Abstract:
A vehicle frame straightening apparatus includes a substantially upright post adapted to engage a rail mounted transversely to a series of rails fixed to the floor on which the vehicle rests, and adapted to apply pressure between the floor and outward on a deformity in the frame from under the vehicle by a ram engaged therebetween. A holding assembly for holding the vehicle in position engages the vehicle frame from the outside and engages a second rail mounted transversely to the rails fixed to the floor. Preferably the post includes a substantially upright lower portion and an upper portion pivotally attached thereto in order to extend its height, wherein the lower portion does not exceed the ground clearance of the vehicle. Thus, the post may be placed into position against the deformity from beside the vehicle without requiring an increase in the vehicle&#39;s ground clearance.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to vehicular body work systems and in particular to an improved vehicle frame straightening apparatus.  
         BACKGROUND OF THE INVENTION  
         [0002]    Since the dawn of the automotive age, there has been a need for automotive bodywork. Originally, frame damage was minimal and bodywork was restricted to the repair of dents in the vehicle using hammers and mallets. On occasion, frame damage was sustained. Because of the relatively light weight of vehicles and the slow speeds at which they operated, such damage was usually slight and no corrective action was necessary.  
           [0003]    As the speed of automotive travel and as the weight of vehicle bodies increased, so did the frequency and severity of frame damage. The complexity of auto body repair increased correspondingly.  
           [0004]    At present there are two basic approaches to body work, namely frame pulling and frame pushing. The former approach involves the attachment of chains to the vehicle frame and the application of tension to pull the frame into a desired shape. Frame pushing involves the positioning of posts at particular points along the frame and the application of pressure to push the frame into the desired shape.  
           [0005]    There is much to commend the frame pulling approach. The apparatus is often lighter and cheaper. Moreover, most vehicular collisions result in the frame being bent inward, so that a frame pulling apparatus may be conveniently set up outside the frame, to pull the frame outward.  
           [0006]    However, notwithstanding the foregoing, it is generally recognized that the frame pushing approach is superiour to the frame pulling approach. This is because of the limited number of points on a vehicle frame to which the chains of a frame pulling apparatus may be attached. Furthermore, the use of chains to apply tension generally introduces a downward force component in addition to the desired lateral force component, which must be taken into account. Accordingly, the quality of the repair using such an apparatus is generally sub-optimal.  
           [0007]    On the other hand, frame pushing posts need not be fastened to the frame, but merely moved into place. Moreover, frame pushing does not introduce any vertical force component.  
           [0008]    The drawback to the frame pushing approach has been that the apparatus is generally larger, heavier and bulkier. Solid posts are required, as compared to chains. This is compounded by the fact that the apparatus must generally be installed inside the frame in order to push the inward-facing deformities outward.  
           [0009]    Therefore, frame pushing apparata have required the vehicle under repair to be positioned above ground, in order to permit the solid posts, which exceed the ground clearance height for the vehicle, to be inserted from below the vehicle.  
           [0010]    Furthermore, set-up times for frame pushing machines are typically much longer than those for frame pulling machines, although these too may eclipse the actual time required to conduct the actual repair.  
           [0011]    Thus, in U.S. Pat. No. 1,907,925 entitled Automobile Frame Straightening Machine issued to Wochner on May 9, 1933, there is disclosed a frame pushing apparatus comprising a pair of elevated longitudinal rails adapted to accept the wheels of the vehicle to be repaired. A pair of ramped rails extends from ground level to the elevated rails to permit the vehicle to be wheeled onto the elevated rails. Transverse rails extend below the elevated rails and solid one-piece pushing posts are attached thereon to extend above the surface of the elevated rails and engage the frame body, taking advantage of the increased ground clearance of the vehicle while on the elevated rails.  
           [0012]    Because of the different wheel bases of vehicles, the separation between the elevated rails in the Wochner apparatus must be adjusted for every vehicle. In effect, the apparatus must be repositioned and rebuilt for every repair operation. Further, the wheeling of the vehicle up the ramps and onto the elevated rails is somewhat precarious. As a result, the set-up time required may be considerable.  
           [0013]    In U.S. Pat. No. 2,597,234 entitled Frame Straightening Device and issued May 20, 1952 to Elam, there is disclosed a portable device consisting of a single rail from which extends a solid one-piece pushing rod and a holding rod. The Elam device avoids the problem of ground clearance because it is small enough to be inserted under the vehicle while on its side and stood upright once in position. Indeed, there is no requirement that the Elam device be stood upright on the ground, much less secured to it.  
           [0014]    Rather, the Elam device requires that the rail be positioned so that the holding rod engages a portion of the frame that is not susceptible to bending and acts as a bracing point for the pushing rod as it applies pressure to the frame portion to be repaired.  
           [0015]    Because of its portable nature, the Elam device must necessarily be completely repositioned for every repair activity, even when, as is often the case, multiple repairs must be effected on the same frame. Accordingly, the set-up time for the Elam device may also be considerable.  
           [0016]    More importantly, the Elam device is necessarily restricted in the nature of repairs that may be effected because of the need to locate a bracing point elsewhere on the frame. In this regard, the Elam apparatus suffers from the deficiencies noted above in respect to frame-pulling apparata.  
