| 摘要 |
<p>The control system allows selected parallel seed tubes to be blocked by hydraulic or electric shutter plates so that the corresponding furrows are left unseeded to provide circulation paths for subsequent plant treatment operations. The movement of the shutter plates is initiated by a counted sequence of changes in the control signal, where two different control signals are provided successively as a function of the measured distance along a furrow and the turning angle of the tractor steering wheels. Pref. a pulse generator is coupled to one of the wheels of the seeder supplying pulses to a counter operating as a distance recorder, with one of the control signals supplied each time a given distance has been traversed. The measurement of the turning angle of the tractor wheels may be effected via a switch allowing the second control signal to be provided each time they are turned through a given angle. The system ensures a constant spacing between the furrows left unplanted.</p> |
