Tunnel excavator
Patent 3985390 Issued on October 12, 1976. Estimated Expiration Date: 
October 12, 1993. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
October 12, 1993. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3325217 3547493 3840271 InventorsAssigneeApplicationNo. 559539 filed on 03/18/1975US Classes:299/31, Stepper-type advance-causing means299/33, With mine roof-supporting means405/141ShieldExaminersPrimary: Purser, Ernest R.Assistant: Pate, III, William F. Attorney, Agent or FirmInternational ClassE21D 9/10 (20060101)Foreign Application Priority Data1974-03-18 JAAbstractTunnel excavator for forming an upper half annular hollow space in the solid earth. The excavator has an arch shaped shield provided with a plurality of chambers in which excavating machines are located. Each of the excavating machines is swingably supported in the respective chamber and gripper means for securely abutting against the outer and inner surfaces of the solid earth formed by the upper half annular hollow space is located in each of the chambers. Thrust generating means is connected between the respective excavating machines and the respective gripper means so that the excavating machines can be advanced by the action of the thrust generating means when the gripper means is actuated to abut against the earth.Field of SearchStepper-type advance-causing means | |
