PURPOSE: To obtain an expansion type kelly bar device having a cushion material provided with both shock absorbing performance and abrasion resistance.
CONSTITUTION: At least the first Kelly bar and the second Kelly bar expanding each other are provided, and in an expansion type Kelly bar device holding the second Kelly bar with a holding section provided to the first Kelly bar, a cushion material 20 of two layer construction is provided to at least one of the holding section 8 and a contact section of the second Kelly bar 2 therewith. The first layer 21 having abrasion resistance is provided to the surface of the cushion material 20, and the second layer 22 absorbing a shock in the case where the second Kelly bar comes into collision with the holding section 8 is provided under the first layer.
| WO/2015/084345 | VIBRATION DAMPER |
| WO/2008/127894 | MULTIPART SLIDING JOINT FOR FLOATING RIG |
NOZAKI SATOSHI
AJIRO SHUICHI
