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: The device is provided with an engagement pin carried by a differential housing of the differential operable to rigidly angularly interconnect the differential housing with one of the bevel gears of the differential, and an actuator manually controlled by an operator to bring the engagement pin from a rest position to a working position. The device is further provided with a spring for urging the engagement pin towards the rest position, and locking device for releasably locking the engagement pin against the action of the spring; the locking device automatically disengages, and disengaging the engagement pins when the vehicle brake is actuated, there being provided a hydraulic disengagement piston connected to a brake.

Abstract: A force measuring device for an implement for towing an agricultural machine comprising at least one connection arm between the implement and a flexure bar mounted on said agricultural machine, at least one lever connecting the arm to a control system, wherein said control system comprises an electrical circuit arranged to control the movement of the lever by means of a mechanical and/or hydraulic member, the electrical circuit comprising at least one resistive element fixed to a portion of the flexure bar, the resistive element being constructed of a material the resistance of which is proportional to the deformation which the element undergoes when in use.

Abstract: A sealing device for a flexible dynamometric bar associated with a hydraulic power-lift of an agricultural tractor comprises an elastomer sealing ring formed in one piece by a collar element which surrounds the bar, and a bell-shaped element, which coaxially surrounds the collar element. The collar element is provided with a pair of internal circumferential sealing lips which, having diameters smaller than that of the bar, are deformed when fitted to the latter to ensure an effective seal. Sealing is also ensured by a pair of resilient metal rings which press the collar element against the bar. The elastomer of the sealing ring has an additive of graphite or laminar cleavage salts to reduce the friction which results from sliding between the bar and the lips, during deformation of the bar in use.

Abstract: A device for controlling an agricultural implement mounted on a tractor includes an auxiliary hydraulic jack which exerts a force on a resiliently flexible bar sufficient to limit the deformation of the bar due to reaction forces, when the implement is in use in a ground-engaging position, thereby acting, through a transmission linkage, on a movable control member of an hydaulic distributor to urge the member into its rest position and return the implement rapidly to its lowered position to achieve an even working of the ground. An adjustable throttle valve meters the operation of the auxiliary jack to maintain a desired working characteristic.

Abstract: A tractor vehicle has a driving station including a driver's seat and steering console which is mounted on a base for swivelling movement about a vertical axis through 180.degree. between a tractor configuration and a pushing power unit configuration. In the latter configuration the driving station is supported on a higher tractor cab floor level to enable the driver to see over equipment being pushed. The driving station has a support which is connected to the tractor cab floor by at least one parallelogram linkage and weight compensating springs which lift the support off the cab floor.

Abstract: A speed change gearbox for agricultural tractors and similar vehicles has an elongate casing rotatably mounting input and output shafts which are coupled by gearing comprising reduction means selectively operable to provide one of a plurality of reduction ratios, and a final gearing stage which serves to set a particular range of ratios. The reduction means includes an epicyclic gear mechanism provided with associated hydraulic control means for selectively controlling movement of various of its elements, and pairs of continuously meshing gears operatively selectable by further hydraulic control means. The arrangement of the hydraulic control means is such that they are all centered on the input shaft which enables the transverse bulk of the gearbox to be minimized.

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.

Abstract: A tractor three-point linkage has a hydraulic single-acting actuator for raising lower linkage arms through a linkage including respective vertical tie rods. A flexible compensating bar is rotatably supported by two fixed brackets on the tractor, the central region of the bar cooperating with a cam surface on a pivoted intermediate member acting through a mechanical transmission on the displaceable valve member of a distributor which controls the operation of the actuator to lift the linkage arms when the ground reaction force on the implement exceeds a limit. To increase the speed of return of the implement to the ground the invention provides for return movement of the distributor valve in response to vertical flexure of the bar caused by the weight of the implement, when lifted out of the ground, acting on the bar through the arms.

Abstract: A track for a track-laying vehicle such as an agricultural tractor comprising a plurality of links pivoted together to form a closed loop chain, each link having bolted thereto a sole plate equipped with one or more ground-engaging cleats is disclosed. Sole plates on alternate links are of one type having two or more cleats aligned with one another across the width of the track and separated by a space of the same order as the width of each cleat, and between these sole plates are sole plates of another type having one or three cleats all aligned with one another across the width of the track. The single or central cleat is longitudinally aligned with the space between cleats of the sole plate of the first type and the outer cleats, if provided, are separated from the central cleat by respective spaces longitudinally aligned with the two cleats of the sole plates of the first mentioned type.

Abstract: A three-point linkage for coupling farm implements to a tractor has two lower links pivoted at their forward ends to a tractor and lie in a plane which from the rear to the front ends of the links is downwardly inclined and the links converge towards a point at or near ground level, and an upper link whose center line converges with the lower links towards the said point. In lieu of a single upper link, a pair of links which diverge from one another as they extend toward the tractor are preferred.