Abstract: A vertically adjustable hitch for an agricultural tractor includes a pair of guide rails and a retainer which moves up and down on the rails. A chain has fixed ends and a central region which engages a pair of pulleys which are rotatably mounted on the retainer. As the pulleys rotate, they roll along the chain and move the retainer. A drive mechanism is coupled to rotate at least one of the pulleys. A locking mechanism is releasably engageable with the chain to prevent movement of the retainer relative to the chain.

Abstract: A hitch for attaching an implement with a tongue to an agricultural vehicle has at least one spacer bar which is pivotally coupled to the vehicle body about a horizontal axis. A rear end of the spacer bar is pivotally connected to the middle area of a lift arm. A drawbar hook is connected to a rear end of the lift arm and the lift is pivotal about an axis to adjust the height of the drawbar hook. A lift mechanism is pivotally connected to a forward end of the lift arm. This lift mechanism draws the forward end of the lift arm generally upwards. The hitch operates so that the drawbar hook moves substantially vertically and then horizontally when moved from its lowest position to a work height.

Abstract: A brake control valve has a valve bore, a piston member and an end member closing one end of the valve bore. One of the piston and end members has a projection and the other member has a corresponding blind bore for sealingly receiving the projection. The blind bore and the projection are spaced apart axially in the rest position of the piston. Upon axial movement of the piston the projection is sealingly received by the blind bore so that the effective working area of piston is reduced. By means of appropriate channels and grooves the chamber surrounding the projection is connected to reservoir.

Abstract: A hydraulic circuit is disclosed for activating a clutch as well as a throttle valve which is used in the circuit. The hydraulic circuit includes a hydraulic actuator which is connected to a source of pressurized fluid to alternatively activate the clutch. Connected between the source of pressurized fluid in the actuator is a control valve and a pressure-responsive throttle valve. The control valve is basically an on/off valve which controls the flow of fluid to the clutch actuator or from the clutch actuator to a reservoir. The throttle valve, on the other hand, is arranged in series with the control valve and is responsive to fluid pressure on its downstream side to cause increased throttling of the fluid as the fluid pressure to the actuator increases. Such a circuit is beneficial in preventing the clutch from snatching as it is being engaged.

Abstract: A modulation valve for controlling flow to a fluid consuming device which valve provides a gradual buildup of fluid pressure and during at least part of the buildup restricts flow to the consuming unit. The valve includes a slide movable by a spring on one end and fluid pressure on the other. The slide has a blind bore on the pressure end which is adapted to move over a projection having a restricted passage therethrough. In at least one position of the slide, fluid flow to the consuming unit is through the projection and through a passage in the slide to the consuming unit. In another position of the slide, fluid flow is through the blind bore and through the passage in the slide to the consuming unit.

Abstract: An oil seal is formed between two casing parts which have oil passages which are joined by a hollow dowel. A sealing ring surrounds the dowel and is compressed between the casing parts. In order to allow relatively loose fitting dowels and appreciable tolerances in the spacing between the passages and the gap between casing parts, the sealing ring has the form of two annular webs which are pressed together as the casing parts are clamped together. Moreover, one web has a frustoconical surface which engages a frustoconical countersunk surface in one of the casing parts. In a modified embodiment, the oil pressure is communicated to the space below the webs and spreads these into pressure contact with the casing parts.

Abstract: A hydraulic circuit is disclosed for activating a clutch as well as a throttle valve which is used in the circuit. The hydraulic circuit includes a hydraulic actuator which is connected to a source of pressurized fluid to alternatively activate the clutch. Connected between the source of pressurized fluid in the actuator is a control valve and a pressure-responsive throttle valve. The control valve is basically an on/off valve which controls the flow of fluid to the clutch actuator or from the clutch actuator to a reservoir. The throttle valve, on the other hand, is arranged in series with the control valve and is responsive to fluid pressure on its downstream side to cause increased throttling of the fluid as the fluid pressure to the actuator increases. Such a circuit is beneficial in preventing the clutch from snatching as it is being engaged.