivotal connection thereof with the anchoring frame assembly  12  at the pivot axis  15  through a mid-point orientation as depicted in FIG. 4, to a fully opened, operative position as is depicted in FIG.  3 . Such pivoting of the attaching frame assembly  14  will bring its king pin  33  near to the fifth wheel  29  of the disabled tractor  25 . 
     The towing tractor  20  can then be backed toward the disabled tractor  25  to complete coupling of the king pin  33  to the fifth wheel  29 , as seen in FIG.  6 . At this point, the frame assemblies  12 ,  14  of the recovery unit  10  are resting on the respective frames  22 ,  26  of the truck tractors  20 ,  25 . A chain (not shown) or another attaching mechanism (not shown) is then employed for attaching the frame  26  of the disabled, towed truck tractor  25  to the attaching frame assembly  14 . This attaching mechanism (not shown) can be in the form of a pair of adjustable brackets (not shown) slidable along ledges (as is described in the aforementioned U.S. Pat. No. 4,708,358) on the longitudinal beams  16 . Flexible chains (not shown) are connected to the brackets (not shown) which are used by the operator in a conventional manner to interconnect the brackets and the frame  26  of the disabled tractor  25 . 
     After the attaching frame assembly  14  is coupled to the fifth wheel  29  of the disabled tractor  25  and the chains extended about the disabled tractor frame  26 , the hydraulic cylinder  42  is then extended to move the actuation linkage  40  as described above and urge the attaching frame assembly  14  upwardly. This movement of the attaching frame assembly  14  with the fifth wheel  29  of the disabled towed truck tractor  25  attached thereto first try to lift the disabled truck tractor  25 . Since the connection of the attaching frame assembly  14  to the towed truck tractor  25  is off center with respect to the center of gravity of the towed truck tractor  25 , the resultant action is to cause a tipping of the truck tractor  25 , and a corresponding raising of the rear wheels  27  of the towed truck off the surface of the ground, leaving the towed truck tractor  25  supported by the front wheels  28  and the attaching frame assembly  12 , as is depicted in FIG.  7 . 
     After reaching this operative towing position, pins  39  are then inserted by the operator into lower aligned holes  35   a ,  37   a  to lock the pivot plates  34 ,  36  of the respective frame assemblies  12 ,  14  together in this operative towing position to form the solid towing beam extending between and interconnecting the fifth wheels  24 ,  29  of the respective tractors  20 ,  25 . Reversal of the above-described operations will result in detachment of the attaching frame assembly  14  of the recovery unit  10  from the disabled tractor  25  after arrival at the repair service facility. The fixing of the disabled truck  25  to the attaching frame  14 , while leaving the anchoring frame  12  pivotally connected to the towing truck  20  through the connection of the king pin  31  and the fifth wheel  24  of the towing truck  20 , allows the recovery unit  10  and attached disabled truck  25  to simulate a normal trailer. Accordingly, the towed disabled truck  25  can turn freely about the fifth wheel  24  of the towing truck  20 . 
     After disconnection of the disabled truck tractor  25  from the attaching frame  14 , the hydraulic cylinder  42  is extended to push the pivot mechanism  45  away from the pivot axis  15  and cause a pivotal movement of the pivot links  44 ,  46  in a scissors-like manner to draw the attaching frame assembly  14  toward the anchoring frame assembly  12  through a pivotal movement thereof about the pivot axis  15 . A full extension of the hydraulic cylinder  42  will pivot the attaching frame assembly  14  into a compact transport configuration positioned over top of the anchoring frame assembly  12 . Re-attachment of the support legs (not shown) and associated structure as described in U.S. Pat. No. 4,708,358 will permit the anchoring frame assembly  12  to be disconnected from the towing truck tractor  30  and stored in an elevated position at a remote location for subsequent utilization. Alternatively, a fork lift (not shown) can be utilized to lift the recovery unit off the towing truck  20  and placed into storage. 
     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 embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.