Cutter Head

A cutterhead is a big device which is mounted on a front portion of a tunnel excavating machine. During operations cutterhead rotates with great force. Cutter head is provided with numerous cutters. With the specially designed bearings the cutterhead is attached to the main body or the shield of the tunnel boring machines. The motor which rotates the cutterhead lies within the shield. The shield also house the thrust cylinder which provides the forward thrust on the cutting discs. Hydraulic cylinders thrust the cutter discs into the rock. The harder the rock, the more thrust that is required to break it.

Shields also protects the workers who install the initial tunnel support system behind the tunnel boring machines. The precast concrete rings which supports the main spine tunnel are assembled inside of the shield. These rings are expanded to fit the tunnel excavation as the shield moves forward. Ring is build and positioned by hydraulic ring erectors that are mounted inside the shield. The rock chips, are scooped into the cutterhead through holes in the head, called buckets, as it rotates. The chip is carried by the conveyor, through the shield and into the supported tunnel where it is loaded into rail cars and hauled out of the tunnel.