Steering gear for a vehicle, in particular a commercial vehicle

Abstract

The invention relates to a recirculating ball steering gear (10) for a steering system of a vehicle, in particular a commercial vehicle, having: at least one housing (12); at least one steering spindle (14); at least one steering spindle nut (16), which is guided axially displaceably inside the housing (12) and which is coupled to the steering spindle (14) by means of a plurality of balls (14a) in the assembled state; and at least one bearing device (18), by means of which the steering spindle (14) is supported in the housing (12); wherein the bearing device (18), the steering spindle (14) and the housing (12) form an adjusted support section.

Description

Technical Field

[0001] The present invention relates to a recirculating ball steering gear for a steering system of a vehicle, in particular a commercial vehicle, having at least one housing; having at least one steering spindle; having at least one steering spindle nut which is axially displaceably guided inside the housing and which, in the assembled state, is coupled to the steering spindle by means of a plurality of balls; and having at least one bearing device. Background Art

[0002] Today's steering gears for commercial vehicles or for heavy commercial vehicles are usually implemented as recirculating ball steering gears. In the case of the particularly high axle loads of heavy commercial vehicles, this type of construction offers the advantage of providing high steering forces or steering torque support while having a simple construction concept.

[0003] Such recirculating ball steering gears are known from the prior art.

[0004] Thus, DE 3714833 A1 shows an assisted steering device which includes a first force amplification device having a working piston mounted in a basic housing of the steering gear, the working piston cooperating with a lead screw. The working piston drives a steering spindle carrying a steering sector gear by means of a toothing. As a second force amplification device, an electric motor is provided which drives a shaft projection via a reduction gearing and a switchable engagement device. The shaft projection is torsionally rigidly connected to the lead screw. The second force amplification device is arranged in a housing flange-connected to the basic housing.

[0005] Furthermore, EP 3192719 A1 discloses an electric servo steering device which includes a housing, a rotary shaft for steering, a worm wheel, a worm shaft, end-side bearings, an electric motor, and a prestressing mechanism. The prestressing mechanism includes a wedge and an elastic element for the wedge. In a state where the wedge is movable in the circumferential direction, the wedge is arranged between the outer circumferential surface of the end-side bearing and the inner circumferential surface of the housing. The elastic element for the wedge applies an elastic force to the wedge in the circumferential direction.

[0006] Furthermore, US 9731753 B2 shows a steering gear component for a vehicle which includes a worm and a ball nut, the worm being rotatably and non-axially displaceably supported, wherein the worm has a ball recirculation spindle for receiving a ball train, the ball nut being drivingly connected to the worm by means of the ball train, wherein the ball nut acts as a piston of a cylinder for steering force support, wherein a signal generator for a sensor element is arranged on the steering spindle and the sensor element is arranged on the worm, or, wherein the sensor element is arranged on the steering spindle and the signal generator for the sensor element is arranged on the worm.

[0007] Furthermore, a servo steering system for multi-axle steering of a motor vehicle is disclosed in WO 2013058752 A1, which includes a main steering drive controlled by a steering wheel. The main steering drive includes a piston fixed to the steering wheel of the first axle of the motor vehicle, a second steering drive fixed to the steering wheel of the second axle of the motor vehicle, and a drive assembly connecting the first and second servo steering drives to each other. The main steering drive includes a fluid control valve having an output element, which is connected to the piston and to the drive assembly.

[0008] Furthermore, DE 10351618 B4 discloses a steering system for a commercial vehicle, which has a steering drive that transmits the steering movement introduced at the drive input to a steering rocker via a shaft rotatably supported in a drive housing and a piston movable along the shaft by rotation of the shaft. The commercial vehicle steering system also has a hydraulic power assist device that supports the piston movement by controllably applying pressure to hydraulic fluid. An additional power assist device is provided, which has an electric motor, and the torque of the electric motor is transmitted to the shaft via a reduction gearing.

[0009] The core components of such a ball circulation steering drive are a ball screw with a ball screw nut coupled thereto and a ball circulation section coupling the two components. However, during operation, especially in the steering spindle, a complex three-dimensional stress state occurs, and this assembly is subject to strong wear. This is especially the case when the ball screw nut rotates the sector gear shaft meshing therewith and, due to its action, bears a radial force component, which causes bending of the steering spindle. This is especially the case when steering support energy is supplied to the ball screw via a servo drive stage and an electric motor.

