DE102011085204A1 - Combined radial-axial bearing for drive shaft of spur gear, has roller bearing which is in contact with four-point contact bearing whose contact angle is set to specific value - Google Patents

Abstract

The invention relates to a storage concept for transmission shafts with a combined radial-axial bearing with an axially extending arrangement of a four-point bearing and an axially fixedly coupled to the four-point bearing cylindrical roller bearing, wherein a pressure angle of the four-point bearing is in a range of 40 ° to 50 °.

Description

The present invention relates to a concept for the storage of both axially and radially loaded transmission shafts, in particular of the input and output shafts of a spur gear, as can be used for example in high-speed rail vehicles.

Rail vehicles, such. B. long-distance trains, are often provided with a distributed drive in which a certain proportion of traction axles is driven. For this purpose, located in a vicinity of the drive axles mounted gear, which is generally one-stage gear in rail vehicles. A single-stage transmission is a transmission with only a fixed ratio - ie without inter-gear ratio - in which one reaches a top speed without switching, which can be at 400 km / h in current high-speed trains, for example.

A mechanical single-stage gearbox, in particular a single-stage helical gearbox, can have a drive shaft and an output shaft coupled thereto and parallel thereto. For coupling the parallel Anund output shafts sit on both in each case in an axis normal plane gears whose teeth can mesh. Frequently, helical gears are used in such spur gears. The teeth are then not parallel to the transmission axis, but at an angle at an angle to it. If a toothed pair (of the input and output gears) comes into contact, it does not bear directly over its entire width, as is the case with straight-toothed spur gears without profile correction. Instead, a loaded tooth width increases slowly as the wheels continue to turn, until the pair of teeth on full width, and falls when unscrewing from a contact zone only slowly. In most cases, two or more teeth are always in contact with helical gear pairs, and only one or two teeth in the case of spur gear pairs. In helical gears so less hard shocks occur during tooth engagement. This leads to lower vibration excitations and quieter running. Disadvantage of helical gearing is, however, a slightly higher friction, resulting in greater losses. In addition, axial forces arise, the gears laterally, d. H. axially, push apart and therefore require a more complex storage required.

From the prior art bearings for input and output shaft such spur gear are known. In this case, the drive shaft for storing them on a first side of the drive gear on a first cylindrical roller bearing and on a second side of the drive gear on a combined radial-axial bearing. The combined radial-axial bearing comprises an arrangement extending in the axial direction from a four-point bearing and a second cylindrical roller bearing axially clamped with the four-point bearing. The two cylindrical roller bearings of the bearing assembly should each act as a radial bearing. By contrast, the four-point bearing of the drive shaft bearing should act primarily as a thrust bearing (that is to say for absorbing axial forces), which is why it should not be loaded radially or only slightly. For this reason, its bearing outer ring also generally has no contact with a bearing housing, i. h., it is exposed radially. However, the radially exposed four-point bearing outer ring can be clamped axially in order to prevent wear on the housing cover. In this case, the radially-exposed outer ring of the four-point bearing is axially clamped so tightly that it can hardly radially center or move during a load change due to a clamping friction. Conventionally used for such radial-axial bearings four-point bearing regularly have a pressure angle of about 35 °, which should be understood by pressure angle of the nominal angle between a radial plane (perpendicular to the bearing axis) and a pressure line.

Such known transmission bearings have been proven for previously realized high-speed trains thoroughly. Up to now, high-speed trains have mostly been used only on routes with relatively short high-speed sections, so that previous shaft bearings for high-speed trains do not have to be designed for excessively high-speed drives. A conventional S0 heat stabilization (up to 150 ° C) of the bearings used therefore quite corresponds to the component temperatures resulting from the short high-speed partial sections.

