AN ICE SKATE WITH EXCHANGEABLE BLADE

Abstract

An ice skate for skating on ice, which comprises; an upper chassis section comprising a first contact surface having a front end and a rear end, a lower chassis section comprising a second contact surface having a front end and a rear end, and a coupling arrangement comprising a spring back means, which coupling arrangement is arranged to mechanically connect the upper and lower chassis sections.

Claims

1. An ice skate for skating on ice, which comprises; an upper chassis section comprising a first contact surface having a front end and a rear end a lower chassis section comprising a second contact surface having a front end and a rear end, and a coupling arrangement comprising a spring back means which coupling arrangement is arranged to mechanically connect the upper and lower chassis sections, wherein at least one of the first and second contact surfaces is curved; wherein the coupling arrangement is arranged to allow the upper chassis section to pivot relative to the lower chassis section by rolling contact motion between the first and second contact surface such that a momentary contact region (CR) of the first and second contact surfaces moves back and forth between the front and rear ends of the first and second contact surface, wherein the spring back means is arranged to apply an urging force between the upper and lower chassis sections for urging the momentary contact region (CR) to a neutral position along the first and second contact surfaces, and wherein the coupling arrangement comprises a release means arranged to be selectively set to a locking position for applying the urging force between the upper and lower chassis sections and a release position for relieving the urging force and allowing the lower chassis section to be removed from the upper chassis section .

2. An ice skate according to claim 1, wherein the release means comprises the spring back means .

3. An ice skate according to claim 2, wherein the spring back means is fixed to the upper chassis section and arranged to be selectively set to be engaged with the lower chassis section for urging the momentary contact region (CR) to the neutral position and to be disengaged from the lower chassis section, for allowing the lower chassis section to be removed from the upper chassis section.

4. An ice skate according to claim 3, wherein the spring back means comprises a first engagement surface and the lower chassis section comprises an upwardly protruding engagement member with a second engagement surface and wherein the first and second engagement surfaces are engaged when the spring back means is set to be engaged with the lower chassis section.

5. An ice skate according to claim 4, wherein the spring back means is arranged in a front cavity of the upper chassis section and wherein the engagement member is receivable in the front cavity.

6. An ice skate according to claim 2, wherein the spring back means is pivotal between an engagement position for engaging the lower chassis section and a disengagement position for being disengaged from the lower chassis section.

7. An ice skate according to claim 1, wherein the release means comprises a tool receiving means arranged to receive a tool for conversion of the release means between the locking position and the release position.

8. An ice skate according to claim 1, wherein the first and/or second contact surface is arranged on an exchangeable insert which is removably fixed to the upper chassis section.

9. An ice skate according to claim 8, further comprising an insert retention means arranged to releasably retain the insert to the upper chassis section when the lower chassis section has been removed.

10. An ice skate according to claim 1, wherein the spring back means comprises a first link arm which is pivotally connected to the upper chassis section, a second link arm which is pivotally connected to the first pivot arm and a spring arranged to urge respective free ends of the first and second pivot arm towards each other.

11. An ice skate according to claim 1, wherein the curvature of at least a portion of the first and/or second contact surface exhibits a radius of > 1 meters .

12. An ice skate according to claim 1, wherein the curvature and the length of the first and/or second contact surface are arranged such that the maximum pivot angle is between, 0.5-5° when the contact region (CR) moves between the front and rear ends of the first and second contact surfaces.

13. An ice skate according toclaim 1, wherein the upper chassis section is fixed to a boot for receiving the foot of a user and the lower chassis section comprises a skate blade.

14. An ice skate according to claim 1, wherein the upper chassis section is injection moulded from a polymer material.

15. An ice skate according to claim 1, wherein the spring back means is arranged to urge the momentary contact region (CR) to a neutral position which is located at the front end of the first and second contact surfaces, and wherein the spring back means 80)-is entirely arranged in front of the front ends of the first and second contact surfaces.

16. An ice skate according to claim 1, wherein the curvature of at least a portion of the first and/or second contact surface exhibits a radius of 1 - 10 meters.

17. An ice skate according to claim 1, wherein the curvature of at least a portion of the first and/or second contact surface exhibits a radius of 2-8 meters and most preferably 3-7 m.

18. An ice skate according to claim 1, wherein the curvature of at least a portion of the first and/or second contact surface exhibits a radius of 3-7 meters.