[0010] The bending of the steering spindle in turn leads to locally increased pressures on the individual ball rows of the ball circulation section. These pressures can locally exceed the permissible surface pressure of the ball circulation section and thus cause damage to the balls, the raceways of the ball screw or the steering spindle, and the ball screw nut. SUMMARY OF THE INVENTION

[0011] Accordingly, it is an object of the present invention to further develop a steering drive of the type described at the beginning in an advantageous manner, in particular such that the wear of the steering drive is minimized and its installation space is optimized.

[0012] According to the present invention, this task is solved by a steering gear having the features of the present invention. Accordingly, a recirculating ball steering gear for a steering system of a vehicle, in particular a commercial vehicle, is provided, which has: at least one housing; at least one steering spindle; at least one steering spindle nut, which is axially movably guided inside the housing and which is coupled to the steering spindle by means of a plurality of balls in the assembled state; and at least one bearing device, by means of which the steering spindle is supported in the housing; wherein the bearing device, the steering spindle and the housing form the adjusted support portion.

[0013] The basic idea on which the present invention is based is that, by means of the adjusted support portion, the steering spindle can be prestressed at least with respect to the housing by means of the bearing device, which cannot be achieved by the fixed-separated support portions common in the prior art. By prestressing the steering spindle, the bending of the steering spindle is reduced, which is mainly caused by the radial force component of the sector gear shaft acting portion. This reduction additionally enables a more uniform load curve of the balls or the ball circulation portion, so that local or point overloads can be more effectively avoided. In addition, the present invention also takes into account the trend of pure electro-mechanical steering systems, since the steering spindle will be subject to increased wear in the future due to the cancellation of the hydraulic steering support device in terms of the component dimensions required for force transmission within the steering gear to meet the product life. In order to ensure the service life expectancy, for pure electro-mechanical applications, it is necessary to increase the spindle diameter and the number of ball circulation portions, which thus causes installation space problems. In this regard, the prestressing of the steering spindle can offset this installation space problem and the increased wear, and thus provide an associated optimization of the steering gear. However, within the scope of the present invention, the steering gear according to the present invention, in addition to the pure electro-mechanical configuration, can also be provided in an electro-hydraulic configuration additionally or alternatively.

[0014] In particular, the adjusted support portion enables prestressing of the spindle.

[0015] In an advantageous configuration, the bearing device, the steering spindle and the housing form the adjusted support portion such that the steering spindle is prestressed. By prestressing, the diameter of the spindle can be reduced. Therefore, the diameter reduction can be achieved by prestressing, which can also reduce the overall size or installation space requirement of the entire assembly including at least the bearing device, the steering spindle and the housing.

[0016] Furthermore, it can be provided that the bearing device has at least one prestressing device by means of which the steering spindle can be prestressed in an axially and / or radially adjustable manner. This prestressing device enables precise and defined adjustment of the prestress of the steering spindle, which is therefore particularly important since the prestress should be maintained within narrow limits. If the prestress is selected too large, this will have an adverse effect on the balls or the ball circulation wear of the steering spindle and the ball circulation nut. If, conversely, the prestress is selected too small, excessive bending will always occur due to the action of the ball circulation nut on the sector gear shaft, which in turn has an adverse effect on the closure of these components.

[0017] Furthermore, it can be envisaged that the bearing device has at least one first bearing unit and at least one second bearing unit. Thus, it is advantageous to divide the bearing device into at least one first and second bearing unit since this enables more precise adjustment of the prestress. Furthermore, by means of a suitable arrangement and configuration of the bearing units, the loads, stresses and wear on the steering spindle and the ball circulation nut can be further optimized.

[0018] Furthermore, it can be considered that in the assembled state, the first bearing unit is arranged in the region of the first end of the steering spindle and the second bearing unit is arranged in the region of the second end of the steering spindle. This arrangement of the two bearing units ensures a particularly rigid configuration of the bearing device in the radial direction. Since the axial support distance can be increased (at least within meaningful limits) as the axial spacing between them increases, and thus the forces, especially the torques, acting on the steering spindle and the ball circulation nut can be effectively counteracted. Furthermore, being arranged in the two end regions of the steering spindle is advantageous with regard to assemblability and accessibility since this is simplified.