           [0017]    In U.S. Pat. No. 5,257,526 entitled Automotive Frame Straightening Apparatus and issued Nov. 2, 1993 to Teixeria, there is disclosed an apparatus comprising a plurality of solid towers in slidable engagement along three sides of a grooved rectangular frame. The towers provide both pushing/holding elements and pulling elements, but the vehicle is loaded onto the frame along the fourth side and positioned inside all of the towers. The pushing/holding elements thus only apply pressure from the outside of the frame inward. In essence, then, the Teixeria device acts as a frame pulling apparatus. Moreover, because the solid towers are mounted outside the vehicle frame, there is no concern about ground clearance.  
         SUMMARY OF THE INVENTION  
         [0018]    Accordingly, it is desirable to provide an improved vehicle frame straightening apparatus.  
           [0019]    It is further desirable to provide an improved apparatus that provides the advantages of the frame pushing approaches without the disadvantages of slow and difficult set-up previously associated with such approaches.  
           [0020]    It is still further desirable to provide an improved apparatus that permits frame pushing repair from the interior of the vehicle frame without concern for ground clearance.  
           [0021]    The present invention accomplishes these aims by providing a frame straightening apparatus using vertical posts positioned under the vehicle to push outward to straighten deformities in the frame. The apparatus is lightweight, strong and easily configurable from beside the vehicle under repair, without requiring increased ground clearance. The apparatus comprises a pair of floor rails bolted to, embedded within or forming part of the floor of the repair facility. The top of each floor rail has a partially closed channel into which a series of bolts can be inserted and slid longitudinally along the rail. The bolts can be used to quickly fasten and adjust a transverse U-shaped pushing rail and one or more transverse holding rails. The pushing rail has a series of bores along each leg, to which a U-shaped pivot base may be attached using pins. The pivot base is short enough to clear the undercarriage of a vehicle under repair positioned over the floor rails. A pushing post may then be positioned into place and quickly fastened into place at the top of the pivot base using pins. The pushing post pivots about the pivot base and, under the force of a ram assembly attached at the other end to the pushing rail, can apply pushing pressure on the frame of the vehicle under repair. Each holding rail permits a sliding post to slide along its length. One of the sliding posts may conveniently be short enough to clear the undercarriage of the vehicle under repair. A holding post may be positioned into place and quickly fastened into place at the top of the sliding post using pins. The holding post grips the exterior of the vehicle frame and is held in position by a chain attached at its other end to the holding rail. Diamond repairs may be effected using a set of diamond rails comparable to and abutting the floor rails in a transverse direction. Minor downward frame pulling repairs may be effected by the use of a pulley assembly attached to the pushing rail and a chain assembly. The apparatus may be conveniently mounted onto the bed of a towed platform to permit remote repairs.  
           [0022]    According to a first broad aspect of an embodiment of the present invention there is disclosed a vehicle frame straightening apparatus comprising a substantially upright post for engagement with the floor on which the vehicle rests, and adapted to apply pressure between the floor and outward on a deformity in the frame from under the vehicle, whereby the post may be placed into position against the deformity from beside the vehicle without requiring an increase in the vehicle&#39;s ground clearance.  
           [0023]    According to a second broad aspect of an embodiment of the present invention there is disclosed a vehicle frame straightening apparatus comprising a substantially upright post adapted to engage a rail to be mounted transversely to a series of rails fixed to the floor on which the vehicle rests, and adapted to apply pressure between the floor and outward on a deformity in the frame from under the vehicle by a ram engaged there between, wherein the vehicle may be held in position by at least one holding assembly adapted to engage the vehicle frame from the outside and to engage to a second rail to be mounted transversely to the rails fixed to the floor, and wherein the post comprises a substantially upright lower portion and an upper portion adapted to be pivotally attached thereto in order to extend its height and wherein the lower portion does not exceed the ground clearance of the vehicle, whereby the post may be placed into position against the deformity from beside the vehicle, without requiring an increase in the vehicle&#39;s ground clearance. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    The embodiments of the present invention will now be described by reference to the following figures, in which identical reference numbers in different figures indicate identical elements and in which:  
         [0025]    [0025]FIG. 1 is a plan view of an embodiment of the present invention;  
         [0026]    [0026]FIG. 2 is a sectional view of the embodiment of FIG. 1 taken along the section II-II with background detail deleted for clarity;  
         [0027]    [0027]FIG. 3 is a sectional view of the embodiment of FIG. 1 taken along the section III-III with background detail deleted for clarity;  
         [0028]    [0028]FIGS. 4 a  through  4   d  are diagrammatic representations of the forces applied in various configurations of the embodiment of FIG. 1;  
         [0029]    [0029]FIG. 5 is a plan view of a second embodiment of the present invention;  
         [0030]    [0030]FIG. 6 is a diagrammatic representation of the forces applied in the embodiment of FIG. 5;  
         [0031]    [0031]FIG. 7 is a sectional view of a third embodiment of the present invention;  
         [0032]    [0032]FIG. 8 is an end view of a fourth embodiment of the present invention; and  
         [0033]    [0033]FIG. 9 is a perspective view of a fifth embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]    Referring now to FIG. 1, there is shown a plan view of a first embodiment of the present invention. The apparatus, shown generally at  100 , comprises a pair of longitudinal floor rails  110 , a transverse pushing assembly  120 , and two transverse holding assemblies  170 .  
         [0035]    The floor rails  110  extend parallel to each other in a longitudinal direction. The floor rails  110  comprise a flat portion  111  containing a series of bores  112  through which the floor rails  110  may be bolted to the floor  101  of the repair facility.  