19. An ice skate according claim 1, wherein the curvature and the length of the first and/or second contact surface are arranged such that the maximum pivot angle is between 1-3° when the contact region (CR) moves between the front and rear ends of the first and second contact surfaces.

20. An ice skate according claim 1, wherein the curvature and the length of the first and/or second contact surface are arranged such that the maximum pivot angle is approximately 2° when the contact region (CR) moves between the front and rear ends of the first and second contact surfaces.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Aspects and embodiments are now described, by way of example, with reference to the accompanying drawings, in which:

[0045] FIG. 1 is a perspective view illustrating an upper and a lower chassis section of an ice skate according to one embodiment.

[0046] FIGS. 2a-c are longitudinal sections through the ice skate shown in FIG. 1 illustrating respective states of a spring back means.

[0047] FIG. 3 is a longitudinal section corresponding to FIG. 2a illustrating another embodiment.

[0048] FIG. 4 is a longitudinal section corresponding to FIGS. 2a and 3 illustrating a further embodiment.

[0049] FIG. 4 is a longitudinal section corresponding to FIGS. 2a, 3 and 4 illustrating a yet an embodiment.

[0050] FIGS. 5a-c are longitudinal sections corresponding to FIGS. 2a-c illustrating a further embodiment.

[0051] FIG. 6 is a perspective view illustrating a component shown in FIGS. 5a-c in enlarged scale.

DETAILED DESCRIPTION

[0052] The aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown.

[0053] These aspects may, however, be embodied in many different forms and should not be construed as limiting; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and to fully convey the scope of all aspects of invention to those skilled in the art. Like numbers refer to like elements throughout the description.

[0054] FIG. 1 illustrates an upper chassis section 10 and a lower chassis section 30 of an ice skate according to an embodiment of the invention. The ice skate is intended for use at ice hockey playing. The upper chassis section 10 is arranged to be fixed to a boot (not shown) for receiving a foot of the user. The upper chassis section 10 constitutes a blade holder and is formed in one piece by injection moulding of a polymer material, such as polyamide. The upper chassis section is generally hollow and comprises a rear post 11, a front post 12 and a lower channel portion 13 which connects the rear 11 and front 12 posts. The channel portion 13 comprises two vertical channel walls 13a, 13b which extend longitudinally from the front end to the rear end of the upper chassis section 10. The channel walls 13a, 13b defines longitudinally extending channel for receiving an upper portion of the lower chassis section 30. The upper chassis section 10 further comprises a reinforcing portion 14 comprising a number of beams which interconnect the rear post 11, the front post 12 and the channel portion 13. The rear 11 and front 12 posts each has an upper flange portion 11a, 12a which projects laterally with through holes 11b, 12b for support and fixation of the boot.

[0055] The lower chassis section 30 is made of steel and comprises a blade portion 31 with a lower ice contacting edge 32. By grinding the blade portion 31, it may be given any desired profile or rocker in order to suit each user’s individual needs and preferences. Correspondingly, the edge 32 may be sharpened to any cross-sectional geometry which suits the ice and other conditions at hand as well as the user’s personal preferences.

[0056] As best seen in FIGS. 1 and 2a-c, the lower chassis section 30 is formed as a single piece integral component. The lower chassis section may e.g. be formed by stamping, cutting or milling a metal blank. Preferably the lower chassis section 30 has a constant cross-sectional width which typically may be 2-5 mm and normally is approx. 3 mm.

[0057] The upper portion of the lower chassis section’s 30 blade portion 31 is received in the channel formed between the channel walls 13a, 13b. For secure and steady guiding and sideways fixation of the lower chassis section 30, the lateral distance between the channel walls 13a, 13b is essentially equal to the cross-sectional width of the lower chassis section 30. The lower chassis section 30 further comprises a number of protrusions which extend upwardly, towards the upper chassis section 10 from the blade portion 31. These protrusions comprise a first engagement member in the form of a first hook member 33 which extends upwardly from the blade portion 31 and is received within a cavity 12c of the front post 12. A second engagement member in the form of a second hook member 34 extends upwardly from the rear end of the blade portion 31 and is received in a cavity 11c of the rear post 11.

