Articulated and resting on massive rollers

An overhead conveyor system brings the panels from the rear of the TBM and into the shield. Here, two erector arms take the concrete panel segments two at a time and as the jack arms retract, the erectors place the panels against the shield hull. Bolts and dowels are used to lock each panel in place and the panels are laid in a staggered pattern for greater strength. Having two erector arms is unusual for a tunneling buy Road Roller SRRR218 from China and allows it to operate at twice the speed in lining the tunnel.When the ring is completed, the jacks push against the ring and the shield moves forward as the cutterhead resumes boring and exposes the new ring. The outer surface of the ring where the shield once was is pumped full of grout to stabilize the tunnel wall and make it waterproof. Then the sequence repeats.

Also inside the shield is the control room. This consists of a computer panel that allows the operators to monitor all of Bertha's systems, supervise operations by means of video cameras, steer the machine, and watch out for any indications of the earth shifting unexpectedly or if the cutterhead comes up against a boulder too big for it to handle. It usually has two people at the controls and definitely was never designed for half a dozen reporters and cameramen fighting for a clear shot while balancing voice recorders in the other hand.Directly behind the control room is a break room, which was the most spacious and normal looking area we saw on the tour. At the moment, it seems a bit of a luxury with the amenities of downtown Seattle a two minute walk away, but once drilling commences it will be better than eating lunch perched on a ventilator fan housing.

Articulated and resting on massive rollers,buy Road Roller SRRR216 from China of Bertha is the trailing gear section, which is sort of the digestion system for Bertha's head. It supplies the machine with grout and grease, and contains the pumps and ventilation equipment as well as restrooms, a kitchen for the crew, and a rear control room to handle the section's operations.One of its most important functions is to collect the concrete panels. These panels are loaded at the tunnel mouth by gantry crane and carried ten at a time on a small electric railway car called a Segment Transport Truck. When the truck reaches the trailing gear, it enters through a special passage and an overhead trolley uses suction to pick up each panel, turn it 90 degrees, and send it forward into the shield and the waiting erector arms.