Patent Publication Number: US-2003231944-A1

Title: Wheel-lift assembly for wreckers

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] The present application is based on U.S. Provisional Application Serial No. 60/371,418, filed on Apr. 11, 2002, entitled “Improved Underlift Assembly for Tow Trucks” by the inventors of the present application. The present application is further based on U.S. Provisional Application Serial No. 60/396,740, filed on Jul. 19, 2002, also entitled “Improved Underlift Assembly for Tow Trucks,” and also by the inventors of the present application. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention relates generally to tow trucks or “wreckers” for towing a vehicle, and more particularly to a tow assembly for wreckers which engages and lifts the two front wheels or the two rear wheels of the vehicle to be towed.  
       BACKGROUND OF THE INVENTION  
       [0003] From time to time, automobiles must be moved by external force or without the assistance of a driver for the automobile. These situations may arise when automobiles become disabled due to, for example, mechanical or electrical malfunctions. At other times, automobiles may be deemed to be parked illegally. At still others, repossession of the automobile may be desired by a creditor due to lack of payment or otherwise. Wreckers for towing automobiles by lifting either the front or rear wheels off the ground have long been used for these situations. The more modern and readily used types of wreckers or are known as “underlift” or “wheel-lift” wreckers. An underlift wrecker engages and lifts the vehicle to be towed at its frame members, and a wheel-lift wrecker engages and lifts the vehicle to be towed at its front or rear wheels, or tires.  
       [0004] Wheel-lift wreckers generally employ a telescoping or folding main crossbar element attached to the rear of the truck and extending rearwardly from or out beyond the truck&#39;s rear deck (the space between the rear of the cab and the rear bumper). The crossbar element represents the main lifting or leverage component for lifting one end of the vehicle to be towed (target automobile). Such wreckers also use a wheel engaging apparatus for engaging and holding the front or rear wheels of a vehicle. The wheel engaging apparatus (wheel cradle) typically includes a crossbar (also referred to as a “wheel boom”) pivotally attached to the end of a tow bar or main boom, and wheel retainers or lifting arms for engaging the wheels of the vehicle to be towed. When positioning the system for towing, the crossbar is maneuvered into a position against the tread of the tires and the lifting arms are then locked into a position securing the tires in place against the crossbar.  
       [0005] Examples of such prior art wheel-lift/underlift tow systems are found in U.S. Pat. No. 4,564,207 (the “&#39;207 Patent”) to Russ et al., entitled “Hydraulic Wheel Lift System for Tow Vehicles,” dated Jan. 14, 1986. The &#39;207 Patent employs a loosely fitting “sock” to adjust the wheel cradle. This “sock” of the &#39;207 Patent is not secure to the lifting arm and allows only a single adjustment of the wheel cradle. When a target automobile has been loaded onto a tow assembly, bumpy and uneven roads may be encountered. When such terrain is encountered, the towed vehicle&#39;s suspension sometimes allows vertical movement (“jounce”) toward the crossbar assembly, thus increasing chances that the oil pan or transmission of a towed vehicle might be damaged. The thicker the crossbar assembly of the wrecker, the greater the chances that the oil pan or transmission could be damaged upon transport of the target automobile.  
       [0006] Another example of a prior art wheel-lift tow system is found in U.S. Pat. No. 6,139,250 (the “&#39;250 Patent”) to Nolasco, entitled “Wheel Lift with Laterally Movable, Rotatable Swivel Arm Wheel Scoops,” dated Oct. 31, 2000, the entire disclosure of which is hereby incorporated by reference herein. As indicated hereinabove, the oil pan or transmission of a target automobile can possibly be damaged during towing if the automobile is not secured within the wheel cradle. The &#39;250 Patent lacks efficient safety or locking mechanisms for securing the tires of the target automobile to the wheel cradle.  
