FI ELD OF THE I NVENTION AND PRIOR ART The present invention relates to a gearbox according to the preamble of claim 1 .

In a motor vehicle gearbox, it is common for the input shaft of the gearbox to be rotatably mounted on the gearbox housing with the help of a rolling bearing , in the form of a conical rolling bearing made of steel , wherein such a rolling bearing is mounted in a bearing seat of the gearbox housing with an interference fit between the outer ring of the bearing and the bearing seat. Where the gearbox housing is made of aluminium or another material with an expansion coefficient other than that of steel , the interference fit between the outer ring of the bearing and the bearing seat may loosen when the temperature rises, because of the divergent expansion coefficients of the gearbox housing material and the rolling bearing steel material , so that the bearing's outer ring may rotate in relation to the bearing seat. This may in turn lead to abrasion damage to the bearing's outer ring and the bearing seat and a gap between the input shaft and the gearbox housing . In order to prevent such a rotation of the bearing's outer ring in relation to the bearing seat, according to prior art, an O-ring or a wedge is arranged between the outer ring of the bearing and the bearing seat. One disadvantage of such a solution is, however, that the insertion of an O-ring or wedge between the outer ring of the bearing and the bearing seat makes it more difficult to fit the bearing's outer ring in the bearing seat. With the use of a wedge which engages in a groove in the outer ring of the bearing and in a corresponding groove in the bearing seat, the outer ring of the bearing must be arranged in a predetermined rotational position in relation to the bearing seat when the bearing seat is fitted , in order to allow for the insertion of the wedge between the bearing's outer ring and the bearing seat, which may be difficult and time consuming to achieve. With the use of an O-ring which is arranged inside a groove in the outer ring of the bearing or in the bearing seat, there is a risk that the O-ring may be cut to pieces between the outer ring of the bearing and the bearing seat when the bearing's outer ring is pressed into the bearing seat, so that there is a risk that the O-ring may end up between the rolling bearing and the bearing seat's bottom surface, thus preventing the outer ring of the bearing from assuming a correct end position, abutting against the bottom surface of the bearing seat. Further, an O-ring which is cut to pieces will not fulfil the intended rotation- preventing function.

OBJECTIVE OF THE I NVENTION

The objective of the present invention is to achieve a novel and advantageous solution to the problem explained above.

SUMMARY OF THE I NVENTION

According to the present invention , the objective mentioned above is achieved with the help of a gearbox having the characteristics defined in claim 1 . The gearbox according to the invention comprises: - a gearbox housing ;

- a rotatable shaft, extending horizontally or at least in a substantially horizontal direction ;

- a rolling bearing , via which said shaft is rotatably mounted in the gearbox housing and featuring :

^■ an outer ring of the bearing fitted in a bearing seat arranged in the gearbox housing , wherein such an outer ring of the bearing features, at a first axial end , a first edge surface abutting against a supporting surface in the bearing seat and at an opposite second axial end , a second edge surface,

^■ an inner ring of the bearing attached to said shaft, and

^■ several rolling bodies arranged between the bearing's outer ring and the bearing's inner ring ;

- a mounting plate, which abuts against the second edge surface of the bearing's outer ring and is screwed onto the gearbox housing , in order to thus keep the outer ring of the bearing biased between the mounting plate and said supporting surface in the bearing's seat; and

- a reservoir for receipt of gearbox oil arranged in the gearbox housing on the outside of and above the bearing seat, wherein the mounting plate forms an end wall of such a reservoir, and a groove for leading gearbox oil from the reservoir into the bearing seat is arranged in the bearing seat.

The mounting plate ensures that the outer ring of the bearing is maintained in an axial direction, pressed against its supporting surface in the bearing seat, so that the friction force between the outer ring of the bearing and said supporting surface will counteract a rotation of the outer ring of the bearing in relation to the bearing seat, even if the interference fit between the bearing's outer ring and the bearing seat were to loosen at rising temperatures. The mounting plate also contributes to forming a reservoir for gearbox oil above the bearing seat, whereby the required lu brication of the rolling bearing is ensured by way of the gearbox oil being led via a groove in the bearing seat into the bearing seat from said reservoir. Accordingly, an effective lubrication of the rolling bearing may be achieved in a simple way, without the need to pump gearbox oil into the bearing seat with the help of an oil pump.

