GB2261288A

GB2261288A - Device for determining the axial internal clearance and preload in rolling bearing assemblies

Info

Publication number: GB2261288A
Application number: GB9221469A
Authority: GB
Inventors: Keith William Woodbridge
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 1991-11-05
Filing date: 1992-10-13
Publication date: 1993-05-12
Anticipated expiration: 2012-10-13
Also published as: GB2261288B; GB9221469D0

Abstract

A device for determining the axial internal clearance and preload in rolling bearing assemblies having first and second components (26, 14) which are rotatable with respect to each other about a common axis comprises first means for applying a predetermined axial load in both directions to the first component (26); and second means for indicating the total axial movement of the first component (26) relative to the second component (14). The device also includes third means for applying an increasing torque to the first component (26), and fourth means for indicating the torque which causes rotation of the first component (26) with respect to the second component (14). The torque is used to determine the preload. The first means includes handles (56) on a slider (48), compression springs (50, 52), a support member (32), a hub connector (36) and a hub sleeve (16). The second means includes a spindle (84) and a linear transducer (86). The third means includes the handles (56), a cover sleeve (46), the support member (32), hub connector (36) and hub sleeve (16). The fourth means includes a tube (64), drive adaptor (80), socket (82), collar (68), arm (72) and a load cell device (74). <IMAGE>

Description

DEVICE FOR DETERMINING THE AXIAL INTERNAL CLEARANCE AND PRELOAD IN ROLLING BEARING ASSEMBLIES This invention concerns a device for determining the axial internal clearance and preload in rolling bearing assemblies having first and second components which are rotatable with respect to each other about a common axis. An example of such a rolling bearing assembly is the wheel hub bearing of a motor car or automobile.

It is emphasised that this device is for measuring the axial clearance and preload after the assembly has been put together. The device is not to be confused with a device or apparatus used in presetting the clearance or preload.

For example, US-A-4,054,999 (HARBOTTLE) discloses a process of mounting taper roller bearings for wheels to achieve a high probability of a mounting having a clearance or preload within desired limits. Also, US-A-4,530,144 (HAGELTHORN) discloses a method of presetting the internal axial clearance on a wheel bearing mounting.

The device the subject of the invention is intended to be used after such wheel bearing mountings have been assembled to measure the actual clearance or preload of the assembly.

The optimum internal axial clearance or preload in a wheel hub bearing is essential for good handling and steering behaviour, particularly at high speeds, and for the correct function of the brakes and for optimum performance of the bearing. Provision of a device which enables the internal axial clearance or preload to be repeatedly and accurately measured will allow the axial clearance or preload to be closely controlled.

According to the invention, the device comprises: means for applying a predetermined axial load in both directions to the first component; means for indicating the total axial movement of the first component with respect to the second component; means for applying an increasing torque to the first component; and means for indicating the torque which causes rotation of the first component with respect to the second component.

A device according to the invention can be used to determine whether a rolling bearing assembly has an internal axial clearance or preload and readings can be taken from the device to determine what that clearance or preload is thus combining in one device two separate functions. By being capable of applying a predetermined axial load, repeatability of measurement is ensured enabling useful comparisons to be made of the same assembly over its life and between different assemblies of the same type. Also, since the axial load can be applied in both directions, it avoids the time consuming procedure of, for example, in an assembly having a clearance, setting the clearance to zero in one direction and applying an axial force in the other direction to measure the clearance.

Since the device includes means for indicating the total axial movement, this avoids the problem of having separate devices for applying the load and for measuring the movement.

If the device has been used on an assembly and no axial clearance found, the same device is used to determine the preload by measuring the torque which causes relative rotation of two components of the assembly. Once this torque has been measured, it is a relatively simple matter of reading the preload from a graph of torque against preload.

Preferably, the device includes support means through which both axial loads and torque are transmittable to the first component. By using one component of the device for two purposes can lead to savings in weight, simplication of design and construction and reduced cost.

Preferably, the axial load applying means includes resilient means through which the axial load is transmitted. Transmitting the axial load through resilient means provides a convenient and relatively simple way of ensuring that the axial load is predetermined and is repeatable.