However, if high-speed trains are to be used on routes which, for example, have high-speed partial sections (for example between two stations) of several hundred or thousand kilometers, this leads to considerably higher continuous operating states and temperatures of known bearings. When using a conventional four-point bearing with a pressure angle of about 35 ° assumes this in one direction due to the axially jammed bearing outer ring not only an axial load, but due to acting at high speeds low torques and a total acting on the radial-axial bearing radial load. The placed next to the four-point bearing cylindrical roller bearing of the drive-side radial-axial bearing is then often unloaded, causing sliding movements of the rolling elements with the risk of high temperatures, smearing and thus premature destruction of storage can occur. In contrast, but should to Ensuring trouble-free operation on single-row cylindrical roller bearings as well as on the other rolling bearings always has a minimum load. This applies in particular to high-speed bearings and bearings which are exposed to strong accelerations and fast load changes. Higher operating temperatures lead to a structural transformation of the retained austenite with associated ring growth over time, even with S0 heat stabilization of the bearings. Residual austenite is a usually unwanted phase in steel or cast iron in conventional steel tempering. It is relatively unstable and converts by temperature increase in ferrite and cementite. In the case of a dimensional change associated therewith, rotation of the inner rings prior to the occurrence of an inspection or main inspection interval, in particular during starting torques, can not be ruled out.

It is therefore an object of the present invention to improve conventional storage concepts for particular used in high-speed trains single-stage transmission.

The present invention is based on the recognition that with respect to a full rolling movement of rolling elements in rolling bearings used a certain minimum radial force is required. That is, a radial minimum load corresponding to this minimum radial force should always be ensured. The above object can thus be achieved by a radial load of placed next to the four-point bearing cylindrical roller bearing a drive-side radial-axial bearing even at low torques, which act at high speed rides, is increased.

To this end, embodiments of the present invention provide a prior art modified combined radial-axial bearing for supporting a transmission input shaft. The modified combined radial-axial bearing comprises an axially extending arrangement of a four-point bearing and an axially fixedly coupled to the four-point bearing cylindrical roller bearing, the four-point bearing has an increased pressure angle in a range of 40 ° to 50 °.

Preferably, the increased pressure angle of the four-point bearing is in a range of 45 ° ± 3 ° and more preferably in a range of 45 ° ± 1 °, depending on achievable manufacturing accuracies.

For the axial fixed coupling of the four-point bearing with the cylindrical roller bearing spacers between adjacent bearing rings of the axially adjacent bearing provided to hold the four-point bearing and the cylindrical roller bearing in a fixed, predetermined axial distance from each other or to fix. In this case, a bearing outer ring of the four-point bearing by means of a corresponding axial spacer with a bearing outer ring of the cylindrical roller bearing can be axially coupled or clamped so that the bearing outer ring of the four-point bearing remains radially movable even at lower high-speed torques despite a caused by the axial coupling friction.

Bearing ventilations of the adjacent bearings of the radial-axial bearing, depending on the application and appropriate requirements, matched to each other, so that the adjacent bearing according to an embodiment in about the same time (radial) can absorb forces. According to another embodiment, the bearing ventilations are coordinated so that the cylindrical roller bearing receives radial forces first. D. h., In embodiments, a bearing clearance of the modified four-point bearing depends on a bearing clearance of the cylindrical roller bearing, and vice versa.

In some embodiments of the present invention, the four-point bearing and / or the cylindrical roller bearing may each comprise a one-piece, shoulder-guided and solid brass bearing cage. Brass solid cages allow higher speeds and are advantageous when, in addition to pure orbital movements, e.g. still high accelerations occur.

Further, the four-point bearing and / or the cylindrical roller bearing may each be heat-stabilized S1 (i.e., up to 200 ° C), and parts of the four-point bearing and / or parts of the cylindrical roller bearing may each be nitrocarburized to better withstand higher temperatures.

In another aspect, the present invention provides a drive shaft for a transmission, the drive shaft having a drive gear with teeth extending obliquely to the drive shaft for coupling the drive shaft to an output shaft of the transmission. The drive shaft has for its storage on a first side of the drive gear a first cylindrical roller bearing and on a second side of the drive gear an inventive combined radial-axial bearing.