         [0036]    A narrower partially closed channel  115  is superimposed over the flat portion  111 . The opening in the channel  115  extends upward away from the flat portion  111 . At one or more points intermediate to each extremity of the floor rail  110  there is a larger opening in the channel  115 . The floor rails  110  may be cast or extruded out of aluminum. Alternatively, the floor rails  110  may be composed out of separate pieces of similar material welded or otherwise fastened together.  
         [0037]    Aluminum provides a desirable combination of relatively light weight and high tensile strength, with little or no bending. However, those having ordinary skill in this art will recognize that there are a variety of other suitable high strength materials that may be substituted therefor.  
         [0038]    The pushing assembly  120  comprises a pushing rail  121 , a pivot base  130 , a pushing post  140 , a swivel plate  146 , a clevis  139 , a ram assembly  150 , a pushing fork  160 , and pushing extensions  166 .  
         [0039]    The pushing rail  121  is generally U-shaped, with a series of bores  122  extending through each of the pushing rail legs  123  near their extremities. The series of bores  122  are generally uniformly spaced apart and correspond as between legs  123 . The width of the pushing rail  121  is sufficient to accommodate the ram assembly  150 , and its height is sufficient to accommodate the ram assembly  150  when positioned proximate to the pivot base  130 . The pushing rail  121  may be cast or extruded out of aluminum. Alternatively, it may be composed out of separate pieces of similar material welded or otherwise fastened together.  
         [0040]    One end (the notch end)  127  of the pushing rail  121  terminates in a notch having a width generally corresponding to the diameter of the bolt  116 . The notch extends between the two pushing rail legs  123 .  
         [0041]    The pushing rail  121  may be fixed at the notch end  127  to one of the floor rails  110  by fasteners, such as by a bolt assembly comprising a bolt  116 , a plate washer  117 , a thin washer  118  and a nut  119 .  
         [0042]    The bolts  116  have large rectangular heads, one dimension of which generally corresponds to the size of the channel  115  of the floor rail.  
         [0043]    The wider opening in the channel  115  of the floor rail  110  permits the easy insertion of the bolt  116 , head down within the floor rail  110 . The bolt  116  protrudes out of the floor rail channel  115  and is easily slideable along it. The pushing rail  121  may be mounted on the top of the floor rail channel  115 , such that the notch surrounds the bolt. Once in position, the channel  125  is effectively closed off by the addition of a plate washer  117  over the bolt  116 . A thin washer  118  and nut  119  are applied and when tightened, securely fix the notch end  127  of the pushing rail  121  to a floor rail  110 .  
         [0044]    At the other end (the flange end)  126  of the pushing rail  121 , a pair of horizontal flanges  124  extend away from the flange end of the pushing rail  121 . Each of the horizontal flanges  124  is partially closed. The opening  125  in the flange  124  extends away from the pushing rail  121 . Once the notch end  127  is attached to the floor rail  110 , the flange end  126  may be attached to the remaining floor rail  110 , through the opening  125  in each of the flanges  124 .  
         [0045]    When the three bolt assemblies  116 - 119  are slightly loosened, the pushing rail  121  may be slideably moved along the length of the floor rail in relatively parallel position.  
         [0046]    The combination of the fixed floor rails  110  and the three loosened bolt assemblies  116 - 119  permits easy and quick adjustment of the position of the pushing rail  121  whenever needed. The bolt assemblies  116 - 119  need only be slightly loosened and the pushing rail  121  slid along the floor rails  110  to the desired position. When this position has been reached, the pushing rail  121  may be quickly fixed in place by tightening the bolt assemblies  116 - 119 , typically using air driven wrenches as are prevalent in automotive repair facilities.  
         [0047]    The pivot base  130  is a U-shaped post adapted to fit within the legs  123  of the pushing rail  121 . The pivot base  130  may be cast or extruded out of aluminum. Alternatively, it may be composed out of separate pieces of similar material welded or otherwise fastened together.  
         [0048]    The legs  131  of the pivot base  130  are longer than the legs  123  of the pushing rail  121 . However, as may be better seen in FIG. 2, they remain short enough to clear the bottom of a vehicle positioned on the floor  101  above it, even when mounted between the legs  123  of the pushing rail  121  mounted on the floor rails  110 . In the present embodiment, a height of 12 inches has been found to be satisfactory.  
         [0049]    Each pivot base leg  131  has a series of horizontal bores  132  near the base  133  of the pivot base  130 . The size of the bores and their separation correspond to that of the bores  122  on the pushing rail legs  123 . Thus, pins  134  may be inserted through a bore  122  on one leg  123  of the pushing rail  121 , through the bores  132  on each pivot base leg  131  and through the corresponding bore  122  on the other leg  123  of the pushing rail  121 . When two pins  134  are passed through pairs of bores  132  in the pivot base  130 , the pivot base  130  is fixed in position along the pushing rail  121 .  
         [0050]    The use of pins  134  further assists in the easy set-up of the embodiment of the present invention. The pins  134  are cylindrical and have no heads or threads. Rather, the diameter of the pins  134  generally corresponds to the size of the bores  122 ,  132 . In combination with the length of the pins  134 , which is several inches longer than the width of the pivot rail  121 , this serves to ensure that the pins  134  will not be accidentally displaced. optionally, a cap may transversely surround the pin  134  at an intermediate point to provide a stopping surface to prevent over-insertion of the pin  134 , together with a convenient handle with which to withdraw it.  
