This invention relates to in-line roller skates, otherwise known as roller blades, and to roller skate attachments for such skates.

My existing international patent application published under W096/22818 describes an in-line skate attachment and includes reference to examples of prior art in-line roller skates. In-line roller skates, irrespective of the number of wheels, perform more favourably for straight line travel in terms of their rolling performance, or speed, when the wheels are all on the same horizontal plane, and therefore all in contact with the ground. With such an arrangement the wheels are set "level" . When turning corners, in-line roller skates perform better when the foremost and rearmost wheels are raised slightly relative to the other wheels. If the wheels are set in this manner, then the skate is said to be set for "rocking" . Existing in-line roller skates are frequently provided with mechanical means to change the arrangement of the wheels from "level" to "rocking", leaving the skater to make the choice between the two. The skater therefore has to choose between optimum rolling performance and optimum cornering performance, as it is not possible to have the best of both arrangements at the same time.

In my aforesaid international patent application there is described an in-line roller skate with a flexible chassis so that the arrangement of the wheels can be changed from "level" to "rocking" by flexing of the chassis in response to forces between the wearer's foot and the ground. The boot (or

a carrier for securing to the boot) is secured to the chassis centrally. In order to provide strength and desired modes of flexing between the central region of the skate and its ends, the securing extends over an extended central region, limited to allow flexing over substantial end regions. The roller skate attachment of the aforesaid application comprises a single row of aligned wheels for travelling on the ground, a resilient chassis for supporting the wheels, and a rigid carrier secured to the chassis at at least two fixing points, the carrier being adapted for securing to a boot, the chassis being resiliently deformable in the plane of rotation of the wheels, and the distance between the axis of the front wheel and the axis of the rear wheel being at least 1.5 times the distance between the front fixing point and the rear fixing point .

It is an object of the present invention to provide a roller skate attachment in which one has both level and rocking arrangements available at the same time without having to use a resilient chassis for supporting the wheels. It is a further object of the present invention to provide a roller skate attachment for securement to a boot in which, by the use of simple and economical means, one can have, simultaneously, the advantages of both the "level" and "rocking" arrangements. In accordance with one aspect of the present invention there is provided a roller skate attachment for securement to a boot, comprising a single row of at least three aligned wheels arranged for contact with the ground, wherein at least the foremost wheel and/or the rearmost wheel are mounted for sprung movement independently of the remaining wheel or wheels so as to permit displacement thereof in the plane of rotation

of the wheels .

Preferably, the sprung wheel or wheels is/are rotatably mounted on spring-biassed arms attached to a rigid chassis.

In a preferred embodiment, pivot axes about which the arms move are coincident with axes of rotation of other wheels of the row of wheels which are not mounted for sprung movement .

It is advantageous to use arms which are substantially triangular in shape in side elevation with the axis of rotation of the or each sprung wheel being located adjacent to an apex of the triangle.

Desirably, the attachment includes limit means to limit displacement of the sprung wheel or wheels.

Also in accordance with the invention there is provided a roller skate comprising a boot, a chassis fixed to or integral with the sole of the boot, a single row of at least three aligned wheels arranged for contact with the ground, at least the foremost and/or the rearmost wheel being mounted for sprung movement independently of the remaining wheel or wheels so as to permit displacement thereof in the plane of rotation of the wheels, and said remaining wheel or wheels being mounted on the chassis for rotatable movement only.

Among the advantages of this arrangement in accordance with the present invention are that one achieves the best of both the "level" and "rocking" arrangements commonly in use, at the same time. Also, this arrangement provides good rolling performance over level ground with an improved ride over bumpy or uneven ground. Additionally, with sprung mounting of the rearmost and foremost wheels, one has, when cornering, a curved trajectory through the contact points between the ground and all the wheels, thus providing improved

cornering. Moreover, as compared with a roller skate having all the wheels set level in a totally rigid chassis, one has reduced scrub of the rearmost and foremost wheels because of their sprung mounting. In order that the invention may be fully understood, a number of embodiments of roller skate attachment in accordance with the invention will now be described by way of example and with reference to the accompanying drawings. In the drawings:

Fig. 1 is a schematic side view of a first embodiment of roller skate in accordance with the invention;

Fig. 2 is a schematic side view of a second embodiment of roller skate in accordance with the invention;

Fig. 3 is a schematic side elevation of a third embodiment of skate in accordance with the invention; Fig. 3A is a detail view, on an enlarged scale, of part of the skate shown in Fig. 3;

Fig. 4 is a schematic side elevation of a fourth embodiment of skate in accordance with the invention;

Fig. 5 is a schematic side view of a fifth embodiment of skate in accordance with the invention;

Fig. 6 is a schematic side elevation of a sixth embodiment of skate in accordance with the invention;

Fig. 6A is a detail view, on an enlarged scale, of the torsion bar used in the embodiment shown in Fig. 6; and, Fig. 7 is a schematic side view of a seventh embodiment of skate in accordance with the invention.