According to yet another aspect, a transmission, in particular a spur gear, provided with a drive shaft according to the invention and an output shaft having a driven gear with teeth extending obliquely to the output shaft to couple the output shaft with the drive shaft of the spur gear, wherein the output shaft for their storage on a first side of the output gear, a first tapered roller bearing and on a second side of the output gear has a second tapered roller bearing.

In this case, the tapered roller bearings may be formed such that a roughness of a Kegenrollenstirnfläche is less than 0.18 microns and preferably less than 0.16 microns, and a Kegenrollenstirnfläche facing side surface of a Kegenrollenlagerinnenring a roughness less than 0.25μm and preferably less than 0.20 microns.

A helix angle of the relative to a rotational axis of the input or output shaft obliquely extending teeth of the respective gears is according to embodiments in terms of magnitude greater than 15 °, for example, 18 °.

Embodiments of the present invention allow the drive side, even at lower torques, as present for example in high-speed driving, a lower radial force of the modified four-point bearing and thus at the same time a correspondingly increased radial force absorption of the axially adjacent cylindrical roller bearing. As a result, the minimum required radial force corresponding radial minimum load of the cylindrical roller bearing can always be ensured - even with smaller drive torques than when acceleration and deceleration of a train are present. By using the four-point bearing with a pressure angle of about 45 ° this assumes in the direction of rotation, despite its axially jammed bearing outer ring no longer the entire radial load. The cylindrical roller bearing placed next to it is also loaded radially, which reduces the risk of sliding movements with the risk of smearing and thus premature destruction of the bearing. A minimum load on single-row cylindrical roller bearings to ensure trouble-free operation can be ensured by embodiments. This is especially true for high speed bearings and bearings that are subject to strong accelerations and fast load changes.

The provided on the drive side tapered roller bearings of the output shaft bearing advantageously cooperate with the relatively large helix angle of the gear teeth. The tapered roller bearings can absorb better than for example alternative cylindrical roller bearings in an advantageous axial forces caused by a large skew.

Embodiments of the present invention will be explained below with reference to the accompanying figures. Show it:

1 a schematic representation of a combined radial-axial bearing according to an embodiment of the present invention;

2a a schematic representation of a drive shaft with a combined radial-axial bearing according to an embodiment of the present invention; and

2 B a schematic representation of coupled input and output shafts according to an embodiment of the present invention; and

3 a schematic representation of a spur gear with a drive shaft with a combined radial-axial bearing and mounted by means of tapered roller bearings output shaft, according to an embodiment of the present invention.

1 shows on its right side a schematic representation of a combined radial-axial bearing 10 according to an embodiment for supporting a shaft 11 , which may be, for example, a transmission input shaft.

The combined radial-axial bearing 10 includes an axially, ie in the direction of a rotation axis 12 the wave 11 or a rotation axis of the radial-axial bearing 10 , extending arrangement of a four-point bearing 13 and a cylindrical roller bearing axially coupled or clamped to the four-point bearing 14 , wherein a pressure angle μ of the four-point bearing 13 in a range of 40 ° to 50 °. Under the pressure angle μ of the four-point bearing 13 is a nominal angle between a radial plane 15 (perpendicular to the bearing axis 12 ) and a printing line 16 to understand. The printing line 16 arises from the theoretical consideration that individual rolling elements (balls) guide their tracks on an inner 17 and outer ring 18 in each touch exactly one point. If you connect these points of contact, you get the pressure line 16 , which passes through the center of the rolling element (ball).

At a certain speed of the shaft 11 is a certain minimum radial force with respect to a full or undisturbed rolling movement of the rolling elements of the bearings 13 . 14 required, in particular with regard to the rolling bearing 14 , A minimum load should therefore always be ensured. An insufficient load on the bearings 13 . 14 influences the rolling behavior of the rolling elements (the slippage of the bearings). A rapid rise in temperature in one direction of rotation may be due to an insufficient (radial) load. Because this leads to a very high slip (or in unfavorable case can until the standstill of a set of rollers), where danger of greasing (damage a running surface) and can be unfavorable by sliding friction between the inner ring and roller set, the heat transfer to the outer ring / housing. This is especially true for fast running bearings.