       SUMMARY OF THE INVENTION  
       [0007] The present invention relates to an improved wheel-lift assembly that includes an adjustable wheel engaging apparatus, or wheel cradle. The present invention includes a wheel cradle that is adjustable in several positions, thus allowing for adjustment for various sizes of automobiles and tires. The adjustable wheel cradle of the present invention reduces the chance that the oil pan or transmission of a target automobile will be damaged during transport. The adjustable wheel cradle is formed using a pair of substantially L-shaped rotatable lifting arms, a pair of support arms and a pivotable crossbar which form two substantially U-shaped configurations for receiving the front or rear tires of a target automobile. The L-shaped lifting arms are laterally displaceable. These lifting arms can be used to adjust the size of the wheel cradle when they are extended or shortened by sliding the lifting arms on a pair of support arms. The present invention also includes a relatively thin crossbar assembly which further reduces the chance that the oil pan or transmission will come into contact with the crossbar assembly during transport.  
       [0008] The present invention further includes an over-center locking mechanism such as the type generally described in U.S. Pat. No. 5,722,810 to Young et al., entitled “Over-Center Locking Mechanism for Tow Truck Wheel-Lift or the Like,” the entire disclosure of which is hereby incorporated by reference, and in U.S. Pat. No. 6,315,515 to Young et al., entitled “Over-Center Locking Mechanism for Tow Truck Wheel-Lift or the Like,” the entire disclosure of which is hereby incorporated by reference. The over-center locking mechanism used in the present invention automatically secures the lifting arms of the wheel cradle in place. This overcenter locking mechanism requires no manual engagement or extra steps beyond the normal procedure for engaging, lifting and towing the target automobile. Engagement of the lift arms and crossbar assembly with the wheels of the vehicle to be towed automatically sets the overcenter locking mechanism without the continued support of the linear actuators. The present invention further provides a tilt lock-out which may serve as either a back-up or primary security system. The tilt lock-out, like the over-center lock, is automatic and requires no manual engagement.  
       [0009] Another aspect of the present invention is a mechanism for preventing excessive movement of the wheel-lift assembly, as generally described in U.S. Pat. No. 5,672,042 to Bartel, entitled “Underlift Assembly Tow Trucks,” the entire disclosure of which is hereby incorporated by reference. A further aspect of the present invention is the improved wheel-lift in combination with an adjustable truck body, as described in U.S. Pat. No. 6,290,450 to Humphries, et al., entitled “Universal Wrecker Sub-Frame and Body Panel Assemblies,” the entire disclosure of which is hereby incorporated by reference. Still another aspect of the present invention is the improved wheel-lift together with an adjustable truck body having a lightweight body assembly, as described in U.S. Pat. No. 5,839,775 to Young et al., entitled “Lightweight Rust-Resistant Body Assembly for Tow Trucks and a Method of Manufacture,” the entire disclosure of which is hereby incorporated by reference. The Young, Humphries and Bartel patents are all assigned to the assignee of the present invention, Jerr-Dan Corp. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0010] Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent like elements throughout, and wherein:  
     [0011]FIG. 1 is a perspective view of a wrecker incorporating the wheel-lift tow assembly of an embodiment of the present invention.  
     [0012] FIGS.  2 A- 2 C are sequential side views of the wheel-lift tow assembly of an embodiment of the present invention as the wheel cradle is lowered in preparation for towing.  
     [0013]FIG. 3 is a top perspective view of the wheel cradle of an embodiment of the present invention as shown in FIG. 2C.  
     [0014] FIGS.  4 A- 4 C are sequential top views of an inventive wheel cradle&#39;s lifting arms as they are moved into position for towing.  
     [0015]FIG. 5A is a perspective view of the wheel-lift of an embodiment of the present invention showing the wheel cradles after full rotation of the lifting arms of the wheel-lift tow assembly.  
     [0016]FIG. 5B is a perspective view of the slideable wheel receiving grids of an embodiment of the present invention during adjustment for the wheel size of the target automobile.  
     [0017] FIGS.  6 - 14  are sequential side views of a wrecker incorporating the wheel-lift tow assembly of an embodiment of the present invention showing the operation of the wheel-lift tow assembly.  
     [0018]FIG. 15 shows a side view of the wheel-lift tow assembly of an embodiment of the present invention.  
     [0019]FIG. 16 shows a top view of a body assembly and sub-frame assembly used with a wheel-lift tow assembly according to an embodiment of the present invention.  
     [0020]FIG. 17 shows a left side view of a wrecker with adjustable sub-frame and body panel assemblies used with a wheel-lift tow assembly of an embodiment of the present invention.  