[0019] Furthermore, the prestressing device can have at least one first prestressing element which in the assembled state is arranged in the region of the first end of the steering spindle or in the region of the second end of the steering spindle. As a supplement to improving the assemblability of the bearing unit and the prestressing unit by arranging the bearing unit and the prestressing unit in the two end regions, the accessibility and adjustability of the prestressing unit are simplified and can also be more precise. Thus, the prestress of the steering spindle can be adjusted more precisely and targeted, whereby the wear of the ball circulation section, the ball circulation nut and the steering spindle can be further reduced, which achieves a longer service life and improved functional reliability of the steering transmission.

[0020] Furthermore, it can be provided that the prestressing device has at least one second prestressing element which, in the assembled state, is arranged in the region of the second end of the steering spindle, wherein the first prestressing element is arranged in the region of the first end of the steering spindle. By providing two prestressing elements at the two end regions of the steering spindle, unilateral axial and radial prestressing of the steering spindle is prevented. Thus, if the distances of the two bearing units and the prestressing elements from the axial center of the steering spindle are selected to be substantially the same, the prestressing of the steering spindle can be achieved substantially symmetrically. This configuration reduces the stresses and loads occurring in the ball circulation section, the ball circulation nut, and inside the steering spindle, thereby further effectively reducing their wear.

[0021] It is also conceivable that the first bearing unit has at least one first tapered roller bearing and the second bearing unit has at least one second tapered roller bearing. Tapered roller bearings are already known from the prior art as mature and reliable machine elements and are particularly well-suited for the adjusted and prestressed support, since their force-bearing or load-carrying capacity is high in the radial and axial directions and at the same time enables a very simple, precise, and reliable adjustment of the entire support and its prestressing. Furthermore, by arranging two tapered roller bearings, the entire support can be hardened, such that in particular the steering spindle bends even less under load (i.e., in the dynamic interaction with the sector gear shaft), which enables the above-mentioned advantages with regard to wear, reliability, and service life. To increase the rigidity of the entire support and / or the first and / or second bearing units, the first bearing unit can also be configured as multi-row, for example, a two-row, three-row, or four-row tapered roller bearing, and this similarly applies to the second bearing unit. The multi-row tapered roller bearings can be composed of individual tapered roller bearings arranged in rows with each other or of combined one-piece tapered roller bearings.

[0022] Furthermore, it can be considered that the first tapered roller bearing and the second tapered roller bearing form an O-shaped assembly in the assembled state. The O-shaped assembly increases the tilt moment that the support can withstand due to the orientation of the pressure lines (force flow lines) passing through the two tapered roller bearings, and the pressure lines are axially located outside the first and second bearing units or intersect outside the first and second bearing units in the O-shaped assembly. The reason for the increased tilt moment resistance is the increased distance between the pressure centers of the pressure lines, thereby further increasing the rigidity of the support.

[0023] Furthermore, it is possible that, in the assembled state, the first prestressing element is screwed onto the steering spindle in the region of the first end of the steering spindle and is seated on at least one inner ring of the first tapered roller bearing. This configuration simplifies the manufacture of the steering gear, since it is not necessary to introduce an additional thread for receiving the first prestressing element into the bearing receiving bore of the housing. Furthermore, the prestressing element can be configured smaller and thus more favorably, and can furthermore be assembled more simply.

[0024] Additionally, it can be provided that, in the assembled state, the second prestressing element is screwed onto the steering spindle in the region of the second end of the steering spindle and is seated on at least one inner ring of the second tapered roller bearing. This arrangement enables the same advantages as already discussed above in connection with the first prestressing element. Furthermore, since the two prestressing elements act directly on the steering spindle or are screwed onto the steering spindle, the prestressing of the steering spindle can be adjusted particularly precisely, symmetrically and accurately by the combined action of the two prestressing elements on the steering spindle.

[0025] Furthermore, it can be envisaged that, in the assembled and seated state of the first and second prestressing elements, the prestressing of the steering spindle is at least configured as a pre-tensile stress. The advantage of pre-tensile stress is that it firstly cancels out the elastic bending of the steering spindle in the unloaded state, so that on the one hand this bending can be reduced. On the other hand, the sector gear shaft acts at the maximum bending point of the steering spindle, so that the deformation potential energy is always maximum due to this configuration. If the shaft is now pre-tensioned, the elastic bending of the steering spindle in the unloaded state can thus firstly be reduced. Thus, in a first step, the deformation potential energy is reduced, since the elastic deformation in the unloaded state can basically no longer act together with the deformation under load. In this regard, the steering spindle undergoes significantly less deformation even under load, since the elastic deformation part has basically been eliminated by the pre-tensile stress. Thus, by pre-tensile stress in the unloaded and loaded states of the steering gear, the elastic deformation of the steering spindle is reduced, whereby the wear of the ball circulation section and the ball circulation nut is further reduced.

