| 摘要 |
In a turbodrill, there is no guarantee that a rotary friction ring (1) is or will remain exactly at right angles to its shaft (2). Wear against a co-operating non-rotary friction ring (6) is thus uneven, and if the surrounding medium is drilling mud, small abrasive grains can penetrate between the friction rings where they are not in contact and score them where they are in contact. The non-rotary friction ring is mounted on a moving sleeve (28) which is connected to a fixed sleeve (33). A spring (17) urges the friction rings into contact. An arrangement of balls in axial grooves between the sleeves allows the moving sleeve (28) to tilt slightly relative to the fixed sleeve (33). The non-rotary friction ring can thus wobble to keep in good contact with the rotary friction ring.
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