The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 20, 1993
Filed:
Jun. 17, 1991
Richard J Robbins, Seattle, WA (US);
David T Cass, Seattle, WA (US);
Peter B Dowden, Kirkland, WA (US);
The Robbins Company, Kent, WA (US);
Abstract
A tunneling machine convertible between a 'closed mode' and an 'open mode' of operation, having a rotatable cutterhead with muck openings communicating with a pressurizable cutterhead chamber and a pressure maintenance system to stabilize the tunnel workface when operating in the 'closed mode'. In the 'closed mode' low slurry flow is employed as a liquid pressure balance solely to support the unstable tunnel face. Low slurry flow is supplied through a pressure bulkhead sealing the cutterhead chamber and pressurized conveyor means through the bulkhead removes tunneled material from the cutterhead chamber. A pressure lock connected to the pressurized conveyor means transfers tunneled material to dewatering and reservoir/accumulator means operated at substantially atmospheric pressure. Slurry, with at least most of the solids removed, is recycled to the slurry inlet at a controlled low flow rate matching the rate of removal of tunneled material and slurry from the tunnel face so the otherwise unstable tunnel face is maintained stable. In the 'open mode' of operation, for use in boring a self-stabilizing tunnel face, the pressure bulkhead is removed and a second conveyor, such as a belt conveyor, is disposed adjacent to the 'closed mode' conveyor to withdraw cuttings from the cutterhead chamber.