The specially increased pressure angle μ of the four-point bearing 13 , which can also be called FPCBB (Four-Point Contact Ball Bearing), is therefore an elementary aspect of the inventive concept for supporting transmission shafts, in particular for drive trains of a high-speed rail vehicle. As shown in the enlarged detail on the left side of the 1 is indicated, a pressure angle of a conventional four-point bearing is normally at about 35 °. However, according to embodiments of the present invention, a novel four-point bearing becomes available 13 proposed, the increased pressure angle μ in a range of 45 ° ± 5 °, preferably in a range of 45 ° ± 3 ° and more preferably in a range of 45 ° ± 1 °. As it is in 1 is indicated, it can be increased at the same radial load F _R axial force component by an amount of F _A1 to F _A2 . Ie. a force absorption in the axial direction is increased, while the power consumption in the radial direction is reduced.

In addition to an inner ring dressing or a split bearing inner ring 17 of the four-point camp 13 is a bearing outer ring 18 of the four-point camp 13 axially with the bearing outer ring 19 of the cylindrical roller bearing 14 , which can also be referred to as CRB (Cylindrical Roller Bearing) coupled. Up to a limit torque, which is exceeded in terms of absolute value during start-up and braking, however, by this axial coupling or clamping of the bearing rings 18 . 19 or by the friction caused thereby at the end faces of the bearing outer rings 18 . 19 , a radial deflection of the axially fixed four-point bearing outer ring 18 be prevented.

It is assumed that the radially-exposed outer ring 18 of the four-point camp 13 axially clamped so tightly that he at least during load changes and moments below the limit torque due to axial friction or contact forces by the jamming also radially not centered (move) can.

The bearing outer ring 18 of the four-point camp 13 Thus, for example, by means of an axial spacer 20 with the bearing outer ring 19 of the cylindrical roller bearing 14 be axially (fixed) coupled so that the bearing outer ring 18 of the four-point camp 13 despite the axial coupling or the resulting friction remains radially movable - at least when a minimum required radial force (corresponding to the limit torque) is exceeded. In this case, the axial spacing element is for the axial clamping 20 but not mandatory. The axial clamping or fixing of the bearings 13 . 14 can also by an axially immediate juxtaposition of bearings 13 . 14 be achieved so that their end faces directly form a contact area.

The minimum required radial force or the limit torque is thanks to the modified four-point bearing 13 less than with the conventional four-point bearings described above. When using a conventional four-point bearing would be at a constant maximum speed of a train and a resulting low torque, the four-point bearing not only on the storage 10 acting axial load, but also take over an entire radial load. The cylindrical roller bearing placed next to the (conventional) four-point bearing 14 would then be radially unloaded, causing high sliding movements with the risk of harmful effects, such. B. lubrication, and thus premature destruction can occur. In contrast, however, to ensure a trouble-free operation on the single-row cylindrical roller bearing 14 , As well as on other (not shown) bearings of a shaft bearing, always act a minimum load. This is especially true for high speed bearings and bearings that are subject to strong accelerations and fast load changes.

If one would not axially fix a four-point bearing of a radial-axial bearing, a wear protection of its lateral or circumferential surfaces as well as a wear protection of the opposing surfaces would have to be provided, eg. B. by carbonitriding, which would mean an increased production cost.

