Skateboard

Abstract: The invention relates to a skateboard which includes two footboards (10, 12) with each footboard (10, 12) consisting of a foot platform (18) and a wheel-set (16, 52) which carries two wheels (24) in axial alignment fixed to the underside of the platform (18), a spacer element (14) for holding the footboards (10, 12) in a spaced relationship and a pivot arrangement (30) having a vertical pivot axis A connecting each footboard (10, 12) to the spacer element (14) to enable both footboards (10, 12) to pivot relatively to the spacer element (14) about said vertical axes A.

Description: BACKGROUND TO THE INVENTION Conventional skateboards consist of a substantially rigid board which carries two spaced wheel-sets or trucks which are fixed to its underside with the wheels of the wheel-sets lined on a common track. The wheels of each wheel-set, on the more elaborate boards, are very slightly steerable through an offset suspension system with the skater steering the board by shifting his feet on and his body position above the board so that the centre of gravity of his weight may be used to vary the adhesion of the wheels on a common wheel-set with the road surface. U.S. Patent Nos. 3,771,811 and 4,202,559 disclose boards in which one of the wheel-sets is fixed to the underside of the board while the other is attached to the underside of a rotatable platform at the other end of the board so that the platform and its wheel-set are steerable as a unit by a foot of the skater. The purpose of the steering platforms on both boards is, according to the specifications, to provide a board for children or novices which may easily be foot steered without positional shifting of the skaters body on the board. In yet a further variation of a known skateboard which is described in U.S. Patent N° 4,076,267 the footboard is transversely split at its centre with the two board halves being connected together by a pivot connection which enables the board halves to pivot relatively to each on an axis which lies in the long direction of the board. This board carries conventional wheel trucks as described above with the transversely pivotable board halves perhaps slightly improving the steering capability referred to in connection with conventional wheel trucks. OBJECT OF THE INVENTION It is the object of this invention to provide a skateboard which is steerable and is highly manoeuverable relatively to conventional boards. SUMMARY OF THE INVENTION A skateboard according to the invention includes two footboards which lie in a common plane with each footboard including a foot platform and a wheel-set which carries two wheels in axial alignment which are fixed to the underside of the platform characterised in that the footboards are spaced from each other by a spacer element for holding the footboards in their spaced relationship and a pivot arrangement having a pivot axis which is perpendicular to the plane of the foot platforms connecting each footboard to the spacer element to enable both footboards to pivot about their pivot axes relatively to the spacer element thereby providing movement of said wheels which corresponds to the movement of said footboards. Further according to the invention each wheel-set includes a resilient suspension member which is located in the wheel-set to enable limited resilient pivotal movement of the platform relatively to wheel-set attached to it in a direction transverse to the direction of the axis of rotation of the wheels of the wheel-set. In one form of the invention each wheel-set includes a wheel body, wheel axles, which are fixed to and project from the opposite sides of the body with the wheels being journalled for rotation on the axles, a first pivot pin which is attached to the wheel body with its axis perpendicular to the plane of the foot platforms, a support arrangement on the wheel body, a second pivot pin pivotally connecting the foot platform to the support arrangement on a pivot axis normal to the wheel axis, with the resilient suspension member being located between the support arrangement and the underside of the foot platform to hold the platform horizontal and a pivot arm on the spacer element which is pivotally engaged with the first pivot pin. Still further according to the invention the pivot arrangements on the spacer element each carry a rotatable bearing which rides on horizontal faces of the wheel-set body slots to prevent the pivot arms from binding with the wheel-set bodies during pivotal rotation of the footboards relatively to the support element. The skateboard may include foot straps which are attached to the foot platforms. BRIEF DESCRIPTION OF THE DRAWINGS The invention is now described by way of example only with reference to the drawings in which : FIGURE 1 is a partially sectioned plan view of one embodiment of the skateboard of the invention, FIGURE 2 is a side elevation fo the Figure 1 board, FIGURE 3 is an exploded perspective view as seen from below of one of the footboards of the skateboard of Figures 1 and 2, FIGURE 4 is a sectioned side elevation of the assembled footboard of Figure 3. FIGURE 5 is a plan view of the Figure 4 footboard shown sectioned on the line 5 - 5 in Figure 4, and FIGURE 6 is a side elevation of a second embodiment of the board of the invention. DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS The skateboard of Figures 1 and 2 is shown in the drawings to consist of two footboards 10 and 12 and a spacer element 14 which is pivotally connected at each of its ends to a footboard to hold the footboards in the spaced relationship shown in the drawings. Each of the footboards consists, as is more clearly seen in Figures 3 and 4, of a wheel-set body 16 and a foot platform 18. The wheel-set bodies each include two stub axles 20 which are threadedly located in bosses 22 which project from opposite sides of the body, wheels 24 which are made from a fairly hard resilient material