Mechanical transmission ■ Including ◆ Gears Chains Belts Worm gear ■ Advantage: Simple Direct Reliable High efficiency ■Disadvantage Difficult to control Difficult to automateMechanical transmission  Including  Gears  Chains  Belts  Worm gear  …  Advantage:  Simple  Direct  Reliable  High efficiency  Disadvantage  Difficult to control  Difficult to automate