Abstract: A rock crushing device according to the present invention is designed to crush rocks by the use of the expansion pressure generated when an elastic expandable member of a cylindrical configuration is expanded by pressure fluid to be injected into looped pockets provided within the elastic member. The elastic member, made of rubber or similar materials, is provided tightly to cover around a metal shaft having a fluid passage to introduce pressure fluid into the looped pockets of the elastic member.

Abstract: Method and apparatus for determining angular and transversal displacements of a shield machine and a succeeding pipe relative to a pre-determined schedule central axis of a tunnel to be constructed by pipe-jacking tunneling which includes providing on the shield machine a first light emitter which emits rearwardly a light beam along the central longitudinal axis of the shield machine and a reference position on the axis of the shield machine, projecting the light beam to a pair of targets, each having a scale and being provided in a succeeding pipe spaced from each other by a predetermined distance along the central longitudinal axis of the succeeding pipe to form light spots on the targets, projecting to the pair of targets a light beam emitted from a second light emitter along the scheduled central axis of the tunnel to be constructed to form further light spots on the targets with the second light emitter being located at the rear portion of the tunnel, and reading the light spots and the further light spo