A transmission for an opposed-piston engine with two crankshafts includes a crankshaft gear train that combines the torque inputs from the two crankshafts and a gear arrangement coupled to the gear train that is operable to obtain various speed ratios for an output torque drive.

A pedally propelled vehicle multi speed gear system includes a gear mechanism including a main shaft; a hollow first shaft and a hollow second shaft, both axially stationary and rotatably arranged about the main shaft; an epicyclical first gear section arranged about the main shaft between the first and second shafts, and including two radially stacked carrier elements; and a first shift mechanism arranged between the first shaft and the first gear section, and configured to rotationally engage the first shaft with either of the two radially stacked carriers. The first shift mechanism includes two first clutches radially stacked about the main shaft.

A pedally propelled vehicle multi speed gear system includes a gear mechanism including a main shaft; a hollow first shaft and a hollow second shaft, both axially stationary and rotatably arranged about the main shaft; an epicyclical first gear section arranged about the main shaft between the first and second shafts, and including two radially stacked carrier elements; and a first shift mechanism arranged between the first shaft and the first gear section, and configured to rotationally engage the first shaft with either of the two radially stacked carriers. The first shift mechanism includes two first clutches radially stacked about the main shaft.

An automatic transmission has a first clutch shaft that constantly connects first and fourth planetary gear sets, a second clutch shaft that constantly connects second and third planetary gear sets, and a third clutch shaft that constantly connects the third and first planetary gear sets. A drive shaft is constantly connected to the fourth planetary gear set; an output shaft is constantly connected to the third planetary gear set. The first planetary gear set is directly connected to two shift elements, the second planetary gear set is directly connected to four shift elements, the third planetary gear set is directly connected to two shift elements, the fourth planetary gear set is directly connected to four shift elements. The drive shaft is directly connected to only one shift element. The output shaft is directly connected to only one shift element.

An automatic transmission has a first clutch shaft that constantly connects first and fourth planetary gear sets, a second clutch shaft that constantly connects second and third planetary gear sets, and a third clutch shaft that constantly connects the third and first planetary gear sets. A drive shaft is constantly connected to the fourth planetary gear set; an output shaft is constantly connected to the third planetary gear set. The first planetary gear set is directly connected to two shift elements, the second planetary gear set is directly connected to four shift elements, the third planetary gear set is directly connected to two shift elements, the fourth planetary gear set is directly connected to four shift elements. The drive shaft is directly connected to only one shift element. The output shaft is directly connected to only one shift element.

An automatic transmission has eight rotatable shafts, four planetary gear sets and seven shift elements for shifting several forward gears and one reverse gear. A first element of the second planetary gear set forms the first shaft designed as the drive shaft of the transmission. A second element of the third planetary gear set forms the second shaft designed as the output shaft of the transmission. A second element of the first planetary gear set forms the third shaft. A first element of the first planetary gear set forms the fourth shaft. A third element of third planetary gear set forms the fifth shaft. As the sixth shaft, a third element of the first planetary gear set, a second element of the second planetary gear set and a first element of the third planetary gear set are constantly connected. A third element of the second planetary gear set forms the seventh shaft. A first brake is arranged in the power flow between the third shaft and the housing. A second brake is arranged in the power flow between the fourth shaft and the housing, a third brake is arranged in the power flow between the fifth shaft) and the housing. A first clutch (C1) is arranged in the power flow between the first and the seventh shafts. A second clutch is arranged in the power flow between the first and third shafts. A third clutch is constantly connected to the eighth shaft. A fourth clutch is in the power flow between the first and fourth shafts.

An automatic transmission has eight rotatable shafts, four planetary gear sets and seven shift elements for shifting several forward gears and one reverse gear. A first element of the second planetary gear set forms the first shaft designed as the drive shaft of the transmission. A second element of the third planetary gear set forms the second shaft designed as the output shaft of the transmission. A second element of the first planetary gear set forms the third shaft. A first element of the first planetary gear set forms the fourth shaft. A third element of third planetary gear set forms the fifth shaft. As the sixth shaft, a third element of the first planetary gear set, a second element of the second planetary gear set and a first element of the third planetary gear set are constantly connected. A third element of the second planetary gear set forms the seventh shaft. A first brake is arranged in the power flow between the third shaft and the housing. A second brake is arranged in the power flow between the fourth shaft and the housing, a third brake is arranged in the power flow between the fifth shaft) and the housing. A first clutch (C1) is arranged in the power flow between the first and the seventh shafts. A second clutch is arranged in the power flow between the first and third shafts. A third clutch is constantly connected to the eighth shaft. A fourth clutch is in the power flow between the first and fourth shafts.

A transmission (GA) for an axle drive (1) of a motor vehicle includes a drive shaft (AN), two output shafts (AB1, AB2), at least four shafts (W1, W2, W3, W4), a differential, and two interconnected planetary gear sets (PS1, PS2). The drive shaft (AN) is a hollow shaft, and the drive shaft (AN) is coaxial with at least one of the two output shafts (AB1, AB2). The differential (D) is arranged, at least partly, within a cylindrical volume. An outer shell surface of the cylindrical volume is defined by an inner shell surface of a sun gear (SO2) of the second planetary gear set (PS2). A diameter of inner shell surface corresponds to an inner diameter of the sun gear (SO2) of the second planetary gear set (PS2).

A positive-locking shifting device of a transmission connects one element of a first planetary gear set to one element of a second planetary gear set in a first shifting position and connects an additional element of the second planetary gear set to a torque-proof element of the transmission in a second shifting position. A single element of the shifting device is axially displacable between the first and second shifting positions. A shiftable operative connection between the torque-proof element of the transmission and the additional element of the second planetary gear set disposed, at least in sections, axially between the first and second planetary gear sets. The shiftable operative connection between the torque-proof element of the transmission and the additional element of the second planetary gear set intersecting a shiftable operative connection between the one element of the first planetary gear set and the one element of the second planetary gear set.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying and discharging hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying and discharging hydraulic pressure to and from the chambers, first and second oil paths communicating the valve with the chambers, and a pressure reducing valve disposed in the second oil path and for preventing hydraulic pressure of the disengaging hydraulic pressure chamber from exceeding a given set pressure. The second surface has a larger area for receiving hydraulic pressure than an area of the first surface for receiving hydraulic pressure. The method includes changing the given set pressure according to information regarding a state of the automatic transmission.