| 摘要 |
A support arm carried by a carrier base. A base tooth ring on the carrier base and an arm tooth ring on the support arm, wherein the arm tooth ring releasably interlocks with the base tooth ring. A base column having a hollow interior chamber carried by the carrier base, and an arm column carried by the support arm extending into the hollow interior chamber. A first stop block channel disposed in a bottom surface of the base column, and a second stop block channel disposed in the support arm adjacent an exterior side of the arm column. A first stop block carried by a distal end of the base column received into the second stop block channel, and a second stop block carried by a distal end of the arm column being received into the first stop block channel to define a range of pivotal movement. |
