Patent Application
20160045814
1. Field of the Disclosure
The subject disclosure relates to skateboards and similar devices and particularly to a rider driven skateboard.
2. Related Art
Attempts have been made in the past to provide skateboards with mechanical drives. However, such devices have exhibited various problems and disadvantages.
According to illustrative embodiments, a rider driven skateboard is provided comprising a pair of front wheels mounted on a front axle having first and second sprag (“one way”) clutches mounted in respective front wheels, and a pair of rear wheels mounted on a rear axle having respective third and fourth sprag clutches mounted in respective rear wheels. A drive mechanism is configured to drive the front axle so as to rotate the front wheels to drive the board forward when a rider's weight is shifted to the rear of the skateboard deck and is further configured to drive the rear axle so as to rotate the rear wheels to drive the board forward when the rider's weight is shifted to the front of the skateboard deck. In one illustrative embodiment, the skateboard drive mechanism may comprise a belt and pulley system, while in another it may comprise a plurality of gears and a constant torque or constant force spring or other self-winding device. Additionally, in other embodiments, a one way clutch is only installed in one of the front wheels and one of the rear wheels.
The componentry of the rear truck housing 18 is shown in
The componentry of the front truck housing 17 is illustrated in
From the above, it will be seen that the main components of the skateboard assembly include skateboard truck housings 17, 18, each including a main axle 102 running on two ball bearings 103. One or both wheels 106 on the axle 102 has inboard a one way sprag clutch bearing 105, with a regular ball bearing 107 mounted outboard and inboard on any wheel 106 where there is no one way clutch 105. There is a woodruff key 112 between the main axle 102 and the inside diameter of each one way clutch bearings 105.
The skateboard “deck 12” hinges on a shaft 16 in the middle of the board 11, allowing the deck 12 to pivot up and down, front to back and vice versa. In an illustrative embodiment, there is a 1:2 gear ratio between the spring shaft gear 113a and the main axle gear 116, but various gear ratios may be utilized. There are two ways to machine and assemble the truck gears: with or without an intermediate shaft, which determines if the truck can be installed on the front or the rear of the skateboard 11.
The illustrative drive system also utilizes a so-called “Constant Torque Spring” (or constant force spring) 114, which is a flat spring that is wound on a spring shaft 113 which is larger in diameter than the natural wound diameter of the spring. The CT spring 114 stays tight around this spring shaft 113 and when extended will always want to roll itself back around the spring shaft 113, i.e. each spring 114 is self-winding. Each spring 114 is attached to the deck 12 by a swivel attachment mechanism 122.
The operation of the illustrative embodiment of
During this action, the front main axle 102 is spinning freely in the two main ball bearings 103 that are held in aluminum truck housing 17. Inside one or both wheels 106 is located a one way sprag clutch bearing 105 that is keyed to the main axle 102 by way of a woodruff key 112. Outboard, each wheel 106 has a ball bearing 107 and inboard on any wheel 106 where there is no one way clutch 105. The one way sprag clutch bearing 105 is mounted such that it will transfer the rotational driving force from the main axle 102 to a respective wheel 106 and thereby will drive the board 11 forward.
When the rear of the deck 12 is in the lowest position, the skateboard 11 will continue to roll due to its kinetic energy, and the one way sprag clutch bearings 105 utilized in one or more of the wheels 106 will prevent the forward motion of the wheels 106 driving backward through the mechanism and moving the deck 12. At this point, the skateboard 11 is essentially freewheeling. In an embodiment where only one front wheel and only one rear wheel is equipped with a one-way or sprag clutch, it is only the wheels which are so equipped which are driven by the shifting of the rider's weight.
Now the rider will move his weight onto the front half of the deck 12, causing the deck 12 to pivot forward with the front of the deck 12 moving down, which will then force the rear of deck 12 upwards. The front constant torque spring 114 has sufficient spring tension that it will retract and roll itself back up onto front spring shaft 113. At the same time, the rear of the deck 12 will pull on the rear constant torque spring 114, which will extend, causing the rear spring shaft 113 with its main gear 113a to rotate.
