Abstract: A static hydraulic system provides yieldable hold-down force to the ground-engaging tools of an implement when the system is in its hold-down mode. Alternatively, the system can be operated in a way to lift the tools into an elevated ground-clearing position when placed in the lifting mode. An accumulator and pressure-reducing valve are incorporated into the hydraulic circuit in such a way that the system need not be an active hydraulic system in which a pump on the tractor would continuously circulate pressurized fluid in the system during ground-engaging operations in the hold-down mode.

Abstract: The primary distribution hoses on the tillage implement of a pneumatic seeding machine are of different lengths as needed to reach distribution heads or splitters on the implement that further divide the primary streams of materials into individual streams leading directly to the ground-engaging openers of the implement. Notwithstanding the differential in hose length, outlet pressures at the distribution heads are made uniform through the provision of internal flow restrictors associated with those hoses that are shorter than the longest hoses on the machine. Throat diameters of the restrictors vary in accordance with the pressure drop that is needed to match the difference in hose length between the longest hose and the restricted hose. In a preferred embodiment, the restrictors are mounted within nipples on the coupling assembly that releasably connects conduits from a seed cart with the primary hoses on the implement.