A hydrostatic transmission system includes a hydraulic motor and at least one proportional control valve and at least one pump connected to the hydraulic motor to provide fluid to operate the hydraulic motor. The at least one pump includes at least one fluid driver having a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from the pump inlet to the pump outlet. The hydrostatic transmission system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover and concurrently establishes an opening of the at least one proportional control valve to adjust at least one of a flow and a pressure in the hydrostatic transmission system to an operational set point.

A hydrostatic transmission system includes a hydraulic motor and at least one proportional control valve and at least one pump connected to the hydraulic motor to provide fluid to operate the hydraulic motor. The at least one pump includes at least one fluid driver having a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from the pump inlet to the pump outlet. The hydrostatic transmission system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover and concurrently establishes an opening of the at least one proportional control valve to adjust at least one of a flow and a pressure in the hydrostatic transmission system to an operational set point.

A working machine includes a prime mover, a traveling pump driven by power of the prime mover to deliver hydraulic fluid, a traveling motor rotated by the hydraulic fluid delivered from the traveling pump, an operation valve configured to change a pilot pressure of pilot fluid output therefrom to the traveling pump according to operation of an operation member, an actuation valve to be activated according to a control signal so as to change a primary pressure supplied to the operation valve, a controller to perform setting of the control signal to be output to the actuation valve, and a pressure detection device to detect a secondary pressure output from the operation valve. The controller includes a setting change unit to change, based on the primary pressure and the secondary pressure, the setting of the control signal to be output to the actuation valve.

A travel control device is provided with hydraulic pumps of a variable capacity type that are driven by an engine; hydraulic motors that are driven by discharged oil from the hydraulic pumps; traveling devices that are rotation-driven by the hydraulic motors; a travel operation lever that is operated so as to instruct a traveling operation; a first control valve for generating a charged hydraulic pressure by adjusting the discharged oil from a charge pump and a second control valve for generating a capacity control hydraulic pressure in accordance with the operation of the travel operation lever. The first control valve is designed to pressure-adjust and generate a charged hydraulic pressure in accordance with the rotation speed of the engine, and the hydraulic pump is subjected to a variable capacity control process by a capacity control hydraulic pressure that is pressure-adjusted and generated by the second control valve.

A hydraulic pump is driven by an engine. A hydraulic motor is driven by hydraulic fluid discharged from the hydraulic pump thereby causing a vehicle to travel. A controller controls a rotation speed of the engine and a displacement of the hydraulic pump. The controller acquires a tractive force of the vehicle. The controller changes the rotation speed of the engine to a low speed side in accordance with a reduction in the tractive force.

A hydraulic pump is driven by an engine. A hydraulic motor is driven by hydraulic fluid discharged from the hydraulic pump thereby causing a vehicle to travel. A controller controls a rotation speed of the engine and a displacement of the hydraulic pump. The controller acquires a tractive force of the vehicle. The controller changes the rotation speed of the engine to a low speed side in accordance with a reduction in the tractive force.

A process for determining a setpoint rotational speed of a work machine engine, having a continuously variable transmission, based on operation of power hydraulics. The setpoint rotational speed for highly productive operation is determined, without knowledge current operation of the power hydraulics, by a basic engine speed setting. With knowledge of the current operating state, the setpoint rotational speed is determined by the basic speed settings and low or high engine speed settings. The low speed setting alone determines setpoint rotational speeds that are lower than the basic speed setting or a combination of the low and basic speed settings. The high speed setting alone determines setpoint rotational speeds that are higher than the basic speed setting or a combination of the basic and high speed settings. The speed settings can comprise a setpoint rotational speed range of above a reciprocal transmission range of the variable transmission.

Power machines, control systems and methods are disclosed that automatically control engine speed and travel speed, in two different modes of operation. In a first mode of operation, both of engine speed and travel speed are controlled responsive to actuation of a foot throttle. In a second mode of operation, the foot throttle controls travel speed, but engine speed is controlled by a hand throttle. Selection of which of the first and second modes to utilize is based upon an actuation position of the hand throttle.

An anti-stall system to prevent an engine, particularly a low-powered engine, from stalling when encountering a load that the machine is capable of overcoming but due to the nature of the engine, the load encounter would result in a stall. The system includes a hydraulic system in communication with a control system that has one or more sensors that detect, determine, and/or transmit an operational variable. The control system further comprises a plurality of anti-stall blocks having unique configurations, including a first configured to limit output flow upon determination of an engine droop, a second configured to limit output flow based on available engine torque, a third configured to limit output pressure upon rapid engine droop detection, and a fourth configured to prioritize and share output flow between the machine functions. The anti-stall blocks provide for complementary and cooperative configuration to prevent a stall from occurring based on responses to the detection and determination of various dynamic and continuous operational variables in real-time or near real-time with operational parameters.

A work vehicle includes an engine, a traveling pump driven by the engine, a hydraulic circuit connected to the traveling pump, a traveling motor connected to the traveling pump via the hydraulic circuit, a rotational speed sensor configured to output a signal indicative of engine speed a hydraulic pressure sensor configured to output a signal indicative of hydraulic pressure of the hydraulic circuit, a controller. The controller receives the signals from the rotational speed sensor and the hydraulic pressure sensor. The controller determines whether the engine is in an over-rotation state based on engine speed. The controller determines an upper limit value of a displacement of the traveling pump based on hydraulic pressure of the hydraulic circuit. The controller limits the displacement of the traveling pump to the upper limit value or less upon determining that the engine is in the over-rotation state.