Keywords: HooverDamJumboRig.jpg en wikipedia 2011 March 23 This piece of equipment named a Jumbo Rig was designed to speed up the Hoover Dam's tunnel drilling process Built on the back of a 10-ton truck 24 to 30 drills could be operated at once http //www usbr gov/lc/hooverdam/images/jumbo jpg Bureau of Reclamation PD-USGov Original upload log en wikipedia NortyNort CommonsHelper page en wikipedia Hooverdamjumborig jpg 2010-06-20 03 47 NortyNort 770×557× 137028 bytes <nowiki> This piece of equipment named a Jumbo Rig was designed to speed up the Hoover Dam's tunnel drilling process Built on the back of a 10-ton truck 24 to 30 drills could be operated at once http //www u</nowiki> Drilling machines 1930s Hoover Dam construction equipment Jumbo Rig People associated with the construction of Hoover Dam workers |