CONNECTION ARRANGEMENT FOR AXIALLY SECURING A SHAFT-HUB CONNECTION, AND METHOD FOR AXIALLY SECURING A SHAFT-HUB CONNECTION

Abstract

A connection arrangement for axially securing a shaft-hub connection includes a shaft and a hub with an inner stop surface for the shaft and an outer groove for axially positioning a securing device. The securing device has an axially extending sleeve-shaped part and a radial collar. The sleeve-shaped part at least partly surrounds the circumference of the hub, and the radial collar at least partly engages behind the annular end surface of the hub. The inner stop surface for the shaft in the housing is formed by a recess. The securing device includes a radially deformable holding socket, the axially extending sleeve-shaped part of which is surrounded by a tensioning strap. The holding socket region which is offset radially inwards surrounds the expanded outer groove of the hub coaxially in the assembled state of the shaft-hub connection and can be locked in the expanded outer groove of the hub by the tensioning strap, the radial collar of the holding socket resting against the axial securing ring of the shaft in the locked state.

Claims

1: Connection arrangement for axially securing a shaft/hub connection, comprising a shaft (1) having an outer splined cog (3) and a groove (4) for accommodating an axial securing ring (13), as well as a hub (5) having an inner splined cog (10), an inner stop surface for the shaft (1), and an outer groove (6) for axially positioning a securing means, wherein the securing means has an axially extending sleeve-shaped part and a radial collar, wherein the sleeve-shaped part surrounds the circumference of the hub (5), at least in part, and the radial collar engages behind the annular face surface of the hub (5), at least in part, wherein the inner stop surface (8) for the shaft (1) is formed in the hub (5) by a recess (7) that proceeds from the face side of the hub (5), the axial depth of which recess (7) maximally corresponds to the axial thickness of the axial securing ring (13), that wherein the securing means comprises a radially deformable holding socket (14), the axially extending sleeve-shaped part (15) of which is offset radially inward from the outside diameter of the holding socket (14), at least in part, and surrounded by a tensioning band (19) in this region (18), wherein the width of the outer groove (6) of the hub (5) corresponds at least to the length of the axially extending sleeve-shaped part (15) of the holding socket (14), wherein the region (18) of the holding socket (14) that is radially offset inward coaxially surrounds the widened outer groove (6) of the hub (5) in the assembled state of the shaft/hub connection, in other words when the shaft (1) is provided with the axial securing ring (13) and pushed into the hub (5), and can be locked in place in the widened outer groove (6) of the hub (5) by means of the tensioning band (19), wherein the radial collar (16) of the holding socket (14) lies against the axial securing ring (13) of the shaft (1) in the locked state.

2: Connection arrangement according to claim 1, wherein the holding socket (14) is divided in the axial direction on its circumference.

3: Connection arrangement according to claim 2, wherein the ends of the holding socket (14) that lie opposite one another at the division are at a distance from one another and form a gap (20) between them.

4: Connection arrangement according to claim 3, wherein the radial collar (16) that surrounds the face surface of the hub (5) has an additional gap (21) on its circumference region that lies opposite the gap (20).

5: Connection arrangement according to claim 1, wherein the inside diameter of the region (18) of the holding socket (14) that is radially offset inward and surrounded by the tensioning band (19) approximately corresponds to the outside diameter of the hub (5).

6: Connection arrangement according to claim 1, wherein the inside diameter of the region (18) of the holding socket (14) that is radially offset inward and surrounded by the tensioning band (19) is slightly less than the outside diameter of the hub (5).

7: Connection arrangement according to claim 1, wherein the inside diameter of the region (18) of the holding socket (14) that is radially offset inward and surrounded by the tensioning band (19) approximately corresponds to the widened outer groove (6) of the hub (5).

8: Connection arrangement according to claim 1, wherein the radial collar (16) of the holding socket (14) comprises multiple elastic elements.

9: Securing means according to claim 1, wherein the circumference region (18) of the holding socket (14) that is radially offset inward comprises individual segments (22).

10: Securing means according to claim 1, wherein the circumference region (18) of the holding socket (14) that is radially offset inward is configured as a U profile in cross-section.

11: Securing means according to claim 1, wherein the holding socket (14) comprises an elastic material.