and rotatably located on the stub axles 20, an upper support arrangement indicated generally at 26, a sector shaped slot 28 which is more clearly seen in Figures 4 and 5, a first pivot pin 30, a resilient suspension pad 32 and a second pivot pin 34 for pivotally holding the foot platform 18 to the support arrangement 26. The suspension pad 32 is made from a hard rubber or suitable plastic and, as shown in Figure 3, includes a rectangular base portion and two upwardly and outwardly directed wings 35. The upper surface of the pad is grooved between the wings to locate the pad on the pivot pin 34 in use. The support arrangement 26 includes two upwardly directed gabled lugs 36 which are holed to receive the pivot pin 34 and a rectangular recess, not shown, in which the base of the suspension pad 32 is located in use. The spacer element 14 consists of an elongated frame member 37 which carries a pivot arm 38 on each of its ends. The frame member is made from any suitably rigid and robust material such as reinforced plastic, alluminium or the like. The pivot arms 38 each consist of a pivot lug 40 which carries a suitable bush 42, a roller bearing 44 and a spigot 46 which is a press fit in a bore in the end of the frame member 37. A locking pin 48 passes through the spigot 46 and the frame member to hold the pivot arm against rotation and withdrawal from the bore in which it is located. The slots 28 in the wheel-set body 16 are each outwardly stepped at 50 to a dimension at which the roller bearing 44 on the pivot arm is a nice fit as shown in Figure 4. To assemble the skateboard the pivot arm lugs 40 are located in the slots 28 in the wheel-set bodies, the pivot pins 30 are passed from the underside of the bodies through the bush in the lugs 40 and are locked to the bodies by lock nuts 52 which are located in recesses in the bases of the suspension pad recesses in the support arrangement 26. The suspension pad 32 is now located in the recess in the upper surface of the support arrangement 26 and the foot platforms are pressed heavily down on to the wings 35 of the suspension pad resiliently to deform the wings downwardly against the bias of the pad material until holes in lugs 54 on the undersides of the foot platforms are in register with the holes in the support arrangement gable lugs 36. The pivot pin 34 is now pressed through the registering holes in the gable lugs 36 and lugs 54 on the foot platform and locked in position by means of circlips as shown in Figure 4. The pivot pin is now firmly located in the central groove on the upper surface of the suspension pad firmly to locate the suspension pad in the wheel-set. The upward bias of the suspension pad wings 35 on the underside of the foot platform holds the platform horizontal while allowing a limited resilient pivotal movement of the platform about the pivot axis of the pin 34. From the above it will be appreciated that the foot platforms 10 and 12 are rotatable about the axes A of the pivot pins 30 within angular limits imposed on them by vertical edges 51 of the slots 28 in the wheel-set bodies 16. This is illustrated in Figures 1 and 5 in which the chain lines B illustrate the limit positions of the angle of rotation of the support element relatively to the footboards at which the vertical side edges of the slots 28 come into contact with the sides of the pivot arm lugs 40. At the limit positions of rotation of the footboards the wheels 24 are just out of breaking contact with the spacer element 37 as illustrated on the left hand side of Figure 1. The skateboard of Figure 6, as with the skateboard of the previous embodiment, includes two footboards 10' and 12' and a spacer element 14. In this embodiment of the invention, however, the foot platforms 18 are supported on substantially conventional skateboard wheel-sets 52. The spacer element 14 of this embodiment of the invention consists of two metal straps 56 and a spacer 58 which is sandwiched between and fixed to the straps to keep them spaced apart vertically. The wheel-sets 52 each consist of separate upper and lower portions 60 and 62 and an annular rubber or like resilient torsion member 64. The lower portion 62 of each wheel set includes a ring portion which tightly surrounds the torsion member 64 with a ball and socket arrangement 66 connecting the outer ends of the wheel set components. A pivot bolt 68 passes through the spacer straps 56 and the bore of the torsion member 64 to be threadedly anchored in the wheel set portion 60. The footboards, in this embodiment of the invention, are therefore pivotable relatively to the spacer element on the axes A. The lower portion 62 of the wheel-sets enable the foot platforms 18 resiliently to pivot in a direction transverse to the spacer element 14 by the torsion members 64 being able resiliently to deform and so tilt within the rings of the lower portion 62 of the wheel-sets while the tilting motion of the platforms is supported by the ball and socket joints 66 on the outer ends of the wheel-sets. The footboards 18 of the skateboards of the invention may conveniently include footstraps which are fixed to the platforms to pass over the upper surfaces of the boards in a direction transversed to the wheel axes. The upper surfaces of each of the footboards preferably carries a non-skid surface material 90. The skateboard of the invention is primarily intended for use as a dynamically operational vehicle for competitive use. The board is steered or turned by the rider of the board standing astride the board with his feet on the foot platforms with his foot direction lying in the direction of the wheel axes of the wheel-sets while the board is in motion and splaying his feet to rotate the boards 10 and 12 about their pivot axes A so that each of the wheel sets follows a common curved track with the centre of the curve being the crossing point of lines in register with the axes of the wheels on each footboard. The