Abstract: A hydraulic steering system for a tractor is provided which can be operated in a conventional steering mode or in a fast steering mode. In conventional steering mode, a conventional steering wheel and steering motor direct pressurized oil to the steerable wheels for selecting the turning direction, the turning angle, and the speed with which the turning angle is achieved. In fast steering mode, a fast-turning valve is controlled by the operator to direct oil directly to the steerable wheels, thereby by-passing the steering motor. The conventional steering wheel and steering motor continue however to control the steering operation.

Abstract: A hydraulic steering system for a tractor is provided which can be operated in a conventional steering mode or in a fast steering mode. In conventional steering mode, a conventional steering wheel and steering motor direct pressurized oil to the steerable wheels for selecting the turning direction, the turning angle, and the speed with which the turning angle is achieved. In fast steering mode, a fast-turning valve is controlled by the operator to direct oil directly to the steerable wheels, thereby by-passing the steering motor. The conventional steering wheel and steering motor continue however to control the steering operation.

Abstract: A control valve is provided for use in a hydraulic steering system of an agricultural vehicle of the type having a steering valve of the reactive type for controlling the supply of hydraulic fluid to hydraulic cylinders having opposed working chambers serving to move the steerable vehicle wheels in opposite directions. The control valve is connectable between the steering valve and the hydraulic cylinders and has a first setting in which fluid flow in both directions between the steering valve and the working chambers of the hydraulic steering cylinders is possible at all times and a second setting in which return flow of hydraulic fluid from any one working chamber of the hydraulic cylinders to the steering valve is only possible when a positive pressure is present at the outlet of the steering valve connected by the control valve to the opposed working chamber of the hydraulic cylinders.

Abstract: A unit for raising and lowering an agricultural implement, which unit is connected to a tractor. The unit includes an attachment device (6) for attaching the implement to the tractor, a raising and lowering device (2, 5) for raising and lowering the implement, and a control and regulation device including a linkage and regulation device including a linkage system and an operating lever (27) disposed between the attachment device (6) and the raising and lowering device (2, 5). The unit further includes a flexure bar (7) and is controlled by two control levers (36 and 38) which act on the operating lever (27) to determine the furrow depth and maximum force acceptable by the bar (7).

Abstract: A device for lifting an implement carried by an agricultural tractor three-point linkage has a flexible bar connected at its ends to the said lower linkage arms for rotation about a transverse axis, the reaction forces transmitted from the ground to the implement, when the latter is lowered into the ground, causing flexural deformation of the bar in a horizontal plane to effect operation of a distributor control shaft through a linkage which includes a first lever fixed at one end to the center of the bar, and acting through an inclined slot and pin on a second lever so that the weight of the implement when lifted from the ground causes the linkage arms to rotate about their connections to the respective tie-rods, deforming the flexible bar in a vertical plane and causing rotation of the distributor control shaft in a sense to return the implement rapidly to the ground.