A vehicle and a hydraulic propulsion system for the vehicle are provided with first and second motors diagonally arranged relative to one another on the vehicle, and third and fourth motors diagonally arranged relative to one another on the vehicle. First, second and third flow divider combiner assemblies are provided and are arranged in a closed fluid loop with the motors. A first port of each of the assemblies are fluidly connected to one another. The first assembly has a second port fluidly coupled to the first and second motors, and a third port fluidly coupled to the third and fourth motors. The second assembly has second and third ports fluidly coupled to the first and third motors, respectively. The third assembly has second and third ports fluidly coupled to the second and fourth motors, respectively. A method of controlling the hydraulic system is also provided.

A system, apparatus and method are provided for limiting operating speed at high temperatures of a self-propelled, agricultural product applicator having a hydraulic drive system including a pump supplying pressurized hydraulic fluid to a variable-displacement hydraulic motor operatively connected for propelling the applicator. A temperature sensor detects a temperature of the pressurized hydraulic fluid in the hydraulic system. A propel controller is operatively connected between the temperature sensor and the propulsion motor and configured for limiting displacement of the propulsion motor according to one or more predetermined de-rated conditions resulting in reduced motor speed, in accordance with a predetermined schedule, when predetermined motor de-rating activation temperature limits of the hydraulic fluid are detected by the temperature sensor. The controller is further configured for providing a de-rated condition warning signal prior to limiting displacement of the propulsion motor.

A system, apparatus and method are provided for limiting operating speed at high temperatures of a self-propelled, agricultural product applicator having a hydraulic drive system including a pump supplying pressurized hydraulic fluid to a variable-displacement hydraulic motor operatively connected for propelling the applicator. A temperature sensor detects a temperature of the pressurized hydraulic fluid in the hydraulic system. A propel controller is operatively connected between the temperature sensor and the propulsion motor and configured for limiting displacement of the propulsion motor according to one or more predetermined de-rated conditions resulting in reduced motor speed, in accordance with a predetermined schedule, when predetermined motor de-rating activation temperature limits of the hydraulic fluid are detected by the temperature sensor. The controller is further configured for providing a de-rated condition warning signal prior to limiting displacement of the propulsion motor.

Method for the load-dependent regulation of a hydrostatic drive (1), with a closed hydraulic fluid circuit comprising a first hydraulic motor (5) and, parallel to this, a second hydraulic motor (6), whereby both hydraulic motors (5 and 6) are capable of being powered by a hydraulic pump (3) via a high-pressure line (7) and a low-pressure line (8) and are mechanically coupled to each other via a transmission (70). The displacement of the first hydraulic motor (5) can be adjusted proportionally to an electrical signal of an electronic control system (50) by means of an electro-proportional control valve (10) and the displacement of the second hydraulic motor (6) can be adjusted by means of a pressure-proportional control valve (20) which is hydraulically connected to the high-pressure line (7) via a control pressure line (21). The pressure-proportional control valve can be activated by means of a control pressure which is dependent on the high pressure. By means of automatic opening of the pressure-proportional control valve (20) dependent on the high pressure, proportional to the exceedance of a predefinable pressure limit in the high-pressure line (7), the displacement of the second hydraulic motor (6) is adjusted by means of a second servo control unit which can be controlled via the pressure-proportional control valve (20). By means of the electronic control system (50), the actual volume flow passing through the first hydraulic motor (5) is determined and compared with a target value for the volume flow. Based on a deviation between the actual and target value for the volume flow, the electronic control system (50) calculates an adapted control signal and transmits this to the electro-proportional control valve (10), as a result of which the displacement of the first hydraulic motor (5) is adaptable by means of a first servo control unit (14), which is controlled via the electro-proportional control valve (10).

