Provided is a transmission control system that enables more precise control of the transmission ratio. This transmission control system is provided with a motor, an actuator, a transmission, a position sensor, a current sensor, and a control unit. The control unit includes: a drive unit that drives the motor while the vehicle is stopped; and a first estimation unit that estimates the initial transmission ratio, which indicates the transmission ratio when the ignition switch is turned on, on the basis of a rotation position detected by the position sensor, a load current detected by the current sensor, and a characteristic curve over a period during which the drive unit is operating.

A continuously variable transmission, a vehicular powertrain that includes a continuously variable transmission and a method of limiting belt slippage in a continuously variable transmission in a vehicle. The continuously variable transmission includes a pulley assembly, shafts, a clutch and hydraulic system. The hydraulic system is cooperative with both the clutch and the pulley assembly so that hydraulic pressures and associated clamping forces sent to both allow the clutch to preferentially absorb any driving load coming from the axle and wheels that is in excess of the normal load experienced at the continuously variable transmission. This in turn means that any additional load that would ordinarily cause slippage in the belt is instead experienced by the clutch. By providing such a clutch, the pump of the hydraulic system does not need to be oversized in order to provide excess clamping force, as any excess load experienced by the shaft that is coupled to the wheels of the vehicle will be taken up by slippage in the clutch so that slippage-related wear to the belt is avoided.

A method teaches a control function, preferably a characteristic curve, of a hydrostatic motor of a traction drive of a work machine when in drive mode. The traction drive is provided with the hydrostatic motor and a hydrostatic pump, which is hydraulically connected to the hydrostatic motor. The method includes setting a pivot angle of the hydrostatic motor while taking into account a desired velocity of the work machine when in the drive mode, and checking whether predefined conditions are met. If the predefined conditions are met and a current velocity differs from the desired velocity, the method includes correcting the control function of the hydrostatic motor by taking into account a difference between the desired velocity and the current velocity. At least one value of the corrected control function of the hydrostatic motor is taught during the correcting.

A transmission arrangement for a travel drive, in particular a mobile machine, includes a first hydraulic machine configured to be coupled to a drive machine, and a second hydraulic machine having an adjustable second expulsion volume, the second hydraulic machine configured to be connected fluidically to the first hydraulic machine via a first working line and a second working line of the transmission arrangement. The second hydraulic machine configured to be coupled or is coupled to a manual transmission of the transmission arrangement. The manual transmission has at least two transmission stages, and coupling of the second hydraulic machine to the manual transmission has the result that a torque can be transmitted. The transmission arrangement further includes a control apparatus configured to reduce to zero or to nearly zero the second expulsion volume at least during a changeover from one transmission stage to another transmission stage of the manual transmission.

A control system to control an operation of a power transmission of a work vehicle includes a storage to store data indicating a relationship between a ratio between a rotational speed of a predetermined component on a power transmission path to transmit the rotation of the planetary transmission to wheels and a rotational speed of the internal combustion engine, and switching points at which the transmission gear of the planetary transmission is switched, and a controller to control the hydraulic clutch mechanism to perform switching of the transmission gear. Where the transmission gear is switched when the ratio changes to reach a first value corresponding to a first switching point or after the ratio reaches the first value, the controller controls the hydraulic clutch mechanism so as to start hydraulic fluid charging to perform switching of the transmission gear before the ratio reaches the first value.

A system for preventing shifting between a plurality of gear ratios in a mechanical gearset. An operating sensor detecting rotation of a moving component in the mechanical gearset, a shift solenoid controlling shifting among the plurality of gear ratios, and a microcontroller communicatively coupled to the shift solenoid and the operating sensor that prevents activation of the shift solenoid when rotation is detected by the rotation sensor.

A method for estimating torque transmitted to a structure located downstream of a transmission system of a vehicle is disclosed. The vehicle comprises an engine for generating torque, a transmission system configured to transmit a fraction of the torque generated by the engine to a plurality of wheels of the vehicle, and a further fraction of the torque generated by the engine to the structure. The transmission system includes a shaft arrangement interposed between the engine and the structure, a planetary gearing supported by the shaft arrangement, and a transmission unit arranged in parallel to the shaft arrangement. The torque transmitted to the structure is estimated on the basis of a group of parameters which comprise torque upstream of the transmission system, twist of the shaft arrangement, and a parameter which is indicative of the ratio between an output rotational speed at an output of the transmission unit and an input rotational speed at an input of the transmission unit.

A swash plate angle for a hydrostatic power unit of a continuously variable hydromechanical transmission is determined using a feedforward compensation term, to reduce reliance on closed loop control. The feedforward term is based on knowledge of the hydrostatic power unit determined as a function of knowledge of certain parameters, including, but not limited to, hydrostatic power unit pressure, swash plate angle, desired hydrostatic power unit ratio, and pump speed.

A system for preventing shifting between a plurality of gear ratios in a mechanical gearset. An operating sensor detecting rotation of a moving component in the mechanical gearset, a shift solenoid controlling shifting among the plurality of gear ratios, and a microcontroller communicatively coupled to the shift solenoid and the operating sensor that prevents activation of the shift solenoid when rotation is detected by the rotation sensor.

A method is for calibrating a pivot angle sensor of a hydraulic machine of a propulsion or working machine. A control device is configured to operationally control the hydraulic machine. The control device is also configured to process a sensor signal from the pivot angle sensor. The pivot angle sensor is calibrated, preferably in an automated manner, via the control device.