Pneumatic single-grain sowing machine

1. 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.

2. The pneumatic single-grain sowing machine according to claim 1 , wherein the housing is formed by a stationary housing part and a removable cover, the rotary plate is supported in the cover by a bearing, the drive shaft is supported in the stationary housing part by another bearing, and the drive shaft is guided through the perforated disk so as to drive the perforated disk.

3. The pneumatic single-grain sowing machine according to claim 2 , wherein the hollow drum is separated by removing the cover.

4. The pneumatic single-grain sowing machine according to claim 1 , wherein the distance between the perforated disk and the stationary part of the housing is adjustable between approximately 0 and 6 mm.

5. The pneumatic single-grain sowing machine according to claim 1 , wherein the seal is arranged on the rotary plate and the seal forms a frictional coupling between the rotary plate and the perforated disk.

6. The pneumatic single-grain sowing machine according to claim 1 , wherein the seal is configured to seal a gap between rotary plate and perforated disk in an axial direction of the hollow drum.

7. The pneumatic single-grain sowing machine according to claim 1 , wherein the housing comprises a drive which is configured to drive the drive shaft, the drive is operated electrically or mechanically, and an electric drive and a mechanical drive are interchangeable with one another.

8. The pneumatic single-grain sowing machine according to claim 1 , wherein the hole covering element rolls on the perforations of the perforated disk so as to rotate about its own central axis, the hole covering element is supported in a stationary, rotatable manner by a support arm rigidly connected to a cover, and the central axis of the hole covering element encloses an angle of more than 5 degrees with the perforated disk.