One embodiment of the invention is characterised in that:

- said bearing seat constitutes a first bearing seat of the gearbox housing , wherein a second bearing seat for a rolling bearing is arranged inside the gearbox housing below the first bearing's seat, and

- a groove for leading gearbox oil from the first bearing seat to the second bearing seat is arranged inside the first bearing seat. Thus, a lubrication of the rolling bearing arranged in the second bearing seat may be ensured in a simple way with the help of gearbox oil from said reservoir.

According to another embodiment of the invention, the mounting plate comprises axially resilient mounting sections, which via the mounting plate abut against the outer ring of the bearing , and which are distributed circumferentially around the second edge surface of the outer ring of the bearing . With the help of these axially resilient mounting sections, the mounting plate obtains a good ability to absorb axially acting forces, which are transmitted from said shaft, via the bearing's inner ring and the rolling bodies to the bearing's outer ring .

According to another embodiment of the invention, said mounting sections of the mounting plate are biased against the second edge surface of the outer ring of the bearing in order to keep the outer ring of the bearing biased between the mounting plate and said supporting surface in the bearing seat, under the impact of a resilient force exerted by the mounting plate's mounting sections. This means it is possible to ensure that the mounting plate constantly exerts an axial pressure force against the outer ring of the bearing , which force is evenly distributed circumferentially around the second edge surface of the bearing's outer ring . According to another embodiment of the invention , said reservoir is open at the top. Since it is open at the top, the reservoir is able to receive gearbox oil , which under the action of rotating cogwheels inside the gearbox housing is splashed up from an oil sump at the bottom of the gearbox housing .

Other advantageous features of the gearbox according to the invention are set out in the non-independent claims and the description below. BRI EF DESCRI PTION OF TH E DRAWI NGS

The invention is described below with the help of example embodiments, with reference to the enclosed drawings. Displayed in: is a perspective view of a part of a gearbox, according to one embodiment of the present invention , with a first rolling bearing , firmly pressed into a first bearing seat with the help of a mounting plate, and a second rolling bearing arranged in a second bearing seat, is a perspective view corresponding to Fig . 1 , but with the mounting plate and the second rolling bearing omitted , is a perspective view corresponding to Fig . 1 , but with the mounting plate and the two rolling bearings omitted , a perspective view corresponding to Fig . 3, but from different angle, is a vertical longitudinal section through the gearbox section displayed in Fig . 1 , and a rotatably mounted shaft inside such a gearbox section, is a longitudinal section corresponding to Fig . 5, but with said shaft and the second rolling bearing omitted , is a horizontal section according to the line VII-VII in Fig . 6, and is a perspective view of the mounting plate of the gearbox section displayed in Fig . 1 . DETAI LED DESCRI PTION OF EMBODI M ENTS ACCORD I NG TO THE I NVENTION

In Figs. 1 -7 a section 1 of a gearbox according to one embodiment of the present invention is displayed . The illustrated section constitutes the part of the gearbox which is intended to face an engine connected to the gearbox, e.g . in the form of a combustion engine of a motor vehicle. The gearbox comprises an outer gearbox housing 2, which is preferably made of aluminium. Figs. 1 -7 show only an end portion of the gearbox housing 2. In the illustrated example, the gearbox housing 2 comprises an external cover 3, which is intended to face said engine and intended to house a part of a clutch arranged between the engine and the gearbox.