[0058] The upper chassis portion 10 comprises a first curved contact surface 15 which exhibits a front end 15a and a rear end 15b. In the shown example, the first contact surface 15 is arranged as a lower edge of an exchangeable insert 16 which is removably received in a downwardly open insert cavity 17 of the upper chassis section 10. At a not shown alternative, the second contact surface may be arranged as a downwardly facing edge surface formed integral with the upper chassis section. The lower chassis section 30 exhibits a corresponding second contact surface 35 which extends along the upper edge of the blade portion 31 between a longitudinal mid region and a rear region of the lower chassis section 30. The second contact surface 35 exhibits a front end 35a which is vertically aligned with the front end 15a of the first contact surface 15 and a rear end 35b, which is vertically aligned with the rear end 15a of the first contact surface 15. The front ends 15a, 35a are arranged approximately at the longitudinal centre of the lower chassis section 30 and the rear ends 15b, 35b are arranged in proximity to the rear end of the lower chassis section 30. Typically, the length of the first 15 and second 35 contact surface, i.e. the distance between the front ends 15a, 35a and the rear ends 15b, 35b may constitute approx. half of the total length of the lower chassis section 30. For example, at an ice skate where the total length of the lower chassis section is 300 mm, the ice contacting edge of the blade portion may be 200 mm and the length of the first and second contact surfaces may be approx. 120 mm.

[0059] The first contact surface 15 is curved in the longitudinal direction. In the shown example the curvature is constant with a radius of approx. 4 m. However, the radius of curvature may be selected depending of e.g. the type of ice skate and the user’s preferences. Additionally, the curvature needs not to be constant but may vary over the length of the contact surface.

[0060] By arranging the first contact surface 15 on an exchangeable insert 16, which is removably fixed to the upper chassis section 10, the ice skate may readily be adapted to the prevailing circumstances and the user’s desires by easy exchange of the insert. At the shown example, the second contact surface 35 is planar over its entire length. However, the second contact surface may also be curved. At further alternative, not shown embodiments, the lower second contact surface may be curved and the upper first contact surface may be planar.

[0061] In any case, the first 15 and second 35 contact surfaces, at least one of which is curved, allows for that the upper chassis section 10 may pivot by a rolling contact motion without a fixed point of rotation relative to the lower chassis section 30. During such relative pivotal movement, a momentary contact region CR between the first 15 and second 35 contact surfaces will move back and forth between the front ends 15a, 16a and rear ends 15b, 16b of the first 15 and second 35 contact surface. In FIG. 2a the upper chassis section 10 has been pivoted forwardly to its frontmost position whereby the momentary contact region CR is positioned at the front ends 15a, 35a of the first 15 and second 35 contact surfaces. Correspondingly, In FIG. 2b the upper chassis section 10 has been pivoted rearwardly to its rearmost position, whereby the momentary contact region CR is positioned at the rear ends 15b, 35b of the first 15 and second 35 contact surfaces.

[0062] The ice skate further comprises a coupling arrangement which connects the upper 10 and lower 30 chassis sections while allowing said relative pivotal movement. The coupling arrangement comprises a spring back means 50 which is arranged to resiliently urge the relative pivotal movement forwardly to a neutral position where the momentary contact region CR is located at the front ends 15a, 35a of the first 15 and second 35 contact surfaces. This neutral position is shown in FIG. 2a. By applying a force to the upper chassis section 10, behind the front ends 15a, 35 of the contact surfaces 15, 35, it is possible to temporarily pivot the upper chassis section 30 rearwardly such that the momentary contact region CR moves backwards towards the rear ends 15b, 35b as shown in FIG. 2b. A soon as such an external force is released, the spring back means 50 urges the relative movement back to the neutral position shown in FIG. 2a.

[0063] At the embodiment shown in FIGS. 2a-c, the spring back means 50 comprises a spring member 51 which is received in the cavity 12c of the upper chassis section’s 10 front post 12. The spring member 51 is pivotally fixed to the front post 12 and it comprises a generally U-formed resilient arm. A first end 51a of the arm exhibits a circular through hole which receives a circular stem 12d extending laterally between opposing sidewalls of the front post 12, through the front post’s cavity 12c. A second end 51b of the arm comprises a cylindrical portion with an outer first engagement surface 51c which is removably received in an engagement seat forming a second engagement surface 33a of the first hook member 33 of the lower chassis section 30. The cylindrical portion of the second end 51b further exhibits a lateral recess or through opening 52 for receiving a tool (not shown) as will be described further below.

