Patent Publication Number: US-4649730-A

Title: Automobile body and frame straightening tool

Description:
This invention is a tool for pulling automobile frames back into shape after a crash. The tool is very helpful for unibody construction where the body and frame are welded together. 
    
    
     In the drawing, 
     FIG. 1 is an exploded view of the front end of an automobile frame, 
     FIG. 2 is an exploded view of the front end of the frame and the frame straightening tool. 
     FIG. 3 is a plan view of an extensible bar for connecting two tools. 
     FIG. 4 is an elevation of FIG. 3 and 
     FIG. 5 is a diagrammatic view of the drive for extending the bar of FIGS. 3 and 4. 
    
    
     In typical automobile construction, the front end of the frame has a cross member 1 and sockets 2 for shock absorbers 3. The back ends of the shock absorbers may be bolted in place by through bolts 4 at the bottom of the sockets 2. At the forward end of the shock absorbers are brackets 5 bolted to a bumper structure 6 which typically comprises an inner structural member for receiving the load and outer decorative member which is for appearance. The brackets 5 are sometimes dispensed with and the front end 7 of the shock absorbers are connected directly to the structural member of the bumper 6. A similar shock absorber structure is used for the bumper at the back end of the automobile. 
     Even in severe crashes, the shock absorber sockets are not seriously distorted. The sockets are designed to receive heavy loads and to transmit the same to the frame and body of the car. While the frame and body may be distorted by the crash, the shock absorbers by reason of the inherent design are not distorted. 
     The first step in straightening an automobile frame after a crash is to remove the shock absorbers 3 by removing the bolts 4 and if necessary, also removing or disconnecting the brackets 5 from the bumper 6. The next step is to insert a pulling tool 8 in each socket and secure it in place by suitable means such as bolts 9 and washers 10. The pulling tools will rarely be in the rectilinear position illustrated because of the distortion due to the crash. It is desirable that at the end of the straightening operation the pulling tools 8 be in line with (or parallel to) the frame members 11 and that the spacing between front members 11 be within design tolerance. This is accomplished by the direction of pull on the tools 8 and by extensible bar 12 shown in detail in FIGS. 3, 4 and 5. The bar 12 has universal joints 13 at each end which are clamped over flats 14 by screws 15 extending from clamping member 16 into universal joint member 17 so as to accurately position the universal joint with respect to the tool 8. The length of the bar 12 is adjusted by gears 18, 19 driving an oppositely threaded shaft 21 connected to universal joint members 22. 
     Each of the pulling tools 8 has an eye 23 which permits pulling in any direction. By varying the direction and amount of pull, it is possible to bring even a badly damaged frame back into the rectilinear relationship indicated in FIGS. 1 and 2. This straightening of the frame also straightens parts of the body which were damaged by the crash. This straightening is desirable even though the damaged parts of the body are to be replaced. The damaged parts provide a convenient way of transmitting force to other parts of the body which are not to be replaced.