         [0051]    Each of the legs  131  of the pivot base  130  also contains a vertical series of bores  135  extending from the pair of bores  132  and along the length of the legs  131 . As a convenience, standard sizes of bores and pins are used throughout the embodiment of the present invention. A bore diameter of ⅞″ and capable of accepting a pin  134  that is {fraction (13/16)}″ in diameter has been found to be satisfactory.  
         [0052]    The pushing post  140  is relatively planar, having a thickness that generally corresponds to the separation between the legs  131  of the pivot base  130 , into which it is inserted. The pushing post  140  may be constructed out of steel or cast iron, or other very high strength material. A pushing post  140  height of 18 inches is suitable for the present embodiment.  
         [0053]    At one end (the pivoting end)  141  of the pushing post  140 , a first series of bores  142  extend partially along the length of the pushing post  140 . The spacing of the pushing post bores  142  need not be comparable to that of the pivot base  130 , because only one pin  134  will pass through the two series of bores  135 ,  142 . Accordingly, the pushing post  135  is able to pivot about the pin  134 . The pivot point may be adjusted by judicious choice of which pair of bores  135  in the pivot base  130  and which bore  142  in the pushing post  140  are chosen.  
         [0054]    At the other end (the shaped end)  144  of the pushing post  140 , there is a second series of bores  145 . The shape of the shaped end  144  and the positioning of the second series of bores  145  may be chosen to permit such subtleties in pushing pressure as may be necessary for the task. The shape and bore positions shown in FIG. 2 are eminently suitable for the purpose, but it will be understood by those having ordinary skill in this art that other shapes and/or bore positions may be equally satisfactory and will not depart from the spirit and scope of the present invention.  
         [0055]    The swivel plate  146  is roughly polyhedral in shape. It too may be constructed out of steel or cast iron, or other very high strength material. The base  148  of the swivel plate  146  is flat. The other end of the swivel plate  146  is forked and has a bore  147  passing therethrough. Thus, the swivel plate  146  may be pivotally attached by a pin  134  to the shaped end  144  of the pushing post  140  to provide a wide and flat pushing surface  148 .  
         [0056]    The clevis  139  is U-shaped having bores at the extremities of its legs, by which it can be bolted to the pushing post  140 .  
         [0057]    The ram assembly  150  comprises a ram  151 , a pivoting head  155  and a pivot fastener  159 . The ram  151  may be a 10 ton hydraulic ram that is well known in the art, driven by a hydraulic source (not shown) through a hose  149  interconnecting the two.  
         [0058]    The ram  151  comprises an outer cylindrical sleeve  152  and an inner cylindrical extension element  153  in slidable engagement therewith. The outer sleeve  152  is externally threaded at one end and open at the other. At a point intermediate between the two ends, however, the outer sleeve  152  is completely closed. A hose connection is positioned proximate to the closed point but on the other side from the threaded end. The inner cylindrical extension element  153  is housed in the unthreaded side of the outer sleeve  152 , and extends slightly beyond it. When hydraulic fluid is introduced in through the hose connection, from a hydraulic source (not shown)via the hose  149 , the hydraulic pressure forces the inner extension to protrude farther out of the ram  151  in response.  
         [0059]    The pivoting head  155  is generally cylindrical in shape having a closed end  156  and open end  157 . The open end  157  is internally threaded and adapted to engage with the external threads on the ram  151 . The closed end  156  has a scalloped contour and bears a protrusion  158  along one side, as shown in dotted outline in FIG. 2. The pivot fastener  159  is adapted to pass through a pair of bores  122  in the pushing rail  121 . The pivot fastener  159  comprises a bolt. Alternatively, a pin  134  may be substituted.  
         [0060]    The scalloped contour  156  of the pivoting head  155  is adapted to partially surround the pivot fastener  159  and permits the ram assembly  150  to pivot about it. The protrusion  158  passes between the pushing rail legs  123  and below the pivot fastener  159  so as to restrict the pivoting motion in one direction.  
         [0061]    The pushing fork  160  is U-shaped. The separation between the legs generally corresponds to the thickness of the pushing post  140 . The legs of the pushing fork  160  each have a bore  162  passing therethrough proximate to their end. Thus, a pin  134  may be passed through the pushing fork bores  162  and through one of the bores  145  in the pushing post  140 , to permit the pushing post  140  to pivot about the pin  134 . The closed end of the pushing fork  160  has, in the surface pointing away from the legs, an internal bore  165 . The internal bore of the pushing fork  160  is adapted to engage the exposed portion of the inner cylindrical extension element  153  of the ram  151 .  
         [0062]    The pushing extensions  166  are cylindrical extension pieces having an external protrusion  167  at one end and an internal bore  168  at the other. The protrusions  167  are adapted to engage the internal bore  165  of the pushing fork  160  and the internal bore  168  of other pushing extensions  166 .  
         [0063]    A number of pushing extensions  166  of varying lengths, such as 4 inches, 8 inches and 16 inches may be joined together. The pushing fork  160  and the pushing extensions  166  may be composed of steel.  
         [0064]    The holding assembly  170  comprises a holding rail  171 , a holding post assembly  180  and a chain assembly  190 .  
         [0065]    The holding rail  171  is a flat elongate bar having approximately the same length as the pushing rail  121 . It may be cast or extruded out of aluminum. Alternatively, it may be composed out of separate pieces of similar material welded or otherwise fastened together.  
         [0066]    At one end (the parallel end)  172 , the holding rail  171  terminates in a notch  174  having a longer dimension parallel to the axis of the holding rail  171 . The notch has a width generally corresponding to the width of the bolt  116 . At the other end (the transverse end)  173 , a notch  175  of substantially the same dimension extends transverse to the axis of the holding rail  171  and proximate to its end.  
