Methods and systems for controlling a hydromechanical transmission are proposed. In one example, a control method for a hydrostatic unit of a hydromechanical variable transmission (HVT) is presented, comprising controlling the hydrostatic unit via a feedforward control architecture including a non-linear, multi-coefficient model, wherein the hydrostatic unit comprises a hydrostatic pump and a hydrostatic motor. A desired differential pressure of the hydrostatic unit or a desired hydraulic pump displacement may be used as inputs for the model, where the model's output is a pressure difference for a pump control piston coupled to a swash plate of the hydrostatic unit. Use of the non-linear model permits the hydrostatic unit to be controlled based on load, speed, and/or torque, thereby increasing the adaptability of the control system.

Control systems and feedback assemblies for hydraulic axial displacement machines, such as pumps and motors. The control systems and feedback assemblies can reduce friction on the charging spools and provide for a more reliable return of the swashplate to a neutral position. Aspects of the control systems and feedback assemblies can be modularized for, e.g., easy maintenance and to reduce the overall size of the system.

Control systems and feedback assemblies for hydraulic axial displacement machines, such as pumps and motors. The control systems and feedback assemblies can reduce friction on the charging spools and provide for a more reliable return of the swashplate to a neutral position. Aspects of the control systems and feedback assemblies can be modularized for, e.g., easy maintenance and to reduce the overall size of the system.

Methods and systems for controlling a hydromechanical transmission are proposed. In one example, a control method for a hydrostatic unit of a hydromechanical variable transmission (HVT) is presented, comprising controlling the hydrostatic unit via a feedforward control architecture including a non-linear, multi-coefficient model, wherein the hydrostatic unit comprises a hydrostatic pump and a hydrostatic motor and a desired differential pressure of the hydrostatic unit or a desired hydraulic pump displacement may be used as inputs for the model, where the model’s output is a pressure difference for a pump control piston coupled to a swash plate of the hydrostatic unit. Use of the non-linear model permits the hydrostatic unit to be controlled based on load, speed, and/or torque, thereby increasing the adaptability of the control system.

Methods and systems for controlling a hydromechanical transmission are proposed. In one example, a control method for a hydrostatic unit of a hydromechanical variable transmission (HVT) is presented, comprising controlling the hydrostatic unit via a feedforward control architecture including a non-linear, multi-coefficient model, wherein the hydrostatic unit comprises a hydrostatic pump and a hydrostatic motor and a desired differential pressure of the hydrostatic unit or a desired hydraulic pump displacement may be used as inputs for the model, where the model’s output is a pressure difference for a pump control piston coupled to a swash plate of the hydrostatic unit. Use of the non-linear model permits the hydrostatic unit to be controlled based on load, speed, and/or torque, thereby increasing the adaptability of the control system.

A system, for providing a rotary power to an implement of a machine, includes a first motor control valve associated with a first motor of the machine and a second motor control valve associated with a second motor of the machine. The first motor control valve is configured to be actuated at a first shift point to shift the first motor such that the first motor and the second motor switch between a first implement drive speed and a second implement drive speed. The second motor control valve is configured to be actuated at a second shift point to shift the second motor such that the first motor and the second motor switch between the second implement drive speed and a third implement drive speed. The first and second shift points are based on loading of the implement during operation. In addition, the first and second shift points are different.

A system, for providing a rotary power to an implement of a machine, includes a first motor control valve associated with a first motor of the machine and a second motor control valve associated with a second motor of the machine. The first motor control valve is configured to be actuated at a first shift point to shift the first motor such that the first motor and the second motor switch between a first implement drive speed and a second implement drive speed. The second motor control valve is configured to be actuated at a second shift point to shift the second motor such that the first motor and the second motor switch between the second implement drive speed and a third implement drive speed. The first and second shift points are based on loading of the implement during operation. In addition, the first and second shift points are different.

Methods and systems for a hydromechanical transmission are provided. In one example, the method includes responsive to rotation of a portion of a mechanical assembly induced by cranking of an engine, blocking an output shaft of the hydromechanical transmission via joint engagement of a forward drive clutch and a reverse drive clutch. The method further includes pressurizing a hydrostatic assembly while the forward drive clutch and the reverse drive clutch remain jointly engaged, where the mechanical assembly is coupled in parallel with the hydrostatic assembly.

A hydraulic system in a work machine includes a hydraulic pump to supply pilot hydraulic oil. A work hydraulic actuator is to move a work device of the work machine. A control valve is to control the work hydraulic actuator based on a pilot pressure of the pilot hydraulic oil. A target pilot pressure of the pilot hydraulic oil is input through the work operation device to control, according to the target pilot pressure, the pilot pressure supplied from the hydraulic pump to the control valve. A pilot oil path connects the work operation device and the control valve to supply the pilot pressure to the control valve. A drain oil path is divided from the pilot oil path. A pressure adjustment valve is provided in the drain oil path to adjust the pilot pressure to be less than the target pilot pressure when a condition is satisfied.

A hydraulic apparatus for stretching conductors for power lines comprising: a variable displacement hydraulic pump (10) that supplies by means of a hydraulic fluid a hydraulic motor (11) with a closed circuit connection; a displacement regulation system (15) of said hydraulic pump (10); a regulation system (20) of said hydraulic apparatus; characterised in that said regulation system (20) comprises: an inlet (21) that receives said hydraulic fluid that supplies said hydraulic motor (11); a first outlet (22) that supplies said displacement regulation system (15); a second discharge outlet (23); a flow limiter (30) connected to said inlet (21); a regulatable valve (31) connected to said flow limiter (30); a tap (36) connected between the outlet of said regulatable valve (31) and said first outlet (22); a measurement instrument (33) connected to the outlet of said regulatable valve (31), to measure the regulation pressure of said regulation system (20); a safety valve (34) connected to the outlet of said regulatable valve (31), the outlet of which is connected to said second discharge outlet (23).