This type of repair is done on a frame machine which is a platform onto which the vehicle can be clamped. It also uses hydraulic rams which will pull with a force of up to 20,000 lbs.
Along with the devices for pulling, a measuring system is utilized. A common system uses a laser and reflective targets which are accurate to within one millimeter. This system can be used live and the dimensions of the vehicle can be monitored during the pull. The vehicle is measured in three dimensions: height, width, and length. Once the frame has been restored to its original condition, all other parts will fit and the wheels will align correctly.