Fastening device for a trampoline
10898748 ยท 2021-01-26
Assignee
Inventors
- Erwin Bisang (Huenenberg, CH)
- Ludwig Durrer-Kuettel (Immensee, CH)
- Christian Mehr (Kirchberg, CH)
- Silvan Schwarz (Lichtensteig, CH)
Cpc classification
F16B5/0692
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16B45/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F16B5/06
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A cord hook for fastening a jump mat to a trampoline frame includes a holding section for holding a first and a second loop end section of the cord loop and a fastening section for fastening the flexible band element, wherein a main tension vector (V) is defined by tension at the band element. The hook has a transition section connecting the holding section and the fastening section and is designed in such a way that a straight line (g) through the main tension vector (V) divides the holding space into a first partial space and a second partial space in such a way that, when the cord hook is used as intended, the first loop end section lies in the first partial space and the second loop end section lies in the second partial space. Also disclosed are a trampoline and a method for fastening the jump mat.
Claims
1. A cord hook for securing a jump mat to a trampoline frame by means of a cord loop and at least one flexible band element having a distal end portion, the cord hook comprising: a distal receiving portion, wherein the receiving portion extends along a first direction and defines a receiving space for receiving a first loop end portion and a second loop end portion of the cord loop; a proximal securing portion, which extends along a second direction and which is designed such that the distal end portion of the flexible band element can be secured thereto; a transition portion which connects the receiving portion and the securing portion and which delimits the receiving space on one side; wherein, when the cord hook is put under tension by means of the cord loop securing the jump mat, a main tension vector is defined by tension on a proximal end portion of the at least one flexible band element; wherein the cord hook is designed such that a straight line through the main tension vector of the cord hook under tension and the flexible band element divides the receiving space into a first partial space and a second partial space such that, during intended use of the cord hook, the first loop end portion lies in the first partial space and the second loop end portion lies in the second partial space; wherein the cord hook is formed as a single-piece plastic part which has a vertical ridge which projects centrally into the receiving space and which serves for centering a clamping region of a cord loop in the receiving space.
2. The cord hook as claimed in claim 1, wherein the first direction and the second direction run transversely with respect to one another.
3. The cord hook as claimed in claim 1, which is furthermore designed such that the straight line through the main tension vector intersects the receiving portion centrally with respect to a longitudinal extent along the first direction.
4. The cord hook as claimed in claim 1, which is furthermore designed such that the straight line through the main tension vector intersects the securing portion centrally with respect to a longitudinal extent along the second direction.
5. A cord hook for securing a jump mat to a trampoline frame by means of a cord loop and at least one flexible band element having a distal end portion, the cord hook comprising: a distal receiving portion, wherein the receiving portion extends along a first direction and defines a receiving space for receiving a first loop end portion and a second loop end portion of the cord loop; a proximal securing portion, which extends along a second direction and which is designed such that the distal end portion of the flexible band element can be secured thereto; a transition portion which connects the receiving portion and the securing portion and which delimits the receiving space on one side; wherein, when the cord hook is put under tension by means of the cord loop securing the jump mat, a main tension vector is defined by tension on a proximal end portion of the at least one flexible band element; wherein the cord hook is designed such that a straight line through the main tension vector of the cord hook under tension and the flexible band element divides the receiving space into a first partial space and a second partial space such that, during intended use of the cord hook, the first loop end portion lies in the first partial space and the second loop end portion lies in the second partial space; wherein the cord hook is formed as a single-piece plastic part; and at least one abutment element is provided which narrows the receiving space and which is arranged on the transition portion such that the abutment element is spaced apart from the receiving portion in the direction of the main tension vector and, at least in sections, extends parallel to the receiving portion along the first direction away from the transition portion and laterally proximally delimits the first partial space and the second partial space of the receiving space and is suitable for centering a clamping region of a cord loop in the receiving space.
6. The cord hook as claimed in claim 5, wherein the first direction and the second direction run transversely with respect to one another.
7. The cord hook as claimed in claim 5, which is furthermore designed such that the straight line through the main tension vector intersects the receiving portion centrally with respect to a longitudinal extent along the first direction.
8. The cord hook as claimed in claim 5, which is furthermore designed such that the straight line through the main tension vector intersects the securing portion centrally with respect to a longitudinal extent along the second direction.
