Tunnel boring machine

tunnel boring machine (TBM), also known as a "mole", is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock

excavating-equipmentsExcavating Equipments
from 1p1vcxhskaju, ago in
short and simple

Profitable use of excavation equipment
Elmer R. Drevdahl, published 1961, 156 pages