| 摘要 |
<p>A rotatable disk (28) has circumferential rows of seed apertures (34). The back side of the disk confronts a seed chamber. Seeds picked up at the apertures (34) are carried round to a discharge zone and drop through a shoot (58). On the front side of the disk (28), when a hinged cover (16) is closed, a vacuum chamber (46) sucks the seeds to the apertures (34). The vacuum chamber is partitioned from a third chamber (62) which is opposed to the discharge zone; the vacuum is interrupted in the third chamber. Within the third chamber a cleaning device (64) acts on the front face of the disc to dislodge debris and clean the apertures (34). The cleaning device comprises a brush 66 with two circular brushes which rotate against the front face of the disk so that the bristles poke into the apertures (34). Upstream of the brush (66) there is a resiliently mounted scraper blade (68). The scraper blade alone may suffice for large seed apertures. The brush alone may suffice for small seed apertures. Both are preferably provided to cater for seed discs with different size apertures.</p> |