9. A trampoline having a jump mat and having a trampoline frame, wherein the trampoline furthermore comprises a multiplicity of cord hooks, a multiplicity of elastic cord loops, wherein the number of cord hooks is equal to the number of elastic cord loops, and one flexible band element for each cord hook, wherein the multiplicity of cord hooks, the multiplicity of elastic cord loop and the flexible band elements are used to mount the jump mat in the trampoline frame, wherein the cord hook comprises: a distal receiving portion, wherein the receiving portion extends along a first direction and defines a receiving space for receiving a first loop end portion and a second loop end portion of the cord loop; a proximal securing portion, which extends along a second direction and which is designed such that the distal end portion of the flexible band element can be secured thereto; a transition portion which connects the receiving portion and the securing portion and which delimits the receiving space on one side; wherein, when the cord hook is put under tension by means of the cord loop securing the jump mat, a main tension vector is defined by tension on a proximal end portion of the at least one flexible band element; wherein the cord hook is designed such that a straight line through the main tension vector of the cord hook under tension and the flexible band element divides the receiving space into a first partial space and a second partial space such that, during intended use of the cord hook, the first loop end portion lies in the first partial space and the second loop end portion lies in the second partial space; wherein the cord loops are formed from a first cord portion, or from a first cord portion and a second cord portion, wherein each cord portion has in each case one first end portion and one second end portion, wherein the first end portion of the first cord portion is clamped to the second end portion of the first or of the second cord portion in a clamping region, and the second end portion of the first cord portion is clamped to the first end portion of the first or of the second cord portion respectively in a clamping region, such that the free portions of those end portions which are clamped together in each case point in the same direction, wherein the clamping region are mountable into the first or second partial space of the corresponding cord hook.
10. The trampoline according to claim 9, wherein the cord loops are formed from a first cord portion, wherein each cord portion has in each case one first end portion and one second end portion, and wherein the first and second end portions are in each case bent to form a first loop and a second loop and are fixedly clamped in each case by means of at least one clamping element, wherein the first and second loops are mountable into the first and second partial space of the corresponding cord hook.
11. The trampoline as claimed in claim 9, wherein the cord loops are in each case tensioned such that the clamping region is situated in each case in the first or in the second partial space corresponding cord hook.
12. The trampoline as claimed in claim 10, wherein the first and second loop are mounted into the first and second partial space of the corresponding cord hook.
13. A method for securing a jump mat to a trampoline frame, i) providing a multiplicity of cord hooks, ii) providing a multiplicity of elastic cord loops, iii) providing a multiplicity of flexible bands, wherein the number of cord hooks is equal to the number of elastic cord loops, and one flexible band element is provided for each cord hook, wherein the multiplicity of cord hooks, the multiplicity of elastic cord loop and the flexible band elements are used to mount the jump mat in the trampoline frame, wherein the cord hook comprises: a distal receiving portion, wherein the receiving portion extends along a first direction and defines a receiving space for receiving a first loop end portion and a second loop end portion of the cord loop; a proximal securing portion, which extends along a second direction and which is designed such that the distal end portion of the flexible band element can be secured thereto; a transition portion which connects the receiving portion and the securing portion and which delimits the receiving space on one side; wherein, when the cord hook is put under tension by means of the cord loop securing the jump mat, a main tension vector is defined by tension on a proximal end portion of the at least one flexible band element; wherein the cord hook is designed such that a straight line through the main tension vector of the cord hook under tension and the flexible band element divides the receiving space into a first partial space and a second partial space such that, during intended use of the cord hook, the first loop end portion lies in the first partial space and the second loop end portion lies in the second partial space, wherein the method further comprises iv) looping the cord loop around a portion of the trampoline frame and mounting the first loop end portion and the second loop end portion into the receiving space of the cord hook in order to tension the jump mat in the trampoline frame; wherein the cord loop is formed from a first cord portion or from a first cord portion and a second cord portion, wherein each cord portion has in each case one first end portion and one second end portion, wherein the first end portion of the first cord portion is clamped to the second end portion of the first or of the second cord portion in a clamping region, and the second end portion of the first cord portion is clamped to the first end portion of the first or of the second cord portion respectively in a clamping region, such that the free portions of those end portions which are clamped together in each case point in the same direction, wherein the clamping region is mounted into the first or second partial space of the corresponding cord hook.