The gearbox comprises an input shaft 4 (see Fig . 5) extending horizontally or at least su bstantially horizontally through an opening 5 into the gearbox housing 2. For purposes of clarity, the input shaft 4 is not drawn in the other figures. The input shaft 4 is rotatably mounted in the gearbox housing 2 via a rolling bearing 6. The rolling bearing 6 is made of steel and comprises, in a conventional manner, an outer ring 7 of the bearing , an inner ring 8 of the bearing , which is rotatably connected with the input shaft 4, several rolling bodies 9 arranged between the bearing's outer ring 7 and the bearing's inner ring 8, and a holder 10 for the rolling bodies 9. In the illustrated example, the rolling bearing 6 is a conical rolling bearing with rolling bodies 9 in the form of rolls. The rolling bearing 6 could , however, also consist of a ball bearing , with rolling bodies consisting of balls. The outer ring 7 of the bearing is fitted with an interference fit into a bearing seat 1 1 arranged inside a gearbox housing 2, which bearing seat hereafter is referred to as a first bearing seat. The mantle surface of the bearing's outer ring abuts against a cylindrical internal wall 1 2 of the first bearings seat 1 1 , as illustrated in Fig . 7. At a first axial end , the bearing outer ring 7 has an annular first edge surface 13, abutting against an annular supporting surface 14 in the first bearing seat 1 1 , and at an opposite second axial end , the bearing outer ring has an annular second edge surface 15. A mounting plate 16 abuts against the second edge surface 15 of the bearing's outer ring and is screwed onto the gearbox housing 2 , in order to thus keep the bearing outer ring 7 biased between the mounting plate 16 and said supporting surface 14 in the first bearing seat 1 1 . The mounting plate 16 is annular and has a central opening 1 7 (see Fig . 8), through which the input shaft 4 extends. The mounting plate 16 is arranged on the inside of the gearbox housing 2.

In the illustrated example the mounting plate 1 6 is screwed onto the gearbox housing 2 with the help of a number of screws 1 8, which are distributed around the central opening 1 7 of the mounting plate. Each of the screws 18 extends through a hole 1 9 (see Fig . 8) in an annular base section 20 of the mounting plate 16, and is screwed into a threaded hole 21 in the gearbox housing 2, wherein the screw head of the screw 18 abuts against the base section 20 of the mounting plate.

The mounting plate 1 6 is advantageously equipped with axially resilient mounting sections 23 (see Figs. 1 and 8), via which the mounting plate 16 abuts against the outer ring 7 of the bearing , and which are distributed circumferentially around the second edge surface 15 of the bearing's outer ring . These mounting sections 23 are fixedly connected to the mounting plate's base section 20, and extend radially inwards from the base section 20. The mounting sections 23 form protrusions in the central opening 1 7 of the mounting plate 16, and are biased against the second edge surface 15 of the outer ring of the bearing , in order to keep the outer ring 7 of the bearing biased between the mounting plate 16 and said supporting surface 14 in the first bearing seat 1 1 , under the impact of a resilient force exerted by the mounting plate's mounting sections 23.

The mounting plate 16 is made of metal , preferably steel , and its base section 20 is suitably embossed to provide the mounting plate with increased strength.

A reservoir 25 for receipt of gearbox oil is arranged in the gearbox housing 2 on the outside of, and above, the first bearing seat 1 1 . The mounting plate 16 forms an end wall 26 of this reservoir 25, as illustrated in Figs. 5 and 6. The reservoir 25 is otherwise defined by walls that are integrated in the gearbox housing 2. The first bearing seat 1 1 has an edge surface 28 facing the mounting plate 16, wherein the mounting plate 16 is snug against this edge surface 28, so that gearbox oil which has accumulated in the reservoir 25 is prevented from trickling out of the reservoir via the contact surfaces between the first bearing seat 1 1 and the mounting plate 16. The reservoir 25 is open at the top, and the compartment 29 directly above the reservoir is connected with the other compartment 30 inside the gearbox housing 2, via an opening 31 directly above the mounting plate 16, as illustrated in Figs. 1 and 5.

A groove 32 (see Figs. 4-6) for leading gearbox oil out of the reservoir 25 and into the first bearing seat 1 1 is arranged in the first bearing seat. Such a groove 32 comprises:

- a first section 32a, extending in a radial direction over the abovementioned edge surface 28 of the first bearing seat 1 1 ,

- a second section 32b, connected with the first section 32a, extending axially along the internal wall 1 2 of the first bearing seat 1 1 , and

- a third section 32c connected with the second section 32b, extending radially over the abovementioned supporting surface 14 in the first bearing seat 1 1 .

