Abstract: This invention is related to the process and apparatus for applying stressed skin sheet coverings to large passenger vehicles. The apparatus for the process, provided by this invention includes a single phase transformer, conductors, electric contactors and a guiding apparatus. The present invention uses a specialized transformer, capable of producing a strong electric current of low voltage as an energy source, utilizing the steel skin sheet as a resistor element in the output circuit, welding the steel sheet onto the frame while the steel sheet is heated by the electric current passing through the sheet, thereby elongating the sheet at a set value due to the rise in temperature, cutting off the electricity and welding the upper and lower sides quickly onto the frame, thus finishing the process of skin covering and resulting in residual stresses within the steel skin sheet.