Liquid feeder for automatic culture apparatus

A liquid supply switching system for automatic culture apparatus comprising a hollow shaft extending through and secured to a stationary outer plate of an incubator, a drive shaft extending through the hollow shaft for rotation and vertical motion therein, the drive shaft being peripherally formed with a keyway and a rotation controlling cam groove in which a pin secured to the hollow shaft is fitted, the drive shaft being urged to move upwardly so that its upper end face bears against a vertical movement controlling cam, a rotating plate carrying a key which engages the keyway and rotatably fitted between the hollow shaft and the drive shaft so as to be capable of only rotation integrally with the drive shaft, a vertical movement controlling cam fixedly mounted on the output shaft of a drive motor and disposed in abutment against the upper end face of the drive shaft for controlling the vertical movement thereof as the motor rotates, a tube support arm extending from the lower end of the drive shaft and adapted to have the inner end of a flexible liquid supply tube mounted thereon, and an angular position detecting mechanism including a switch operating member mounted on the rotating plate and also including a pair of motor stopping limit switches disposed adjacent to the rotating plate at the opposite ends of the angular extent of rotation of the plate, the detecting mechanism causing the switches to deenergize the motor at a given angular position at which the vertical movement of the drive shaft is stopped for bringing the discharge port of the liquid supply tube to a given three dimensional position.