Abstract: These and other features and objects are achieved by providing an over-running load control valve integral with the remote valve section of an agricultural tractor to allow it to efficiently work in a multipurpose agricultural environment. A counterbalance cartridge valve, with reverse flow check, is manifolded to an agricultural remote valve section.

Abstract: A remote drop box can be provided for tractor hydraulic drives; however, a system for providing lubrication to and cooling of the remote drop box is necessary. Maximum drawbar pull and maximum road speed capability are both desirable when a variable hydrostatic motor defines the working range. The hydrostatic motor must be operated very close to its maximum rated operating speed during roading, which leaves very little margin for overspeeding that occurs when the tractor is roading downhill. An improved overspeed control is also desirable. A problem encountered when a hydrostatic drive is used with a high torque engine in that, as the engine speed drops, the available charge pump flow also drops and eventually reaches a point where the required servo pressure to maintain the hydraulic pump in stroke cannot be maintained. Such a condition needs to be alleviated to provide an effectively operating hydrostatic drive system.

Abstract: A remote drop box can be provided for tractor hydraulic drives; however, a system for providing lubrication to and cooling of the remote drop box is necessary. Maximum drawbar pull and maximum road speed capability are both desirable when a variable hydrostatic motor defines the working range. The hydrostatic motor must be operated very close to its maximum rated operating speed during roading, which leaves very little margin for overspeeding that occurs when the tractor is roading downhill. An improved overspeed control is also desirable. A problem encountered when a hydrostatic drive is used with a high torque engine in that, as the engine speed drops, the available charge pump flow also drops and eventually reaches a point where the required servo pressure to maintain the hydraulic pump in stroke cannot be maintained. Such a condition needs to be alleviated to provide an effectively operating hydrostatic drive system.

Abstract: A splitter gearbox for a four wheel drive, hydrostatically driven tractor integrates both the input drive train and the output drive train into a single gearbox. The splitter gearbox is mounted to the rear axle housing to allow the sharing of a common oil sump. The front and rear axles of the tractor are driven from a single hydrostatic motor associated with a gear drive system that provides a shaft extending forwardly and rearwardly out of the splitter gearbox to drive, respectively, the front and rear axles of the tractor. An auxiliary pump drive is mounted to the side of the splitter gearbox and driven from an idler gear appropriately positioned within the splitter gearbox.

Abstract: A splitter gearbox for a four wheel drive, hydrostatically driven tractor integrates both the input drive train and the output drive train into a single gearbox. The drive mechanism eliminates the need for a separate mechanical gearbox by establishing pre-set fixed displacement settings that are electronically controlled along with the variable displacement of the hydrostatic motor and hydrostatic pump, to provide a smooth power shift through all ranges without requiring the tractor to stop. The drive mechanism is configured so that essentially all components are individually controlled so that the entire power generated by the tractor engine can be diverted to any one of the traction drive, the PTO mechanism, the auxiliary hydraulic drive or, to a somewhat lesser extent, the tractor hydraulic system. The splitter gearbox is mounted to the rear axle housing to allow the sharing of a common oil sump.

Abstract: A splitter gearbox for a four wheel drive, hydrostatically driven tractor integrates both the input drive train and the output drive train into a single gearbox. The drive mechanism eliminates the need for a separate mechanical gearbox by establishing pre-set fixed displacement settings that are electronically controlled along with the variable displacement of the hydrostatic motor and hydrostatic pump, to provide a smooth power shift through all ranges without requiring the tractor to stop. The drive mechanism is configured so that essentially all components are individually controlled so that the entire power generated by the tractor engine can be diverted to any one of the traction drive, the PTO mechanism, the auxiliary hydraulic drive or, to a somewhat lesser extent, the tractor hydraulic system. The splitter gearbox is mounted to the rear axle housing to allow the sharing of a common oil sump.

Abstract: A hydraulic circuit is disclosed for a tractor in which a steering circuit and an implement circuit are utilized to provide a high flow capability to the implement valve stack. A series of priority valves are operable to divert hydraulic flow from the steering circuit to the implement circuit under conditions where the steering mechanism is not being operated and the implement circuit pump is operating at full capacity. The first priority valve diverts the hydraulic flow from the steering circuit to a second priority valve that is controlled by a pressure differential valve that senses the implement circuit pump working at full displacement, whereupon the second priority valve directs the diverted hydraulic flow into the implement circuit. The first priority valve retains hydraulic flow within the steering circuit whenever the steering mechanism is being operated.