14. A method for securing a lump mat to a trampoline frame, i) providing a multiplicity of cord hooks, ii) providing a multiplicity of elastic cord loops, iii) providing a multiplicity of flexible bands, wherein the number of cord hooks is equal to the number of elastic cord loops, and one flexible band element is provided for each cord hook, wherein the multiplicity of cord hooks, the multiplicity of elastic cord loop and the flexible band elements are used to mount the jump mat in the trampoline frame, wherein the cord hook comprises: a distal receiving portion, wherein the receiving portion extends along a first direction and defines a receiving space for receiving a first loop end portion and a second loop end portion of the cord loop; a proximal securing portion, which extends along a second direction and which is designed such that the distal end portion of the flexible band element can be secured thereto; a transition portion which connects the receiving portion and the securing portion and which delimits the receiving space on one side; wherein, when the cord hook is put under tension by means of the cord loop securing the jump mat, a main tension vector is defined by tension on a proximal end portion of the at least one flexible band element; wherein the cord hook is designed such that a straight line through the main tension vector of the cord hook under tension and the flexible band element divides the receiving space into a first partial space and a second partial space such that, during intended use of the cord hook, the first loop end portion lies in the first partial space and the second loop end portion lies in the second partial space, wherein the method further comprises iv) looping the cord loop around a portion of the trampoline frame and mounting the first loop end portion and the second loop end portion into the receiving space of the cord hook in order to tension the jump mat in the trampoline frame; wherein each cord portion has in each case one first end portion and one second end portion, and wherein the first and second end portions are in each case bent to form a first and a second loop and are fixedly clamped in each case by means of at least one clamping element, wherein the first and second loops are mounted into the first and second partial space of the corresponding cord hook.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Preferred embodiments of the invention will be described below on the basis of the drawings, which serve merely for explanatory purposes and are not to be interpreted as limiting. In the drawings:
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
DESCRIPTION OF PREFERRED EMBODIMENTS
(20) Preferred embodiments of the present invention will now be described on the basis of
(21)
(22) Sub-
(23) As illustrated in
(24) The securing portion 12 likewise has a free end, which is bent through 90 so as to be directed toward the receiving portion 11. The two bent free ends are thus oriented in opposite directions. With the other end, the securing portion 12 transitions into a proximal end of the transition portion 13. Between the two ends, the securing portion 12 runs in a substantially straight manner over its longitudinal extent L.sub.12 along the second direction R.sub.2. The securing portion 12 is in this case designed such that the securing portion 12 can be mounted into a band element 8 (see
(25) The transition portion 13 runs in a substantially straight manner between the receiving portion 11 and the securing portion 12 and is typically somewhat longer than the receiving portion 11 and somewhat shorter than the securing portion 12.
(26) The dimensions of the cord hook 10 are advantageously selected such that the securing portion 12 can be mounted into a band element 8 and two loop end portions 71, 72 can be mounted into the receiving portion 11. A material and a material thickness should be selected such that the required stability of the cord hook 10 is ensured in the case of the tensioning arrangement typical for the mini trampoline 1 (see
(27) If, as shown in
(28) The cord hook 10 is furthermore designed such that the first partial space 111 can be utilized for receiving the first loop end portion 71 and the second partial space 112 can be utilized for receiving the second loop end portion 72. This is shown in
(29) The point of intersection between the straight line g and that surface of the securing portion 12 which is directed toward the receiving portion 11 defines an action point A. A main tension vector V runs from said action point A along the straight line g. The main tension vector V represents substantially the resultant force which is exerted by a band element 8 on the hook 10 in the tensioned state before the use of the trampoline 1. The main tension vector V is thus substantially perpendicular to the first direction R.sub.1 and to the second direction R.sub.2 and has its point of origin at the action point A.