         [0067]    Two bolt assemblies comprising components similar to the bolt assembly  116 - 119  used to secure the pushing rail  121  to the floor rail  110  may be used to attach the holding rail  171  to the floor rails  110  at each end. The only difference is in the angled plate washer  176 . Whereas the plate washer  117  used to secure the pushing rail  121  was flat, a portion of the angled plate washer  176  is angled so as to protrude upward. A slot  177  extends through the angled portion of the angled plate washer  176 . Such angled plate washers  176  will be used as part of the bolt assembly used to secure at least one end of the holding rail  171  to the floor rail  110 .  
         [0068]    A bolt  116  is inserted into the channel  115  of each floor rail  110  with the head protruding from the opening in the channel  115 . The holding rail  171  is positioned over the bolt  116  in one floor rail  110  such that the straight notch  174  surrounds the bolt  116  and the plate washer  117  (or angled plate washer  176 ), the washer  118  and nut  119  are attached in a loose fit. The bolt  116  in the remaining floor rail  110  may be inserted into the open end of the open bore  175  by suitable pivoting of the holding rail  171 . Once in position, the plate washer  117  (or angled plate washer  176 ), the washer  118  and nut  119  are also attached in a loose fit. At this point, the holding rail  171  may be returned to a position normal to each of the floor rails  110  and moved to the desired position, whereupon the bolt assemblies may be tightened, typically using air-driven wrenches.  
         [0069]    The holding post assembly  180  comprises a sliding post  181  and a holding post  185 . The sliding post  181  comprises a hollow rectangular channel  182  and two vertical holding bases  183  protruding from a flat outer surface of the channel in a U-shaped configuration. The sliding post  181  may be composed of separate pieces of cast or extruded aluminum welded or otherwise fastened together.  
         [0070]    The rectangular channel  182  has interior dimensions that slidably surround and engage the holding rail  171 . Typically the rectangular channel  182  is slid onto the holding rail  171 , with the vertical holding bases  183  extending upward, before the holding rail  171  is attached at both ends to the floor rail  110 .  
         [0071]    As may be better seen in FIG. 3, the vertical holding bases  183  have a series of bores  184  extending vertically along their length, in a generally uniformly spaced pattern. In the present embodiment, the vertical holding base  183  for each of the sliding posts  181  are of different heights but are otherwise substantially identical.  
         [0072]    The shorter sliding post  181  has a height of 12 inches, which permits it to be positioned on a holding rail  171  mounted on the floor rails  110 , without coming into contact with the bottom of most vehicles, when positioned on the floor.  
         [0073]    The taller sliding post  181  has a height of 18 inches, which will not typically fit with clearance under a vehicle.  
         [0074]    The holding post  185  is planar, and may be cast or extruded out of aluminum. The shape of the holding post  185  is polygonal. A ledge  186  is defined on one side of the holding post  185 . A series of bores  187  pass through the planar surface of the holding post  185 . The shape and bore positions shown in FIG. 3 are eminently suitable, but it will be understood by those having ordinary skill in this art that other shapes and/or bore positions may be equally satisfactory and will not depart from the spirit and scope of the present invention.  
         [0075]    The holding post  185  may have a thickness that generally corresponds to the separation between the vertical holding bases  183 , between which it is inserted. The holding post  185  may be fixed in position by inserting a pair of pins  134  between corresponding bores  184  in the vertical holding bases  183  and bores  187  in the holding post  185 .  
         [0076]    The chain assembly  190  comprises a chain  191 , a bottom clip  192 , a top clip  194  and a chain tensioner  198 . The chain  191  may be of standard steel or iron ⅜″ chain, grade 8, having a rated strength of 25,000 pounds. The bottom clip  192  is a curved clip adapted to attach to the chain  191  at one end by a bolt assembly  193  and to engage the slot  177  of the plate washer  176  securing one end of the holding rail  171  to the corresponding floor rail  110 . Thus, the chain  191  may be fixed to the holding rail  171  at one end.  
         [0077]    The top clip  194  comprises two pieces of aluminum  195 , each having bores at either end, through which two bolt assemblies  196 ,  197  may pass. One bolt assembly  196  secures the other end of the chain  191  between the pieces of aluminum  195 . The other bolt assembly  197  secures the holding post  185 , at a point  189  proximate to and below the ledge  186 , between the pieces of aluminum  195 . Thus, the chain  191  may be fixed to the holding post  185  at the other end.  
         [0078]    The chain tensioner  198  engages the chain  191  at an intermediate point and may be activated to take up any slack in the chain  191  in a quick and easy operation. When the chain tensioner  198  is released, the chain  191  tension is reduced, permitting the chain to be disconnected and reconnected at either end.  
         [0079]    In operation, the vehicle to be repaired is usually driven or positioned such that its wheels lie outside the floor rails  110 , which have been fixed to the floor  101  using bolts through the bores  112 , approximately 6 feet apart. Nevertheless, those having ordinary skill in this art will readily recognize that the vehicle may be positioned, relative to the apparatus shown in this embodiment, in any orientation that may prove to be convenient and effective.  
         [0080]    The apparatus shown in this embodiment of the present invention is especially suitable for repairs of full frame vehicle bodies such as found on trucks. In such cases, the frame rarely exceeds four feet in width, which can be easily accommodated by the apparatus with a floor rail separation of six feet. The apparatus shown is also suitable for repairs of the frame portion of unibody frames.  