[0064] In the position shown in FIG. 2a the spring member 51 has been initially pre-tensioned by being pivotally fixed to the stem 12d and brought into engagement with the engagement seat’s second engagement surface 33a, such that it urges the relative pivotal movement between the upper 10 and lower 30 chassis sections to the neutral frontmost pivoted position. By applying a relative force between the upper 10 and lower 30 chassis sections, behind the front ends 15a, 25a of the contact surfaces 15, 35 the spring member will be deformed and further tensioned thereby to allow the backward pivotal movement to the position shown in FIG. 2b. At release of said force, the energy stored in the spring member 51 during the further tensioning causes a reversed pivotal movement back to the neutral position shown in FIG. 2a.

[0065] The upper chassis section 10 further comprises a first stop surface 17 which is formed on a lower laterally extending wall 19 connecting the side walls of the front post 12. The lower chassis section 30 exhibits a corresponding second stop surface 37 arranged on the upper edge of the blade portion 31 in the front region of the blade portion 31. The first 17 and second 37 stop surfaces are arranged to come in mutual contact when the momentary contact region CR has reached the front ends 15a, 35a of the contact surfaces 15, 35. Hereby, any further frontwards pivotal movement passed the neutral position is effectively prevented. The arrangement of the cooperating first 17 and second 37 stop surfaces allows for that any force applied to the upper chassis section 10, in front of the contact surfaces 15, 35 and at the neutral position will be directly and un-elastically transmitted to the blade portion 31 without any yielding.

[0066] The lower lateral wall 19 of the front post 12 also provides an arrest for the spring member 51. If for example the front portion of the lower chassis section 30 would be caught by or hooked up in a surrounding object such that said front portion runs the risk of being separated from the upper chassis section 10, the spring member 51 will make contact with the lower lateral wall 19 to thereby prevent further pivoting and extension of the spring member 51. By this means, the first engagement surface 51c on the second end 51b of the spring member 51 will maintain its engagement with the engagement seat’s second engagement surface 33a of the lower chassis section’s 30 first hook member 33, such that the front portion of the lower chassis section 30 is prevented from being unintentionally separated from the upper chassis section 10. The lower lateral wall portion 19 also prevents the spring member 51 from being excessively deformed and tensioned at such unintentional movement of the lower chassis section’s front portion, thereby to reduce the risk fatigue failure of the spring member 51.

[0067] At the rear post 11, the upper chassis section 10 exhibits an upwardly facing third contact surface 18 which is arranged at a lower wall portion 20 extending laterally through the rear post cavity 11c between opposite sidewalls and a rear wall of the rear post 11. A downwardly facing fourth stop surface 38 is arranged on the second hook member 34 of the lower chassis section. The third 18 and fourth 38 stop surfaces are arranged such that there exists a small distance therebetween when the first 17 and second 37 stop surface are in mutual contact and the relative pivotal movement thus is in the neutral position. Hence the third 18 and fourth 38 stop surfaces do not contribute to define the frontmost neutral position of the relative pivotal movement. Instead, the third 18 and fourth 38 stop surfaces are arranged for security purposes to prevent that the rear portion of the lower chassis section 30 is unintentionally separated from the upper chassis section 10 in case this rear blade portion is caught or hooked up to any surrounding object.

[0068] A downwardly facing fifth contact surface 21 is arranged on the lower side of the rear post’s 11 lower wall portion 20 and a sixth stop surface 41 is arranged on the blade portion’s 31 upper edge, behind the second hook member 34. The fifth 21 and sixth 41 stop surface come in mutual contact when, during backward pivoting, the momentary contact region CR reaches the rear ends 15b, 35b of the first 15 and second 35 contact surfaces, such that the pivotal movement is limited passed the rearmost pivotal position shown in FIG. 2b, where the momentary contact region is located at the rear ends 15b 35b of the contact surfaces 15, 35.

[0069] With reference to FIGS. 2a and 2c, the ice skate is further arranged to allow easy removal and exchange of the lower chassis section 30. Such exchange of the lower chassis section may be highly advantageous e.g. at ice hockey matches where it allows a worn or damaged blade to be quickly exchanged by a sharpened blade. For this purpose, the coupling arrangement comprises a release means as explained below.