12: Method for axially securing a shaft/hub connection, comprising a shaft (1) having an outer splined cog (3) and a groove (4) for accommodating an axial securing ring (13), as well as a hub (5) having an inner splined cog (10), an inner stop surface for the shaft (1), and a groove for axially positioning a securing means that has an axially extending sleeve-shaped part and a radial collar, wherein shaft (1) and hub (5) are brought into engagement with their splined cogs (3, 10) to produce the connection, and secured in their axial position, relative to one another, by pushing the securing means onto the hub (5), which means engages into the outer groove of the hub (5) during this process, wherein the sleeve-shaped part of the securing means surrounds the circumference of the hub (5), at least in part, and the radial collar engages behind the annular face surface of the hub (5), at least in part, wherein a hub (5) having an outer groove (6), the width of which corresponds at least to the length of the axially extending sleeve-shaped part (15.1; 15.3) of the securing means, and having an annular recess (7) for accommodating the axial securing ring (13), the depth of which recess maximally corresponds to the axial thickness of the axial securing ring (13), proceeding from the face side of the hub (5), is used, a holding socket (14.1; 14.3) divided in the axial direction, having a tensioning band (19) that surrounds the axially extending sleeve-shaped-part (15.1; 15.3) of the socket, is used as a securing means; wherein first, the holding socket (14.1; 14.3) is pushed onto the said hub (5) until it makes contact with the face surface of the hub (5) with its radial collar (16.1; 16.3), and the sleeve-shaped part (15.1; 15.3) comes to lie above the said widened outer groove (6) of the hub (5), wherein subsequently, the shaft (1), with the axial securing ring (13) set into it, is inserted into the hub (5), or, vice versa, the hub (5) is pushed onto the shaft (1) until the axial securing ring (13) makes contact with the stop surface (8) of the recess (7) of the hub (5), and wherein finally, the tensioning band (19) is tightened, thereby pressing the sleeve-shaped part (15.1; 15.3) of the holding socket (14.1; 14.3) into the widened outer groove (6) of the hub (5), and bringing the radial collar (16.1; 16.3) of the holding socket (14.1; 14.3) to lie against the axial securing ring (13) of the shaft (1).

13: Method for axially securing a shaft/hub connection, comprising a shaft (1) having an outer splined cog (3) and a groove (4) for accommodating an axial securing ring (13), as well as a hub (5) having an inner splined cog (10), an inner stop surface for the shaft (1), and a groove for axially positioning a securing means that has an axially extending sleeve-shaped part and a radial collar, wherein shaft (1) and hub (5) are brought into engagement with their splined cogs (3, 10) to produce the connection, and secured in their axial position, relative to one another, by pushing the securing means onto the hub (5), which means engages into the outer groove of the hub (5) during this process, wherein the sleeve-shaped part of the securing means surrounds the circumference of the hub (5), at least in part, and the radial collar engages behind the annular face surface of the hub (5), at least in part, wherein a hub (5) having an outer groove (6), the width of which corresponds at least to the length of the axially extending sleeve-shaped part (15.2) of the securing means, and having an annular recess (7) for accommodating the axial securing ring (13), the depth of which recess maximally corresponds to the axial thickness of the axial securing ring (13), proceeding from the face side of the hub (5), is used, wherein a holding socket (14.2) having an axially extending sleeve-shaped part (15.2) and a radial collar (16.2), together with a tensioning band (19) that surrounds the collar, is used as a securing means, wherein the inside diameter of the radial collar (16.2) is less than the outside diameter of the axial securing ring (13), wherein first, the shaft (1) is pre-assembled with the holding socket (14.2) and the axial securing ring (13), wherein the holding socket (14.2), seen in the direction of the hub (5), engages behind the axial securing ring (13), at least in part, which ring is inserted into the groove (4) of the shaft (1), wherein subsequently, the pre-assembled shaft (1) is inserted into the hub (5), or, vice versa, the hub (5) is pushed onto the pre-assembled shaft (1) until the axial securing ring (13) makes contact with the stop surface (8) of the recess (7) of the hub (5), and the sleeve-shaped part (15.2) of the holding socket (14.2) comes to lie above the widened outer groove (6) of the hub (5), and wherein finally, the tensioning band (19) is tightened, thereby pressing the sleeve-shaped part (15.2) of the holding socket (14.2) into the widened outer groove (6) of the hub (5).