     [0021]FIG. 18 shows a top view of another embodiment of a body assembly and sub-frame assembly used with the wheel-lift tow assembly of an embodiment of the present invention.  
     [0022]FIG. 19 shows a top view of yet another embodiment of a body assembly and sub-frame assembly used with the wheel-lift tow assembly of an embodiment of the present invention. 
    
    
     DESCRIPTION OF THE INVENTION  
     [0023] The present invention is an improved wheel-lift tow assembly (also called an autoloader or self load wheel cradle) for towing vehicles with a wrecker. The wheel-lift is adapted to be mounted onto a wrecker, preferably on the rear deck.  
     [0024] Referring now to FIG. 1, illustrated is a perspective view of a wrecker  2  incorporating the wheel-lift tow assembly of the present invention. In this view, the tow assembly  1  is stowed prior to use. The wheel-lift tow assembly  1  is adapted to be mounted on the rear deck  3  of the wrecker  2 . The wheel-lift tow assembly  1  includes a crossbar assembly  10 , hydraulic cylinders  66 ,  68 , and a pair of moveable support arms  30 ,  32  which are connected to a pair of lifting arms  40 ,  42 . The support arms  30 ,  32  are spaced apart from each other, and pivot or swivel on the crossbar  10  to prepare the lifting arms  40 ,  42  for use.  
     [0025] The crossbar assembly  10  is relatively thin, and has no bolt projections or the like. The thickness of the crossbar assembly  10  is, for example, about four (4) inches. The relatively thin crossbar assembly  10  of the present invention presents a low profile in that it is of a lesser thickness than prior art crossbar assemblies. For example, the commercial version of the tow assembly described in the &#39;207 Patent, described hereinabove, known as the Dynamic autoloader, has a crossbar thickness of about 5-¼″ with extending projections.  
     [0026] The low profile of the wheel-lift tow assembly of the present invention facilitates safety and reduces the chance of damage to the target vehicle in that it lessens the possibility of the oil pan or transmission or body component of the towed vehicle engaging the crossbar assembly  10 . The crossbar assembly includes two slideable wheel receiving grids  15 ,  16  which engage the front portions of the front or rear tires of the target automobile during towing. The crossbar assembly  10  also includes a support beam  27  which telescopes when the tow assembly is in use so that the crossbar assembly  10  may be extended for target automobiles which are at a further distance from the wrecker. The telescoping functionality is provided by a hydraulic cylinder  67  or other actuating devices. Such actuating devices may be controlled by the operator of the wrecker using controls that are within his or her reach from the driver&#39;s seat.  
     [0027] Referring now to FIG. 2A, illustrated is a side view of the wheel-lift tow assembly  1  as the tow assembly is stowed prior to use. Multiple hydraulic cylinders  60 ,  62  or other actuating devices are used to control the position of the crossbar assembly  10 .  
     [0028] Referring now to FIG. 2B, hydraulic cylinders  60 ,  62  are used to lower and, if necessary, tilt, the wheel-lift tow assembly  1  closer to ground level. The tilting functionality is especially useful where the target vehicle is parked downhill or uphill from the wrecker. These cylinders  60 ,  62  also help to maintain the position of the crossbar assembly  10 , and allow the wheel-lift to maintain a substantially horizontal position. For example, when the wheel lift is about  30 ″ above the ground, the crossbar assembly  10  is also about  30 ″ above the ground. Referring now to FIG. 2C, the wheel-lift tow assembly  1  is shown after it has been fully lowered.  
     [0029] Referring now to FIG. 3, lifting arms  40 ,  42  include corresponding extension arm segments  44 ,  46  and engaging arm segments  47 ,  48 . The extension arm segments  44 ,  46  are operatively connected to the support arms  30 ,  32 . The extension arm segments  44 ,  46  are slideably moveable upon the support arms  30 ,  32 . The extension arm segments  44 ,  46  are relatively transverse to the crossbar assembly  10  at positions disposed to fit between the front or rear wheels of a target vehicle when the wheel-lift tow assembly  1  is in operation. The width of the extension arm segments  44 ,  46  of each of lifting arms  40 ,  42  are adjusted by slideably moving the lifting arms upon the support arms, and fixing lifting arms  40 ,  42  relative to support arms  30 ,  32 , as by inserting a mating pin  38  into one of several holes  33 ,  35  in extension arm segments  44 ,  46 , which hole has been aligned with a hole in each of support arms  30 ,  32 , so that the extension arm segments  44 ,  46  are set at a desired width responsive to the size of the tire of the target automobile. Each mating pin  38  should be secured, such as with a cotter pin  39 , and jam nut  41 , so that the extension arm segment does not move when the target automobile is mounted and towed. One such mating pin assembly may include a conventional cotter pin, jam nut and socket head capscrew.  
