| 摘要 |
An hydraulic shock absorber for protecting the drill bit and drill pipe in rotary earth drilling consists of a casing with an upper sub mounted in its one end for connection to a string of drill pipe. An anvil is slidably mounted on the other end. A plurality of hollow pistons are slidably mounted inside the casing. The pistons each have a hollow sleeve portion extending in sealing relationship through seating rings mounted on the inside of said casing. The pistons also have a radial flange portion at their upper end slidably sealing with the walls of the casing and a fluid passage extends through the wall of the casing between the flange portion and the seating ring. |
