An earthworking tool suspension system composed of a pair of vertically disposed and fore-and-aft extending four bar linkages in which the coupler link of the front linkage is the base link of the rear linkage, the tool standard has an upper part that is pivotally connected to the lower link of the front linkage and the coupler link of the second linkage, and the part serves as the lower link of the rear four bar linkage. A biasing means is provided and is connected to both four bar linkages. The front four bar linkage permits the tool to float vertically with little change in attitude. The two four bar linkages in series permit the tool to rotate and rise relative to the main frame of the implement, when the tool strikes an obstruction requiring such action.

A jump mechanism for a plough having a frame and at least one digging shank, the jump mechanism includes a main draw bar pivotally coupling the shank to the frame so that the shank can pivot about each end of the bar and a movement control bar also pivotally coupling the shank to the frame so as to govern pivoting of the shank about one end of the main bar relative to the pivoting of the main bar relative to the shank.

A tool bar adapted to carry ground-working tools is carried on the three-point hitch of a tractor and the weight of the tool bar and ground-working tools is in part supported by one or more lift assist wheels extending rearwardly of the tool bar. The wheels are carried on the lower ends of arms pivotally connected to the tool bar and a power cylinder extends from the tool bar to an upstanding post on the arm. An accumulator cylinder positioned on the arm receives fluid from one side of the piston in the power cylinder. A piston in the accumulator is yieldable under a selective pressure applied thereto such that a predetermined upward force on the lift wheel arm causes oil from the power cylinder to flow into the accumulator and then return after the force on the arm has been removed. A telescopic adjustment member extends between the upstanding pivotal post to the arm for selectively setting the power cylinder for the given conditions. Depth control wheels are provided on the forward side of the tool bar.

Soil tillage apparatus with a hydraulic reset mechanism has a rigid vertical shank mounted to an elongate arm fixed below a lower plate which is pivotable upon an upper plate. The upper plate is adapted for mounting to an agricultural tool bar. A hydraulic cylinder is vertically mounted to the upper plate and is biased by pressurized hydraulic fluid to resist extension of the ram therefrom. The hydraulic cylinder is pivotal upon the upper plate and the ram is fixed by a pin to the elongate arm. A pressure reducing/relieving valve is adjustable to supply a fixed hydraulic fluid pressure to the hydraulic cylinder at all times.