Abstract:
A wheel lift tow accessory device includes coupling knuckles which are pinned to the ends of the piston rods of two hydraulic cylinders, which are used to deploy and retract the rotatable arms of the wheel lift arm accessories. A plate of the wheel lift arm accessory has a recess to couple with a groove in the attachment knuckle. The plate is welded to the rotating subassembly of each of the two wheel lift arm accessories. A rotary cam pin lock is securely welded to the same subassembly and positioned in registration with the open end of the recess is used to lock the knuckle securely in place or to permit its withdrawal from the recess when detaching each removable wheel lift arm.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of application Ser. No. 10/955,484, filed on Sep. 30, 2004, which is based in part upon provisional patent application Ser. No. 60/580,274, filed Jun. 15, 2004, and claims benefit under 35 USC 119(e) therefrom. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to interchangeable, multifunctional tow crossbars for tow trucks.  
       BACKGROUND OF THE INVENTION  
       [0003]     Hydraulically operated wheel lift arms are described in U.S. Pat. No. 6,139,250 of Nolasco for lifting medium weight vehicles, such as automobiles. Heavier vehicles are towed by hooks and axle forks.  
       OBJECTS OF THE INVENTION  
       [0004]     It is therefore an object of the present invention to provide interchangeable, multifunctional tow crossbars for tow trucks with structurally sound temporary connections for rotatable wheel lift arms, hooks or axle forks.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention is directed to a multifunctional tow crossbar with interchangeable components, allowing a tow truck to use a variety of towing accessories as need be under the circumstances.  
         [0006]     Existing tow crossbars are each attached to the outer distal end of a telescoping probe arm. A typical tow crossbar is located perpendicular to the probe arm.  
         [0007]     In the present invention, the tow crossbar is modified to accommodate the interchangeable towing accessories. For example, the tow crossbar of the present invention contains two integral hydraulic cylinders, which are removably attached to a pair of interchangeable rotatable wheel lift arm scoop claws.  
         [0008]     Removable and interchangeable accessories are provided which include the rotatable hydraulic wheel lift arm claws, chain (or cable) and sling, axle forks, and grab hook adapters and chains to tow very damaged vehicles. The axle forks and grab hook adapters and chain can be used with or without the chain and sling to protect the vehicle being towed as needed. All accessories can be attached or removed by a single worker. The accessories are compact and easy to store.  
         [0009]     Only the rotatable wheel lift arms require the use of the hydraulic cylinders built into the tow crossbar. For the other towing accessories, the two hydraulic cylinders swing slightly away from the tow crossbar at their respective outer distal ends, to create space for attachment. Manually operated spring pins insure securement of the removable wheel lifts to the tow crossbar. The wheel lift arm accessory includes two separate components, left and right. Each has a single fixed claw and one claw which rotates by hydraulic power from a retracted position, to a deployed position, which engages a vehicle wheel.  
         [0010]     Since inadvertent swinging of the rotatable wheel lift arm claw during attachment or detachment can be a safety hazard, a sleeve with a spring loaded ball is installed in the insert shaft of the removable wheel lift arm claw component. The ball is urged and engages a depression in the bracket of the rotating wheel lift arm claw, thereby locking it in the deployed position, so that it can be carried manually without slippage before or after use. Once the hydraulic cylinder is attached, it has no problem overpowering this safety latch.  
         [0011]     The chain and sling is simply attached by engaging an attachment ring in the rigid bar at the top to the snap hook attached to the end of the winch-operated chain or steel cable. The latter is suspended from the upper chain boom of the tow truck. The lower loop of each wide rubberized or fabric sling section is simply engaged with the left and right ends of the tow crossbar.  
         [0012]     The axle forks are weldments which include a fork welded to a short section of square crossection steel tubing. The latter is sized to slide over one end of the tow crossbar.  
         [0013]     The grab hooks are welded to the end of a short piece of square crossection steel tubing sized to fit inside the open end of the tow crossbar. Optionally, they are locked in place within the tow crossbar with a spring pin.  
         [0014]     In the preferred embodiment, specially designed attachment knuckles are permanently pinned to the ends of the piston rods of the two hydraulic cylinders, which are used to deploy and retract the rotatable arms of the wheel lift apparatus.  
         [0015]     This completely eliminates the use of straight drop pins or bolts in the attachment of the rotatable arms of this invention. Drop pins or bolts are easily lost and damaged.  
         [0016]     In the preferred embodiment, a plate with a recess to couple with a groove in the attachment knuckle is welded to the rotating subassembly of each of the two wheel lift arms. A rotary pin lock, which is securely welded to the same subassembly and positioned in registration with the open end of the recess, is used to lock the coupling knuckle securely in place, or to permit its withdrawal from the recess when detaching each wheel lift removable arm.  
