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

power-shovel-60021035Power shovel
from Ashigupta9, ago in
Power shovel is a bucket equipped constuction equipment used for excavating and transporting all classes of earth (except solicd rocks without prior loosening) to nearby trucks or other hauling equipments.

Notes on Mechanical Excavating Equipment
Cecil George Calman, published 1922, 26 pages