     [0030] Because of the dual pivoting connections  5 ,  7  for the support arm  32 /lifting arm  42  assembly, the pistons of the hydraulic cylinders  66 ,  68  travel along an arcuate path, rather than in a linear path as described in greater detail hereinbelow in connection with FIGS.  4 A- 4 C.  
     [0031] Since a wrecker is often moving during normal towing operation, it is preferable that the automobile or other vehicle being towed is securely engaged with the tow assembly. The hydraulic cylinders  66 ,  68  enable the lifting arms  40 ,  42  to maintain engagement with the wheels of the towed vehicle, e.g., when the wrecker turns corners, thus promoting stability. The hydraulic cylinders  66 ,  68  of the improved wheel-lift of the present invention are pivotally connected to the end of each of the support arms  30 ,  32 .  
     [0032] In FIG. 3, the wheel-lift tow assembly  1  has been unfolded and lowered from the wrecker nearer to ground level, so that the support arms  30 ,  32  and lifting arms  40 ,  42  would be substantially horizontal to a level ground.  
     [0033] FIGS.  4 A- 4 C depict one representative side view of the wheel-lift of an embodiment of the present invention. The other side is substantially identical. Referring now to FIG. 4A, when the wheel-lift tow assembly  1  is first lowered, the hydraulic cylinder  66  near the support arm  32  has not been actuated. Referring now to FIG. 4B, the hydraulic cylinder  66  is actuated, thus rotating the lifting arm  42  outward via links  52   a ,  52   b . The lifting arm  42  moves in an arcuate pattern until the base portion of lifting arm  42  is substantially parallel with the wrecker&#39;s length.  
     [0034] Referring now to FIG. 4C, as the lifting arm  42  rotates into position, the cylinder  66  pushes links  52   a ,  52   b  into an over-center position, i.e., where the pivotal joint between links  52   a  and  52   b  are located at or beyond the 180 degree point. The lifting arm  42  is locked into position by the links  52   a ,  52   b  and the lifting arm  42  cannot be forced out of position by a loss of hydraulic pressure.  
     [0035] Referring now to FIG. 5A, which shows both sides of the wheel-lift of this embodiment of the present invention, over-center locking mechanisms  50  and  52  include links  50   a ,  50   b  and  52   a ,  52   b , respectively, whereby extension of the hydraulic cylinders  66 ,  68  position the links  50   a ,  50   b ,  52   a ,  52   b  in a locking position, such that outward pressure by the wheels of a vehicle in tow against the engaging arm segments  44 ,  46  forces the links  50   a ,  50   b ,  52   a ,  52   b  toward the locking position. The locked or wheel engaging position is therefore automatically maintained without the aid of the hydraulic cylinders  66 ,  68 , in case of a failure of hydraulic cylinders  66 ,  68 . In other embodiments of the present invention, the over-center locking mechanisms  50 ,  52  are attached to wheel receiving grids that are fixed to the crossbar  10  rather than slidable, or are attached directly to the crossbar  10 .  
     [0036] Still referring to FIG. 5A, wheel cradles  21 ,  22  are formed by the support arms  30 ,  32 , the lifting arms  40 ,  42 , and the slideable wheel receiving grids  15 ,  16 , respectively. In the position shown, the wheel cradles  21 ,  22  are prepared to receive the two front wheels of the target automobile, or the two rear wheels of the target automobile.  