[0026] It can also be considered that the first prestressing element is configured as a slotted nut and the second prestressing element is configured as a slotted nut. A slotted nut is a very robust, proven or mature and anti-loosening machine element, which enables very precise prestressing by means of a correspondingly defined screwing torque. Description of the Drawings

[0027] Other details and advantages of the invention will now be explained in more detail with reference to the embodiment shown in a single drawing.

[0028] The sole drawing ( Figure 1)Shows a schematic cross-sectional view of an embodiment of a steering gear 10 according to the present invention. Detailed Description

[0029] The steering gear 10 is configured as a recirculating ball steering gear 10 for a steering system (not shown) of a commercial vehicle. Figure 1 in the

[0030] The steering gear 10 has a housing 12, a steering spindle 14, and a steering spindle nut 16 that is axially movably guided inside the housing.

[0031] Here, the steering spindle nut 16 is axially movably guided in a circular guide hole 12a of the housing 12.

[0032] The guide hole 12a may particularly have a circular cross-section, and the guide surface of the steering spindle nut 16 may contact the guide hole 12a over the entire circumference or a partial circumference here.

[0033] Furthermore, in the assembled state, the steering spindle nut 16 is coupled to the steering spindle 14 by a plurality of balls or ball recirculation parts 14a.

[0034] Here, the ball recirculation part 14a should be understood as having a plurality of spiral wraps at the balls 14a in the axial direction, as visible in Figure 1 in.

[0035] Therefore, the balls 14a are guided in an axially extending spiral or helical spindle groove 14b of the steering spindle, wherein the spindle groove 14b has a semi-circular cross-section.

[0036] Correspondingly, the balls or ball recirculation parts 14a cooperate with another nut groove 16a, which corresponds to the balls or ball recirculation parts and extends axially, wherein the nut groove 16a also has a semi-circular cross-section.

[0037] According to Figure 1 , the rotational movement of the steering spindle 14 is transmitted to the steering spindle nut 16 by a plurality of balls or ball recirculation parts 14a, thereby causing an axial movement of the steering spindle nut 16 inside the housing 14.

[0038] The steering spindle nut 16 also has a partial tooth part 16b in a partial area of its circumferential surface, which cooperates with a sector gear of a sector gear shaft in the assembled state.

[0039] The steering gear 10 according to Figure 1 also includes a bearing device 18, through which the steering spindle 14 is supported in the housing 12.

[0040] The bearing device 18, the steering spindle 14 and the housing 12 hereby form the adjusted bearing part.

[0041] Furthermore, the bearing device 18 has a prestressing device 20 by means of which the steering spindle 14 can be prestressed in an axially adjustable manner.

[0042] Additionally or alternatively, it can be considered that the steering spindle 14 can be prestressed in a radially adjustable manner by means of the prestressing device 20 accordingly.

[0043] The bearing device 18 also has a first bearing unit 18a and a second bearing unit 18b.

[0044] In the assembled state, the first bearing unit 18a is arranged in the region of the first end 14c of the steering spindle 14.

[0045] Correspondingly, the second bearing unit 18b is arranged in the region of the second end 14d of the steering spindle 14.

[0046] For this purpose, the steering spindle 14 has bearing seats for receiving the first bearing unit 18a and the second bearing unit 18b respectively in the corresponding regions or sections of its first end 14c and second end 14d.

[0047] The first end of the steering spindle 14 is also integrally connected to a steering through - part 14e which can be connected to a steering column ( Figure 1 not shown) and a steering wheel.

[0048] The above - mentioned prestressing device 20 also includes a first prestressing element 20a which is arranged in the region of the first end 14c of the steering spindle 14 in the assembled state.

[0049] Thus, the prestressing device 20 has a second prestressing element 20b which is arranged in the region of the second end 14d of the steering spindle 14 in the assembled state.

[0050] Instead of the first and second prestressing elements 20a, 20b, the prestressing device 20 can have only one prestressing element 20a, 20b which is then arranged in the region of the first or second end 14c, 14d of the steering spindle 14.

[0051] The prestressing of the steering spindle 14 is then achieved by means of corresponding shoulders of the steering spindle 14 ( Figure 1 not shown) which are arranged in the first or second region of the opposite ends 14c, 14d of the steering spindle 14 where no separate prestressing elements 20a, 20b are arranged.

