The present invention relates to a motor vehicle gearbox, comprising a housing in which an input shaft is carried in a first bearing in a first housing end wall on the input side ofthe input shaft and in a second bearing in a second opposite housing end wall and at least one countershaft mounted in bearings in said end walls and having gears meshing with gears on the input shaft, at least one gear in each pair of intermeshing gears on said shafts being disengageable on its shaft.

It is a known fact that gearboxes used in automobiles with transverse engines must be made short in order to make room for the entire drive unit. The more cylinders an engine has. the shorter the gearbox and clutch must be. A known method of achieving a short five-speed gearbox for a transverse engine is to provide it with two countershafts instead of one.

The purpose of the present invention is to achieve a design in a gearbox of the type described by way of introduction which can be used either as an alternative to the design with two countershafts or as a supplement thereto, to permit, for example, the expansion of an existing short five-speed gearbox to a six-speed without having to increase the total length ofthe gearbox and clutch.

This is achieved according to the invention by virtue ofthe fact that a gear which is carried by one ofthe countershafts and which is arranged to transmit torque to the reverse shaft and the first bearing ofthe input shaft are disposed so that they overlap each other axially.

The invention is based on the idea of moving the first bearing farther into the gear¬ box housing and thus creating more space outside the end wall for the clutch dis-

engaging mechanism so that it can be sunk into the end wall, thus making it possible to place the entire clutch arrangement closer to the gearbox. This makes it possible to shorten the entire gearbox - clutch installation.

In a preferred embodiment which constitutes a further development ofthe gearbox described in SE-A-8601247-3, a bearing-overlapping reversing gear meshes with a reversing gear which is mounted on a second countershaft and which is arranged so that it overlaps the first bearing of the input shaft.

By modifying the gearbox shown and described in said specification so that the intermeshing reverse gears are placed at the input side o the gearbox, the input bearing can be moved further into the gearbox housing since there is no gear on the input shaft in engagement with the reverse gears. This solution makes it possible to expand the known five-speed gearbox to a six-speed gearbox without requiring more total space for the engine and transmission.

The invention will be described in more detail below with reference to the examples shown in the accompanying drawing, where the Figure shows a longitudinal section through one embodiment o a gearbox according to the invention with a clutch device connected thereto.

1 in the Figure generally designates a gearbox housing, which has a central housing portion 2 and front and rear end walls 3 and 4. respectively, screwed securely to the central housing portion 2. A clutch housing 5 is cast in one piece with the forward end wall 3, which is made with a depression 6. which at its bottom portion 7 forms a seat for a taper roller bearing 8, which forms a bearing for an input shaft 9 on the input side. A second taper roller bearing 10 seated in the opposite end wall 4 carries the opposite end ofthe input shaft 9.

To the input shaft 9. six gears 11.12.13.1-t.l 5 and 16 are non-rotatably fixed for torque transmission in first, second, sixth, third, fourth and fifth gear (in said order) via gears 19. 20. 21, 22, 23 and 24 rotatably mounted on a first and a second countershaft 17 and 18. respectively. The rotatably mounted gears are engageable to the respective shafts by means of associated engaging and synchronizing devices

25, 26 and 27.

The countershafts 17 and 18 are mounted in taper roller bearinss 28. 29 and 30. 3 1 in the front and rear end walls 3 and 4. respectively.

The gear 19 for the first gear speed is non-rotatably joined to a first reverse gear 32 meshing with a second reverse sear 33. which is rotatablv mounted on the second countershaft 18 and can be engaged thereto by means of an engaging and synchro¬ nizing device 34. As can be seen in the Figure, the placement ofthe bearing 8 in the bottom ofthe depression 6 will mean that the bearing 8 overlaps the gears 32. 33. so that the end surface 35 ofthe inner ring of the bearing 8 is almost co-planar with the inner surface 36 of the gear 32.

In the depression 6 on the outside ofthe bearing 8, a disengaging device, generally designated 40. for a clutch 41 is mounted. The disengaging device 40 comprises a first sleeve 42 arranged concentrically with the input shaft 9, and a second sleeve 43 arranged concentrically therewith. The sieeves define an annular cylinder space 44 for a ring piston 45, which abuts against a release bearing 46 slidable on sleeve 42. The clutch 41 is of conventional type and comprises a cover 48 securely screwed to the engine flywheel 47. The cover 48 supports a pressure plate 49 and a plate spring 50. The release bearing 46 abuts against a central portion ofthe spring 50 and as it is moved to the right in the Figure, due to supply of pressure medium to the cylinder chamber 44. the pressure plate 49 is lifted from the disc 51 non-rotatably carried by the input shaft 9. thus releasing the clutch.

As can be seen in the Figure, the depression 6 for the release arrangement 40 enables the clutch to be placed as close as is at all possible to the end wall 3 ofthe gearbox housing, i.e. the cover 48 has poπions which lie immediately adjacent to those portions ofthe housing end wall 3 which form seats for the countershaft bearings 28 and 30. Thus the total axial extent ofthe transmission unit will be as short as possible. In practice this means that the described six-speed gearbox with associated clutch need not take up more space than the previously known five-speed version.

In addition to the above described components, the complete transmission unit has a final drive, generally designated 52, the crown gear 53 of which engages two gears 54, 55 each non-rotatably joined to an individual countershaft 17 and 18, respective¬ ly. The gears 54, 55 in the example shown are of equal size and partially overlap the bearing 8 and the release arrangement 40.