BACKGROUND TO THE INVENTION.

While developing roller skate prototypes, which needed the use of a tension loaded permanent elastic springs of well-vulcanised rubber or well-polymerised EPDM or similar with progressive growing tensile stress to elongation characteristics within its action range. It was discovered that when profiles, made of said materials, included a closed circular shape, the length-tension properties of these profiles showed remarkable increase in stiffness when deformed by pressure and this increase in stiffness is amplified by pulling. Said effect was particularly clear when an elliptic shape was used having its longest axis at right angle to the line of pull before assembly. It was found that the springs can be sufficient tension loaded by deforming under pressure and than by pulling through pushing on by hand.

Said amplified stiffness will continue during the further function of the spring.

Different load characteristics can be obtained by changing the unloaded shape of the elastic profile. Said springs can be included in a suspension, which allows the spring to be pre- tensioned, so that at the beginning of loading of the suspension a high stiffness of the suspension is achieved by means of the elastic ring.

OBJECT OF THE INVENTION: The object of the invention is, to reduce the number of parts in roller skates which uses springs for vibration insulation, load

adjusting and shock absorption and thereby meet the demands related to limited space, low weight and restricted complexity and to make it possible to adapt the roller skate to the individual quick without any tools.

SUMMARY OF THE INVENTION: The present invention comprises a permanent elastic spring that is pre-tensioned by deformation through pressure and pulling.

Said spring is used in roller skates and has as its function:- The adjustment of a wheel in a roller skate when it is exposed to increased loads caused by for example uneven surface and thereby keeping all wheels in ground contact.-To provides shock absorption and vibration insulation.-To exercise a constant pre-set force equalising in effect the initial load on one of the wheels. The material of which the spring is made increases in stiffness at deformation, the increase in stiffness is amplified by pulling on the all ready deformed profile.

Progressive increasing in stiffness is favourable in many human operated mechanisms, due to the same characteristic of connective tissue in the human body. Said springs can easily be exchange in their suspension, so that an optimal stiffness and damping characteristic can be chosen. Such an adjustment can be made guided by the weight of the individual, the riding style and even guided by the stiffness of the muscular connective tissue of the individual.

Said springs have been stressed to achieve initial elongation and will under the permitted operating mode remain fully form fast. Said springs have to be pre-tensioned in order that sets a limit from which they will start to operate. The springs have a progressive growing tensile stress elongation and they can be produced over a wide capacity variety. They are also easy to exchange. Said springs can act as vibration insulators, shock absorbers and load-adapters on brakes. The configuration of said spring makes it also possible to accept recoils generated at the contraction of the spring by thereto-related parts.

The invention also serves the purpose of making it possible to be adapted for the other tensioning devices on a roller skate

and structure them to the individual for obtaining optimum skating conditions.

The said purpose is fulfilled with a spring embodiment within the scope of the present claims.

DESCRIPTION OF THE DRAWINGS: A detailed description of the invention will now be given with reference to the accompanying drawings of which: Fig. 1 shows a three-dimensional view of a spring according to the present invention.

Fig. 2 shows a frontal view of the device shown in Fig. l.

Fig. 3 shows a frontal view of the device shown in Fig. l, when compressed by hand or a tool.

Fig. 4 shows a detailed longitudinal section view of the device shown in Fig. 1 assembled onto a roller skate.

Fig. 5 shows a detailed longitudinal section view of the device shown in Fig. 1 assembled onto a roller skate and fully activated.

Fig. 6 shows a detailed longitudinal section view of the device shown in Fig. 1 assembled onto a roller skate serving different purposes.

Fig. 7 shows a front view of a spring as shown in Fig. 6.

Fig. 8 shows a detailed longitudinal section view of a spring with double sections assembled onto a roller skate brake.

DESCRIPTION OF THE INVENTION: The embodiment hereafter described consists of a permanent elastic spring, of which the initial elongation has been reached by pre-stressing it. It is used for load adjustment; vibration insulation, shock absorbing, brake operation as well as all

other functions on roller skates requiring a spring loaded reciprocal movement. The springs are mounted in a roller skate frame 100 (See fig. 4,5,6,8).

Fig. 1 is showing the profile of the spring 1 the with a nearly elliptical first hole 2 and a second hole 3 for attaching a member of a part that operates the spring. The spring is made from permanent elastic vulcanised and stabilised rubber or EPDM well polymerised and saturated with peroxide and/or alternatives, has a progressive growing stress elongation relation and has been stressed in order to compensate for the initial elongation, which otherwise might occur during use, when necessary. it is well known that the form of permanent elastic material in the aforementioned qualities may undergo an initial elongation at intermitting stress loads but thereafter does not elongate further. The deformation in order to install the spring will take place at pressure points 4 and 5. The flattening that occurs at point 22 will bring that part all ready quite a bit along the stress-strain curve, so that it becomes stiffer. The first part of the deformation has a low stiffness, while the material has increasing stiffness along the curve. Once the deformation has taken place the spring 1 will be further stress loaded by pushing it to its receptacles at locations 24. Than that the amplification of the stiffness occurs that gives the required stiffness to the spring 1 to attain a high enough stress level to match the initial strain on the wheel. The whole can be done with the hands and needs no additional tools.

Fig. 2 is showing the main areas in which the spring will work.

