Our big picture: The mountain saw
Without traffic disruption, on the Autostrada Adriatica, which connects the north of Italy to the heel of the boot, the two tunnels of the Montedomini Tunnel have been widened from two to three lanes. In the existing tunnel, near the port city of Ancona, a further tunnel was built through which the traffic could keep flowing while people and machines worked in the cavity between the two tunnel ceilings. For this purpose the Italian Palmieri Group designed an eight-and-a-half meters long chainsaw, which sawed the new arch of the tunnel in the rock. The technology was faced with extreme conditions: the machine had to endure a lot of dust, heat and moisture. Palmieri therefore settled for a Hägglunds hydraulic motor and a closed hydraulic system by Rexroth, through which the fluid was pumped using two axial piston variable pumps.
Image: Palmieri S.p.A.