14: Method according to claim 12, wherein a holding socket (14.1; 14.2; 14.3) is used.

Description

DRAWING

[0031] Preferred exemplary embodiments of the object according to the invention are shown in the drawing and will be explained in greater detail below. The figures show:

[0032] FIG. 1 the principle of the axial securing device, according to the invention, of a shaft/hub connection,

[0033] FIG. 2 an enlarged detail of the axial securing device,

[0034] FIG. 3 the holding socket pre-assembled on a hub,

[0035] FIG. 4 the holding socket locked in place in the outer groove of the hub, by means of a tensioning band,

[0036] FIG. 5 a divided holding socket,

[0037] FIG. 6 the holding socket from FIG. 5 in the assembled position relative to a shaft and the inner ring of a joint,

[0038] FIG. 7 a second embodiment of a holding socket,

[0039] FIG. 8 the holding socket from FIG. 6 in the assembled position relative to a shaft and the inner ring of a joint,

[0040] FIG. 9 a third embodiment of a holding socket,

[0041] FIG. 10 the holding socket from FIG. 9 in the assembled position relative to a shaft and the inner ring of a joint,

[0042] FIG. 11a a shaft pre-assembled with an undivided holding socket from FIG. 7,

[0043] FIG. 11b the pre-assembled shaft from FIG. 11a introduced into a hub, and

[0044] FIG. 11c the finished, assembled shaft/hub connection.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

[0045] FIG. 1 shows the principle of a connection arrangement according to the invention for axially securing a shaft/hub connection, in the assembled state, and FIG. 2 shows an enlarged representation of a detail of this connection arrangement. It consists of a shaft 1, which has a shaft journal 2 having an outer splined cog 3 at its one end and is provided with a groove 4 at a short axial distance from this journal, and a hub 5, which is configured, in the present case, as an inner ring of a joint. On its outer circumference, the hub 5 has a widened outer groove 6, and on its face side, facing the shaft 1, it has a recess 7 having a greater diameter than its inside diameter, so that an axial stop surface 8 forms at a short axial distance behind its face surface. Axially following this recess 7, the inside diameter of the hub 5 corresponds to the outside diameter of the shaft 1, wherein both diameters form a fit with one another in this region, which fit allows the shaft 1 to be pushed into the hub 5. In this fit region, the hub 5 furthermore has an inner sealing groove 9. The part of the hub 5 that follows the fit region is provided with an inner splined cog 10 that is complementary to the outer splined cog 3 of the shaft journal 2. For a seal between shaft 1 and hub 5, a sealing ring 11 is laid into the inner sealing groove 9 of the hub 5. However, as can be seen in FIGS. 3 and 4, the seal can also be produced by means of positioning the sealing ring 11 in an outer sealing groove 12 of the shaft 1, which groove is deeper in comparison with the groove 4 mentioned above, so that the sealing ring 11 lies against the inner fit surface of the hub 5. In contrast to the hub 5 shown in FIGS. 1 and 2, in these two figures the stop surface 8 is structured conically. For the sake of a better overview, the details of the shaft/hub connection shown in FIGS. 2 to 4 are merely shown with their upper half.

[0046] The depth of the groove 4 of the shaft 1 is selected in such a manner that an axial securing ring 13 is partially accommodated by this groove 4. In the present example, the greater part of its radial thickness still projects out of the groove 4. The inside diameter of the recess 7 of the hub 5 is equal to or somewhat greater than the outside diameter of this axial securing ring 13 set onto the shaft 1. In the joined state, in other words when the outer and inner splined cogs 3, 10 of shaft 1 and hub 5 are in engagement with one another, the axial securing ring 13 lies against the stop surface 8 of the hub 5 with its ring surface that projects out of the groove 4 of the shaft 1, and projects, at least with part of its opposite side, at least all the way to the face surface of the hub 5, but even better, slightly beyond it. In this way, either the axial thickness of the axial securing ring 13 determines the axial position of the stop surface 8, i.e. the depth of the recess 7 of the hub 5, or the dimensions of the axial securing ring 13 must be selected according to the inside diameter and the depth of the recess 7, in such a manner that when the ring makes contact with the stop surface 8, it still projects beyond the face surface of the hub or ends precisely with it, at least with parts of its circumference.

