A method of controlling an electric vehicle transmission includes: a torque-securing step of securing a predetermined spare torque to be generated by a motor in accordance with a current motor torque when a controller determines that there is a need for downshift from an upper gear step to a lower gear step; a slip-controlling step of generating a friction force through a servo clutch applying a friction force between an input shaft and a servo driving gear of a pair of servo gears; a shifting-to-neutral step of shifting to a neutral gear by disengaging a synchronizer for the upper gear step; a motor-synchronizing step of synchronizing a rotational speed of the motor with a desired speed of a lower gear step using the spare torque of the motor secured in the torque-securing step; a gear-engaging step of engaging a synchronizer for the lower gear step; and a clutch-disengaging step of finishing shifting by disengaging the servo clutch.

A hydrostatic transmission control system includes a controller that monitors inputs for shifting a transmission of a tractor to a different range gear; determines if an engine on the tractor is operating in a desired and acceptable shift range based on a sensed speed and a load of the engine, and determines if a hydrostatic transmission on the tractor is operating in a desired and acceptable shift range based on a sensed load and a speed of the hydrostatic transmission. If the controller determines the engine and the hydrostatic transmission are operating in the desired and acceptable shift range, the controller commands an oncoming clutch to ramp up and an off going clutch to ramp down, and synchronizes speeds of the engine and the hydrostatic transmission.

A fixed-gear transmission including a plurality of planetary gear sets and a plurality of clutches is described. A method for controlling the fixed-gear transmission includes commanding a first iteration of a skip-at-sync transmission shift and monitoring clutch slip of an oncoming holding clutch associated with the skip-at-sync transmission shift during execution of the shift, which includes monitoring synchronization of the on-coming holding clutch and a maximum clutch slip overshoot value. A progressive clutch pressure ramp rate for the oncoming holding clutch is adaptively controlled in response to the clutch synchronization of the on-coming hold clutch during execution of a subsequent iteration of the skip-at-sync transmission shift.

A fixed-gear transmission including a plurality of planetary gear sets and a plurality of clutches is described. A method for controlling the fixed-gear transmission includes commanding a first iteration of a skip-at-sync transmission shift and monitoring clutch slip of an oncoming holding clutch associated with the skip-at-sync transmission shift during execution of the shift, which includes monitoring synchronization of the on-coming holding clutch and a maximum clutch slip overshoot value. A progressive clutch pressure ramp rate for the oncoming holding clutch is adaptively controlled in response to the clutch synchronization of the on-coming hold clutch during execution of a subsequent iteration of the skip-at-sync transmission shift.

Provided are gearboxes including compound planet gear assemblies as well as methods of using such gearboxes. A gearbox includes at least a first ring gear and a second ring gear. Depending on the current gear selection, one of these ring gears may be engaged with a shifting mechanism or not engaged with any ring gears when in a neutral gear. The first ring gear may be constantly engaged with a first planet gear of a compound planet gear assembly, while the second ring gear may be constantly engaged with a second planet gear of the same compound planet gear assembly. The first planet gear may be also engaged with a sun gear coupled to a shaft. Another shaft is coupled to the shifting mechanism. Different gear selections of the gearbox engage different ring gears to the shifting mechanism thereby changing the rotational speed ratio of the two shafts.

A method controls synchronization of a pinion rotating on a primary shaft driven by a traction machine of a vehicle and rotatably connected to a secondary shaft of a parallel shaft gearbox without synchronization mechanisms. The method includes sending to the traction machine, before coupling of the pinion on the primary shaft, a torque command which depends on a torque signal calculated to minimize a difference between a primary speed and a secondary speed multiplied by a reduction ratio between the primary shaft and the secondary shaft. The calculated torque signal is limited in amplitude when the speed difference is greater in absolute value than a desired accuracy on the targeted primary speed upon completion of the synchronization. The calculated torque signal is saturated on a maximum or minimum torque of the traction machine if the calculated torque signal is not between the maximum or minimum torque.

A method for controlling a powertrain of a vehicle, the powertrain a dual-clutch transmission including a first clutch and a second clutch selectively actuated to transmit motion from the engine to a first shaft and a second shaft respectively. The method includes producing a first shift request for shifting from an initial gear to a different gear; in response to the first shift request, executing a first shift sequence to shift from the initial gear to the different gear; during execution of the first shift sequence, producing a second shift request for shifting from the different gear to the initial gear; in response to the second shift request: interrupting the first shift sequence prior to the first shift sequence having finished; and executing a second shift sequence to reverse the first shift sequence such that the transmission engages the initial gear for driving on the first shaft.

Provided are gearboxes including compound planet gear assemblies as well as methods of using such gearboxes. A gearbox includes at least a first ring gear and a second ring gear. Depending on the current gear selection, one of these ring gears may be engaged with a shifting mechanism or not engaged with any ring gears when in a neutral gear. The first ring gear may be constantly engaged with a first planet gear of a compound planet gear assembly, while the second ring gear may be constantly engaged with a second planet gear of the same compound planet gear assembly. The first planet gear may be also engaged with a sun gear coupled to a shaft. Another shaft is coupled to the shifting mechanism. Different gear selections of the gearbox engage different ring gears to the shifting mechanism thereby changing the rotational speed ratio of the two shafts.

A method for controlling a powertrain of a vehicle, the powertrain a dual-clutch transmission including a first clutch and a second clutch selectively actuated to transmit motion from the engine to a first shaft and a second shaft respectively. The method includes producing a first shift request for shifting from an initial gear to a different gear; in response to the first shift request, executing a first shift sequence to shift from the initial gear to the different gear; during execution of the first shift sequence, producing a second shift request for shifting from the different gear to the initial gear; in response to the second shift request: interrupting the first shift sequence prior to the first shift sequence having finished; and executing a second shift sequence to reverse the first shift sequence such that the transmission engages the initial gear for driving on the first shaft.

Methods and systems for shifting a multi-gear step ratio transmission that includes a dog clutch are described. In one example, rotational positions of different transmission components are measured by tone wheels and a shifter actuator position is adjusted in response to a phase angle difference between the rotational positions of the different transmission components.