(30)
(31) The cord hook 10 with the cord loop 7 and the band element 8 constitutes a securing system 100 as shown in
(32)
(33) The cord loop 7 according to the first embodiment as per
(34) In
(35) The securing portion 12 is mounted into a band element 8 which is likewise formed in the manner of a loop. Said band element 8 is flexible and is connected to the jump mat 6 (see
(36) The band element 8 is advantageously designed to exhibit considerably lower elasticity than the cord loop 7, or to be inelastic. In the tensioned state, the band element 8 exerts a force on the cord hook 10, such that the hook 10 retains the received loop end portion 71, 72 counter to the tension of the first cord portion 73. The force exerted by the band element 8 can be represented by the main tension vector V, which acts at the action point A of the cord hook 10 and points in the direction of the jump mat 6.
(37)
(38) This additional sleeve 15 has a U-shaped main body 152 extending along a longitudinal axis. At end sides in relation to the longitudinal axis of the main body 152, there are provided end plates 153, 154 which project beyond the main body 152 toward the bottom side of the U shape. The additional sleeve 15 is in this case designed such that the U shape of the main body 152 can be slid over the receiving portion 11 of the wire hook 10 as per
(39) The U shape has a bottom side and two limbs which project from said bottom side. On the bottom side opposite the receiving space of the U shape, there is formed a vertical ridge 151 which extends between the two end plates 153, 154. Said vertical ridge projects from the outer bottom side of the U shape by 1 millimeter to 3 millimeters. A length of the additional sleeve 15 is selected such that substantially the entire portion of the receiving portion 11 extending in a straight manner over the longitudinal extent L.sub.12 is received in the receiving space of the U shape.
(40)
(41) The loop 7 as per the second embodiment has a first receiving portion 73 and additionally a second cord portion 74. The loop 7 is thus formed from two cord portions. The first cord portion 73 again has the first and second end portions 731, 732. The second cord portion 74 likewise has a first end portion 741 and a second end portion 742.
(42) The loop 7 as per the second embodiment is now produced by virtue of the first cord portion 73 and the second cord portion 74 being laid parallel and adjacent to one another, such that firstly the first end portion 731 of the first cord portion 73 and the second end portion 742 of the second cord portion 74 make contact, and secondly also the second end portion 732 of the first cord portion 73 and the first end portion 741 of the second cord portion 74 make contact. The end portions 731, 742 and 732, 741 which are in contact are then fixedly clamped to one another by means of a first clamping element 76 and a second clamping element 77, whereby clamping regions 75 are formed in each case.
(43) The clamping element 76, 77 may again be a pinchable metal bracket or metal sleeve which fixedly connects the corresponding end portions 731, 742 and 732, 741 to one another. Here, the two clamping regions 75 form the first loop end portion 71 and the second loop end portion 72.
(44) As shown in
(45) As illustrated in
(46) By means of the insertion of the additional sleeve 15 as per the refinement of the securing system 100, it is additionally achieved, for the lateral fixing of the loop end portion 71, 72, that the loop end portions 71, 72 are spread apart by means of the U shape of the main body 152 of the additional sleeve 15, such that the four cord portions proceeding from the additional sleeve 15, which run between the cord hook 10 and the tubular frame 9, are spatially separated from one another to a relatively great extent. This has the advantage that, during the intended use of the trampoline 1, contact between these four cord portions is prevented, which further improves the wear resistance of the securing system 100 and furthermore minimizes the generation of disturbing noises.
(47) The additional sleeve 15 thus has a dual function: firstly, it is the intention for the cord loop 7 to be fixed, and secondly, it is the intention for contact between cord loop end portions to be prevented, other than in the clamping regions 75, during intended use.
(48)
(49)
(50) The cord hook 10 has a drum-like main body 113 which is closed off at its free end by means of a plate-like covering 114 which projects beyond the main body 113. The covering 114 projects with its free end toward the securing portion 12 and thus ensures that the received loop end portions 71, 72 are mounted in the receiving space 110 so as to be secured against slipping relative to the first direction R.sub.1. The drum-like receiving portion 113 provides the receiving space 110 and has substantially the form and function of the above-described main body 152 of the additional sleeve 15. Again, the transition portion 13 is integrally formed at that end of the drum-like receiving portion 113 which is situated opposite the covering 114. Said transition portion 13 is likewise of plate-like form and delimits the receiving space 110 counter to the first direction R.sub.1. The securing portion 12 is integrally formed at the proximal end of the transition portion 13.