Method for the load-dependent regulation of a hydrostatic drive (1), with a closed hydraulic fluid circuit comprising a first hydraulic motor (5) and, parallel to this, a second hydraulic motor (6), whereby both hydraulic motors (5 and 6) are capable of being powered by a hydraulic pump (3) via a high-pressure line (7) and a low-pressure line (8) and are mechanically coupled to each other via a transmission (70). The displacement of the first hydraulic motor (5) can be adjusted proportionally to an electrical signal of an electronic control system (50) by means of an electro-proportional control valve (10) and the displacement of the second hydraulic motor (6) can be adjusted by means of a pressure-proportional control valve (20) which is hydraulically connected to the high-pressure line (7) via a control pressure line (21). The pressure-proportional control valve can be activated by means of a control pressure which is dependent on the high pressure. By means of automatic opening of the pressure-proportional control valve (20) dependent on the high pressure, proportional to the exceedance of a predefinable pressure limit in the high-pressure line (7), the displacement of the second hydraulic motor (6) is adjusted by means of a second servo control unit which can be controlled via the pressure-proportional control valve (20). By means of the electronic control system (50), the actual volume flow passing through the first hydraulic motor (5) is determined and compared with a target value for the volume flow. Based on a deviation between the actual and target value for the volume flow, the electronic control system (50) calculates an adapted control signal and transmits this to the electro-proportional control valve (10), as a result of which the displacement of the first hydraulic motor (5) is adaptable by means of a first servo control unit (14), which is controlled via the electro-proportional control valve (10).

A propel system of an agricultural vehicle has an active pump displacement control system for equalizing or balancing pressure output of hydrostatic pumps of a tandem pump propel arrangement. The active pump displacement control system may include a pressure sensor(s) for determining output pressure of hydrostatic pumps and use the output pressure values within a feedback loop to provide coil input values of coils that control displacement of the hydrostatic pumps so that the pressure outputted by the hydrostatic pumps can be equalized in real-time while on the go during use of the agricultural vehicle.

A propel system of an agricultural vehicle has an active pump displacement control system for equalizing or balancing pressure output of hydrostatic pumps of a tandem pump propel arrangement. The active pump displacement control system may include a pressure sensor(s) for determining output pressure of hydrostatic pumps and use the output pressure values within a feedback loop to provide coil input values of coils that control displacement of the hydrostatic pumps so that the pressure outputted by the hydrostatic pumps can be equalized in real-time while on the go during use of the agricultural vehicle.

A drive apparatus includes an internal sump and a center section having a pump running surface for mounting a pump cylinder block and at least one motor running surface for mounting at least one motor cylinder block. A brake mechanism includes set of brake rod guides are formed in and extend from the center section adjacent the pump running surface and the one or more motor running surfaces for supporting one or more brake rods. The brake rods may engage the motor cylinder blocks at oblique angle thereto, to provide a braking force. The brake mechanism may include a brake shaft, and a brake arm attached thereto and operatively engaged to the brake rods.

A drive apparatus includes an internal sump and a center section having a pump running surface for mounting a pump cylinder block and at least one motor running surface for mounting at least one motor cylinder block. A brake mechanism includes set of brake rod guides are formed in and extend from the center section adjacent the pump running surface and the one or more motor running surfaces for supporting one or more brake rods. The brake rods may engage the motor cylinder blocks at oblique angle thereto, to provide a braking force. The brake mechanism may include a brake shaft, and a brake arm attached thereto and operatively engaged to the brake rods.

A fluid pressure circuit includes an HST circuit having a variable capacity fluid pressure pump configured to be driven by a mechanism to perform forward-reverse rotation, a fluid pressure motor configured to be driven by fluid discharged from the fluid pressure pump to perform forward-reverse rotation, a first line configured to connect a first port of the fluid pressure pump and a first port of the fluid pressure motor, and a second line configured to connect a second port of the fluid pressure pump and a second port of the fluid pressure motor; an accumulator connected in parallel with the fluid pressure pump; an accumulator pump configured to accumulate pressure fluid in the accumulator; and an accumulator switching valve configured to switch connection between the fluid pressure motor and the accumulator.