[0070] At least one or both opposing lateral side walls of the front post 11 is provided with a generally V-shaped through penetrating slot 22. The slot 22 allows insertion of a pointed tool (not shown) into the recess or through opening 52 arranged at the second end 51b of the spring member 50. At the neutral position shown in FIG. 2a, the tool may be inserted into the recess or opening 52 and thereafter pulled forwards along the V-shaped slot 22 to thereby disengage the first engagement surface 51c of the spring member 51 from the second engagement surface 33a of the first hook member 33. FIG. 2c illustrates how the second end 51b of the spring member 51 in this way has been pulled forwardly, under anti-clockwise pivoting of the spring member 51 about the stem 12d, to an intermediate position. At this intermediate position the spring member 51 is released from the fist hook member 33, such that the front portion of the lower chassis section may be pulled out from the upper chassis section’s 10 channel portion 13. Thereafter, continued removal of the lower chassis section’s 30 front portion allows the second hook member 34 to be disengaged from the lower wall portion 20 of the rear post 12, such that the lower chassis section 30 may be completely separated from the upper chassis section 10.

[0071] For attaching the same or another lower chassis section, the second hook member 34 is first inserted in the channel portion 13 and engaged with the lower wall portion 20 of the rear post 11. Thereafter, the front portion of the lower chassis section 30 is pivoted into the front portion of the channel portion 13 such that the first hook member 33 is inserted into the front post 12. During this insertion the spring member 51 is allowed to pivot anti-clockwise such that its second end 51b does not interfere with the insertion of the first hook member 33. When the lower chassis section 30 has been inserted into the channel portion 13 of the upper chassis section 10, the tool may be inserted through the front portion of the V-shaped slot 22 to engage the recess or through opening 52 of the spring members 51 second end 51b. For completing fixation of the lower chassis section, the tool is then used to bring the second end’s 51b first engagement surface 51c into engagement with the second engagement surface 33a of the first hook member 33. During this engaging operation, the spring member 51 is pivoted clockwise and pre-tensioned for assuring that the momentary contact region CR is securely urged towards the neutral position as described above.

[0072] When the lower chassis section 30 has been removed from the upper chassis section 10, the exchangeable insert 16 may readily be removed from the insert cavity 17. However, in order to prevent the insert 16 from unintentional removal from the insert cavity, e.g. when it is desired to exchange only the lower chassis section 30, the insert 16 and/or the insert cavity 17 may be provided with retention means for retaining the insert 16 from falling out from the cavity 17. In the shown example such releasable retention is accomplished by the insert 16 being lightly press fitted into the insert cavity 17. For removing the insert 16, a pointed tool (not shown) such as a screwdriver may be inserted between the insert 16 and a cavity wall and used for bending the insert out of the press fitted engagement with the cavity 17. At alternative, not shown, embodiments, the retention means may comprise snap-fit means threaded screw means or the like.

[0073] FIG. 3 illustrates another embodiment of the ice skate. At this embodiment the upper chassis section 10 and the lower chassis section 30 are essentially identical with the upper and lower chassis section described above and illustrated in FIGS. 1-2c. These components are therefore not described again here. However, at this embodiment the spring back means differs from the spring member 51 described above. Here the spring back means comprises a torsion spring 60 made of a spring steel wire and comprising a central coil 61. A first leg 62 having a first end 62a and a second leg 63 having a second end 63a extend from the central coil 61. The first end 61a exhibits a circular through hole which receives the lateral stem 12d of the upper chassis section’s 10 front post 12, such that the torsion spring 60 is pivotally fixed to the front post 12 and received in the front post cavity 12c. By this means the torsional spring 60 is pivotally fixed to the front post 12 of the upper chassis section 10. The second end 63a comprises an annular loop with a first engagement surface 63c which may be received in the engagement seat’s second engagement surface 33a of the lower chassis section’s 30 first hook member 33. The annular loop also defines a inner through hole which may receive a tool (not shown) for moving the second end along the V-shaped slot 22 of the front post 12 when first engagement surface 63c is to be brought out from and into engagement with the second engagement surface 33a of the first hook member for releasing and attaching the lower chassis section 30 to the upper chassis section 10.

[0074] The torsion spring 60 functions in the same manner as the spring member 51 described above for urging the momentary contact region of the first 15 and second 35 contact surfaces to the front ends 15a, 35a and for allowing the lower chassis section 30 to be released and attached to the upper chassis section 10.