     [0037] The slideable wheel receiving grids  15 ,  16  automatically adjust position relative to the crossbar  10  according to the distance between the target vehicle&#39;s front or rear tires. FIG. 5B illustrates the wheel receiving grids  15 ,  16  when they have automatically moved outward from the center of wheel-lift  1  due to the extension of hydraulic cylinders  66 ,  68 . During a normal towing operation, the wheel receiving grids  15 ,  16  move outward until support arms  30 ,  32  and/or extension arm segments  44 ,  46  of lifting arms  40 ,  42  contact both front tires and/or wheels of the target automobile. The present invention can include an adjustment mechanism that allows the wheel receiving grids  15 ,  16  to slide outward until a single tire of a target automobile is contacted. Once a single tire is contacted, the wheel receiving grids  15 ,  16 , which have been set into motion by the hydraulic cylinders  66 ,  68 , stop their outward expansion, and the pressure of the hydraulic cylinders  66 ,  68  is equalized so that the target automobile is centered onto the wheel-lift tow assembly.  
     [0038] When lifting arms  40 ,  42  contact the tires and/or wheels, they can maintain or assist retention of the tires in cradles  21 ,  22 . In certain embodiments of the present invention, appropriate bearing surfaces (not shown) can be attached to support arms  30 ,  32  and/or extension arm segments  44 ,  46  to engage the wheels; e.g., a concave cup that bears against each respective wheel.  
     [0039] The wheel-lift tow assembly of the present invention is highly versatile in that the truck need not be positioned directly in front of the car in order for the tow assembly to operate properly. An automobile can be loaded onto the wheel-lift tow assembly of the present invention when the automobile is directly behind the wheel-lift tow assembly so that an angle of approximately zero degrees exists between the driver&#39;s side of the wrecker and the left side of the target automobile. A target automobile can be loaded onto the wheel-lift tow assembly also when the left side of the target automobile and the left side of the wrecker are at substantially a ninety degree angle from one another. A hydraulic cylinder  67  in the telescoping central support beam  27  of the crossbar assembly allows the telescoping central support beam  27  to be extended. As discussed above, the size of the wheel cradles  21 ,  22  can be adjusted by adjusting the lifting arms  40 ,  42  to fit the tire size.  
     [0040] The operation of the wheel-lift of an embodiment of the present invention will now be described with reference to FIGS.  6 - 14 . As shown in FIG. 6, a cradle is prepared for one tire of the target automobile. In this illustration, the automobile&#39;s front right tire is inserted into the cradle. When the crossbar assembly  10  touches the front right tire, the pivot  25  in the crossbar assembly  10  permits the wheel cradles  21 ,  22  to be lined up with the front tires of the target automobile so that the automobile can be towed.  
     [0041] Wheel cradles  21 ,  22  are formed by the lifting arms  40 ,  42  and the wheel receiving grids  15 ,  16  when the wheel-lift tow assembly  1  is in operation. As previously described, over-center locking devices  50 ,  52  ensure that the lifting arms  40 ,  42  of the formed wheel cradles  21 ,  22  are safely maintained in their rotated position even if a hydraulic cylinder fails. Referring now to FIG. 7, after the right front tire of the target automobile is within the frame of the wheel cradle  21 , the wrecker operator moves the wrecker in reverse. The crossbar assembly  10  contacts the right front side tire and begins to pivot around the pivot point  25 , thus turning the wheel cradles  21 ,  22  so that the openings for wheel cradles  21 ,  22  are aligned with the front tires (or rear tires) of the target automobile.  
     [0042] Referring now to FIG. 8, the wrecker operator continues to move the truck in reverse until the crossbar assembly  10  contacts the left front tire of the automobile. The pivot point  25  of the crossbar assembly  10  wheel-lift tow assembly  1  is centered with the tires of the automobile.  
     [0043] Referring now to FIG. 9, over-center locking devices  50 ,  52  are automatically activated when the lifting arms  40 ,  42  are perpendicular to the wheel receiving grids  15 ,  16  and hydraulic pressure is applied to cylinders  66 ,  68 . The wheel receiving grids  15 ,  16  expand outward due to the hydraulic pressure, as explained above, until the wheel cradles  21 ,  22  gently contact both front tires of the target automobile. As also explained above, once a single tire is contacted, the wheel receiving grids  15 ,  16  stop their outward expansion, and the pressure of the hydraulic cylinders  66 ,  68  is equalized so that the target automobile is centered onto the wheel-lift tow assembly.  