[0052] The first bearing unit 18a is based on Figure 1 a first tapered roller bearing, while the second bearing unit 18b correspondingly has a second tapered roller bearing.

[0053] As Figure 1 shown, the first tapered roller bearing and the second tapered roller bearing form an O-shaped assembly in the assembled state.

[0054] The two tapered roller bearings are configured as single-row tapered roller bearings. It is also conceivable that they can be configured as multi-row tapered roller bearings either individually in a row with each other or integrally.

[0055] In this case, particularly double-row or four-row tapered roller bearings can be considered.

[0056] In the case of multi-row tapered roller bearings, these tapered roller bearings can be respectively configured as X-shaped assemblies, O-shaped assemblies or tandem assemblies.

[0057] As Figure 1 can be further seen, in the assembled state, the first prestressing element 20a is screwed onto the steering spindle 14 in the region of the first end 14c of the steering spindle and is arranged on the inner ring of the first tapered roller bearing.

[0058] Correspondingly, in the assembled state, the second prestressing element 20b is further screwed onto the steering spindle 14 in the region of the second end 14d of the steering spindle and is arranged on the inner ring of the second tapered roller bearing.

[0059] Therefore, the first bearing unit 18a and the second bearing unit 18b are constructed or arranged symmetrically with respect to the axial centerline and have the same components.

[0060] The first and second prestressing elements 20a, 20b are respectively configured as slotted nuts.

[0061] Therefore, since the two slotted nuts are arranged on the two inner rings of the corresponding tapered roller bearings, in the assembled and arranged state of these two prestressing elements, the prestress on the steering spindle 14 is configured as pre-tensile stress.

[0062] In addition, the two slotted nuts are respectively prevented from undesired loosening by safety washers, where the safety washers are not shown in Figure 1 .

[0063] In addition, in the assembled state, the outer ring of the first tapered roller bearing is arranged on the first housing shoulder of the housing 12 or the first housing cover in the region of the first end 14c of the steering spindle 14.

[0064] Thus, in the region of the second end 14d of the steering spindle 14, the outer ring of the second tapered roller bearing is seated on the second housing shoulder of the housing 12 or of the second housing cover.

[0065] As can be further seen in Figure 1 , the steering gear 10 is shown without an auxiliary drive for generating an additional steering assistance torque, such as a hydraulic pump, a hydraulic piston or an electric motor.

[0066] In particular, in such a case it can be provided that an electric motor or a servomotor is flange-connected to the Figure 1 steering gear 10 and is torsionally rigidly coupled to the steering spindle 14 directly via a coupling means or indirectly via a reduction gearing.

[0067] The electric motor can be flange-connected to the housing 12 such that the electric motor is coupled to the steering spindle 14 in the region of the first end 14c or the second end 14d of the steering spindle 14.

[0068] Additionally or alternatively it can be provided that the intermediate space of the circular guide bore 12a of the housing 12 can be pressurized by a hydraulic pump, the intermediate space being configured between the steering spindle nut 16 and the two bearing units 18a, 18b.

[0069] Thus, a hydraulic assisted steering force support can be additionally or alternatively achieved.

[0070] However, the housing lines, the hydraulic pump or the corresponding control valves required therefor for actuating the two intermediate spaces of the circular guide bore 12a of the housing 12 are not shown in Figure 1 .

[0071] The same applies to the adaptation of the steering spindle nut 16 for sealing the two intermediate spaces relative to one another and relative to the bearing units 18a, 18b, such that the steering spindle nut 16 then additionally acts as a hydraulic piston.

[0072] The function of the steering gear 10 according to the invention can now be described as follows:

[0073] Via the steering through-passage 14e in the region of the first end 14c of the steering spindle 14, the rotation spindle is put into rotation according to the steering intention of the vehicle driver, the steering through-passage being torsionally rigidly connectable to the steering wheel via a steering column.

[0074] Since the steering spindle 14 is coupled to the steering spindle nut 16 via the ball circulation section 14a, an axial movement or a translational movement of the steering spindle nut 16 takes place inside the housing 12.

[0075] As in Figure 1It can be further seen that the steering spindle nut 16 cooperates with the sector gear of the sector gear shaft on its side through partial teeth on its circumferential surface.

[0076] In this regard, the axial movement or translational movement of the steering spindle nut 16 is transmitted to the sector gear, which causes the sector gear shaft to rotate.