Preferably, the axial load applying means includes load transmitting means which is axially movable with respect to the support means, the axial load transmission path being through the load transmitting means to the resilient means and through the resilient means to the support means. This feature allows a predetermined axial load to be applied each time by controlling how far the load transmitting means is moved with respect to the support means.

Preferably, the support means comprises an elongate support member, the resilient means comprises two compression springs, and the load transmitting means comprises a slider which extends around the elongate support member and is positioned longitudinally between the two springs for sliding movement along the elongate support member. This provides a relatively simple construction with readily available components, particularly the springs which are available with known spring rates to enable the predetermined axial load to be applied in both directions.

A handle may be secured to the slider, which may be detachable, thus providing a simple means for manually applying the load and also allowing the device to be stored in a compact manner.

Preferably, the springs abut shoulders fixed with respect to the elongate support member and the slider. The shoulders keep the springs from rubbing the elongate support member so allowing them to move axially freely.

The axial movement indicating means may comprise means which is axially movable with respect to the support means and adapted to remain axially stationary with respect to the second component of the assembly, means which is responsive to the relative axial movement of the movable means, and display means which is in communication with the responsive means for displaying an indication of the axial movement according to the response of the responsive means.

The responsive means is acted upon by the relative axial movement between the axially movable means and the support means and communicates the action to the display means. The responsive means may be fixed with respect to the support means and, preferably, the support means has an elongate bore, the axially movable means comprises an elongate element extending along the bore and the responsive means comprises a linear transducer. These features allow for a simple, robust and reliable construction.

Preferably, the torque applying means includes a torque transmitting means which is rotationally fixed with respect to the support means, and the support means may comprise an elongate support member and the torque transmitting means may comprise a sleeve which surrounds the elongate support member and has at least one aperture for engagement by a handle. Engagement of the aperture by the handle allows a manually applied torque to be transmitted through the sleeve and elongate support member to the first component of the assembly.

Preferably, the sleeve surrounds the two compression springs and the slider of the axial load applying means, and the aperture comprises a longitudinally extending slot through which the handle extends, the handle being screwed to the slider. Thus, a construction is provided which allows the handle to be used to apply an axial load and torque, the slot allowing the handle to move axially relative to the sleeve and elongate support member.

The torque indicating means comprises means which is rotatable with respect to the support means, means which is responsive to the applied torque, and display means which is in communication with the responsive means for displaying an indication of the applied torque according to the response of the responsive means. The responsive means may be fixed with respect to the support means and prefereably, the support means has an elongate bore, the rotatable means comprises a rotatable elongate element extending along the bore, and the responsive means comprises a load cell device. These features allow the construction to be simple, robust and reliable.

Preferably, the support means has an elongate bore, the rotatable elongate element of the torque indicating means has a longitudinally extending bore and the axially movable elongate element of the axial movement indicating means extends along the bore of the rotatable elongate element. These features allow the construction to be kept compact and lightweight.

Furthermore, the bore of the rotatable elongate element prevents the axially movable elongate element from wandering to a degree that would otherwise prevent an accurate and repeatable measurement from being obtained.

Preferably, the device includes means for detachably connecting the rotatable elongate element to the second component for rotation therewith, which connecting means may be detachably connectable to the rotatable elongate element and may comprise an adaptor and a socket, the adaptor and rotatable elongate element having complementary screw threaded portions.

Preferably, the device includes means for detachably connecting the support means to the first component so as to be both rotationally and axially fixed with respect to the first component, which connecting means may be detachably connectable to the support means and may include a flange with apertures for receiving bolts, the connecting means and the support means having complementary screw threaded portions.

In a construction in which the device is for determining the internal axial clearance or preload of an automotive wheel hub bearing, the socket would be chosen to fit the nut at the shaft end and the appropriate wheel connecting means chosen with the pitch and spacing of the apertures in the flange matching those of the wheel. This construction enables one device to be used with a number of sockets and wheel connecting means to suit a variety of wheels. The wheel connecting means can be constructed to suit a particular wheel or range of wheels.

