A multistage transmission, in particular for a motor vehicle, is provided at least structurally for selecting at least twelve forward transmission gears with different step-up ratios. This multistage transmission has four operatively interconnected planetary gear stages, a transmission input shaft for attaching to an internal combustion engine, a transmission output shaft, for attaching to drive wheels, four clutch units, each of which includes two clutch elements, and three brake units, each of which includes one clutch element.

A planetary gear train of an automatic transmission for a vehicle may include an input shaft receiving torque of an engine, an output shaft outputting changed torque of the engine, a first planetary gear set including first, second, and third rotation elements, a second planetary gear set including fourth, fifth, and sixth rotation elements, a third planetary gear set including seventh, eighth, and ninth rotation elements, a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements, and seven friction elements disposed to selectively connect the rotation elements with each other and selectively connect the rotation elements with a transmission housing.

Transmissions with at least three gearing-arrangements with similar first and second gearing-arrangements that produce a number of transmissions having an eleven forward-speed and two reverse-speed ratios, having ten forward-speed and three reverse-speed ratios, and having five forward-speed and one reverse-speed ratios by selective engagement of three shift-elements in various combinations. Some embodiments include four simple planetary-gearsets and six shift-elements of which two or three are brakes. Another embodiment includes a double-pinion planetary-gearset and six shift-elements of which three are brakes. Other embodiments include three simple planetary-gearsets and five shift-elements of which one or two are brakes.

A dual clutch transmission for motor vehicles has first and second input shafts, two clutches configured to selectively couple the input shafts to an engine, two intermediate shafts arranged parallel to the input shafts, gearwheel pairs of which a fixed gearwheel is arranged on one of the input shafts and a freely rotating gearwheel is arranged on one of the intermediate shafts, freely rotating output gearwheels arranged on each of the two intermediate shafts and meshing with a differential wheel, and coupling devices configured to selectively couple the freely rotating gearwheels to the respective intermediate shaft, of which at least the coupling devices for the output gearwheels are of double acting design. A dual clutch transmission of this kind makes a large number of gears possible without significantly increasing the dimensions of the transmission or the weight thereof.

A dual clutch transmission for motor vehicles has first and second input shafts, two clutches selectively coupling the input shafts the engine, two intermediate shafts arranged parallel to the transmission input shafts, gearwheel pairs configured to transmit power between the input shafts and the intermediate shafts, and output gearwheels arranged on each of the two intermediate shafts. The output gearwheels mesh with the differential wheel and are selectively coupled to the respective intermediate shaft by one of the coupling devices. An additional intermediate gearwheel set is provided, that one gearwheel of the intermediate gearwheel set is seated on the first or second intermediate shaft, that the other gearwheel of the inter-mediate wheel set is arranged on a third intermediate shaft, and that a third output gearwheel, which meshes with one of the output gearwheels of the first or second intermediate shaft, is seated on the third intermediate shaft.

A clutch-side transmission circuit transmits, from a clutch pedal, a restoring action of the depressed clutch pedal. A switching device connects a first clutch-side hydraulic circuit to the pedal-side hydraulic circuit when a shift lever SL is tilted forwards and connects a second clutch-side hydraulic circuit to the pedal-side hydraulic circuit when the shift lever SL is tilted rearwards. A first clutch is engaged in response to the restoring action of the clutch pedal being transmitted from the first clutch-side transmission circuit. A second clutch is engaged in response to the restoring action of the clutch pedal being transmitted from the second clutch-side transmission circuit.

A first carrier rotates integrally with an input shaft. A third sun gear and a fourth sun gear rotate integrally with a first intermediate shaft. A third carrier rotates integrally with a second ring gear. A fourth carrier rotates integrally with a third ring gear, and outputs power. A first clutch couples a first ring gear and a second sun gear to the first intermediate shaft. A second clutch couples the first carrier to a second carrier. A third clutch couples the second carrier to the first intermediate shaft. A first brake brakes rotation of a first sun gear. A second brake brakes rotation of the second ring gear and the third carrier. A third brake brakes rotation of a fourth ring gear.

A transmission device that includes a first clutch that includes a first clutch drum, a first piston, and a first engagement oil chamber; and a second clutch that includes a second clutch drum fixed to an outer circumferential portion of the first clutch drum, a second piston, and a second engagement oil chamber.

A planetary gear train of an automatic transmission for a vehicle includes: an input shaft from an engine; an output shaft; and first, second, third, and fourth planetary gear sets each including three rotating elements. The gear train also includes eight shafts for selectively connecting the planetary gear sets and the input and output shafts in various configurations to achieve at least 11 forward speeds and at least one reverse speed.

A planetary gear train of a transmission for a vehicle is provided. The planetary gear train includes an input shaft that receives power of an engine and an output shaft that outputs power. Multiple planetary gear sets are provided each having three rotation elements. Various shafts then either directly or selectively connect the rotation elements. The transmission is then capable of maximizing engine driving efficiency and improving a power delivery performance and fuel consumption.