Ten forward speeds and one or more reverse speed are achieved by a planetary gear train of an automatic transmission for a vehicle including an input shaft, an output shaft, four planetary gear sets respectively having three rotational elements, and six control elements for selectively interconnecting the rotational elements and a transmission housing.

A planetary gear train of an automatic transmission for the vehicle may include: an input shaft receiving torque of an engine; an output shaft outputting torque; 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; and a fourth planetary gear set including tenth, eleventh, and twelfth rotation elements.

A tolerance ring is formed in an inner circumference of a clutch drum at a more forward position than a spline-fitted part in a forward direction during assembly of the clutch drum to a third sun gear; thus, the tolerance ring is located closer to an axial end of the clutch drum than to the spline-fitted part. Accordingly, it becomes easier to carry out grooving to form an annular groove for housing the tolerance ring therein in the inner circumference of the clutch drum, and thereby deterioration of machinability is suppressed.

When a third sun gear is fitted into a fitting hole of a clutch drum, external circumferential spline teeth and internal circumferential spline teeth that configure a spline-fitted part start meshing with each other before a tolerance ring comes into contact with the third sun gear and the clutch drum. Accordingly, the external circumferential spline teeth and the internal circumferential spline teeth mesh with each other, thereby centering the third sun gear and the clutch drum, thus accurately assembling the third sun gear and the clutch drum without causing eccentricity thereof

An automatic transmission, which is configured such that there is no difference of rotation between a third sun gear and an intermediate shaft in a state where a second clutch is brought into a release state and a seventh speed stage is established, is provided. In the automatic transmission, at the time of a gear shift from a tenth speed stage where second and third clutches and a first brake are brought into an engagement state to a seventh speed stage where first, third, and fourth clutches are brought into an engagement state, the fourth clutch is engaged and the first brake is released to establish the seventh speed stage with the second clutch in the engagement state. Then, the first clutch is engaged and the second clutch is released to make transition to the seventh speed stage with the second clutch in the release state.

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.

In a control apparatus for a vehicle, when it is not determined that a downshift to a second gear stage should be carried out and an accelerator depression amount change rate is equal to or smaller than a predetermined value when it is determined that a downshift to a first gear stage should be carried out, a single downshift command to the first gear stage is output. When it is not determined that the downshift to the second gear stage should be carried out and the accelerator depression amount change rate is larger than the predetermined value when it is determined that the downshift to the first gear stage should be carried out, a current gear stage is maintained. Therefore, a skip downshift to the second gear stage can be carried out when it is determined that the downshift to the second gear stage should be carried out.

Some embodiments are directed to a gearing assembly including a rotary input member, a rotary output member and a gearing arrangement between the input member and the output member selectively engageable to effect a driving engagement between the input member and the output member through at least a first torque connection having a first gear ratio and a second torque connection having a second gear ratio. One of the rotary input member and the rotary output member includes a first shaft and the first torque connection includes a first dog clutch including a dog hub having a hub set of teeth and a surrounding dog ring including a ring set of teeth. The hub and ring sets of teeth are radially projecting and mutually engageable. The dog hub is mounted on the first shaft so as to allow axial movement of the dog hub relative to the shaft.

A transmission for a vehicle may include an input shaft, an output shaft, a first planetary gear set, a second planetary gear set, a third, planetary gear set, a fourth planetary gear set, provided to transfer a torque between the input shaft and the output shaft, and friction members, wherein each of the first, second, third, and fourth planetary gear sets includes three rotary elements and three of the friction members are each selectively connected to at least one of the at least three rotary elements of the first, second, third, and fourth planetary gear sets and control rotation of the rotary elements to achieve gear ratios of ten or more steps of forward shifting and one step of reverse shifting in a vehicle.