Patent ID: 8783786
Filing Date: 2014-07-22
Classification: A61K,E21B,E21D

Abstract:
1. A cutter assembly for a tunnel boring machine comprising: a shaft; a cutter ring assembly rotatably mounted on the shaft; a first end retainer attached to one end of the shaft and a second end retainer attached on an opposite end of the shaft, the first end retainer having a fixed retainer with a pressure port therethrough and a movable piston portion with an outer surface subject to a local hydrostatic pressure, the movable piston portion comprising a floating retainer that slidably engages the fixed retainer such that a gap is defined between the fixed retainer and the floating retainer that is in fluid communication with the pressure port; a first rotary seal group having a first portion engaging the cutter ring assembly and a second portion engaging the first end retainer; and a second rotary seal group having a first portion engaging the cutter ring assembly and a second portion engaging the second end retainer; such that the first rotary seal group is immersed in a lubricant that is in fluid communication with the port and fills the gap between the fixed retainer and the floating retainer such that the movable piston portion is configured to increase the pressure of the lubricant in response to an increase in the local hydrostatic pressure; and further wherein the fixed retainer further comprises an annular channel and an outer perimeter, and further wherein the floating retainer comprises an annular wall that slidably engages the annular channel and an outer wall that slidably engages the outer perimeter of the fixed retainer.