         [0081]    Because the wheels lie beside the floor rails  110 , the bolts  116  may be easily slid into the channel  115  of the floor rail  110  at one of the wider openings and advanced along the track formed by the opening in the channel  115  until they reach the desired position. At this point, the pushing rail  121  and holding rails  171  may be moved into position from the side of the vehicle, as previously described.  
         [0082]    As can be seen in FIG. 4, the pushing rail  121  is positioned  401  directly opposite the frame position where the repair is to be effected by a pushing operation  402 . Force will be applied from the interior of the frame outward at this point. Generally, the pushing rail  121  is oriented such that the flange end  126  is proximate to the ram assembly  150 , and the notch end  127  is proximate to the pivot base  130  and thus to the frame position where the repair is to be effected.  
         [0083]    The holding rails  171  are positioned  403 ,  404  directly opposite the frame position where a corresponding inward force is to be applied to the frame to hold the frame into position in order to effect the repair. Generally, the objective is to separate the pushing rail  121  from the holding rails  171  by a cross member  405 ,  406  in the vehicle frame.  
         [0084]    If only one angled plate washer  176  is used per holding rail  171 , it should be positioned at the end of the holding rail  171  farthest away from where the holding force  403 ,  404  is to be applied.  
         [0085]    Prior to attaching the holding rails  171 , a sliding post  181  must be slid over each holding rail  171 . Generally, the sliding post  181  is left to the outside of the frame. Nevertheless, the height of the sliding post  181  is small enough that there would generally be clearance between its top and the bottom of the vehicle, so that the sliding post  181  would remain free to slide along the holding rail  171  and under the vehicle.  
         [0086]    Generally, the pushing rail  121  is fixed into position first, while the holding rails  171  are left free to slide to permit final adjustment once the pushing post  140  is properly positioned.  
         [0087]    Once the pushing rail  121  has been fixed in position, the pivot base  130  may be installed by positioning it between the pushing rail legs  113  in a suitable position. The pivot base  130  is quickly fixed in place by sliding a pair of pins  134  between corresponding bores  122  in the pushing rail legs  123  and bores  132  in the pivot base  130 .  
         [0088]    The height of the pivot base  130  is small enough that there would generally be clearance between the top of the pivot base  130  and the bottom of the vehicle, so that fine adjustments to the position may be made without catching the bottom of the vehicle.  
         [0089]    The pushing post  140  is thereupon quickly attached to the pivot base by positioning it between the pivot base legs  131  and passing a single pin  134  between corresponding bores  135  in the pivot base legs  131  and a bore  145  in the pushing post  140 . The U-shape of the pivot base  130  permits the pushing post  140  to be raised into position from below the vehicle, generally without requiring the vehicle to be raised off the ground to increase ground clearance. On some lower end or 2 wheel drive pickups having reduced ground clearance, different (lower) heights for the pushing post  140  and pivot base  130  may be required to avoid having to temporarily raise the vehicle off the ground to permit adjustment of these elements.  
         [0090]    Because only a single pin  134  is used, the pushing post  140  may pivot downward toward the pushing rail  121  so as not to catch on the bottom of the vehicle. Alternatively, the pushing post  140  may be held roughly in position by structures in the vehicle interior relative to the frame (not shown). Once in position, the pushing post  140 , together with the pivot base  130 , extends as much as  30  inches high, which is more than sufficient to perform most frame repairs.  
         [0091]    The clevis  139  is attached on the front side of the pushing post  140  and may be used for a variety of convenient purposes generally unrelated to the present invention.  
         [0092]    If desired, the swivel plate  146  may be quickly pivotally attached to the pushing post  140  by inserting a pin  134  through corresponding bores  147  in the swivel plate  146  and a bore  145  in the pushing post  140 , positioned between them.  
         [0093]    The pushing fork  160  may also be quickly pivotally attached to the pushing post  140  by inserting a pin  134  through corresponding bores  162  in the pushing fork legs  161  and a bore  145  in the pushing post  140 , positioned between them. Thereafter, the internal bore  165  may be pressed onto the extended end of the inner cylindrical extension element  153  of the ram  151 , separated as needed by up to four pushing extensions  166 .  
         [0094]    The pivot fastener  159  is inserted between a convenient corresponding set of bores  122  in the pushing rail legs  123 . The pivoting head  155  is attached in a mating fit to the outer cylindrical sleeve  152  and its scalloped closed end  156  is lodged against the pivot fastener  159 , with the protrusion  148  extending toward the floor. Thus, the ram  151  may be quickly positioned between the pushing rail legs  123  and held longitudinally in place.  
         [0095]    The holding posts  185  may be quickly attached to their corresponding sliding posts  181  by inserting a pair of pins  134  into corresponding bores  184  in the vertical holding base  183  of the sliding post  181  and into bores  187  in the holding post  185  positioned between them.  
         [0096]    The chain  191  is attached using the top clip  194  to the top clip bore  189  using bolt assemblies  196 ,  197  and to the thick washer  176  at the floor rail  110  away from where the holding force is to be applied, using the bottom clip  192 . Each holding post  185  is positioned such that the vehicle frame rests on the ledge  186  in the holding post  185 . Once the holding post  185  is in the proper position, the chain tensioner  198  is activated to take up all the slack in the chain  191  and the holding rail  171  is fixed in place.  
