Patent ID: 8540319

Claim:
A bit replacing unit for an excavating machine, in which the excavating machine includes, in a front part thereof, a cutter head rotatably supported about an excavating machine axial center, a roller bit for crushing rocks and pebbles, the roller bit being disposed on a front surface of the cutter head, and a workspace in which an abraded roller bit can be replaced, the workspace being formed inside the cutter head, wherein a housing is disposed in a front part of the cutter head, a bit containing path is formed in the housing along an in-and-out axis along which the roller bit is extended and retracted, a bit containing portion which opens at the front surface of the cutter head and a valve containing portion which is formed behind the bit containing portion are provided on the bit containing path, an opening for replacement is formed in a direction of an insertion-and-removal axis at a predetermined angle relative to the in-and-out axis in the housing, the opening for replacement communicating with the valve containing portion and the workspace, a rotary valve is provided in the valve containing portion, the rotary valve being rotatable about a rotary axis substantially perpendicular to the in-and-out axis and the insertion-and-removal axis, an attachment/detachment path communicating with the bit containing portion is formed in the rotary valve, a bit case containing the roller bit is removably inserted into the attachment/detachment path, the rotary valve is turned at a predetermined angle to cause the attachment/detachment path to communicate with the opening for replacement, so that the bit case is movable between the attachment/detachment path and the workspace, a bit extending/retracting mechanism for extending and retracting the bit case between the attachment/detachment path and the bit containing portion is provided on the rotary valve, a first sealing material is provided for sealing at a gap between the bit case and the valve containing portion, and a second sealing material is provided for sealing at a gap between a periphery of an opening of the attachment/detachment path and an inner surface of the valve containing portion on an outer peripheral surface of the rotary valve.