[0047] In addition to the axial securing ring 13, the connection arrangement according to the invention is also secured with a holding socket 14, which has a sleeve-shaped part 15 in a coaxial expanse toward the hub 5, and a radial collar 16 on its face side facing the shaft 1, which collet, in the assembled state, projects beyond the ring surface of the face surface of the hub 5 that faces the shaft. The sleeve-shaped part 15 is guided coaxially relative to the outer surface of the hub 5, and is offset radially inward directly after projecting beyond the short diameter region of the hub 5 that is situated between face surface and widened outer groove 6, and projects beyond the widened outer groove 6 of the hub 5 with this region, which is reduced in diameter. In the present example, the free end of this sleeve-shaped part 15, which is reduced in diameter, is angled away radially outward toward a collar 17, so that this region that is reduced in diameter, provided with the reference number 18 in FIGS. 1 to 11, is configured in U shape in longitudinal-section, thereby causing the holding socket 14 to have greater radial rigidity. It is advantageous if the holding socket 14 consists of an elastic material, in order to be able to exert an axial counter-force on the axial securing ring 13 during assembly-related deformation, as will still be explained in greater detail below, in the description of the different assembly methods.

[0048] Furthermore, a tensioning band 19 can be seen in FIGS. 1 to 4, which band is structured as an Oetiker clamp in the present example and laid around the sleeve-shaped part 15 of the holding socket 14. Its width must therefore be smaller than or equal to the width of the region 18 of the sleeve-shaped part 15, which region is offset radially inward. In FIGS. 1, 2, and 4, the tensioning band 19 is shown in the tightened state, while in the state shown in FIG. 3, the tensioning band 19 is merely laid loosely around the holding socket 14, which has been pushed onto the hub 5.

[0049] A significant characteristic of the holding socket 14 is furthermore the radial width of its radial collar 16, which can also be seen in FIGS. 1 to 4. This width is selected in such a manner that the radial collar 16 at least lies axially against the axial securing ring 13 of the shaft 1 when the tensioning band 19 is tightened, but in a more advantageous case actually exerts an axial force F on the ring because of the elasticity of the holding socket 14, as can be seen in FIG. 4.

[0050] FIGS. 5, 7, and 9 show different embodiments of the holding socket 14, and FIGS. 6, 8, and 10 show a related assembly arrangement of the respective embodiment. A fundamental difference exists in the embodiments shown, in that the holding sockets 14 can be structured to be axially divided or undivided. To distinguish the different embodiments, the reference numbers previously used for the holding socket 14 and its components were designated with an additional numbering that is separated by a dot behind the previously used reference number, which numbering indicates the respective embodiment.

[0051] Holding sockets 14.1 and 14.3 that are structured to be axially divided are shown in FIGS. 5, 6, and 9, 10, while FIGS. 7 and 8 show a holding socket 14.2 that is structured to be undivided. The two free ends of the holding sockets 14.1 and 14.3 that resulted from the axial division are at a distance from one another, separated by a gap 20. A significant difference also consists in the assembly of the two embodiments of the holding socket 14. In a holding socket 14.1 and 14.3 that is structured to be divided, the two free ends move toward one another when the tensioning band 19 is tightened, so that the inside diameter of their radial collar 16.1; 16.3 is reduced. The movement direction performed by the radial collar 16.1; 16.3 in this regard is indicated in FIG. 3, by means of an arrow that points in the direction of the shaft 1. In contrast, the inside diameter of the radial collar 16.2 does not change, in the case of a holding socket 14.2 that is structured to be undivided, when the tensioning band 19 is tightened, but rather the radially offset region 18.2 of the sleeve-shaped part 15.2 of the holding socket 14.2 merely lies against the groove base of the widened outer groove 6 of the hub 5. This difference in the method of functioning of the holding sockets 14 will be discussed in greater detail below, in the description of the different assembly methods.

[0052] As has already been explained, FIG. 5 shows a divided holding socket 14.1 having a sleeve-shaped part 15.1 and a radial collar 16.1, which is also divided in its region that lies diametrically opposite the gap 20, so that an additional gap 21 is present here. Likewise, the collar 17.1 is divided by the additional gap 21 in the same circumference region. In this way, the holding socket 14.1 can be more easily compressed when the tensioning band 19 is tightened. FIG. 6 shows the assembly arrangement of shaft 1 and hub 5 when using the divided holding socket 14.1. In this embodiment, the sealing ring 11 is inserted into the inner sealing groove 9 of the hub 5. The shaft 1 merely has the groove 4 for accommodating the axial securing ring 13.

