This process can not be performed on HSS or HSLA vehicle design because the heat can change the structural integrity of the rails. Another holding method that has been used is chain and block . However, most holes in rails are not designed to withstand the pulling force applied to correct damage. Most holes are simply shipping slots to assist the transporter in holding the vehicle in place while being delivered. The chain and block method sometimes causes safety problems when the vehicle was hard to hold to the frame machine to prevent movement.
Any movement causes pulling angles to change, affecting the quality of repairs.
Occasionally vehicles moved almost off the machines, causing problems for both the operator and vehicle. A proper holding system uses rigid clamping devices to hold vehicle to the bench or rack. This not only stops movement between the vehicle and machine but also movement within the vehicle frame, which can cause more damage than the original collision. As correction forces are applied to a full frame, the angles in which they are directed may cause damage or stress in areas surrounding the repair. A holding system will counteract this by holding and supporting the frame three dimensionally in length, width and height.