     [0044] Referring now to FIG. 10, the operator raises the telescoping central support beam by activating a hydraulic cylinder in the wheel-lift tow assembly. Accordingly, the front portion of the target automobile is also raised. The operator uses controls within reach of the driver&#39;s seat to control the cylinders. The crossbar pivot  25  is centered with the automobile as shown in this illustration.  
     [0045] Referring now to FIG. 11, the target automobile has been prepared for towing. The operator now moves the wrecker forward, while the target automobile begins to pivot at its rear axle. Referring now to FIG. 12, the wrecker operator continues to move forward, and the target automobile, which is now securely mounted on the wheel-lift tow assembly, begins to straighten and follow the wrecker.  
     [0046] Referring now to FIG. 13, the two truck operator retracts the telescoping central support beam  27  and adds all appropriate towing and safety attachments. For example, a strap may be used to further secure or tie down the wheels of the target automobile to the wheel-lift tow assembly in a conventional manner. The strap could be adjusted with a ratchet mechanism. Another example of such an additional towing or safety attachment is a tow ball attachment that allows the wrecker operator to recover and tow trailers requiring a tow ball hookup.  
     [0047] Referring now to FIG. 14, the wheel-lift tow assembly pulls the car to the desired location.  
     [0048] Referring now to FIG. 15, disclosed is another embodiment of the wheel-lift tow assembly of the present invention. This embodiment of the wheel-lift tow assembly incorporates a mechanism for preventing excessive movement, such as that described in U.S. Pat. No. 5,672,042, which has been incorporated by reference herein. The wheel-lift assembly  118  has a support arm  120  that is coupled to the wrecker. A base  122  is coupled at a first end  124  to the support arm  120 . A boom base  126  is pivotally attached to the base  122  at a first pivot point  128 . The first pivot point  128  is preferably located adjacent to a second end  130  of the base  22  that is opposite to the first end of the base  124 , and adjacent to a first end  132  of the boom base  126 . The boom base  126  has a first end  132  and a second end  134 . The second end  134  is located nearer to the first end of the base  124  than is the first end of the boom base  132 . A boom  136  is pivotally attached to the boom base  126  at a second pivot point  138  that is preferably located further from the first end of the boom base  132  than the first pivot point  128 . A first actuator  140  is coupled to the support arm  120  by a pivot pin  142  and the boom base  126  by a pivot pin  144 . The first actuator  140  pivots the boom base  126  with respect to the support arm  120 . A second actuator  146  is coupled to the boom base  126  by pivot pin  148  and the boom  136  by pivot pin  150 . The second actuator  146  pivots the boom  136  with respect to the boom base  126 . Vehicle engaging attachments, such as the inventive wheel-lift  1 , are connected to a distal end of the boom which may engage the target automobile&#39;s frame or wheels.  
     [0049] In this embodiment of the wheel-lift tow assembly of the present invention, a first stop  152  is attached to the boom base  126 . The first stop  152  is preferably located between the second pivot point  138  and the second end of the boom base  134 . A second stop  154  is attached to the boom base  126 . The second stop  154  is preferably located below the first pivot point  128 . The first and second stops  152 ,  154  restrict the pivot range of the boom  136  with respect to the boom base  126 . The first stop  152  and the second stop  154  restrict the boom  136  from pivoting below a line formed by a lower edge of the boom base  156 .  
     [0050]FIG. 16 shows a top view of the body assembly and sub-frame assembly of another embodiment of the present invention. The body assembly comprises left and right body panels  231  and  232 , each with a pair of mounting brackets  233  and  234 , respectively. The left and right body panels mount on a body sub-frame assembly, which comprises left and right sub-frame members  235  and  236 . Each sub-frame member comprises a sub-frame rail  237 ,  238 , a pair of body support brackets  239 ,  240 , and three sub-frame brace tubes  241 ,  242 . The left and right sub-frame members are held together as the body sub-frame assembly via three sub-frame brace sleeves  245 . Except where expressly stated otherwise, the left and right body panels  231  and  232 , and the left and right sub-frame members  235  and  236 , are mirror images of each other.  