A selection of bearing ventilation of a shaft bearing can be different according to the environment (eg housing material). For a definitive clearance fixing, the knowledge of the real or max. Temperatures in the storage system required and assessed. Particular attention must be paid to the bearing clearance of the axially clamped and radially exposed four-point bearing 13 with that on the shaft 11 located cylindrical roller bearing 14 ,

A bearing clearance of the four-point bearing 13 depends according to embodiments of a bearing clearance of the cylindrical roller bearing 14 off, and vice versa, to approximately ensure that both camps 13 . 14 can simultaneously absorb radial forces or that the radial forces first or alone from the cylindrical roller bearing 14 can be included. As a result, the bearing ventilations of the bearings 13 . 14 be designed differently according to some embodiments. With a uniform choice of bearing clearance of the entire radial-axial bearing 10 can be a very low load on the cylindrical roller bearing 14 in normal operating conditions. The four-point camp 13 then absorbs almost the entire radial load in addition to the axial load. This situation can therefore be interpreted in the interpretation of Lagerlüfte be considered. An axial bearing air of the four-point bearing 13 has virtually no influence, as long as no jamming between two rows of bearings 13 . 14 due to a misalignment of the camp 13 entry. One possible remedy is therefore one opposite the four-point bearing 13 reduced radial clearance of the cylindrical roller bearing 14 , D. h., According to one embodiment, the radial bearing clearance of the cylindrical roller bearing 13 less than the radial clearance of the four-point bearing 13 ,

The use of a four-point bearing according to the invention 13 with a higher pressure angle μ, osculation and tuned radial clearance of the four-point bearing 13 can be a force distribution of the shaft bearing system, in particular the radial-axial bearing 10 improve, especially for high-speed bearings and bearings that are exposed to strong accelerations and rapid load changes. By this measure, in the context of the technically possible in an axially clamped four-point bearing outer ring 18 for the highest possible (radial) load on the cylindrical roller bearing 14 be taken care of.

Nevertheless, there is the possibility that the cylindrical roller bearing in one direction of rotation at low drive torque 14 is not loaded with the required radial force. Such an effect can occur especially at high speeds. A remedy for this would be either a really radially outer ring of the four-point bearing (without axial clamping), a reduced bearing clearance of the cylindrical roller bearing or an even larger pressure angle μ of the four-point bearing 13 , The latter possibility, however, are limited due to space between the bearing cage and shoulders limits.

According to embodiments, it is possible to use a bearing cage of the four-point 13 and / or the cylindrical roller bearing 14 shoulder-trained. In this case, the cage runs with a radial interface on a shoulder (board) of the bearing and is guided by it. Preferably, a bearing cage of the four-point 13 and / or the cylindrical roller bearing 14 Made of solid metal, especially brass. In other words, the four-point bearing points 13 and / or the cylindrical roller bearing 14 According to embodiments, in each case a one-piece, shoulder-mounted and solid bearing cage made of brass. Solid cages made of brass allow higher speeds and are advantageous if, in addition to pure orbital movements, for example, even high accelerations occur.

Conventional heat stabilizers (S0) harmonize with rather lower component temperatures that occur, for example, at low high speed travel rates. Higher storage temperatures, which occur at a longer maximum speed, can also lead to a structural transformation of the retained austenite with associated ring growth over time with an S0 heat stabilization. In the associated dimensional change rotating the inner rings before the main inspection interval, especially at the starting torque can not be excluded.

With regard to ensuring a tight fit of the radial-axial bearing 10 on the wave 12 over longer operating periods, the bearings can 13 . 14 (In addition to possibly further bearings) according to embodiments therefore be designed with an S1 heat stabilization, which corresponds to an increased temperature limit of 200 ° C and a load rating of 75% to 90%. Conventional bearings are typically designed for operating temperatures up to 120 ° C (bearings with seals up to 100 ° C). If a bearing is used at constantly higher temperatures, it should be specially adapted during manufacture to ensure its dimensional stability during operation. High temperature bearings can be heat treated. However, a heat stabilization of a bearing has a softening of its tracks result and thus a reduction in a bearing capacity of the camp.

To obtain an improved surface finish, parts of the four-point bearing can 13 and / or parts of the cylindrical roller bearing 14 each nitrocarburized, wherein nitrocarburizing means a thermochemical method for enriching a surface layer of a workpiece with nitrogen and carbon. Thus, in nitrocarburizing, a nitriding layer is formed, consisting of a bonding layer and a diffusion layer. Furthermore, parts of the four-point camp 13 and / or parts of the cylindrical roller bearing 14 each formed burnished. Burnishing serves to form a weak protective layer (oxide layer) on ferrous surfaces to reduce corrosion.