         [0017]     In this preferred embodiment, attachment coupling knuckles are used with the interchangeable multifunctional tow crossbar of a tow truck. This tow crossbar typically is attached transversely to the rearward telescoping arm extending from a rear of the tow truck. The tow crossbar is mounted on the outer distal end of the telescoping arm. While the pair of hydraulic cylinders are each connected at their respective proximal ends to the tow crossbar, the knuckles are used to attach each piston rod at an opposite, distal ends of each of the hydraulic cylinders to wheel lift arms.  
         [0018]     Preferably, each hydraulic cylinder is pivotally attached to the tow crossbar, so that the hydraulic cylinders can be swung out of the way, when the piston rods are unattached to the wheel lift arms. Preferably, each optional cylindrical knuckle is removably mounted on a free end of each of the piston rods.  
         [0019]     Each coupling knuckle has a first end engaging the free end of a hydraulic cylinder piston rod and a second end engaging a wheel lift arm. The first end of the coupling knuckle has a socket to receive the free end of the piston rod, and a socket wall surrounding the socket. The socket wall includes transversely aligned openings to receive a pin for engagement with the piston rod. Likewise, the piston rod has transverse opening through which the knuckle pin passes.  
         [0020]     A slot in the knuckle socket wall extends from the first end of the coupling knuckle, to allow the coupling knuckle to pivot around the pin, up to 90 degrees with respect to the piston rod. An annular groove in the coupling knuckle is adjacent to the second end of the coupling knuckle, leaving a shoulder between the second end and the annular groove. The annular groove accommodates the wheel lift arm.  
         [0021]     The wheel lift arm preferably has a plate, with a recess, to receive a shoulder of the coupling knuckle. A rotatable lock pin attached to the wheel lift arm plate has a handle for rotating a cam which positions the lock pin linearly between retracted and locking positions. The rotatable lock pin member, operated by rotational movement of the handle, moves the locking pin linearly between the retracted and locking positions, with respect to the annular groove of the coupling knuckle. This allows the coupling knuckle to be placed into engagement with the recess of the plate of the wheel lift arm. The locking pin of the lock pin member, which has an upward locking position extending into the annular groove of the coupling knuckle, locking the coupling knuckle into engagement with the wheel lift arm, which has the lock pin member attached thereto. The movable retractable locking pin is moved in and out of engagement position with the annular groove of the coupling knuckle by the locking cam handle, which rotates the locking pin between retracted and locking positions.  
         [0022]     The coupling knuckle therefore provides releasable engagement between first and second towing accessory members, namely, each hydraulic cylinder and each respective removable wheel lift arm. It is preferably cylindrical in shape, and has a first end for engagement with a free end of the piston rod portion of the first towing accessory, such as the hydraulic cylinder, and a second end for engagement with the second member, which may be the removable wheel lift arm.  
         [0023]     The first end of the coupling knuckle has a socket to receive the free end of the first member, such as the piston rod of the hydraulic cylinder, and a socket wall surrounding the socket. The socket wall has transversely aligned openings to receive the locking pin for engagement with the rod shaped portion of the first tow accessory member, such as the hydraulic cylinder, which has a transverse opening through which the locking pin passes.  
         [0024]     A slot in the socket wall extends from the first end of the knuckle, to allow the knuckle to pivot around the locking pin up to 90 degrees, with respect to the rod shaped portion.  
         [0025]     The annular groove in the coupling knuckle is located adjacent to the second end of the coupling knuckle, leaving a shoulder between the second end and, the annular groove for engagement with the second member, such as a plate of the wheel lift arm assembly.  
         [0026]     The plate of the wheel lift arm has the recess to receive the shoulder of the coupling knuckle and to receive the rotatable lock pin of the cam-operable lock pin member, for rotational movement between a retracted position, allowing the coupling knuckle to be placed into engagement with the lift arm plate recess. Additionally, the locking pin extends into the annular groove of the coupling knuckle, locking the coupling knuckle into engagement with the second member, such as the wheel lift arm.  