In the accompanying drawings: Figure 1 is a longitudinal section of a device for determining the axial internal clearance or preload of a wheel hub bearing; Figure 1A is a scrap view of the outside of the left hand end of the device; Figure 2 is a view of the circled portion II of Figure 1 to an enlarged scale; Figure 3 is a view of the circled portion III of Figure 1 to an enlarged scale; and Figure 4 is a plot of friction torque against preload.

The device 10 is connected to a wheel 12 of a motor car. The parts of the wheel 12 shown are a hub stub shaft 14, a hub sleeve 16 with a flange 18, a double row angular contact ball bearing 20 and a brake drum 22.

The bearing 20 comprises a split or two piece radially inner race ring 24 which is fitted on the shaft 14, and a one piece radially outer race ring 26 which is fitted in the bore of the sleeve 16. The inner ring 24 abuts a shoulder of the shaft 14, and the shaft has a screw threaded nut 28 by means of which the axial internal clearance or preload of the bearing 20 can be adjusted.

The brake drum 22 is secured to the flange 18 of the sleeve 16 by means of screw-threaded bolts 30 which extend with clearance through bores in the drum 22 and engage in screw thread bores in the flange 18.

The device 10 comprises an elongate tubular support member 32 which has an external screw threaded projection 34 at the right hand end. A generally tubular hub connector 36 has a closed left hand end and an annular flange 38 which extends radially outwardly from the open right hand end. The flange 38 has bores through which extend the bolts 30 to detachably connect the connector 36 to the brake drum 22 and the sleeve 16. The connector 36 has a screw threaded bore 40 in its closed left hand end in which is screwed the projection 34 of the support member 32.

The right hand end portion of the support member 32 is stepped, and a stepped end cap 42 is provided at the left hand end portion of the support member. The end cap 42 is prevented from moving leftward by a circlip 44. A cover sleeve 46 surrounds with clearance the central portion of the support member 32 and is press-fitted on the stepped right hand end portion of the support member and on the stepped end cap 42.

An annular slider 48 extends around the support member 32 and inside the sleeve 46 for sliding movement along the support member. First and second compression springs 50 and 52 are positioned inside the sleeve 46 and around the support member 32 with clearance. The first spring 50 abuts shoulders of the stepped end cap 42 and of the slider 48, and the second spring 52 abuts shoulders of the stepped right hand end of the support member 32 and of the slider 48.

The cover sleeve 46 has two diametrically opposed longitudinally extending slots 54 which expose the slider 48 and the springs 50 and 52. Two handles 56 extend through the slots 54 and are screwed into the slider 48.

The extreme left hand end of the support member 32 is screwed threaded. A display unit casing 58 is secured to the support member 32, a wall of the casing being clamped between a nut 60, which is screwed on to the support member, and an abutment ring which is adjacent to the circlip 44 and abuts the end cap 42.

The support member 32 has a longitudinally extending elongate bore 62 which opens at both ends.

A tube 64 is disposed in the bore 62, extends along the bore, and protrudes from both ends.

Plain bearings 66 which are secured at both ends of the bore 62, support the tube 64 for smooth rotational movement with respect to the support member 32.

A collar 68 is secured to the left hand protruding end of the tube 64 by a flat point set screw 70. An arm 72 is fixed to the collar 68 and acts on a load cell device 74 which is fixed to the casing 58. The load cell device 74 is wired to a digital display 76 on the outside of the casing 58 and gives a reading under FRICTION TORQUE. The digital display 78 includes an ON/OFF switch and is powered by a battery 78 secured inside the casing 58.

At the right hand protruding end, the tube 64 has an external screw thread onto which is screwed a drive adaptor 80. Fitted to the adaptor 80 is a nut socket 82 which engages over the wheel hub nut 28 so that the tube 64, adaptor 80, socket 82 and nut 28 all rotate together.

The collar 68 is adjusted along the tube 64 to take up any axial clearance between the adaptor 80 and the collar.

Extending along within the bore of the tube 64 is a spindle 84 which at its right hand end extends through a bore in the adaptor 80 and contacts the free end of the stub shaft 14. The display unit casing 58 has a linear transducer 86 fitted inside and the spindle 84 extends out from the tube 64, through the transucer 86 and out of the casing through a bore 88. Attached to the spindle 84 inside of the casing 58 is a ring 90 and a compression spring 92 is fitted between the transducer 86 and the ring keeping the spindle firmly in contact with the stub shaft 14. The transducer 86 is wired to the digital display 76 and gives a reading under END PLAY which is related to axial movement between the spindle 84 and the transducer 86.