In a further aspect, the present invention also relates to a drive shaft, in particular for a spur gear, with an improved radial-axial bearing described above 10 ,

In addition shows 2a a drive or pinion shaft 21 for example, for a spur gear. The drive shaft 21 has a drive gear 22 with an angle to the drive shaft 21 running teeth 23 on to the drive shaft 21 with an in 2a to couple not shown output shaft of the transmission. The drive shaft 21 points to their storage on a first side (left) of the drive gear 22 a first cylindrical roller bearing 24 and on a second side (right) of the drive gear 22 the combined radial-axial bearing 10 on, wherein the pressure angle μ of the four-point bearing 13 - As described - is in a range of 40 ° to 50 °.

2 B shows the drive shaft 21 out 2a coupled with an output shaft 25 that has a driven gear 26 obliquely to the output shaft 25 running teeth 27 has to the output shaft 25 with the drive shaft 21 to pair. A helix angle β of the oblique to the output shaft 25 extending teeth deviates according to embodiments by an amount greater than 15 °, for example by 18 °, from an axis of rotation of the output shaft 25 from. This is therefore also true for a helix angle obliquely to the drive shaft 21 running teeth 23 , The output shaft 25 indicates for their storage on a first side of the driven gear 26 a first tapered roller bearing 28 and on a second side of the output gear 26 a second tapered roller bearing 29 on.

The tapered roller bearings 28 . 29 the driven side bearing and the bevelled teeth 23 . 27 act synergistically together, in the sense that the tapered roller bearings 28 . 29 in an advantageous manner by the inclined teeth 23 . 27 can absorb transmitted axial forces. This is particularly advantageous for larger helix angles of the teeth, in which alternatively usable cylindrical roller bearings would be a poorer choice due to their lower axial load capacity.

The tapered roller bearings 28 . 29 may be formed according to embodiments such that a roughness of a tapered roller face is less than 0.18 microns, for example, 0.16 microns. A roughness of a tapered roller end surface facing side surface of a tapered roller bearing inner ring may be less than 0.25 microns, in particular 0.2 microns.

According to a further aspect of the present invention, a transmission, in particular a single-stage helical gear, is also provided for rail vehicles. In addition it shows clearly 3 a spur gear 30 with the invention 21 and output shafts 25 and corresponding bearings.

At the drive shaft side, even at lower drive torques, a radial force absorption of the cylindrical roller bearing 14 of the radial-axial bearing 10 to allow for receiving axial forces an inventive four-point bearing 13 used with increased pressure angle μ (40 ° ≤ μ ≤ 50 °). Output shaft side are the advantageous tapered roller bearings 28 . 29 used to absorb axial forces, including the amount of relatively high helix angle of the gear teeth 23 . 27 be caused.

A stress on the bearings 13 . 14 . 24 . 28 . 29 takes place not only due to direct loads, but also due to environmental conditions. As an example, here is a radiation heat from the immediate vicinity of the teeth 22 . 26 , metallic abrasion from the teeth but also called mineral impurities. Ensuring "easy" decontamination could definitely have a positive effect on the expected life expectancy of the rolling bearings. A reduction in a mean operating oil temperature as well.

An effectiveness of lubrication in both directions of rotation as well as a heat dissipation is to be ensured.

In summary, a storage concept has been described in particular for a single-stage traction drive. This drive storage concept comprises two cylindrical roller bearings as well as a modified four-point bearing on the drive side. On the output shaft tapered roller bearings (TRB = Tapered Roller Bearings) are preferably used, according to the gear data, z. B. at smaller helix angles, and cylindrical roller bearings (CRBs) could be used.

