| 摘要 |
Apparatus for slidably positioning a sample tray biased in a first direction by restoring means, the sample tray being coupled to a rack member coacting with a small motor driven gear for driving the sample tray in a direction opposite to the first direction, the small gear being coupled to a large gear having a plurality of position determining protruding fingers engaging a pawl member. The pawl member is configured for limited pivotal movement about an axis, the pawl having a pocket configured in one end thereof for sequentially engaging the protuding fingers, while the other end of said pawl has a shoulder portion engaging a solenoid actuated stop lever for selectively determining the engagement of the pocket with a predetermined protruding finger. Mechanically coupled to the sample tray is a piston engaging a fixed cylinder, the sample tray being initially motor driven to the extreme limit of its first direction with the solenoid energized to permit pivoting of the pawl member, the sample tray then being precisely positioned in the opposite direction to one or more selected positions under action of selective energization of the stop lever, under the force of the restoring means, the speed of return being controlled by the piston and cylinder. Limit switches are provided for selective sequential control. |
