| 摘要 |
<p>A steerable system comprises a first rotatable housing (22), a second rotatable housing (24) connected to the first rotatable housing (22) by an adjustable joint (26), a cam member (42) held against rotation, in use, and cam follower means cooperable with the cam member (42) and moveable to drive the second rotatable housing (24) for movement relative to the first rotatable housing (22) about the adjustable joint (26).</p> |
