Abstract: A mining riser pipe is extended from above water toward a water bottom containing water bottom resources, and a lower portion of an insertion pipe connected to a lower portion of the mining riser pipe is inserted into the water bottom. A liquid is supplied into the insertion pipe and a rotation shaft extends axially inside both of pipes is rotated to rotate stirring blades attached to a lower portion of the rotation shaft inside the insertion pipe, thereby drilling and dissolving mud S inside the insertion pipe into a slurry form is raised to an upper portion of the insertion pipe by a stirring flow generated by the rotation of the stirring blades, and the raised mud is lifted above the water through the mining riser pipe by lifting force.

Abstract: Provided is a dog clutch mechanism that can guarantee a successful engaging operation regardless of relative rotational positions of a sleeve and a transmission gear, with a simple and inexpensive configuration. When sliding of a sleeve (20) toward a transmission gear (30) involves contact (abutting) between dog teeth (21b) of the sleeve (20) and key members (50), an engaged state is achieved so that a rotation shaft (2) and the transmission gear (30) integrally rotate, with the key members (50) retracted toward the transmission gear (30) to a retracted position against biasing force of a coil spring (55), and the dog teeth (21b) fit in keyway (51) between the plurality of key members (50). Thus, the dog clutch mechanism (1) guarantees the successful engagement with only a single engagement operation.

Abstract: A gear includes a toothed portion, a boss, a first connector, a second connector, and a dynamic damper. The toothed portion is disposed at a radially outer side of the gear. The boss is disposed at a radially inner side of the gear. The first connector connects the toothed portion and the boss. The second connector connects the toothed portion and the boss. The second connector faces the first connector such that the toothed portion, the boss, the first connector, and the second connector define a sealed space. The dynamic damper is disposed in the sealed space.

Abstract: Provided is a dog clutch mechanism that can guarantee a successful engaging operation regardless of relative rotational positions of a sleeve and a transmission gear, with a simple and inexpensive configuration. When sliding of a sleeve (20) toward a transmission gear (30) involves contact (abutting) between dog teeth (21b) of the sleeve (20) and key members (50), an engaged state is achieved so that a rotation shaft (2) and the transmission gear (30) integrally rotate, with the key members (50) retracted toward the transmission gear (30) to a retracted position against biasing force of a coil spring (55), and the dog teeth (21b) fit in keyway (51) between the plurality of key members (50). Thus, the dog clutch mechanism (1) guarantees the successful engagement with only a single engagement operation.

Abstract: A gear includes a toothed portion, a boss, a first connector, a second connector, and a dynamic damper. The toothed portion is disposed at a radially outer side of the gear. The boss is disposed at a radially inner side of the gear. The first connector connects the toothed portion and the boss. The second connector connects the toothed portion and the boss. The second connector faces the first connector such that the toothed portion, the boss, the first connector, and the second connector define a sealed space. The dynamic damper is disposed in the sealed space.