         [0097]    At this point, the set-up phase of the repair operation is complete and the repair operation may commence. A repair is effected by pushing from inside against a deformity in the frame with the pushing post  140 , while holding the rest of the frame steady from the outside using the two holding posts  185 .  
         [0098]    The foregoing embodiment presumes that the frame straightening operation is to be performed on a side wall of the frame. Frequently, however, a repair must be effected on the front or back end of the frame. Because front and back end collisions often skew the frame out of square, such repairs are often referred to as a “diamond” repair.  
         [0099]    In FIG. 6, the structural members of a frame that sustained damage requiring a diamond repair are shown. The collision occurred at point  601 , resulting in an acute angle between the closest frame rail  602  and the adjoining frame cross-members  604 ,  605 .  
         [0100]    In order to effect such repairs, it is necessary to apply force at multiple points. Pressure may be applied to cross-member  604  at a point proximate  608  to the distal frame rail  603 , while holding pressure  606  is applied at cross-member  604  proximate to the original collision point. Further holding pressure  607  is applied transversely at frame rail  601 , preferably at a point separated by a cross-member  605 .  
         [0101]    The present invention may be configured to effect diamond repairs, through a slight modification to the apparatus shown in FIG. 1, as may be seen in FIG. 5.  
         [0102]    The modification consists of the addition of two identical diamond rails  500 . Each diamond rail is comparable to that of the floor rails  110  except for length and lie on the floor connecting them.  
         [0103]    Each diamond rail  500  is bolted to the floor of the repair facility through a series of bores  501 . The channel  502  in the diamond rail  500  is substantially identical to the channel  115  in the floor rail.  
         [0104]    The diamond rails  500  may be cast or extruded out of aluminum. Alternatively, the diamond rails  500  may be composed out of separate pieces of similar material welded or otherwise fastened together.  
         [0105]    One diamond rail  500  is attached to the floor proximate to one end of the floor rails  110 , which corresponds to the end of the vehicle frame to be repaired. The other diamond rail  500  is attached to the floor  110  at a distance from the first diamond rail  500 , corresponding to the separation between the floor rails  110 , or six feet.  
         [0106]    Once so attached, in effect, a system of channels  502  will have been created in the direction normal to the channels  115 , to accept the pushing rail  121  and one or both of the holding rails  171 .  
         [0107]    The pushing rail  121  may thereupon be attached to the diamond rails  500  in a manner similar to its attachment to the floor rails  110  in the previous embodiment. It is oriented so that the flange end  126  lies on the outer diamond rail  500 , or proximate to the bumper, while the notch end  127  lies on the inner diamond rail  500 , or proximate to the transmission.  
         [0108]    A holding rail  171  may also be attached to the diamond rails  500  in a manner similar to its attachment to the floor rails  110  in the previous embodiment. It is oriented so that the holding post  185  is proximate to the inner diamond rail  500 .  
         [0109]    The other holding rail  171  is attached to the floor rails  110 , positioned transversely to keep the exterior frame from swaying. Generally, the point of contact is on the side away from the area to be repaired and separated from the area to be repaired by at least one frame cross-member.  
         [0110]    In operation, the vehicle is driven or backed into position relative to the floor rails, with the repair site proximate to the diamond rails  500 .  
         [0111]    Because the wheels lie beside the floor rails  110 , the bolts  116  may be easily slid into the channel  115  of the floor rails  110  or into the channel  502  of the diamond rails  500  as the case may be, at one of the wider openings and advanced along the track formed by the opening in the channel  115  or  502  until they reach the desired position.  
         [0112]    At this point, the pushing rail  121  and holding rails  171  may be moved into position from the side or end of the vehicle, as previously described and the pivot base  130 , pushing post  140 , sliding post  181  and holding posts  185  installed in position as previously described. The shorter of the two sliding posts  181  should be installed on the holding rail  171  that is secured to the diamond rails  500 , because this will be located beneath the vehicle. The ram assembly  150  and the chain  191  may thereafter be installed and adjusted and tensioned.  
         [0113]    At this point, the set-up phase of the repair operation is complete and the repair operation may commence. As before, a repair is effected by pushing from inside against the frame cross-member until the acute angle formed by the frame rail and cross-member is extended to a right angle, while holding the frame steady using the two holding posts  185 .  
         [0114]    The diamond rails  500  may also be used to effect non-diamond frame repairs on the front or back end of the vehicle, such as for motor mounts or cross-members. In such a case, a deformity in the frame is repaired by applying pressure from within using the pushing assembly  120 , while holding the frame steady using the two holding assemblies  170 , all of which are mounted on the diamond rails  500 .  
         [0115]    Turning to FIG. 7, pull down operations may be effected using a third embodiment of the inventive apparatus. Such operations are required when the front or rear bumper of the vehicle have been driven upward or downward relative to the frame as a result of a collision with a low object such as a crash barrier. While such operations are typically repaired using frame-pulling equipment, such equipment may be obviated by implementation of this third embodiment.  
         [0116]    This embodiment of the present invention requires a pulley assembly  700  and a pulling chain  710  in addition to the apparatus of either the first or second embodiments.  
         [0117]    The pulley assembly  700  comprises a pulley base  701  and a pulley wheel  705  attached to the base  701  by a pulley fastener  709 . The pulley base  701  may be cast or extruded out of steel. Alternatively, it may be composed of separate pieces of similar material welded or otherwise fastened together.  
