A transmission selectively coupled to an engine crankshaft of an internal combustion engine arranged on a vehicle includes an input shaft, a mainshaft, an output shaft, a first countershaft and a second countershaft. A first gear set includes a first mainshaft gear arranged on the mainshaft, a first countershaft gear arranged on the first countershaft and a first countershaft gear arranged on the second countershaft. A second gear set includes a second mainshaft gear arranged on the mainshaft, a first countershaft gear arranged on the second countershaft and a second countershaft gear arranged on the second countershaft. The gears of the first gear set all have a first helix angle. The gears of the second gear set all have a second helix angle. The first and second helix angles are selected to provide gear constant leading whereby thrust forces directed onto the first and second countershafts are balanced.

A transmission 20 includes gears 421 through 426 and 441 through 446, sliders 451 through 453, an electric motor 58, a shift drum 50, shift forks 491 through 493, and a control unit 83. The sliders 451 through 453 are members different from the gears 421 through 426 and 441 through 446. The shift drum 50 includes guide grooves 61 through 63 each including a linear portion 64 and a tilt portion 65. An end of each of the shift forks 491 through 493 is located in a corresponding one of the guide grooves 61 through 63. The control unit 83 controls the electric motor 58 to rotate the shift drum 50 in such a manner that a gear-shift rotation angle is less than 60 degrees. With rotation of the shift drum 50 by the gear-shift rotation angle, the shift forks 491 through 493 move the sliders 451 through 453 in the axial direction of the shaft 21 or 22. In this manner, dog portions of the sliders 451 through 453 mesh with dog portions of the gears 441 through 446 so that rotation of the shaft 21 is transferred to the shaft 22.

A transmission 20 includes gears 421 through 426 and 441 through 446, sliders 451 through 453, an electric motor 58, a shift drum 50, shift forks 491 through 493, and a control unit 83. The sliders 451 through 453 are members different from the gears 421 through 426 and 441 through 446. The shift drum 50 includes guide grooves 61 through 63 each including a linear portion 64 and a tilt portion 65. An end of each of the shift forks 491 through 493 is located in a corresponding one of the guide grooves 61 through 63. The control unit 83 controls the electric motor 58 to rotate the shift drum 50 in such a manner that a gear-shift rotation angle is less than 60 degrees. With rotation of the shift drum 50 by the gear-shift rotation angle, the shift forks 491 through 493 move the sliders 451 through 453 in the axial direction of the shaft 21 or 22. In this manner, dog portions of the sliders 451 through 453 mesh with dog portions of the gears 441 through 446 so that rotation of the shaft 21 is transferred to the shaft 22.

Incongruity sense of a driver due to dog clunking noise can be reduced with reduction of dog clunking noise. A fifth-speed driving gear (425) and a sixth-speed driving gear (426) are arranged on a driving shaft (41) along an axial direction. A first slider (451) is disposed to be movable in the axial direction between the fifth-speed driving gear (425) and the sixth-speed driving gear (426). The first slider (451) is not rotatable on the driving shaft (41). In the axial direction, the sum of the widths of the fifth-speed driving gear (425) and the sixth-speed driving gear (426) is smaller than the maximum width of the first slider (451).

Incongruity sense of a driver due to dog clunking noise can be reduced with reduction of dog clunking noise. A fifth-speed driving gear (425) and a sixth-speed driving gear (426) are arranged on a driving shaft (41) along an axial direction. A first slider (451) is disposed to be movable in the axial direction between the fifth-speed driving gear (425) and the sixth-speed driving gear (426). The first slider (451) is not rotatable on the driving shaft (41). In the axial direction, the sum of the widths of the fifth-speed driving gear (425) and the sixth-speed driving gear (426) is smaller than the maximum width of the first slider (451).

A lay-shaft assembly for use in a vehicle transmission, including a lay-shaft which is rotatable around a central axis, a first gearwheel rotatable around the lay-shaft and the central axis, a second gearwheel fixedly connected to the lay-shaft and rotatable with the lay-shaft around the central axis, and a clutching assembly rotatable around the lay-shaft and the central axis. The clutching assembly includes a driven gearwheel and clutching mechanism for selectively coupling the rotation of the driven gearwheel to either the first gearwheel or the second gearwheel. The clutching assembly has a first axial end and a second axial end opposite the first axial end. The first gearwheel and the second gearwheel are arranged on a part of the lay-shaft extending from the first axial end of the clutching assembly.

A lay-shaft assembly for use in a vehicle transmission, including a lay-shaft which is rotatable around a central axis, a first gearwheel rotatable around the lay-shaft and the central axis, a second gearwheel fixedly connected to the lay-shaft and rotatable with the lay-shaft around the central axis, and a clutching assembly rotatable around the lay-shaft and the central axis. The clutching assembly includes a driven gearwheel and clutching mechanism for selectively coupling the rotation of the driven gearwheel to either the first gearwheel or the second gearwheel. The clutching assembly has a first axial end and a second axial end opposite the first axial end. The first gearwheel and the second gearwheel are arranged on a part of the lay-shaft extending from the first axial end of the clutching assembly.

A drive system for a motor vehicle includes a separating clutch, a shiftable transmission, a drive machine, and a transmission gear wheel and a clutch device. In a first operating state either the clutch device or the transmission gear wheel is kinematically coupled to the transmission input shaft and in a second operating state both said clutch device and said transmission gear wheel are kinematically coupled in said manner thereto. The drive system comprises a braking device for transmitting a braking force in a non-contact manner in this first operating state from a first part to a second part of the braking device. In that the first part of the braking device is kinematically coupleable to the transmission input shaft and the second part is kinematically coupleable to the transmission gear wheel.

A drive system for a motor vehicle includes a separating clutch, a shiftable transmission, a drive machine, and a transmission gear wheel and a clutch device. In a first operating state either the clutch device or the transmission gear wheel is kinematically coupled to the transmission input shaft and in a second operating state both said clutch device and said transmission gear wheel are kinematically coupled in said manner thereto. The drive system comprises a braking device for transmitting a braking force in a non-contact manner in this first operating state from a first part to a second part of the braking device. In that the first part of the braking device is kinematically coupleable to the transmission input shaft and the second part is kinematically coupleable to the transmission gear wheel.

A vehicle transmission includes a shaft; speed-changing gears; switching mechanisms; and a shifting mechanism. The shifting mechanism is provided with a double-meshing preventing mechanism configured to switch between a one-way state in which the switching mechanisms are hindered from moving in a downshift direction and allowed to move in an upshift direction and a free state in which the switching mechanisms are allowed to move in both the downshift direction and the upshift direction.