         [0027]     The tow crossbar of the tow truck is multifunctional. For example, when the coupling knuckle is released, instead of the removable wheel lift arm assembly, the tow crossbar towing accessory may also be the aforementioned axle fork assembly or chain grab hook adapter. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]     The present invention can best be understood in connection with the accompanying drawings. It is noted that the invention is not limited to the precise embodiments shown in drawings, in which:  
         [0029]      FIG. 1  is a perspective rear view of a tow truck equipped with the tow crossbar and rotatable wheel lifts of this invention;  
         [0030]      FIG. 2  is a reverse perspective view of the tow crossbar showing hydraulic cylinders;  
         [0031]      FIG. 3  is a perspective view of two rotatable wheel lift arms prior to attachment;  
         [0032]      FIG. 4  is a perspective view of the tow crossbar with attached wheel lift arms showing one in a deployed position and the other in a retracted position;  
         [0033]      FIG. 5  is a perspective view of the driver&#39;s position while removing or installing a rotatable wheel arm;  
         [0034]      FIG. 5   a  is a side crossection of a ball spring plunger in a safety latch depression in a rotatable plate, taken along view lines “ 5   a - 5   a ” of  FIG. 5 ;  
         [0035]      FIG. 6  is a perspective view of a chain and sling accessory attached to a tow crossbar and a chain or cable;  
         [0036]      FIG. 7  is an exploded perspective view of the axle fork components adjacent the tow crossbar;  
         [0037]      FIG. 7   a  is a close-up detail view of the installed axle fork component;  
         [0038]      FIG. 8  is an exploded perspective view of the grab hook inserts adjacent the tow crossbar installation within end of tow crossbar;  
         [0039]      FIG. 8   a  is a reverse perspective view of an installed grab hook insert, secured to the tow crossbar via the spring pin, taken along the dashed line “ 8   a ” of  FIG. 8 ;  
         [0040]      FIG. 9  is a perspective assembly view of the attachment knuckle of the preferred embodiment and its attachment to the end of a piston rod;  
         [0041]      FIG. 9   a  is a perspective view of the attachment knuckle shown at a 90 degree angle to the piston rod;  
         [0042]      FIG. 10  is a reverse perspective view of the tow crossbar showing both hydraulic cylinders with coupling knuckles at the distal ends of their piston rods;  
         [0043]      FIG. 11  is a perspective view of a detail of the rotating subassembly of a wheel lift arm of the preferred embodiment during insertion into the crossbar;  
         [0044]      FIG. 12  is an enlarged reverse perspective detail view of the welded plate with a coupling recess that is part of the rotating wheel lift subassembly of  FIG. 11 ; and,  
         [0045]      FIG. 13  is a side perspective detail showing the pin of a rotary pin lock engaging the coupling knuckle thereby locking it to the rotating subassembly. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0046]      FIG. 1  shows a tow truck  1  equipped with a tow crossbar  13  of this invention. Truck  1  has an upper cable boom  8 , cable and snap hook  10 . Top and bottom plates  12  attach tow crossbar  13  to telescoping lower arm  11 . Hydraulic cylinders  14  and  15  are visible.  
         [0047]      FIG. 2  is a reverse perspective view of tow crossbar  13 . Hydraulic cylinder  14  with piston rod  18  is pivotally mounted between plates  12 . Stop pin  23  is mounted to lower plate  12 , and prevents cylinder  14  from unwanted movement adjacent to tow crossbar  13 . Manually operated spring pins  20  and  21  are shown installed on tow crossbar  13 , below and above cylinders  14  and  15  respectively. These pins serve to secure towing accessories during installation with tow crossbar  13 . Spring pins are manually retracted to allow removal of towing accessories.  
         [0048]      FIG. 3  shows right wheel lift assembly  30  and left wheel lift assembly  31  prior to attachment to tow crossbar  13 . Although only top rotatable plates  36  and  37  are shown, it is understood that identical plates underneath complete the mechanisms. Fixed wheel lift arm claws  32  and  33  are rigidly attached to insertion members  34  and  35  respectively which are to be inserted into the ends of tow crossbar  13 . Pivot pins  40  are also attached to these fixed members and plates  36  and  37  are free to rotate about pins  40 . Rotatable wheel lift arm claws  38  and  39  are rigidly attached to plates  36  and  37  respectively. Holes  41  accept pins  42 , which pass through bores  43  on piston rods  18 .  
         [0049]      FIG. 4  shows wheel lifts attached to tow crossbar  13 . Hydraulic cylinder  14  is extended in this view forcing claw  39  into the retracted position. Cylinder  15  is retracted thereby forcing claw  38  into the deployed position in this view.  
         [0050]      FIG. 5   a  is a crossection detail showing ball spring plunger  46  engaging depression  44  in top plate  36  or  37 , to effect safety latching in the deployed position, even with hydraulic cylinder  14  or  15  detached. This is a safety measure for workers, who have to manipulate either wheel lift assembly  30  or  31  when dislodging it from tow crossbar  13 , and then storing it on the deck of the truck, as seen in  FIG. 5 . The deck of the truck can be modified with recesses or pockets (not shown) for storage of the accessories.  
         [0051]      FIG. 6  shows a perspective detailed view of the portable sling accessory  50 . Top bar  52  is lifted via loop  51  engaged within snap hook  10  to cable  9  which is guided by cable boom  8 . Rubberized, fabric or leather straps  53  with distal flaps  54  protect the vehicle being towed. Loops  55  are installed over the outermost ends of tow crossbar  13 . This is made possible by swinging hydraulic cylinders away from tow crossbar  13 .  
