A shift control device for an automatic transmission includes: an engagement control unit that controls an engagement hydraulic pressure supplied to an engagement hydraulic chamber of an engagement side friction element; a hydraulic pressure detecting unit that detects the engagement hydraulic pressure; a reference setting unit that calculates a predicted value of the engagement hydraulic pressure during shifting, based on a rising characteristic of the engagement hydraulic pressure from when supply of the engagement hydraulic pressure is started to when engagement of the engagement side friction element is started, and sets the predicted value as a reference hydraulic pressure; and an engagement start detecting unit that detects an engagement start time point of the engagement side friction element, based on a difference between the hydraulic pressure detected by the hydraulic pressure detecting unit during the shifting and the reference hydraulic pressure.

An electro-hydraulic control system for a multispeed transmission having a plurality of torque-transmitting mechanisms includes a controller for operably controlling the transmission, a fluid source for supplying hydraulic fluid, and a plurality of torque-transmitting mechanisms being operably selected between an applied and an unapplied state to achieve a plurality of ranges including at least one reverse, a neutral, and a plurality of forward ranges. The system includes a plurality of trim systems having pressure control solenoids and trim valves. The system may also include one or more shift valves disposed in fluid communication with the fluid source and being capable of moving between stroked and de-stroked positions. In any given range, only two of the plurality of torque-transmitting mechanisms may be applied. Moreover, three of the plurality of pressure control solenoids are normally high solenoids, and the remaining solenoids are normally low solenoids.

A transmission includes an input shaft coupled to a prime mover, a countershaft, main shaft, and an output shaft, with gears between the countershaft and the main shaft. A shift actuator selectively couples the input shaft to the main shaft by rotatably coupling gears between the countershaft and the main shaft. The shift actuator is mounted on an exterior wall of a housing including the countershaft and the main shaft. An integrated actuator housing includes a single external power access for the shift actuator. A controller interprets a shaft displacement angle, determines if the transmission is in an imminent zero or zero torque region, and performs a transmission operation in response to the transmission in the imminent zero or zero torque region.

A hydraulic pressure control method for a transmission includes determining whether a current shift range is among a plurality of shift ranges, setting a dither frequency of a pressure control solenoid valve of a hydraulic circuit for the transmission to a predetermined first frequency when the current shift range is a predetermined first range, and setting the dither frequency of the pressure control solenoid valve to a predetermined second frequency when the current shift range is a shift range other than the first range.

An electro-hydraulic control system for a multispeed transmission having a plurality of torque-transmitting mechanisms includes a controller for operably controlling the transmission, a fluid source for supplying hydraulic fluid, and a plurality of torque-transmitting mechanisms being operably selected between an applied and an unapplied state to achieve a plurality of ranges including at least one reverse, a neutral, and a plurality of forward ranges. The system includes a plurality of trim systems having pressure control solenoids and trim valves. The system may also include one or more shift valves disposed in fluid communication with the fluid source and being capable of moving between stroked and de-stroked positions. In any given range, only two of the plurality of torque-transmitting mechanisms may be applied. Moreover, three of the plurality of pressure control solenoids are normally high solenoids, and the remaining solenoids are normally low solenoids.

A transmission is subject to gear shift management that provides for shifting gears in a controlled manner in order to provide for a simplification of part and reduction in system complexity. In particular, a range synchronizer component can be replaced with a simplified range jaw clutch, without incurring a requirement for an installation of other components such as a motor generator or starter-generator.

A transmission (21) as a power transmission device for a vehicle comprises an input shaft (22), an output shaft (23), a planetary continuously variable transmission mechanism (31), a direct connecting mechanism (27), and an idler gear (29). The direct connecting mechanism (27) comprises a direct connecting clutch (30). The planetary continuously variable transmission mechanism (31) comprises a planetary gear mechanism (32), a pump side clutch (33), a hydraulic pump (36), a hydraulic motor (38), and a motor side clutch (40). The hydraulic pump (36) and the hydraulic motor (38) are connected via a pair of main lines (37A, 37B). An electromagnetic on-off valve (41) capable of switching between a communicating state and a blocking state between the pair of main lines (37A, 37B) is provided between the pair of main lines (37A, 37B).

A work vehicle includes an engine, a speed changing apparatus that includes a hydrostatic stepless speed changing mechanism and is configured to subject motive power transmitted from the engine to speed changing and output the motive power, a travelling apparatus configured to travel on the motive power received from the speed changing apparatus, a speed detector configured to detect a speed of the travelling apparatus, a pressure detector configured to detect a hydraulic pressure in a closed circuit of the hydrostatic stepless speed changing mechanism, and a controller.

An output is calculated using, as an input, a measured value of a pump discharge pressure in a neural network having the pump discharge pressure as the input and a pump rotational speed as the output. A leakage degree of oil of the hydraulic circuit of a transmission is estimated based on a difference obtained by subtracting a measured value of the pump rotational speed from the calculated value of the output. Learning of the neural network is performed using, as teacher data, the measured values of the pump discharge pressure and the pump rotational speed in the transmission in which the leakage degree of oil is within an allowable range.

A method for conveying a fluid of a fluid circuit by means of an electric motor-powered fluid pump of a motor vehicle, in particular an oil pump, wherein by means of the fluid pump a fluid pressure of the fluid circuit is adjusted to a target pressure, and wherein an actual pressure of the fluid is determined without a pressure sensor.