[0053] FIGS. 7 and 8 show an undivided holding socket 14.2, the sleeve-shaped part 15.2 of which consists of individual segments 22. Because its radial collar 16.2 does not deform when the tensioning band 19 is tightened, its inside diameter is designed to be smaller than the outside diameter of the axial securing ring 13 set into the groove 4 of the shaft 1. When the tensioning band 19 is tightened, the segments 22 are merely fixed in place on the groove base of the widened outer groove 6 of the hub 5. In this way, such an undivided holding socket 14.2 can be pushed onto the hub 5 only together with the axial securing ring 13 assembled on the shaft 1, wherein the segments 22 at first widen and, when the axial securing ring 13 makes contact with the stop surface 8, engage into the widened outer groove 6 of the hub 5. In this embodiment, too, the sealing ring 11 is inserted into the inner sealing groove 9 of the hub 5.

[0054] The holding socket 14.3 used in the embodiment of FIGS. 9 and 10 is once again structured to be divided. Its sleeve-shaped part 15.3 consists, as in the previous embodiment described, of individual segments 22. The sealing ring 11 is also inserted into the inner sealing groove 9 of the hub 5 in this embodiment. If the holding socket 14.3 in this embodiment consists of an elastic material, and if the region 18.3 of its sleeve-shaped part 15.3 that is radially offset inward is adapted to the dimensions of the widened outer groove 6 of the hub 5, i.e. the inside diameter of the offset region 18.3 is equal to or less than the outside diameter of the widened outer groove 6 of the groove 5 in the groove base, this holding socket 14.3 can easily be pushed onto the hub 5, wherein its segments spread apart and engage into the widened outer groove 6 when they cover it coaxially. Nevertheless, the holding socket 14.3 still has to be secured with the tensioning band 19 to prevent radial widening, which particularly occurs when axial forces act on the shaft 1 and/or hub 5.

[0055] However, the different embodiments of the holding socket 14 bring with them a different sequence of assembly of the shaft/hub connection, as will be explained in greater detail below, in the method descriptions.

[0056] Axially divided holding sockets 14.1; 14.3, as they are shown in FIGS. 5, 6, and 9, 10, can be radially deformed also in the region of their radial collar 16.1 or 16.3, respectively. For this reason they can be set onto the hub 5 and, after being connected with the shaft 1 that was completed with the axial securing ring 13, can be pressed into or secured in the widened outer groove 6 of the hub 5, by means of the tensioning band 19. This method of procedure is shown in FIGS. 3 and 4, wherein the parts relevant to the invention are identified only with their main reference number, for the sake of a better overview. In FIG. 3, the holding socket 14 is shown in its starting form, wherein its inside diameter in the region of its sleeve-shaped part 15 is greater than the outside diameter of the hub 5. The tensioning band 19 has already been laid around its radially offset region 18 but not yet tightened. The radial collar 16 merely projects the annular face surface of the hub 5 while its recess 7 is still free, so that the shaft 1 previously completed with the sealing ring 11 and the axial securing ring 13 can be pushed into the hub 5 without using a tool, until the axial securing ring 13 comes to lie against the stop surface 8 of the hub 5. Afterward, the tensioning band 19 is tightened, thereby causing the radially offset region 18 of the axially divided holding socket 14 to lie against the groove base of the widened outer groove 6 of the hub 5, and, at the same time, causing the radial collar 16 to narrow coaxially to the shaft 1, so that it engages behind the annular region of the axial securing ring 13 that projects out of the groove 4 of the shaft 1. In the embodiment of FIG. 4, it is clearly evident that the axial securing ring 13 projects slightly beyond the face surface of the hub 5, so that the radial collar 16 is deflected slightly from its original right-angle position relative to the axis of the shaft 1. If the holding socket 14 consists of an elastic material, its radial collar 16 exerts an axial force F on the axial securing ring 13 and presses the ring against the stop surface 8, so that the shaft/hub connection is axially free of play.

