A land drilling rig (also commonly called an onshore drilling rig) is a complete set of heavy machinery and equipment designed for drilling oil, gas, or geothermal wells on solid ground (as opposed to offshore platforms at sea). It always include four main systems: 1. Power system: usually have two to four engines, such as diesels engines, gas engines or compond new engergy engines. 2. Hoisting system: main parts are Drawworks + Crown Block + Traveling Block + Drill Line + Hook + Elevators 3. Rotating System: Top Drive + Rotary Table + Kelly + Drill String 4. Circulating System: Mud Pumps + Shale Shakers + Desander/Desilter + centrifuges