Powerball (exercise tool)
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Powerball is the common name for gyroscopic exercise devices such as the Dynabee gyroscopic grip-strengthening exercise device, which was originally produced by Dynabee from Variety Plastics in the USA: later patents for the Powerball device cover its extra features such as rev counters and gyro-powered LED lights. The light-emitting diodes are powered by a small generator embedded in the gyroscope, and these extra patents are owned by both the Dynaflex and Nanosecond companies. The toy itself is a small ball made of plastic or metal, and is commonly marketed as a gyroscopic wrist exerciser. It can be started with a short rip string or by a snap of the thumb. Once the gyroscope inside is going fast enough, a person holding it in his hand can accelerate the gyroscope to incredibly high revs by following a circular wrist motion with the device. Modern devices come with electronic rev counters (current record is 16,317rpm, set by Akis Kritsinelis from Greece Video here or here). He has also set a 90 second strength record of 20,082 revolutions see video.
The most advanced Powerball model on the market today is the 'Powerball 350Hz Metal' - this powerball is made completely of metal and is heavier then the other powerball models. This powerball is harder to spin because of its weight and torque, since it could produce about 250Nm of torque when the internal rotor is rotating at very high revs. The current "world record" for the metal Powerball is 13,731rpm, set by Akis Kritsinelis
In addition to the Powerball 350Hz, another 100% metal powerball is available on the market. They are marketed as 'Ironpower powerballs' and are available with both aluminium rotors and German made RVS steel rotors. There are also a number of rotor upgrades available. This metal powerball was on the Market in excess of a year before the Powerball 350Hz. The link that follows compares the differences of the rotors contained in both the 350Hz and the Ironpower model. Picture of both rotors
In the December of 2006 new Powerball model has been introduced. The model name is "Powerball Signature". This powerball is made of mirror-gray plastic and features much more stable rotor and "saphire" white LEDs. There is a video of this powerball model working available.
Nanosecond's Powerball was the first to feature electronic rev counters, and a generator with some light-emitting diodes, making this toy and training tool more attractive for professional and educational use.
At first sight the physics of this device looks confusing, but is surprisingly simple. It can easily be understood with a little knowledge of gyroscopes. Their striking property is that the axis of a spinning gyroscope will resist a force applied to it and will start rotating perpendicular to the force applied.
The axis of the gyroscope in the gyro powerball is fixed to the spinning mass and it rests in a little groove inside the wrist exerciser device, which almost completely covers the gyroscope inside it, except for a small round opening on top of it, which is where you can manually start the gyroscope. Once the gyro is spinning, tipping the device will cause the gyroscope to start precessing, with its axis slipping around in the groove in a circular fashion. The groove inside the device, is a little wider than the axis, and the gyroscope's evasive action towards the externally applied force will cause one end of the axis to push against the upper rim of the groove, while the other end of the axis pushes against the lower rim of the groove. While the axis is slipping around inside the groove, the friction between the axis and the groove rims will accelerate or brake the spinning gyroscope, with a maximum effect when the axis starts "rolling" inside the groove. Since this friction force is essential for the device's operation, the groove must not be lubricated. The acceleration of the gyroscope is best when the precession of the gyroscope is supported and amplified by wrist motion.
It takes a while until one finds the "rolling" point, but the gyro will also be accelerated to a smaller extent by the slipping friction.
The device is covered by US patents 3,726,146 (1973) and 5,353,655 (1994) by L.A. Mishler and US patent 5,800,311 (1998) by P.S.Chuang and 6,942,601 (2001) by P.S. Chuang
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[edit] External Links
[edit] Community sites
[edit] Shops, english
[edit] Shops, non-english
- Powerball The Original Belgium - Luxemburg Distributer
- Powerball The Original Brasil, Distributer
- Powerball Brasil
- Dynabee Europe website is English and the mother of powerballs
- Powerball Benelux website
- Ironpower metal Powerball website