     [0051] As illustrated in FIG. 16, the body sub-frame assembly is assembled with two opposing sub-frame members  235  and  236  connected together with their respective sub-frame brace tubes  241  and  242  inserted into respective sub-frame brace sleeves  245 . Each of the three sub-frame brace tubes  241  of the left sub-frame member  235  is inserted into one end of a sub-frame brace sleeve  245 . Each of the three sub-frame brace tubes  242  of the right sub-frame member  236  is inserted into the other end of the sub-frame brace sleeve  245  opposite to a corresponding subframe brace tube  241 . The sub-frame brace tubes  241 ,  242  are inserted a predetermined distance into the sub-frame brace sleeves  245 .  
     [0052] The sub-frame brace tubes  242  are fixed to the sub-frame rail  238  of the right sub-frame member  236 , and the sub-frame brace tubes  241  are fixed to the sub-frame rail  237  of the left sub-frame member  235 . The predetermined distance that the sub-frame brace tubes  241 ,  242  are inserted into the sub-frame brace sleeves  245  is set such that the sub-frame rails  237  and  238  line up with the chassis rails  213  and  214 , respectively. The sub-frame brace tubes are welded into the sub-frame brace sleeves in that position. The body sub-frame assembly is then ready for mounting on the desired chassis.  
     [0053]FIG. 17 shows a left side view of a wrecker  210  equipped with adjustable sub-frame and body panel assemblies in accordance with the exemplary embodiment of the present invention. The wrecker also includes a lift assembly for towing a disabled vehicle. A wide variety of different lift assembly embodiments can be employed with the adjustable sub-frame and body panel assemblies of the present invention, and following description illustrates one such embodiment. The wrecker comprises a chassis  212 , with a cab  211  and lift assembly  250  mounted thereon. The lift assembly includes a main boom  255  (or crossbar assembly) pivotally mounted to the truck chassis with a hydraulic system (not shown) for raising, lowering, extending, and/or retracting the main boom  255 . The lift assembly  255  further includes an extension boom  262  pivotally connected to the end of the main boom  255  with a hydraulic system (not shown) for rotating the extension boom  262  up and down. A wheel grid assembly  264  is attached at the end of the extension-boom  262  for engaging the front or rear wheels of a vehicle to be towed.  
     [0054] The body panel  215  includes the pair of mounting brackets  233 , each engaging a body support bracket  239  of the left sub-frame member. The body panel is secured to the sub-frame member by bolting the mounting brackets  233  to the respective body support brackets  239  with bolts  222 . A length spacer panel  220  is cut to cover a portion of the chassis between the cab  211  and the body panel  215 .  
     [0055] For example, comparing FIG. 16 to FIG. 18, the body sub-frame assembly of FIG. 16 is mounted on a wide truck chassis, compared to the body sub-frame assembly of FIG. 18, mounted on a narrower truck chassis. The sub-frame brace tubes  241 ,  242  of the sub-frame members in FIG. 18, are partially inserted into the sub-frame brace sleeves  245 , resulting in a wider positioning of the sub-frame rails  237  and  238  to line up with the wider configuration of chassis rails  213  and  214 , respectively. Comparatively, the sub-frame brace tubes  241 ,  242  of the sub-frame members in FIG. 18, are fully inserted into the sub-frame brace sleeves  245 , resulting in a narrower positioning of the sub-frame rails  237  and  238  to line up with the narrower configuration of chassis rails  213  and  214 , respectively. The sub-frame assembly is thereby adjustable to fit a variety of different chassis widths.  
     [0056] The body sub-frame assembly supports the left and right body panels  231  and  232  via the body support brackets  239  and  240 , respectively. The body support brackets  239  are fixed to the left sub-frame rail  237  on the opposite side from the sub-frame brace tubes  241 , and the body support brackets  240  are fixed to the right sub-frame rail  238  on the opposite side from sub-frame brace tubes  242 . The mounting brackets  233  and  234  of the left and right body panels align with the respective body support brackets  233  and  234 . The mounting brackets  233  and  234 , and the body support brackets  239  and  240 , each have a series of holes at a predetermined spacing along their length. The predetermined spacing is set such that the holes of a given mounting bracket line up with the holes of the corresponding body support bracket in a manner allowing for various lateral mounting positions for the body panel on the body sub-frame assembly. The various lateral positions are designed to accommodate a number of standard truck chassis and cab widths. Each body panel is positioned on the corresponding body support brackets at a desired lateral position with respect to the cab width and width between outer rear wheels, and bolted in that position.  
