A variable resistance device incorporated in an exercise machine for providing selectively-variable resistance, including:
- an exercise machine;
- a primary circular fluid chamber adapted to receive fluid therein, the primary fluid chamber having a circular primary fluid flow region;
- a rotation mechanism, which includes rotating vanes, being positioned and adapted to rotate within the primary fluid flow region such that the rotation mechanism upon rotation encounters a degree of resistance dependent on the amount of liquid in the primary fluid chamber, the rotation mechanism being adapted to be rotated by rotational input from a user of the exercise machine, a gap being defined between the vanes and a wall of the primary fluid chamber such that the vanes can rotate without obstruction by the wall, the primary fluid chamber being adapted to be positioned upright in use;
- a secondary fluid chamber adapted to achieve and maintain an appropriate amount of the liquid in the primary fluid chamber to provide a selected degree of resistance for the exercise machine, the secondary fluid chamber having a secondary fluid flow region, a wall of the secondary fluid chamber being provided with an inlet positioned, in use, at or substantially close to the top of the secondary fluid chamber, the inlet allowing liquid to flow from the primary fluid chamber into the secondary fluid chamber, the secondary fluid chamber being provided with an outlet spaced from the inlet to allow liquid to flow out of the secondary fluid chamber and into the primary fluid chamber;
- a fluid flow circuit, which includes said primary and secondary fluid flow regions, through which circuit the liquid flows to establish a circuit-flow condition that repetitively cycles around the circuit from the primary fluid flow region into the secondary fluid flow region and then back into the primary fluid flow region, the circuit-flow condition being adapted to establish and maintain said appropriate amount of liquid in the primary fluid chamber during use;
- a valve that variably controls flow of liquid through the circuit to selectively establish different circuit-flow conditions each corresponding to a different appropriate amount of the liquid in the primary fluid chamber to provide a different degree of resistance;
- wherein, in use, when the user provides the rotational input, the liquid moves around the primary fluid chamber and also through the fluid flow circuit;
- and
- also wherein, in use, when the user ceases providing the rotational input, the liquid in the uprightly-oriented primary fluid chamber falls to bottom of the primary fluid chamber thereby acting as a body of liquid that stops the rotation of the rotation mechanism;
- the secondary fluid chamber is positioned internally within the primary fluid chamber, the primary fluid flow region of the primary fluid chamber is defined by inner surfaces of the primary fluid chamber and by outer surfaces of the secondary fluid chamber, the inner surfaces of the primary fluid chamber form a first circle, the outer surfaces of the secondary fluid chamber form a second circle which is concentric and coaxial with the first circle, the primary fluid flow region being generally between the two;
- the primary fluid chamber and the secondary fluid chamber are arranged such that the amount of liquid contained in the device remains substantially constant.