Referring first to Fig. 1, there is shown a boot 10, to the sole of which is fixed a rigid chassis 12. Alternatively, the chassis can be an integral part of the boot. The rigid chassis 12 carries two rotatable wheels 14 which are mounted on the chassis by conventional spindles and

screws at axle points 16. The in-line row of wheels for the skate includes a front wheel 18 and a rear wheel 20 in the present embodiment where the row consists of four wheels in line. The front and rear wheels 18, 20 are mounted by axles 22 in pairs of generally triangular arms 24. For each wheel 18, 20 there is provided a pair of parallel arms 24, one each side of the chassis, so that the wheels are mounted between the respective arms. The arms 24 are secured to the chassis 12 at the same axle points 16 as are used for the mounting of the centre wheels 14. The arms 24 are here mounted for limited pivotal movement about the axles 16. The front and rear wheels 18, 20 are mounted adjacent to the free ends of the arms 24. Each of the arms 24 is provided with an arcuate slot 26 therethrough, adjacent to the pivot axles 16. Stop pins 28 limit the pivoting movement of the arms 24 about the axles 16. As shown in Fig. 1, the stops 28 are in the form of screws which are fitted through the slots 26 and which are screwed into threaded holes in the chassis. The location and movement of the front and rear wheels 18, 20 is further controlled by springs of one type or another, which are not shown in Fig. 1. By virtue of the springs and the arms 24 which act as radius arms, the front and rear wheels 18 and 20 are capable of sprung movement up and down as the load on the chassis changes. Fig. 2 shows an alternative embodiment in which substantially triangular shape radius arms 24 are again provided. In this embodiment a single rubber compression spring 30 is fastened to the rigid chassis 12, substantially midway between the two centre wheels 14 of the skate. A push rod 32 is fastened to each of the arms 24 adjacent to that corner of the triangle which is remote from the two wheel-

mounting points. The push rods 32 have end plates 34 which face the compression spring 30. When the front and rear wheels 18 and 20 move vertically upwards upon pivoting about the axles 16, the push rods 32 will be moved inwards towards the spring 30, compressing the rubber of the spring and serving to limit the displacement of the front and rear wheels.

Fig. 3 shows a third embodiment of skate, which is generally similar to that of Fig. 1, except that at the rear end there is provided a rubber compression spring 36 secured to the rigid chassis 12 below the heel of the boot. Below the spring 36 is a push rod 38 which is shown here with a thread and hexagonal nut 40 for adjusting the ride height of the wheel or the tension of the rubber. The lower end of the push rod 38 is connected to the radius arm 24 at a position approximately midway along the length of the upper edge of the arm. Fig. 3A is an end elevation which shows how the push rod 38 is located between the two parallel plates of the radius arm 24. As can be seen, the push rod 38 has an enlarged end which is provided with threaded holes into which screws 42 can be fitted.

Fig. 4 shows yet another variation, in which a wire spring 44 is used to provide the sprung mounting for the radius arms 24. As shown, the wire spring 44 is secured to the rigid chassis 12 at a securing point 46. With this type of spring arrangement as shown in Fig. 4, two springs of different tensions may be used, one for each of the radius arms 24. This can provide different ride characteristics for the front wheel on the one hand and the rear wheel on the other hand. Additionally or alternatively, a means of adjustment (not shown) may be used at the leverage points 48

where the springs are fixed to the radius arms, to vary the spring characteristics.

Fig. 5 shows the use of a single leaf or wire spring 50 secured to the rigid chassis at a fixing point 52. With this arrangement the spring 50 is pulled by tension rods 54, instead of being pushed by push rods. The tension rods 54 are secured at the leverage points 48 to the radius arms 24. The tension rods 54 are connected to the respective ends of the spring 50 by respective sleeves 56 which provide for longitudinal adjustment along the end of the spring, in order to vary the spring characteristics for each of the front and rear wheels.

Fig. 6 shows yet another embodiment in which a torsion bar 58 is provided. The torsion bar 58 may be secured to one side of the chassis 12 or alternatively may be Z-shaped and extend through the rigid chassis, with its ends projecting on opposite sides of the chassis. This is shown most clearly in the detail view of Fig. 6A. The torsion bar 58 is operated by push rods 60 at front and rear. The respective push rods 60 are secured at one end to the torsion rod and at the other end to a mounting point 62 substantially midway along the upper edge of the respective radius arms 24. As shown, one push rod 60 is mounted on one side of one radius arm and the other push rod 60 is mounted on the other side of the other radius arm.

Fig. 7 shows an embodiment in which a leaf spring 64 is fastened between an attachment point 66 on the chassis 12 and an attachment point or points 68 on the rear radius arm 24. Two attachment points 68 on the radius arm 24 are shown. This is for security of fastening.

As will be apparent from the variety of embodiments which

are described above and which are shown in the drawings, various types and combinations of springs can be used to provide the sprung mounting for the foremost and rearmost wheels of the skate. The springs which are shown in the drawings are simply by way of example.

One further alternative would be to provide a single flat spring extending through the wheel axles of the foremost and rearmost wheels. This gives automatic level location.

The present invention is applicable to in-line roller skates which have three or more wheels. It is particularly appropriate for skates which have four or more wheels. Also, although in the illustrated embodiments of the invention both the foremost wheel and the rearmost wheel are mounted for sprung movement independently of the remaining wheel or wheels, it is possible within the scope of the invention to have a skate or skate attachment in which only the foremost wheel or only the rearmost wheel is so mounted. This would be less satisfactory than providing a sprung mounting for both end wheels, but would give some degree of advantage to the user.