Abstract: In order to simplify the construction and to accelerate the change-over of two drive units in the case of a feeding device having a drive shaft and two gear units each drivable by a motor, which gear units are able to be connected alternately to the drive shaft such that each may alternately rotate with the drive shaft independently of the other, it is suggested that both gear units are designed as slip-on gear units and have a driven hollow shaft, that the two ends of the drive shaft each have the hollow shaft of one of the two slip-on gear units mounted around them in a manner permitting relative rotation, that the gear units are secured against rotation about the axis of rotation defined by the drive shaft and that rotary couples are provided, such that one of the hollow shafts at a time is connected to the drive shaft such that the connected hollow shaft secured against rotation relative to the drive shaft.

Abstract: Method and device for pneumatic feeding of materials to be conveyed along a feeding line (10) supplied continually with conveying gas from conveying gas lines (18) discharging into the feeding line and spaced consecutively apart from each other. Each gas line (18) has at a distance from its opening (28) a short cross-sectional constriction (20), in the area of which the velocity of the conveying gas is increased to the velocity of sound and decreased again before the opening (28). A plurality of gas lines (18) are fed from a common supply line (16, 17) which runs adjacent to the feeding line (10). The gas lines (18) open into the feeding line (10) at an acute angle of approx. 35.degree. and have two sections (21, 23) detachably connected with each other by a sealing screw connection (24), an apertured diaphragm, forming the cross-sectional constriction (20), and a filter (22) being held interchangeably by the screw connection.