[0057] Assembly of the shaft/hub connection as described above is also possible with a divided holding socket 14.1 and 14.3, in which the inside diameter of the radially offset region 18.1; 18.3 is less than the outside diameter of the hub 5, but greater than the diameter of its widened outer groove 6. Such a holding socket 14.1 and 14.3 can still be easily pushed onto the hub 5, and furthermore has the advantage that after it is pushed on, it engages into the widened outer groove 6 of the hub 5 and can thereby be captively pre-assembled onto it. In the case that the radial collar 16.1; 16.3 partly covers the recess 8, an axial securing ring 13 that is mounted on the shaft 1 and is round in cross-section is able to slightly widen the holding socket 14.1 and 14.3 for a short time, without significant expenditure of force, when shaft 1 and hub 5 are brought together. During the subsequent tightening of the tensioning strap 19, the radially offset region 18.1; 18.3 then lies against the groove base of the widened outer groove 6 of the hub 5, as described above, so that in this regard, it engages behind the region of the axial securing ring 13 that projects out of the groove 4, with the effect described above, of exerting an axial force F on the ring.

[0058] Disassembly of the shaft/hub connection takes place by loosening the tensioning band 19, manually widening the divided holding socket 14.1; 14.3, and pulling shaft 1 and hub 5 apart from one another. Depending on the strength of the divided holding socket 14.1; 14.3, manual widening can also be eliminated, specifically if the radial forces that act on the divided holding socket 14.1; 14.3 widen it by themselves when shaft 1 and hub 5 are pulled apart, after the tensioning band 19 has been released.

[0059] An axially undivided holding socket 14.2 is shown in FIGS. 7 and 8. Because it is not radially deformable or insufficiently deformable in the region of its radial collar 16.2 when the tensioning band 19 is tightened, the inside diameter of its radial collar 16.2 is designed, right from the start, so that it covers the annular region of the axial securing ring 13 that projects out of the groove 4 of the shaft 1, at least in part. For this reason, the holding socket 14.2 must be pre-assembled on the shaft 1, together with the axial securing ring 13. This pre-assembly is shown in FIG. 11a, wherein the tensioning band 19 is already laid around its radially offset region 18.2. FIG. 11b shows the intermediate step, in which the shaft 1 is pushed into the hub 5 until the axial securing ring 13 makes contact with the conical stop surface 8 of the hub 5. The holding socket 14.2, with the tensioning band 19 loosely laid around it, is still in front of the hub 5. FIG. 11c shows the completion of assembly of the shaft/hub connection, after the holding socket 14.2 has been pushed onto the hub 5 and pressed into the widened groove 6 of the hub 5 with its radially offset region 18.2, when the tensioning band 19 is tightened. Of course, the tensioning band 19 can also be laid around the holding socket 14.2 and tightened only during this last work step. In order to facilitate pushing on the holding socket 14.2, which has been pre-assembled on the shaft 1, while or after shaft 1 and hub 5 have been inserted into one another, and to facilitate pressing the radially offset region 18.2 into the widened groove 6 of the hub 5 while the tensioning band 19 is being tightened, its sleeve-shaped part 15.2 consists of individual segments 22, as has already been described above. The segments 22 spread apart slightly when being pushed onto the hub, and spring into the widened outer groove 6 of the hub 5 when they cover it, if the holding socket 14.2 consists of an elastic material. Finally, the tensioning band 19 is tightened, thereby securing the holding socket 14.2 to prevent it from widening.

[0060] In the case of a holding socket 14.2 that consists of a non-elastic material, the permanently spread segments 22 are pressed into the widened outer groove 6 of the hub 5 by tightening the tensioning band 19.

[0061] Disassembly of the shaft/hub connection having an undivided holding socket 14.2 takes place in the same manner as was described above for those having a divided holding socket 14.1; 14.3.

REFERENCE SYMBOL LIST

[0062] 1 shaft [0063] 2 shaft journal [0064] 3 outer splined cog [0065] 4 groove [0066] 5 hub [0067] 6 widened outer groove [0068] 7 recess [0069] 8 stop surface [0070] 9 inner sealing groove [0071] 10 inner splined cog [0072] 11 sealing ring [0073] 12 outer sealing groove [0074] 13 axial securing ring [0075] 14 holding socket [0076] 15 sleeve-shaped part [0077] 16 radial collar [0078] 17 collar [0079] 18 radially offset region [0080] 19 tensioning band [0081] 20 gap [0082] 21 additional gap [0083] 22 segments [0084] F axial force