| 摘要 |
The present invention includes a pawl releasably engagable with a ratchet, a handle connected directly or indirectly to a user-manipulatable device, a cam movable between an unlocked position in which actuation of the cam by the handle generates sufficient pawl movement to release the ratchet and a locked position in which actuation of the cam by the handle does not generate sufficient pawl movement to release the ratchet, and a lock coupled to the cam for moving the cam between its unlocked and locked positions. The cam has at least one cam surface that, when the cam is moved by the lock toward its unlocked position, cams against one or more surfaces of the pawl, the handle, or the pawl and the handle if the handle is already partially or fully actuated. In some highly preferred embodiments, the cam is movable within an aperture in the pawl, an aperture in the handle, or apertures in the pawl and handle. The apertures can function to guide the cam in its motion between unlocked and locked positions and also to provide cam surfaces against which the cam cams to transmit motion to the pawl. |