     [0057] For example, again comparing FIG. 16 to FIG. 18, the left and right body panels  231  and  232  of FIG. 16, are mounted on a wide truck chassis, compared to the left and right body panels  231  and  232  of FIG. 18, mounted on a narrower truck chassis. The mounting brackets  233  and  234  of the body panels in FIG. 16, are partially inserted over the respective body support brackets  239  and  240  of the respective sub-frame members  235  and  236 , resulting in a wider positioning of the body panels with respect to the truck cab and chassis. Comparatively, the mounting brackets  233  and  234  of the body panels in FIG. 18, are almost fully inserted over the respective body support brackets  239  and  240  of the respective sub-frame members  235  and  236 , resulting in a narrower positioning of the body panels with respect to the truck cab and chassis. A single universal body panel is thereby adjustable to fit truck chassis of a variety of widths, and is also readily removable for replacement or easy access to the chassis and drive train for repairs.  
     [0058] Once the left and right body panels are mounted on the body sub-frame assembly, left deck plates  251  and  252  are connected to each other in an overlapping fashion, as are right deck plates  253  and  254 . The connected deck plate assemblies  251 ,  252  and  253 ,  254  are mounted to the top surfaces at the inner rear ends of the left and right body panels  231  and  232 , respectively, as illustrated in FIG. 16. The amount of overlap between deck panels of a connected pair depends on the width of the particular truck chassis, further increasing the flexibility of fitting universal adjustable body panels on truck chassis of a variety of widths. Alternatively, single left and right deck plates can be cut to size in accordance with the chassis width, and mounted to the top surface at the inner rear ends of the left and right body panels  231  and  232 , respectively.  
     [0059] The deck plates form a deck between the respective body panels  231  and  232  and the automobile lift assembly  250 . The deck plates or deck plate assemblies can be bolted, welded, riveted, or otherwise fixed together and in place. Alternatively, as shown in FIG. 19, single deck plates  271  and  272 , can be integrally provided as part of the respective body panels  231  and  232 . The deck plates  271  and  272  are cut to size in accordance with the desired chassis width. Further, left and right length spacer panels  220  and  221 , respectively, are cut to size and mounted to the left and right body panels, covering spaces between the left and right body panels  231  and  232 , and the truck cab  211 . Body support brackets  257  and  258  are fixed to the outer sides of the left and right chassis rails  213  and  214 , respectively. The body support brackets  257  and  258  align with mounting brackets  259  and  260  of the left and right length spacer panels  220  and  221 , respectively. As with the mounting brackets and body support brackets of the body panels  231  and  232 , the mounting brackets  259  and  260 , and the body support brackets  257  and  258 , each have a series of holes at a predetermined spacing along their length. The predetermined spacing is set such that the holes of a given mounting bracket line up with the holes of the corresponding body support bracket in a manner allowing for various lateral mounting positions for the body panel on the body sub-frame assembly. The various lateral positions are designed to accommodate a number of standard truck chassis and cab widths, and provide for alignment of the length spacer panels  220  and  221  with the respective left and right body panels  231  and  232 . Each length spacer panel is positioned on the corresponding body support bracket at a desired lateral position with respect to the respective body panel, and bolted in that position. Further, each length spacer panel is bolted to the respective body panel, as illustrated in FIGS. 16, 18 and  19 . The length spacer panels thereby accommodate for a variety of truck chassis lengths upon which the universal adjustable body panels of the present invention can be mounted.  
     [0060] The present invention can be practiced by employing conventional material, methodology and equipment. Accordingly, the details of such materials, equipment and methodology are not set forth herein in detail. In the previous descriptions, numerous specific details are set forth, such as specific materials, structures, chemicals, processes, etc., in order to provide a thorough understanding of the present invention However, it should be recognized that the present invention can be practiced without resorting to details specifically set forth. In other instances, well known processing structures have not been described in detail, in order not to unnecessarily obscure the present invention.  
     [0061] Only a few embodiments of the present invention are shown and described in the present disclosure. It is to be understood that the present invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.