Automatic and Semi-Automatic Assembly Units Having a Storage Zone for Storing and Moving a Plurality of Electrical or Mechanical Devices to Be Assembled and a Working Zone for Individually Receiving the Devices to Be Assembled; Automatic and Semi-Automatic Tools to Be Used in Assembling and Manipulating the Parts of Mechanical and Electrical Devices to Be Assembled, for Use with Automatic and Semi-Automatic Assembly Units-Namely, Transfer Arms, Wobble Riveters, Powered Screwdrivers, Powered Presses, Machine Tools and Parts Therefor; and Assembly Line Arrangements Made Up of a Plurality of Assembly Units for Providing Several Work Stations Required for the Total Assembly of Small and/or Medium Sized, Relatively Complex Electrical and Mechanical Devices