In the areas A and B will the pressure forces 6 cause deformation compressing the inner ring and expanding the outer ring which will help the building up of the forces 8 and 9. (See also Fig. 3) The areas C and D will undergo an inverted action, in which the outer ring is compressed and the inner ring stretched. which again will help the building of the forces 8 and 9. The thickness 7 of the spring in area C and D varies in accordance with the spring characteristic required. While the over all dimensions, of the outside of the spring varies in accordance with the capacity.

Fig. 3 is showing the spring as its looks when deformed and stretched at 24 (see Fig. l). The forces 6 signify the reaction vertically. The forces 8 and 9 signify the reaction to the deformation in which surfaces on the in and outside of the ring are respectively stressed and compressed and under strain fitted. may it be understood that this situation is an integration of the whole gradient of forces working and represents a simplification. The lines 12 and 13 are the resultants of forces 6,8 and 9. The inclination of the lines 12 indicates that the smaller the angle, as signified in point 23, becomes the greater the force 9 becomes. During the pressing together by the forces 6 hardly become bigger because the leverage at 11 is growing during the deformation. Be it understood that the location of force centres 6,8 and 9 as well as the lever length 11 depends entirely on the final shape of spring 1.

Fig. 4 is showing a roller skate main frame 100, a hub 14 on the main frame 100 on to which the spring 1 has to be pushed. To facilitate the entrance of the spring the hub 14 is chamfered at its top 15. Once the spring 1 is installed on the hub 14 the spring 1 will clamp with its forces 8 and 9 (See Fig. 3) on the hub 14. A wheel casing 16 can now be installed, by pushing its pinion 18 in the second hole 3 (See Fig. 1) of the spring 1 and secured pivotal to main frame 100 by a hinge screw 17. A wheel 20 can than rotationally be installed to the wheel casing 16 with an axle bolt 19. The wheel encounters on the skating surface unevenness and will lift; thereby lifting the other wheels form the surface and consequently encounter a higher load. The higher load will create a moment of force at hinge screw 17. The counter moment of force is given by the spring 1 at the pinion 18 by expanding and thereby delivering a progressively growing force on the pinion 18. The wheel 20 and the wheel casing 16 will rotate around the hinge bolt 17 and will refrain from doing so until an equilibrium will be found signified in that, by lifting wheel 20, the other wheels regain ground contact. On a fully flat surface and with ground contact on all the wheels, the pretension of spring 1 should be such that the wheel casing does not pivot in the main frame 100.

Fig. 5 is showing a situation in which the wheel casing 16 has pivoted into its maximum position signifying;-further pivoting may bring the wheel 20 in contact with the main frame 100 as well,-further pivoting would over stress the spring 1,-the other wheels have not regained ground contact. The spring will now abut a buffer block 25 at contact area 26 and will start acting as a buffer.

The situation in which the spring 1 abuts the buffer block 25 is anomaly and surfaces, which generate this kind of result, frequently are unfit for roller skating any way.

Fig. 6 is showing another configuration of springs. A spring 30 is used as in the previous embodiment and is again by deformation assembled. However it is assembled simultaneously over frame pins 31 and 32 of a mainframe 200 and a holder pinion 33 of the wheel casing 34. The spring 30 is kept in place by a clip 35. A second spring 40 however has a complete different purpose and here it is used to keep a constant pressure on a pinion 41 on a lever 44. The lever 44 has as a purpose to press different parts together under constant pressure as well as to absorb vibration and shock which might occur in the operation system. The spring 40 has one opening (See Fig. 7) and is after deformation clasped around a pinion 43 of the main frame 200 and the pinion 41 is attached to the lever 44. A pinion 42 is placed on the main frame as a guide. Because of the deformation, again the spring 40 keeps a continuous pressure forward on the lever 44. Once the lever 44 is pushed backward and the spring 40 builds up a progressively growing force against the motion of the lever 44, thereby delivering a progressively growing operation force, which will make the user more aware of which braking power he is using.

Fig. 7 is showing the spring 40 of the device shown in Fig. 6 with its opening 45.

Fig. 8 is showing a spring 50 with two sections defined by openings 59 and 61 in the spring. In the middle of the spring it is an opening that fits a pinion 56 of a rotational operated disc brake 55. The spring characteristics of the part around

opening 61 have a higher progressive growth at elongation than the part surrounding opening 59. They have however after deformation and assembling the same value of pull. The situation drawn represent the spring 50 assembled by deformation and pushing around a pinion 54 of a cable shoe 51 and a pinion 58 which is connected to a frame 53 and pulls with equal force at those pinions 54 and 58. In the middle of the spring a pinion 56 is installed in a hole 60 in the spring together with the aforementioned assembling. The spring 50 does not exert any force on pinion 56 in the drawn position. When the pulling of cable shoe 51 of a cable 52 now stretches the spring 50 the whole spring 50 will expand. The expansion will be greater at the part around opening 59 because of its progressively lower spring capacity.

The pinion 56 will in any case be transported in the direction of the cable shoe 52. Once pinion 56 is drawn enough the disc brake 55 will hit the side of the wheel 57 and increase the roller resistance thereof. This also means that the expansion of the spring around opening 59 has stopped because pinion 56 can not rotate forward anymore. The expansion can than only be executed on the part of the spring around opening 61. Thereby a progressive braking stroke is created. On ending the braking stroke the spring 50 will return first the part around opening 61 and than move pinion 56 backward. Especially the latest part of the movement of bringing pinion 56 back will be relative slow and without shocks because of the equal spring forces and the natural damping of the spring material.