(51) The securing portion 12 is formed by two hook elements 122, 123 directed toward one another. The two hook elements 122, 123 have receiving portions which both run in an aligned manner along the second direction R.sub.2. The band element 8 is formed in 2 parts by two relatively narrow band elements 82, 83. The first partial band element 82 is mounted into the first hook element 122, and the second partial band element 83 is mounted into the second hook element 123. The abovementioned action point A is in this case now situated centrally between the two receiving portions of the first and second hook elements 122, 123. As can be seen from the figures, the transition portion 13 and securing portion 12 are shaped such that the action point A is raised to the level of the center of the main body 113. This may generally be advantageous.
(52) In each case one relatively narrow partial band element 82, 83 is mounted into the two hook elements 122, 123. In the tensioned state, the two partial band elements 82, 83 exert a resultant force on the cord hook 10, which resultant force can again be represented by the main tension vector V which acts at the action point A.
(53)
(54)
(55) This fourth embodiment is likewise designed as a preferably single-piece molded part, wherein the form is based substantially on the additional sleeve 15 as described above. Instead of the plate element 154 shown at the bottom in
(56) The securing portion 12 is a bar element which runs substantially along the second direction R.sub.2 and which has an elliptical or circular cross section, wherein, at lateral ends of the securing portion 12 along the second direction R.sub.2, there are provided covering elements, that is to say securing projections, which covering elements are formed so as to extend the bar element in the distal direction toward the receiving space 110 and secure the received band element 8.
(57) As can be seen in particular in
(58)
(59) It can also be seen from
(60)
(61)
(62)
(63) The optimum inclination of the covering 114 is thus dependent on the diameter of the trampoline frame 9, on the length of the loop 7, and on the hook geometry.
(64) At that end of the main body 113 which is situated opposite the plate-like covering 114, there is arranged the transition portion 13, which extends in a plate-like manner from the main body 113 in the proximal direction. As can be seen from the figures, the plate-like transition portion 13 likewise runs in an inclined manner in relation to the first direction as is the case for the plate-like covering 114. In the proximal region of the transition portion 13, there are arranged two abutment elements 14, which, spaced apart from the main body 113, project in the first direction R.sub.1 from the transition portion 13. The abutment elements 14 are of monolithic design, and those sides of the abutment elements 14 which are directed toward one another are of rounded design. It is thus achieved that the loop 7 is not exposed to any sharp edges. Since the transition portion 13 projects laterally beyond the main body 113 and the abutment elements 14 are arranged in each case at the lateral edge of the transition portion 13, the receiving elements 14 again provide a receiving partial space 115 in which the free portions 78 of the loop 7 can be received, whereby lateral fixing is provided. The receiving partial space 115 adjoins the receiving space 110. As can be seen from
(65) A width of the receiving partial space 115 is generally preferably approximately twice as wide as the cord diameter.
(66) The main body 113 again defines the receiving space 110, which is divided by the straight line g, which extends through the action point A of the securing portion 12 and perpendicular to the first direction R.sub.1, into two partial spaces 111 and 112 for receiving the first and second loop end portions 71, 72.
(67)
(68) The securing portion 12, which is raised upward toward a center of the main body 113, extends in the proximal direction of the abutment elements 14. Said securing portion 12 is of plate-like form and has a proximally arranged slot 125, such that a shackle is formed into which a band element 8 (not illustrated) can be mounted. The action point A, from which the main tension vector V extends in the direction of the band element in the tensioned state, is again situated, centrally with respect to the second direction R.sub.2, on that surface of the securing element 12 which defines the slot 125 counter to the proximal direction.
(69)
(70) In the third embodiment of the loop 7, only a first cord portion 73 is used, which has the two end portions 731 and 732. The end portions 731, 732 are, pointing parallel and in the same direction, fixedly clamped to one another by means of a clamping element 76 so as to form the first loop end portion 71. Correspondingly, the third embodiment of the loop 7 has only one clamping region 75, which is received in the first partial space 111 of the receiving space 110, such that the free portions 78 thereof project from the receiving space into the receiving partial space 115 and, there, are secured against lateral slippage by the abutment elements 14. The second loop end portion 72 is formed by a loop portion situated opposite the clamping region 75 in the case of a spread-out loop 7.
(71) The sixth and seventh embodiment of the cord hook 10 thus have pin-like abutment elements 14 which project from the transition portion 13 and which form a receiving partial space 115 and which serve for the lateral fixing of the clamping region 75 by acting from the outside with respect to the loop 7.
