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.

A transport vehicle is driven by a hydraulic closed circuit system having a variable displacement pump to send an operating fluid to a delivery branch and receive the operating fluid from a return branch, a plurality of hydraulic motors connected to the delivery branch and to the return branch in order to drive relative wheels of the vehicle, a command and control unit to control the pump and the hydraulic motors in an ordinary advancing condition of the vehicle and command and control unit, which is configured to intervene in case of faults or malfunctions of the pump and to control a valve so as to establish a connection between the delivery branch and the return branch regardless of the control of the command and control unit of the pump and of the hydraulic motors.

A transport vehicle is driven by a hydraulic closed circuit system having a variable displacement pump to send an operating fluid to a delivery branch and receive the operating fluid from a return branch, a plurality of hydraulic motors connected to the delivery branch and to the return branch in order to drive relative wheels of the vehicle, a command and control unit to control the pump and the hydraulic motors in an ordinary advancing condition of the vehicle and command and control unit, which is configured to intervene in case of faults or malfunctions of the pump and to control a valve so as to establish a connection between the delivery branch and the return branch regardless of the control of the command and control unit of the pump and of the hydraulic motors.

The present invention relates to a work machine, preferably a mobile work machine, having an attachment device, in particular a trench cutter, wherein the attachment device comprises at least two adjustable hydraulic motors for driving independent, individually controllable loads, and wherein the hydraulic supply of the adjustable hydraulic motors takes place by a hydraulic drive unit arranged externally from the attachment device, in particular by a drive unit of the work machine, and wherein the at least two adjustable hydraulic motors of the attachment device are connected to a constant pressure network provided by the hydraulic drive unit.

Hydrostatic transmission and method for decelerating a hydrostatic transmission with a closed hydraulic fluid circuit, in which a hydraulic pump drivable by a drive engine and a hydraulic motor are arranged and connected fluidly to one another through two working lines. Alternately depending on the operational mode and on the conveying direction of the hydraulic pump, one working line is the low pressure line and the other one is the high pressure line. The hydraulic pump as well as the hydraulic motor are adjustable in their respective displacement volumes by means of a control unit. The hydraulic motor comprises a housing in which a hydrostatic drive mechanism having an inlet and an outlet is arranged. In a connecting line connecting the outlet and the inlet a pressure control valve is arranged, which can be flown through in direction to the inlet. The pressure control valve opens if the high pressure present at the outlet exceeds a predetermined pressure limit of the pressure relief valve. During the coasting operation of the hydrostatic transmission the displacement of the hydraulic pump and/or of the hydraulic motor are adjustable by means of the control unit in function of the speed of the drive motor or of the speed of the hydraulic pump.

Hydrostatic transmission and method for decelerating a hydrostatic transmission with a closed hydraulic fluid circuit, in which a hydraulic pump drivable by a drive engine and a hydraulic motor are arranged and connected fluidly to one another through two working lines. Alternately depending on the operational mode and on the conveying direction of the hydraulic pump, one working line is the low pressure line and the other one is the high pressure line. The hydraulic pump as well as the hydraulic motor are adjustable in their respective displacement volumes by means of a control unit. The hydraulic motor comprises a housing in which a hydrostatic drive mechanism having an inlet and an outlet is arranged. In a connecting line connecting the outlet and the inlet a pressure control valve is arranged, which can be flown through in direction to the inlet. The pressure control valve opens if the high pressure present at the outlet exceeds a predetermined pressure limit of the pressure relief valve. During the coasting operation of the hydrostatic transmission the displacement of the hydraulic pump and/or of the hydraulic motor are adjustable by means of the control unit in function of the speed of the drive motor or of the speed of the hydraulic pump.

This disclosure generally relates to an automatic bicycle, particularly to a hydraulic automatic transmission bicycle which can automatically and adaptively change gear ratios. More particularly, this disclosure relates to those hydraulic automatic transmission bicycles which use fluid pressure to change such gear ratios, and which include various hydraulic automatic transmissions which may be provided in various configurations and may operate in various methods and sequences to provide automatic and infinitely variable gear ratios.

This disclosure generally relates to an automatic bicycle, particularly to a hydraulic automatic transmission bicycle which can automatically and adaptively change gear ratios. More particularly, this disclosure relates to those hydraulic automatic transmission bicycles which use fluid pressure to change such gear ratios, and which include various hydraulic automatic transmissions which may be provided in various configurations and may operate in various methods and sequences to provide automatic and infinitely variable gear ratios.

A hydraulic system includes a hydraulic gear pump with a first gear having a plurality of first gear teeth and a second gear having a plurality of second gear teeth. The hydraulic system also includes a control valve and a control circuit. The control circuit controls the pump to adjust at least one of a flow in the hydraulic system to a flow set point or a pressure in the hydraulic system to a pressure set point, and concurrently establishes an opening of the control valve to adjust at least one of the flow to the flow set point or the pressure to the pressure set point. The control circuit establishes a position of a first tooth relative to a position of a second tooth to seal a fluid path from the outlet of the hydraulic gear pump to the inlet of the hydraulic gear pump.