radius of the curve is determined by the degree of splay of the footboards. The high performance skateboards of the invention which include a resilient suspension member may, however, also be turned by the rider holding his feet parallel on the boards 10 and 12 and shifting his weight above the board to tilt the board as is the case with a conventional skateboard with non-steerable wheel-sets. The optimum turning method of the board of the invention is, however, a combination of both the turning of the footboards about their vertical pivot axes A and by simultaneous weight shift of the rider over the board to tilt the footboards against the bias of the pads 32. In practice in very sharp turns at speed, with the board of the invention the rider leans forwardly or backwardly by as much as 45° towards the inside of the turn with the boards tilted to their maximum extent to resist the centrifical force generated in the turn. His feet and so the footboards are either inwardly or outwardly splayed in dependence on whether he is leaning forwardly or backwardly so that the wheel axes point to the centre of the turning radius. The manoeuvreability of the board is obviously much greater than is the case with a conventional skateboard with non-steerable wheel-sets with which the wheel track of the board may only slightly be varied or a board in which only one of the wheel-sets is steerable. With boards with one steerable wheel-set, if wheel skid is ignored, the turning radius will be the meeting point of lines which lie on the axes of the two wheel-sets. This meeting point will be brought significantly closer to the board if the fixed wheel-set, if it were capable of rotation, was now rotated in the opposite direction to that of the first steerable wheel-set to bring the meeting point on the wheel axle lines far closer to the board significantly to decrease the turning radius of the board as is the case with the board of the invention. Another significant advantage which the board of the invention has over conventional boards with non-steerable wheel-sets or boards which have a single steerable wheel-set is that by pivotal movement of both the footboards and suitable weight distribution the board can be caused to follow a sharp sinusoidal track enabling the board to be propelled at fairly high speed over a flat or even an upwardly inclined surface.

Claims: A skateboard including two footboards (10,12;10',12') which lie in a common plane with each footboard (10,12;10',12') including a foot platform (18) and a wheel-set (16,52) which carries two wheels (24) in axial alignment which are fixed to the underside of the platform (18) characterised in that the footboards (10,12;10',12') are spaced from each other by a spacer element (14) for holding the footboards (10,12;10',12') if their spaced relationship and a pivot arrangement (30,40;62,68) having a pivot axis (A) which is perpendicular to the plane of the foot platforms (10,12;10',12') connecting each footboard (10,12;10',12') to the spacer element (14) to enable both footboards (10,12;10',12') to pivot about their pivot axes (A) relatively to the spacer element (14) thereby providing movement of said wheels (24) which corresponds to the movement of said footboards (10,12;10';12'). A skateboard as claimed in claim 1 characterised in that each wheel-set (16,52) includes a resilient suspension member (32,64) which is located in the wheel set (16,52) to enable limited resilient pivotal movement of the platform (18) relatively to wheel-set (16,52) attached to it in a direction transverse to the direction of the axis of rotation of the wheels (24) of the wheel-set (16,52). A skateboard as claimed in claim 2 characterised in that each wheel-set includes a wheel body (16), wheel axles (20), which are fixed to and project from the opposite sides of the body (16) with the wheels (24) being journalled for rotation on the axles (20), a first pivot pin (30) which is attached to the wheel body (16) with its axis (A) perpendicular to the plane of the foot platforms (10,12;10',12'), a support arrangement (26) on the wheel body (16), a second pivot pin (34) pivotally connecting the foot platform (18) to the support arrangement (26) on a pivot axis normal to the wheel axis, with the resilient suspension menber (32) being located between the support arrangement (26) and the underside of the foot platform (18) to hold the platform (18) horizontal and a pivot arm (38) on the spacer element (14) which is pivotally engaged with the first pivot pin (30). A skateboard as claimed in claim 3 characterised in that the wheel body (16) and the support arrangement (26) of each wheel set (16) are integral to provide a wheel-set body (16) with the pivot arms (38) on the spacer element being engaged with the first pivot pins (30) of each wheel-set (16) trough slots (28) in the wheel-set bodies (16). A skateboard as claimed in claim 4 characterised in that the slots (28) in the wheel set bodies (16) have radially displaced vertical edges (51) to stop rotation of the spacer element (14) pivot arms (38) on the first pivot pins (30) to prevent the wheels (24) from coming into contact with the spacer element (14). A skateboard as claimed in claim 4 characterised in that the pivot arms (38) on the spacer element (14) each carry a rotatable bearing (44) which rides on horizontal faces (50) of the wheel set body slots (28) to prevent the pivot arms (38) from binding with the wheel-set bodies (16) during pivotal rotation of the footboards (10,12) relatively to the support element (14). A skateboard as claimed in any one of the above claims including foot straps which are attached to the foot platforms (10,12).

Inventors: FISHER JAMES, KING SIMON, SMITH ERIC OLIVER MACLEOD, FISHER, JAMES, KING, SIMON, SMITH, ERIC OLIVER MACLEOD
Applicants: ANDERSON ROGER WILLIAM, ANDERSON, ROGER WILLIAM
Application year: 1990
Main classification: A63C17
IPC codes: A63C5, A63C17