The first groove section 32a could be replaced with a corresponding groove on the inside of the mounting plate 16.

In the illustrated embodiment, the third groove section 32c debouches in a compartment 33 for gearbox oil at the bottom of the first bearing seat 1 1 . The groove 32 is accordingly adapted to lead gearbox oil from the reservoir 25 to such a compartment 33. From such a compartment 33, gearbox oil may penetrate between the outer ring 7 of the bearing and the inner ring 8 of the bearing , for lu brication of the contact surfaces between the latters and the rolling bodies 9.

In the illustrated embodiment, a second bearing seat 35 for a ball bearing 36 is arranged in the gearbox housing 2, below the first bearing seat 1 1 . A countershaft (not displayed ) of the gearbox is rotatably mounted in the gearbox housing 2 via such a ball bearing 36. The ball bearing 36 is made of steel and comprises, in a conventional manner, an outer ring 37 of the bearing , an inner ring 38 of the bearing , which is rotatably connected with the countershaft, several rolling bodies 39 arranged between the bearing's outer ring 37 and the bearing's inner ring 38, and a holder 40 for the rolling bodies 39. The bearing's outer ring 37 is fitted with an interference fit into the second bearing seat 35. In the illustrated example, the rolling bearing 36 is a conical rolling bearing with rolling bodies 39 in the form of rolls. The rolling bearing 36 could , however, also consist of a ball bearing with rolling bodies consisting of balls.

In Fig . 5, a cogwheel 41 is displayed , arranged on said countershaft and engaged with a cogwheel 42 arranged on the input shaft 4. One or several additional cogwheels are also arranged on the countershaft, which are not, however, displayed in the figures. A groove 43 (see Figs. 3-6) for leading gearbox oil from the first bearing seat 1 1 to the second bearing seat 35 is arranged in the first bearing seat 1 1 . Such a groove 43 comprises:

- a first section 43a, extending in a radial direction over the abovementioned edge surface 14 of the first bearing seat 1 1 , - a second section 43b connected with the first section 43a, extending axially along the internal wall 1 2 of the first bearing seat 1 1 , and

- a third section 43c connected with the second section 43b, extending radially over the edge surface 28 of the first bearing seat 1 1 , facing the mounting plate 16. The third groove section 43c could be replaced with a corresponding groove on the inside of the mounting plate 1 6. In the illustrated example, the first groove section 43a is connected , at its upstream end , to the abovementioned compartment 33 for gearbox oil at the bottom of the first bearing seat 1 1 , while the third groove section 43c debouches into a compartment 44 of the gearbox housing 2 , located between the first bearing seat 1 1 and the second bearing seat 35, and extending through a cylindrical wall 45 of the second bearing seat 35. Via the compartment 44, the gearbox oil from the first bearing seat 1 1 may thus come into contact with the rolling bearing 36, arranged in the second bearing seat 35.

The lower part of the gearbox housing 2 forms an oil sump 46, intended to contain gearbox oil , wherein the lower parts of the cogwheels 41 arranged on the countershaft of the gearbox are intended to be immersed in the gearbox oil received in the oil sump 46. When such cogwheels 41 rotate, they will splash gearbox oil into the internal compartment 30 in the gearbox housing 2 above the oil sump 46, and a part of this gearbox oil will splash into the reservoir 25 via the opening 31 , above the mounting plate 16, and accumulate in the reservoir. From the reservoir 25, the gearbox oil then flows via the groove 32 into the first bearing seat 1 1 . The gearbox oil may then, via the groove 43 and the compartment 44 above the second bearing seat 35, flow on into the second bearing seat, and subsequently flow back down into the oil sump 46. The gearbox according to the invention is especially intended to be used in a heavy goods vehicle, such as a bus, tractor or truck.

The invention is not limited in any way to the embodiments described above, but numerous possible modifications thereof should be obvious to a person skilled in the area, without such person departing from the spirit of the invention as defined by the appended claims.