         [0052]      FIGS. 7 and 7   a  shows a detail of axle fork assemblies  60 , which includes removable axle fork  62 , which is fitted to tube  61 . Tube  61  is welded to tubing collar of axle fork assembly  60 , sized to slip over tow crossbar  13 .  
         [0053]      FIG. 8   a  is a perspective detail of chain grab hook adapter assembly  70  including short tubing section  71  welded to grab hook  72 . Tubing  71  fits inside distal end of tow crossbar  13  and is locked in place via spring pins  20  and  21  through holes  74  and  75 .  
         [0054]     In the foregoing description certain accessories  30 ,  31  or  70  are shown inserted within the distal ends of the tow crossbar  13  and certain accessories  50  or  60  are shown surrounding the tow crossbar  13  in a cradle configuration.  
         [0055]     In an effort to eliminate the use of drop pins or bolts and to create a more secure and ergonomic coupling for the wheel lift arms of this invention, coupling knuckles  100 , as shown in  FIGS. 9 and 9   a , are pinned to piston rods  18  via the hole near the distal end of rods  18 . Rod  18  is inserted through the axial blind hole at the back end of coupling knuckle  100 . Then pin  107  with distal groove  108  is inserted through transverse holes  101  thereby engaging rod  18 . C-shaped lockring  109  is then inserted into groove  108 , thereby retaining the subassembly.  
         [0056]     In  FIG. 9 , the attachment knuckle  100  is shown axially aligned with respect to the end of a piston rod  18 . In contrast, in  FIG. 9   a  the attachment knuckle  100  shown at a 90 degree angle to the piston rod  18 .  
         [0057]     As shown in  FIGS. 9, 9   a  and  10 , coupling knuckle  100  can rotate a full 90 degrees clockwise by virtue of slot  105  giving access to pivotable movement of rod  18  within slot  105 . Coupling knuckle  100  also has engaging annular groove  103  as defined by spaced apart distal flange part  104 . Coupling knuckles  100  are shown assembled to hydraulic cylinders  14  and  15  in  FIG. 10 .  
         [0058]      FIG. 11  is a close-up detail view of rotating subassembly  110  of one of the two wheel lift arms, as coupling bar  34  is being inserted into tow crossbar  13 . The relative position of hydraulic cylinder  15  is also shown for reference. Welded structure top plate  114 , bottom plate  115 , and rotating wheel lift arm  38  pivot around axle pin  112  welded to fixed wheel lift part  32 . Plate  116  is welded to both top and bottom plates  114  and  115  respectively. Rotary pin lock  117  is poised above coupling recess  118  sized to accept the root diameter inside annular groove  103  of coupling knuckle  100 .  
         [0059]     Rear perspective view  FIG. 12  shows rotary pin lock  117  with handle  119  rotated to retract pin  120  from its bottom surface. Groove  121  in bottom plate  115  gives access to flange  104  of coupling knuckle  100 .  
         [0060]     Although plate  116  with recess  118  is obscured by pin  20  and knuckle groove  103  in this view, the extreme close-up detail view of  FIG. 13  shows coupling knuckle  100  inserted in recess  118  and locked in place with pin  120  extended from rotary pin lock  117  (shown in a rotated position of handle  119 ). Coupling knuckle  100  groove  103  has over 180 degrees contact with plate  116  and bottom plate  115  groove  121 .  
         [0061]     Although only one side of the preferred embodiment is detailed in these last  FIGS. 12 and 13 , the side not shown functions in the same manner. The only changes involve the position of recess  118  that is adjacent to the top plate, instead of the bottom plate, to match the vertical position of hydraulic cylinder  14  which is higher than cylinder  15 . The rotary lock pin is attached closer to the bottom plate and its operating handle is at the bottom with the pin extending from its top surface.  
         [0062]     The articulation of coupling knuckle  100  on pin  107  replaces the freedom of motion formerly afforded by straight drop pins  42  as shown in  FIG. 3  of a different embodiment. Groove  105  is necessary to avoid interference by piston rod  118 , during the motion required during deployment or retraction of the rotatable wheel lift arms  32  or  33 .  
         [0063]     It is noted however, the fact that whether the accessory is inserted internally within, or externally over, the outer opposite distal ends of the tow crossbar is not to be limiting, as those skilled in the art can provide connections to the tow crossbar  13 , regardless of whether the connections are internal or external to the distal ends of the tow crossbar  13 .  
         [0064]     In the foregoing description, certain terms and visual depictions are used to illustrate the preferred embodiment. However, no unnecessary limitations are to be construed by the terms used or illustrations depicted, beyond what is shown in the prior art, since the terms and illustrations are exemplary only, and are not meant to limit the scope of the present invention.  
         [0065]     It is further known that other modifications may be made to the present invention, without departing the scope of the invention.