(72) The securing portion is formed here as a shackle, and the plate-like covering 114 which delimits the main body 113 in the first direction R.sub.1 and the transition portion 13 are of plate-like form and are arranged so as to run toward one another in the proximal direction.
(73) The embodiments as per
(74) It is self-evident that the various securing portions and various hook portions of the various embodiments discussed here may be combined with one another as desired. It is also self-evident that an inclination of the plate-like covering 114 or of the transition portion 13 with respect to the first direction R.sub.1 can be adapted by a diameter of the tube portion 90 of the trampling frame 9, and may be formed in all embodiments. Furthermore, the various embodiments of the loop may also be combined with the various embodiments of the cord hooks.
(75) The cord hooks 10 may, in the tensioned state, be installed in the securing system 100 so as to be in an upwardly open or downwardly open orientation and so as to tension the jump mat 6. The cord hooks 10 are preferably downwardly open in the installed position, such that the risk of injury to the user when using the trampoline 1 is reduced.
(76)
(77) The receiving portion 11 is, in
(78) The transition portion 13 has, at the side situated opposite covering 114, a structure of ribs 131 (see
(79) The transition portion 13 transitions, in the proximal direction, into two laterally attached arms 128, 129, which, as wall elements attached to the lateral edge of the transition portion 13 and of the securing portion 12, laterally delimit the transition portion 13 and the securing portion 12 and, in sections, in the distal region, project beyond the transition portion 13 and the securing portion 12 upward in
(80) It is also the case in the eighth embodiment of the cord hook 10 that a bolt element 124 is provided for the securing of the band element 8, as is already the case in the embodiment as per
(81) It can also be seen from
(82) As shown in
(83) It can also be seen from
(84) Moreover, it can be seen in particular from
(85) The provision of a bolt element 124 in the securing portion 12 for receiving the band element 8 has the advantage, irrespective of the specific embodiment, that the band elements 8 can already be fixedly sewn, or secured in some other way, to the jump mat 6 during the production process, before the corresponding cord hook 10 has to be mounted into the corresponding band element 8. In this way, it is for example the case that the intermediate product of jump mat 6 with secured band elements 8 can be stored in a more effective manner. Furthermore, a possible removal of the bolt element 124 also permits a retroactive exchange of the individual cord hook 10 in the event of a defect.
(86) The advantage of the exchangeability self-evidently also arises from securing portions 12 which permit a mounting of the band elements 8, that is to say which have for example inwardly and/or outwardly open hook elements 122, 123 for the mounting of the corresponding band element 8.
(87) Furthermore, the cord hooks 10 of all embodiments, aside from those in
(88) It is self-evident that the differently designed securing portions 12, transition portions 13 and receiving portions 11 may be combined with one another.
(89) TABLE-US-00001 LIST OF REFERENCE DESIGNATIONS 1 Trampoline 10 Cord hook 100 Securing system 11 Receiving portion 110 Receiving space 111 First partial space of 110 112 Second partial space of 110 113 Main body, drum section 114 Covering 115 Receiving partial space 12 Securing portion 121 Free end of 12 122 First hook element 123 Second hook element 124 Pin element 125 Recess 126 Slot 127 Beam element 128, 129 Arm 13 Transition portion 131 Rib 14 Abutment element 15 Additional sleeve 151 Vertical ridge 152 Main body 153 End plate 154 End plate 6 Jump mat 7 Loop 71 First loop end portion of 7 72 Second loop end portion of 7 73 First cord portion 7 731 First end portion of 73 732 Second end portion of 73 74 Second cord portion of 7 741 First end portion of 74 742 Second end portion of 74 75 Clamping region 76 First clamping element 77 Second clamping element 78 Free portion of 7 791 First loop 792 Second loop 8 Flexible band element 81 Distal end portion of 8 82 First part of a two-part band element 83 Second part of a two-part band element 84 Diversion of 8 9 Trampoline frame 90 Portion of 9 A Action point g Straight line L.sub.11 Longitudinal extent of 11 L.sub.12 Longitudinal extent of 12 R.sub.1 First direction R.sub.2 Second direction R.sub.V Direction of V V Main tension vector