Abstract: A linkage for coupling a vehicle to a ground-engaging implement consists of two links, the first link being connected at one end to the vehicle such that it can pivot both around the longitudinal axis of the link and around a line transverse to that axis and connected at its second end to the implement to pivot around a line transverse to its longitudinal axis; the second link being connected in a similar fashion but oppositely to the first link.

Abstract: The present invention provides in an agricultural ground treating device particularly but not exclusively a seed drill arranged to be towed over the ground and having a plurality of ground engaging implements, means for causing all of the implements to engage the ground with a substantially equal force.Preferably the means to equalizing the forces comprises a pivotal beam arrangement in which the implements are movably mounted on the chassis of the device and connected in pairs at each end of an associated balance beam, these balance beams are pivotally mounted at their mid points on respective ends of further balance beams which are mounted by their mid points at respective ends of yet further balance beams, and so on according to the number of implements on the device, the final balance beam or final pair of balance beams being connected to means on the chassis of the device for urging them, and the implements connected thereto towards the ground.