[0075] FIG. 4 illustrates a further embodiment of the ice skate. Also at this embodiment, the upper chassis section 10 and the lower chassis section 30 are essentially identical with the upper and lower chassis section described above and illustrated in FIGS. 1-2c. These components are therefore not described again here. At this embodiment the spring back means differs from the spring member 51 described above. Here the spring back means comprises a coiled expansion spring 70 made of a spring steel wire and comprising a central coil 71. A first hook 72 and a second hook 73 extend from respective ends of the central coil 71. The first hook 72 is hooked about the lateral stem 12d of the upper chassis section’s 10 front post 12. The second hook 73 has a first engagement surface 73c which engages the second engagement surface 33a of the lower chassis section’s 30 first hook member 33a.

[0076] The coiled expansion spring 70 functions in the same manner as the spring member 51 described above for urging the momentary contact region of the first 15 and second 35 contact surfaces to the front ends 15a, 35a and for allowing the lower chassis section 30 to be released and attached to the upper chassis section 10.

[0077] FIGS. 5a-b and 6 illustrate yet another embodiment of the ice skate. Also at this embodiment, the upper chassis section 10 and the lower chassis section 30 are essentially identical with the upper and lower chassis section described above and illustrated in FIGS. 1-4. These components are therefore not described again here. At this embodiment the spring back means 80 differs from the spring members 51, 60, 70 described above. Here, the spring back means 80 comprises link mechanism which is received in the front post cavity 12c and which comprises a first link arm 81, a second link arm 82 and a coiled expansion spring 83. The first link arm 81 exhibits a circular through opening 84 which receives the stem 12d of the upper chassis section’s front post 12, such that the first link arm 81 is pivotally fixed to the front post 12 of the upper chassis section 10.

[0078] The first arm 81 comprises a first lever portion 85 which extends forwardly and a second lever portion 86 which extends rearwardly from the through opening 84. A first end 82a of the second link arm 82 is pivotally connected to the free end of the second lever portion 86. The second end 82b of the second link arm 82 comprises a rounded portion with a first engagement surface 82c which is releasably received in the second engagement surface 33a of the first hook member 33 of the lower chassis section 30. The second end 82b further exhibits a lateral recess or through opening 82d for receiving a tool (not shown). The spring 83 comprises a first hooked end 83a which is connected to the first lever portion 85 of the fist link arm 81 and a second hooked end 83b which is connected to the second end 82b of the second pivot arm 82. By this means the spring 83 is arranged to urge the first lever portion 85 of the first pivot arm and the second end 82 of the second pivot arm 82 towards each other during relative pivotal movement about the pivotal connection between the first pivot arm’s 81 second lever portion 86 and the second pivot arm’s 82 first end 82a.

[0079] FIG. 5a illustrates how the link mechanism urges the momentary contact region CR to the neutral frontmost position, where the front end 15a of the first contact surface 15 and the front end 35a of the second contact surface 35 are in mutual contact. In FIG. 5b an external force has been applied to the upper chassis section 10, behind the front end 15a, of the first contact surface 15 such that the momentary contact region CR has been moved to the rearmost position where the rear ends 15b, 35b of the first 15 and second 35 contact surfaces are in mutual contact. At this and any intermediate position of the momentary contact region CR, the link mechanism urges, i.e. strives to return the monetary contact region CR to the neutral frontmost position shown in FIG. 5a. When the link mechanism has been extended to the position shown FIG. 5b, the second end 82b of the second pivot arm 82 makes contact with the lower transverse wall portion 19 of the front post 12 to thereby limit the movement of the second limit arm 82 and avoid over extension of the spring 81.

[0080] In FIG. 5c it is illustrated how a pointed tool (not shown) has been inserted into the through opening 82d of the link mechanism’s second arm 82 and how the second end’s 82b first engagement surface 82c has been brought out of engagement with the second engagement surface 33a of the lower chassis section’s 30 first hook member 33 by pulling the tool forwardly. During this operation the pointed tool has been introduced into the front post cavity 12 through a non-shown slot arranged in one or two side walls of the front post 12. When the link mechanism by this means has been brought out of engagement from the lower chassis section 30 the lower chassis section 30 may readily be removed and exchanged as described above. After insertion of a new lower chassis section into the channel portion 18 the lower chassis section 30 is secured to the upper chassis section by using the pointed tool (not shown) for bringing the first engagement surface 82c of the second link arm 82 into engagement with the second engagement surface 33a of the lower chassis section’s first hook member 33.

[0081] The aspects of the present disclosure have mainly been described above with reference to a few embodiments and examples thereof. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.