| Patents for E21D 23 - Mine roof supports for step-by-step movement, e.g. in combination with provisions for shifting of conveyers, mining machines, or guides therefor (3,544) |
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| 09/20/1977 | US4048804 Support assemblies for use in mine workings |
| 09/20/1977 | US4048803 Mining shield support apparatus |
| 09/06/1977 | US4046060 Hydraulic control systems for use with mining apparatus |
| 08/30/1977 | US4045087 Mining apparatus |
| 08/16/1977 | US4041715 Pit prop with liftable front end |
| 08/16/1977 | US4041714 Mine roof supports |
| 07/26/1977 | US4037419 Mine roof support |
| 06/21/1977 | US4030308 Mine roof supports |
| 06/14/1977 | US4029361 Longwall mining roof support for double deck machines |
| 06/14/1977 | US4028898 Pit prop assembly |
| 06/07/1977 | US4027489 Mine roof support |
| 05/31/1977 | US4026118 Movable roof support mechanism |
| 05/31/1977 | US4026116 Mine roof supporting |
| 05/03/1977 | US4020640 Shield structure |
| 04/19/1977 | US4019049 Photoelectric transducing unit and system for detecting the sharpness of the image of object by means of the unit |
| 03/22/1977 | US4013320 Hook plough apparatus for longwall mining |
| 03/22/1977 | US4012914 Mine roof support |
| 03/08/1977 | US4010618 Mine roof support |
| 02/22/1977 | US4008578 Pit prop assembly |
| 01/18/1977 | US4003208 Assembly for preventing the fall of dust and debris in a mine |
| 01/11/1977 | US4002037 Self-advancing support for use in the pit of coal or metal mine |
| 01/11/1977 | US4002036 Mine roof supports |
| 12/14/1976 | US3996753 Mine roof support |
| 11/23/1976 | US3992888 Hydraulic pit prop |
| 11/16/1976 | US3991580 Mine roof supports |
| 11/16/1976 | US3991579 Self advancing support chocks |
| 11/16/1976 | US3991578 Self-advancing mine roof supports |
| 11/09/1976 | US3990251 Excavation roof support |
| 10/26/1976 | US3987634 Roof-supporting arrangement |
| 10/12/1976 | US3985328 Prop-and-shoe assemblies of self-advancing mine roof-supports |
| 10/05/1976 | US3983710 Device for sealing a roof of an excavation |
| 10/05/1976 | US3983709 Roof support structure for excavations |
| 09/14/1976 | US3980340 Method for longwall mining with side-by-side arch sections |
| 09/07/1976 | US3979151 Rock excavating arched tunnel forming machine |
| 07/27/1976 | US3971225 Mine support assemblies |
| 06/08/1976 | US3961487 Mine roof support |
| 06/01/1976 | US3960408 Tunnel layout for longwall mining using shields |
| 06/01/1976 | US3959976 Excavation-roof support |
| 05/25/1976 | US3958830 Longwall mining system and archshield for mining tar sands, oil shales and the like |
| 04/27/1976 | US3952525 Mine roof support |
| 04/13/1976 | US3949563 Mine roof shield |
| 04/13/1976 | US3949562 Apparatus for preventing cave-ins of excavations |
| 03/16/1976 | US3943723 Mine roof support equipment |
| 01/20/1976 | US3932998 Mine roof support |