Pneumatic single-grain sowing machine

A pneumatic single-grain sowing machine, comprising:

• at least one closed housing having a seed storage container, and
• at least one rotatably driven separating device, which has circularly arranged perforations, and a fan for producing a pressure difference between the housing and an interior of the separating device,
• wherein the separating device is configured to separate seed by use of the perforations and the pressure difference,
• wherein the separated seed is configured to be detached from the perforations by interruption of the pressure difference by a hole covering element, so that the detached, separated seed is fed to a dispensing line,
• wherein the separating device is designed as a closed hollow drum having two side walls arranged at a distance from each other, the perforations are arranged in at least one of said side walls,
• wherein a drive shaft is guided through at least one of said side walls, the hollow drum is sealed against the drive shaft by a sealing element, the hollow drum is designed to be divisible by a dividing plane, the hollow drum is formed by a rotary plate and a perforated disk having the perforations, the dividing plane lies between the rotary plate and the perforated disk and is sealed by a seal in the undivided state, and after the interruption of the pressure difference, the separated seed is accelerated by an additional pressure difference in the dispensing line, and
• wherein a front end of the drive shaft comprises an external thread corresponding with an internal thread formed in the perforated disk, the perforated disk with the internal thread being variably arranged in an axial direction on the drive shaft over the length of the external thread for adjusting a distance between the perforated disk and a stationary part of the housing.