In DTH drilling, the percussion mechanism – commonly called the hammer – is located directly above the drill bit. The drill pipes transmit the necessary feed force and rotation to the hammer and the bit, along with the fluid (air, water or drilling mud) used to actuate the hammer and flush the cuttings. The drill pipes are added to the drill string successively behind the hammer as the hole gets deeper.
[pdf] Crawler and truck mounted hydraulic drilling rigs with a pull up capacity ranging from 10 to 30 tonnes, designed and optimized for the construction of water and geothermal wells with the use of double head drilling systems.
[pdf] In this video we assemble a DIY micro drill rig (tiny DC motor + drill bit + frame) and a submersible water pump, then test drilling a small “well” and pumping water through tubing. I explain the mechanism, torque limits, and 3 upgrades for better performance.
[pdf] 