In use of the device 10, the appropriate hub connector 36 and nut socket 82 are selected for the particular wheel and the hub connector is bolted to the brake drum 22. The shaft 14 is likely to have been held between centres for machining so producing an indentation on the shaft axis in which the end of the spindle 84 can locate. Then the complete device 10 and the wheel 12 are rotated to settle the bearing 20. The digital display 76 is switched on and the readings are zeroed. The handles 56 are then grasped and pushed towards the wheel 12 until arrows 94 on the handles are aligned with marks 96 on the sleeve 46 and the reading under END PLAY is noted. Then the handles 56 are pulled back until the arrows 94 are aligned with marks 98 on the sleeve 46 and the reading under END PLAY is again noted. The two readings are used to calculate the axial clearance, if any.

If no axial clearance is found, then the handles 56 are turned applying a torque and the reading under FRICTION TORQUE is noted at the point at which the wheel 12 starts to rotate. This is the break-away torque which is not quite the same as the rotating torque but is close enough as not to make any appreciable difference to the determination of the preload.

Rubbing seals in the bearing 20, not illustrated, have an affect on the torque reading but steps can be taken to take this into account. The friction torque reading taken from the digital display 76 is read in conjunction with the plot of Figure 4 to find the preload, a friction torque reading of A giving a preload of B.

In determining the axial clearance, if any, the load is applied from the handles 56 to the slider 48, from the slider 48 to the spring 50/52, from the spring 50/52 to the support member 32, from the support member 32 to the connector 36, from the connector 36 through the bolts 30 to the flange 18 of the sleeve 16 and then to the outer ring 26 of the bearing 20. The spindle 84 is kept firmly in contact with the shaft 14 by the spring 92, the split inner ring 24 of the bearing 20 being mounted on the shaft. Any axial clearance will lead to axial movement of the spindle 84 relative to the support member 32 and then the transducer 86. The construction of the device ensures that the force is applied on a centre line with no rocking to either side.

In determining the preload, if any, the torque is applied through the handles 56 to the sleeve 46, from the sleeve 46 to the support member 32, from the support member 32 to the connector 36, from the connector 36 through the bolts 30 to the flange 18 of the sleeve -16 and thus to the outer ring 26 of the bearing 20. The tube 64 is prevented from rotating relative to the shaft 14 by means of the adaptor 80 and the socket 82 engaging the nut 28. An increasing torque means that the load cell device 74 is under increasing pressure from the arm 72 which is connected to the collar 68. This is shown in an increasing reading of friction torque on the digital display 76 until the break-away toque is reached.

The particular load cell illustrated is only effective for one direction of rotation. However, a load cell is available which can be secured to the end of the arm so allowing the torque to be determined for either direction of rotation.

The device can be used for rolling bearing assemblies other than those of motor vehicle wheel bearings, for example, gear box bearings. For the illustrated and described example, the stub shaft 14 is assumed to be secured to the motor vehicle so that the shaft does not move when the axial loads are applied to the outer ring 26 and does not turn when torque is applied to be the outer ring of the bearing 20. Similar conditions will have to apply for other rolling bearing assemblies.

Claims

CLAIMS:

1. A device for determining the axial internal clearance and preload in rolling bearing assemblies having first and second components (26,14) which are rotatable with respect to each other about a common axis, the device comprising: means (56,48,50,52,32,36,16) for applying a pre-determined axial load in both directions to the first component (26); means (84,86) for indicating the total axial movement of the first component (26) with respect to the second component (14); means (56,46,32,36,16) for applying an increasing torque to the first component (26), and means (64,80,82,68,72,74) for indicating the torque which causes rotation of the first component (26) with respect to the second component (14).

2. A device as claimed in claim 1 and including support means (32) through which both axial loads and torque are transmittable to the first component (26).