The use of the four-point bearing with the higher pressure angle, osculation and matched radial bearing clearance of the four-point bearing can improve the force distribution of the storage system. As a result of this measure, as far as is technically possible - with an axially clamped four-point bearing outer ring - the highest possible load on the adjacent cylindrical roller bearing is ensured.

LIST OF REFERENCE NUMBERS

10

 combined radial-axial bearing

11

 wave

12

 axis of rotation

13

 Four point contact bearings

14

 Cylindrical roller bearings

15

 radial plane

16

 pressure line

17

 divided bearing inner ring

18

 Four point contact bearing outer ring

19

 Cylindrical roller bearing outer ring

20

 axial spacer

21

 Drive or pinion shaft

22

 drive gear

23

 Teeth of the drive gear

24

 first cylindrical roller bearing

25

 output shaft

26

 drive gear

27

 Teeth of the output gear

28

 first tapered roller bearing

29

 second tapered roller bearing

30

 transmission

Claims (10)

A combined radial-axial bearing ( 10 ) with an axially extending arrangement of a four-point bearing ( 13 ) and an axially fixedly coupled to the four-point bearing cylindrical roller bearings ( 14 ), wherein a pressure angle (μ) of the four-point bearing ( 13 ) is in a range of 40 ° to 50 °. The combined radial-axial bearing according to claim 1, wherein the pressure angle (μ) of the four-point bearing ( 13 ) is in a range of 45 ° ± 3 ° and preferably in a range of 45 ° ± 1 °. The combined radial-axial bearing according to one of the preceding claims, wherein a bearing outer ring ( 18 ) of the four-point bearing ( 13 ) by means of an axial spacer element ( 20 ) with a bearing outer ring ( 19 ) of the cylindrical roller bearing in the axial direction ( 14 ) is so firmly coupled that the bearing outer ring ( 18 ) of the four-point bearing ( 13 ) remains radially movable despite the axial coupling. The combined radial-axial bearing according to one of the preceding claims, wherein a radial bearing clearance of the four-point bearing ( 13 ) of a radial bearing clearance of the cylindrical roller bearing ( 14 ) and vice versa. The combined radial-axial bearing according to one of the preceding claims, wherein the four-point bearing ( 13 ) and / or the cylindrical roller bearing ( 14 ) each has a one-piece, shoulder-mounted and solid bearing cage made of brass. The combined radial-axial bearing according to one of the preceding claims, wherein the four-point bearing ( 13 ) and / or the cylindrical roller bearing ( 14 ) each S1 is heat stabilized. The combined radial-axial bearing according to one of the preceding claims, wherein the four-point bearing ( 13 ) and / or the cylindrical roller bearing ( 14 ) is in each case at least partially nitrocarburized. A drive shaft ( 11 ; 21 ) for a transmission that has a drive gear ( 22 ) obliquely to the drive shaft ( 11 ; 21 ) teeth ( 23 ) to the drive shaft ( 11 ; 21 ) with an output shaft ( 25 ) of the transmission, wherein the drive shaft ( 11 ; 21 ) for their storage on a first side of the drive gear ( 22 ) a first cylindrical roller bearing ( 24 ) and on a second side of the drive gear ( 22 ) the combined radial-axial bearing ( 10 ) according to one of the preceding claims. A spur gear ( 30 ) with a drive shaft ( 21 ) according to claim 8 and an output shaft ( 25 ), which has an output gear ( 26 ) obliquely to the output shaft ( 25 ) teeth ( 27 ) to the output shaft ( 25 ) with the drive shaft ( 21 ) of the spur gear ( 30 ), the output shaft ( 25 ) for their storage on a first side of the output gear ( 26 ) a first tapered roller bearing ( 28 ) and on a second side of the output gear, a second tapered roller bearing ( 29 ) having. The spur gear according to claim 9, wherein the tapered roller bearings ( 28 ; 29 ) are formed such that an average roughness of a Kegenrollenstirnfläche is less than 0.18 microns and a Kegenrollenstirnfläche facing side surface of a Kegenrollenlagerinnenrings an average roughness less than 0.25 microns.

Images