The rear spring shaft 113 main gear 113a engages directly into an intermediate gear 109 that has half the number of teeth as compared to the rear spring shaft main gear 113a, causing the rear axle 102 to spin at twice the rate of the spring shaft gear 113a. The intermediate gear 109 is freely spinning on an intermediate shaft 110 using needle bearings 111 and engages directly into a main gear 116 cut into rear main axle 102. The use of the intermediate gear 109 reverses the driving direction which means that extension of the rear constant torque spring 114 will rotate the rear wheels 106 in the same direction as the front wheels 106, driving the board 11 forward as well. In one embodiment, the main gear 116 has the same number of teeth as the intermediate gear 109.
Thus, the pivoting deck 12 will generate rotational driving force alternating between the front and the rear axle 102, with each axle driving the board in a forward direction. When keeping the deck 12 stationary (not pivoting), the skateboard 11 will continue to move as long as there is sufficient forward momentum, and the clutches 105 will enable a freewheeling drive system.
The componentry of one of the trucks, e.g. 129, is illustrated in
The skateboard 120 operates as follows, the rider steps onto the deck 121, and when the rider shifts weight onto the rear half 133 of the deck 121, the front of deck 121 will move the front belt pulley plate 209 up. Because the end of tooth belt 214 is clamped in clamp 215 and fixed to the truck housing 201 by means of a clamp lock plate 216, the increase in distance between truck housing 201 and belt pulley plate 209 will rotate belt pulleys 211 that are mounted in belt pulley plate 209. Since the configuration of the belt pulleys 211 is a so-called “block and tackle system” the number of rotations of the main pulley 216 located on main axle 202 will be twice the number of rotations of the bottom pulley 211 that is mounted in the front belt pulley plate 209.
The front main axle 202 spins freely in two main ball bearings 203 that are held in the aluminum truck housing 201. Inside one or both wheels 206 inboard, closest to the truck 201, is located one of the one way sprag clutch bearings 205, which is keyed to the main axle 202 by way of a woodruff key 212. Outboard, each wheel 206 has a ball bearing 207 and inboard on any wheel 206 where there is no one way clutch 205. Each one way sprag clutch bearing 205 is mounted such that it will transfer the rotational driving force from the main axle 202 to a respective wheel 206 and therefore will drive the board 120 forward.
When the rear 133 of deck 121 is in its lowest position, the skateboard 120 will continue to roll due to its kinetic energy, and the one way sprag clutch bearings 205 in the wheels 206 will prevent the forward motion of the wheels 206 from driving backward through the mechanism and moving the deck 121. The skateboard 120 is essentially freewheeling.
Now the rider will move his weight onto the front half 134 of deck 121, causing deck 121 to pivot forward with the front of the deck 121 moving down. The rear section 133 of deck 121 will move upwards and with it also rear belt pulley plate 209, which also provides a “block and tackle” configuration on a belt/pulley system at the rear of the board 120. When the rear belt pulley plate 209 moves up, the increased distance between rear truck housing 201 forces the bottom pulley 211 in rear belt pulley plate 209 to rotate and the toothed belt 214 will then rotate the main pulley 216 on the rear main axle 202. The pulley configuration in the rear 133 is such that the rotational direction of rear main axle 202 is identical to front main axle 202.
As will be appreciated, the front block and tackle pulley system is linked to the rear block and tackle pulley system by means of the tooth belt 214. Since the deck 121 pivots in the middle, and since the distance from the middle of deck 121 to either the front belt pulley plate 209 and rear belt pulley plate 209 is identical, the increase in length of the belt 214 in the front pulley system results in a similar decrease in belt length in the rear pulley system. In the illustrative embodiment, the tooth belt 214 is a single side tooth belt that will need to be turned 180 degrees, as illustrated in
Thus, in the illustrative embodiment of
From the above, it will be seen that the main components of the illustrative skateboard assembly of
As illustrated in
As noted above, illustrative embodiments employ one-way clutches, with a sprag clutch being one example. Illustrative one-way clutches can maintain high torque capacity in one direction and no torque capacity in the other direction. Illustrative embodiments of sprag type clutches transmit torque from an inner raceway to an outer raceway or vice versa. Such clutches have precision components known as sprags, which are rotatably mounted between annular rings that form a cage to hold the sprags in position. Many sprag clutches include spring biasing elements to align the sprags in desired position when torque is not being transferred by the clutch. Typically, the spring biasing elements are mounted inside the cage, between the annular plates.
Thus, those skilled in the art will appreciate that various adaptations and modifications of the just described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.