         [0118]    The pulley base  701  has a U-shaped cross-section with triangular legs  702 . The legs  702  have a series of horizontal bores  703  extending across their width near the base of the pulley base  701 . The size of the bores  703  and their separation correspond to that of the bores  122  on the pushing rail legs  123 . Thus, pins  134  may be inserted through a bore  122  on one leg  123  of the pushing rail  121 , through the bores  703  on each pulley base leg  702  and through the corresponding bore  122  on the other leg  123  of the pushing rail  121 . When two pins  134  are passed through pairs of bores  703  in the pulley base  701 , the pulley base  701  is fixed in position along the pushing rail  121 .  
         [0119]    The pulley base legs  702  also have a single bore  704  extending through them proximate to their apex. The apex of the pulley base legs  702  may be interconnected at their apex by a narrow bar.  
         [0120]    The pulley wheel  705  is a cylindrical wheel with a bore  706  passing through its axis. The wheel  705  has a sufficient diameter to permit the pulling chain  710  to wrap around it without kinking, but is small enough to fit within the pulley base  701 . The pulley wheel  705  is attached to the pulley base  701  between the pulley base legs  702  in free rotational engagement by passing the pulley fastener  709  through the bore  703  in the pulley base legs and the bore  806  in the pulley wheel  705 .  
         [0121]    The pulling chain  710  is approximately six feet long, may be standard steel or iron ⅜″ chain, grade 8, and has a rated strength of 25,000 pounds. One end terminates in a hook assembly  711 . The other end may terminate in a clip  712  with which it can fasten about itself. Optionally, the clip  712  may be replaced by a second hook.  
         [0122]    In operation, the vehicle is driven or backed into position relative to the floor rails  110 . In many situations, the vehicle is positioned in front of the floor rails  110 , such that the repair site extends slightly over them.  
         [0123]    Whether the wheels lie beside the floor rails  110  or away from them entirely, the bolts  116  may be easily slid into the channel  115  of the floor rails  110  or into the channel  502  of the diamond rails  500  as the case may be, at one of the wider openings and advanced along the track formed by the opening in the channel  115 , 502  until they reach the desired position.  
         [0124]    At this point, the pushing rail  121  may be moved into position and in the fashion described previously and the pivot base  130  and pushing post  140  installed in position as previously described. In most situations, the pushing assembly  120  is installed in front, beside or behind the vehicle, not under it. The ram assembly  150  and the chain  191  may thereafter be installed and adjusted and tensioned.  
         [0125]    The pulling chain  710  is attached at its hook end  711  to the clevis  139  attached to the shaped end  144  of the pushing post  140 . The other end of the pulling chain  710  is fed under the pulley wheel  705  and between the pulley base legs  702  and then upward and wrapped around the frame to be repaired. The clip  712  may be used to lock the pulling chain  710  in position and at the proper length.  
         [0126]    Finally, a jack stand (not shown) is positioned under the vehicle frame proximate to the point at which the pulling chain is attached to the frame. A single jack stand will suffice where the frame has been bent upward. In such a case, the jack stand should be positioned proximate to an undamaged portion of the frame. Where the frame has been bent downward, a repair may be effected by using two jack stands, one on either side of the bend in the frame.  
         [0127]    At this point, the set-up phase of the repair operation is complete and the repair operation may commence. Here, however, a repair is effected by pushing the pushing post forward, causing the pulling chain  710  to apply downward tension on the deformed frame. The tension cannot be relieved by the entire frame moving downward because it is fixed in place vertically by the jack stand(s). Thus, the frame will be forced downward.  
         [0128]    In a fourth embodiment of the present invention, shown in FIG. 8, the floor rails  800  need not be bolted to the floor of the repair facility, but may be embedded within or form part of the floor itself, such that the top  801  of the floor rail  110  is flush with or extends slightly beyond the floor surface. Thus, the bores  112  and bolts are obviated, and the vehicle may be easily driven over the rails  800  with minimal impediment.  
         [0129]    The combination of floor rails  110 , lightweight but strong pushing rails  121  and holding rails  171  and two piece vertical posts for pushing and holding actions permits the frame pushing repair process to be effected directly over the floor of a repair facility, without the need for elevating the vehicle on rails or for excavating a pit below the floor level in order to provide sufficient ground clearance to permit installation of the posts.  
         [0130]    With the use of sliding channels in the floor rails, pins for easy insertion and removal, lightweight and small pivoting components, the set-up phase need no longer dominate the repair process, with a consequent increase in throughput and reduced cost to the repair facility and ultimately the consumer.  
         [0131]    These features permit other innovations to be implemented. For instance, the floor rails  110  may be mounted on the bed  910  of a small towed platform  900 , as shown in FIG. 9, to provide a portable repair facility. Thus the platform  900  may be transported to the vehicle to be repaired and the vehicle repaired on-site, only requiring that the vehicle be pushed or driven up ramps  915  onto the platform bed. If the platform  900  has no walls, or sufficient clearance between the rails  110  and the walls (not shown), there would be no impediment to inserting the pushing rail  121  and holding rails  171  under the vehicle from the side or end as required. Alternatively, the walls (not shown) may be configured to be removeable or to fold down in order to provide the required access.  
         [0132]    It will be apparent to those skilled in this art that various modifications and variations may be made to the embodiments disclosed herein, consistent with the present invention, without departing from the spirit and scope of the present invention.  
         [0133]    Other embodiments consistent with the present invention will become apparent from consideration of the specification and the practice of the invention disclosed therein.  
         [0134]    Accordingly, the specification and the embodiments are to be considered exemplary only, with a true scope and spirit of the invention being disclosed by the following claims.