[0077] The sector gear shaft is torsionally resistant and connected to a steering swing arm ( Figure 1 not shown in the figure), and the steering swing arm pivots through the rotation of the sector gear shaft and transmits this pivoting movement to the steering mechanism, and then the steering mechanism pivots the wheels of the axle corresponding to the driver's expectation.

[0078] Due to the tooth engagement between the steering spindle nut 16 and the sector gear, the steering spindle nut 16 is subjected to a radial force during each translational movement, and this radial force transmits the translational movement to the steering spindle 14 through the ball circulation part 14a.

[0079] However, since the steering spindle 14 according to the present invention is axially prestressed by tensile stress, the steering spindle 14 is subjected to a smaller radial force or radial deformation from the steering spindle nut 16, so that the wear of the steering spindle 14, the ball circulation part 14a and the steering spindle nut 16 can be reduced according to the present invention.

[0080] List of reference numerals

[0081] 10 Recirculating ball steering gear

[0082] 12 Housing

[0083] 12a Guide hole

[0084] 14 Steering spindle

[0085] 14a Ball or ball circulation part

[0086] 14b Spindle groove

[0087] 14c Region of the first end of the steering spindle

[0088] 14d Region of the second end of the steering spindle

[0089] 14e Steering through-hole

[0090] 16 Steering spindle nut

[0091] 16a Nut groove

[0092] 16b Partial teeth

[0093] 18 Bearing device

[0094] 18a First bearing unit

[0095] 18b Second bearing unit

[0096] 20 Prestressing device

[0097] 20a First prestressing element

[0098] 20b Second prestressing element

Claims

1. A recirculating ball steering gear (10) for a steering system of a vehicle, having: at least one housing (12); at least one steering spindle (14); at least one steering spindle nut (16) which is guided axially displaceably inside the housing (12) and which is coupled to the steering spindle (14) by means of a plurality of balls (14a) in the assembled state; and at least one bearing device (18) by means of which the steering spindle (14) is supported in the housing (12); wherein, the bearing device (18) has at least one prestressing device (20) by means of which a prestress is applied to the steering spindle (14) in order to reduce bending of the steering spindle, wherein the prestressing device (20) has at least one first prestressing element (20a) which is arranged in the region of a first end (14c) of the steering spindle (14) in the assembled state, and wherein the prestressing device (20) has at least one second prestressing element (20b) which is arranged in the region of a second end (14d) of the steering spindle (14) in the assembled state.

2. The recirculating ball steering gear (10) according to claim 1, characterized in that, the vehicle is a commercial vehicle.

3. The recirculating ball steering gear (10) according to claim 1 or 2, characterized in that, the bearing device (18) has at least one first bearing unit (18a) and at least one second bearing unit (18b).

4. The recirculating ball steering gear (10) according to claim 3, characterized in that, in the assembled state, the first bearing unit (18a) is arranged in the region of a first end (14c) of the steering spindle (14) and the second bearing unit (18b) is arranged in the region of a second end (14d) of the steering spindle (14).

5. The recirculating ball steering gear (10) according to claim 3, characterized in that, the first bearing unit (18a) has at least one first tapered roller bearing and the second bearing unit (18b) has at least one second tapered roller bearing.

6. The recirculating ball steering gear (10) according to claim 5, characterized in that, the first tapered roller bearing and the second tapered roller bearing form an O-shaped assembly in the assembled state.

7. The recirculating ball steering gear (10) according to claim 5 or claim 6, characterized in that, in the assembled state, the first prestressing element (20a) is screwed onto the steering spindle (14) in the region of the first end (14c) of the steering spindle (14) and is seated on at least one inner ring of the first tapered roller bearing.

8. The recirculating ball steering gear (10) according to claim 5 or 6, characterized in that, In the assembled state, the second prestressing element (20b) is screwed onto the steering spindle (14) in the region of the second end (14d) of the steering spindle (14) and is arranged on at least one inner ring of the second tapered roller bearing.

9. The recirculating ball steering gear (10) according to claim 1 or 2, characterized in that in the assembled and arranged state of the first prestressing element and the second prestressing element (20b), the prestressing of the steering spindle (14) is at least configured as a pre-tensile stress.

10. The recirculating ball steering gear (10) according to claim 1 or 2, characterized in that the first prestressing element (20a) is configured as a slotted nut, and the second prestressing element (20b) is configured as a slotted nut.

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