| 摘要 |
Manual control apparatus is provided for use with normally automatically powered driving assemblies such as valve actuators. The control apparatus (10) has a body (14) with a bore (20) therethrough, a housing (60) secured to the body (14) and having an axial bore (62) which registers with the bore (20) in the body (14), a rotatable split drive nut (84, 86) mounted in the housing (60), a drive screw (50) extending into the registering bores (20, 62) in the body (14) and the housing (60) and mounted for axial movement therein, a camming system (90, 94, 106, 108) for selectively engaging and disengaging the drive nut (84, 86) with the drive screw (50) whereby engagement of the drive screw (50) with the drive nut (84, 86) and rotation of the drive nut (84, 86) causes axial movement of the drive screw (50), and a biasing assembly (130, 160) operatively connected to the split drive nut (84, 86) which exerts a biasing engagement force on the drive nut (84, 86) when a given magnitude of resistance to engagement is encountered. |