3. A device as claimed in claim 1 or claim 2, wherein the axial load applying means includes resilient means (50,52) through which the axial load is transmitted.

4. A device as claimed in claim 2 and 3, wherein the axial load applying means includes load transmitting means (48) which is axially movable with respect to the support means (32), the axial load transmission path being through the load transmitting means (48) to the resilient means (50,52) and through the resilient means to the support means (32).

5. A device as claimed in claim 4, wherein the support means comprises an elongate support member (32), the resilient means comprises two compression springs (50,52), and the load transmitting means comprises a slider (48) which extends around the elongate support member (32) and is positioned longitudinally between the two springs for sliding movement along the elongate support member.

6. A device as claimed in claim 5, wherein a handle (56) is secured to the slider (48).

7. A device as claimed in claim 6, wherein the handle (56) is detachably secured to the slider (48).

8. A device as claimed in claim 5, 6 or 7, wherein the springs (50,52) abut shoulders fixed with respect to the elongate support member (32) and the slider (48).

9. A device as claimed in claim 2, wherein the axial movement indicating means comprises means (84) which is axially movable with respect to the support means (32) and adapted to remain axially stationary with respect to the second component (14) of the assembly, means (86) which is responsive to the relative axial movement of the movable means (84), and display means (76) which is in communication with the responsive means (86) for displaying an indication of the axial movement according to the response of the responsive means.

10. A device as claimed in claim 9, wherein the responsive means (86) is fixed with respect to the support means (32).

11. A device as claimed in claim 9 or 10, wherein the support means (32) has an elongate bore (62), the axially movable means comprises an elongate element (84) extending along the bore and the responsive means comprises a linear transducer (86).

12. A device as claimed in claim 2, wherein the torque applying means includes a torque transmitting means (46) which is rotationally fixed with respect to the support means (32).

13. A device as claimed in claim 12, wherein the support means comprises an elongate support member (32) and the torque transmitting means comprises a sleeve (46) which surrounds the elongate support member and has at least one aperture (54) for engagement by a handle (56).

14. A device as claimed in Claims 6 and 13, wherein the sleeve (46) surrounds the two compression springs (50,52) and the slider (48) and the aperture comprises a longitudinally extending slot (54) through which the handle extends.

15. A device as claimed in claim 2, wherein the torque indicating means comprises means (64) which is rotatable with respect to the support means (32), means (74) which is responsive to the applied torque, and display means (76) which is in communication with the responsive means for displaying an indication of the applied torque according to the response of the responsive means.

16. A device as claimed in claim 15, wherein the responsive means (74) is fixed with respect to the support means (32).

17. A device as claimed in claim 15 or 16, wherein the support means (32) has an elongate bore (62), the rotatable means comprises a rotatable elongate element (64) extending along the bore, and the responsive means comprises a load cell device (74).

18. A device as claimed in Claims 11 and 17, wherein the rotatable elongate element (64) of the torque indicating means has a longitudinally extending bore and the axially movable elongate element (84) of the axial movement indicating means extends along the bore of the rotatable elongate element (64).

19. A device as claimed in claim 17 or 18, and including means (80,82) for detachably connecting the rotatable elongate element (64) to the second component (14) for rotation therewith.

20. A device as claimed in claim 19, wherein the connecting means (80,82) is detachably connectable to the rotatable elongate element (64).

21. A device as claimed in claim 19 or 20, wherein the connecting means comprises an adaptor (80) and a socket (82).

22. A device as claimed in claim 21, wherein the adaptor (80) and rotatable elongate element (64) have complementary screw- threaded portions.

23. A device as claimed in claim 2 and including means (36) for detachably connecting the support means (32) so as to be both rotationally and axially fixed with respect to the first component.

24. A device as claimed in claim 23, wherein the connecting means (36) is detachably connectable to the support means (32).

25. A device as claimed in claim 23 or 24, wherein the connecting means (36) includes a flange (38) with apertures for receiving bolts (30).

26. A device as claimed in claim 24, wherein the connecting means (36) and the support means (32) have complementary screw-threaded portions (34).

27. A device for determining the axial internalclearance and preload in rolling bearing assemblies substantially as herein described with reference to and as shown in the accompanying drawings.