1. Field of the Invention
The present invention relates to weight lifting equipment and more particularly pertains to devices used for weight lifting and weight training, such as barbells and dumbbells. The present invention also relates to weights for weight lifting equipment.
2. Description of Related Art
Prior art dumbbells and barbells consisting of a handle with a weight at either end are well known in the art. In the current popular form, dumbbells and barbells are made by the attachment of discs to either end of the handle. The disks may be permanently attached, unitarily formed to the handle, or they may be attached by locking collars. By using locking collars, a dumbbell becomes unnecessarily wide and difficult to balance.
A tight tolerance between the weights and the handle is preferred in manufacturing and using dumbbells. Without a tight tolerance, the weights can wear out. They will wobble and eventually rotate around the handle. The wobble and rotation will continue to worsen over time. Eventually the weights may even fall apart and injure the user. Even if the weights are not an actual danger, they may cause apprehension or otherwise distract the user. Thus, the user cannot focus solely on lifting the resistance weight and the user will not be able to obtain the full benefit of a weightlifting regimen.
U.S. Pat. No. 5,484,367 to Martinez illustrates a toy barbell set with a polycarbonate material bar that simulates the bending characteristics of steel. A key extends from the bar, and the weights and locking collars have a corresponding hole formed therein. U.S. Pat. No. 4,529,197 to Gogarty describes a dumbbell wherein the weights on either end of the handle have corresponding grooves so additional weights may be added outside of weights already attached to the dumbbell. U.S. Pat. No. 6,120,420 to Pearson et al. discloses a unitary exercise device with a light shell surrounding a denser core.
A dumbbell or barbell with a tight tolerance between the weight and the handle might be made if a weight were made entirely out of a tough, rigid material, such as steel. However, such a weight would be very expensive to manufacture. Metal casting is a simple manufacturing process which is inexpensive for forming weights. However, cast weights generally wear out. In addition, metal weights without a protective coating can mar flooring if they are dropped.
None of the prior art references teaches a weight or an exercise device that combines the benefits of a tight tolerance fit between the tough, rigid materials in the handle and in the weight, with the ease of manufacture and low cost of casting. Consequently, there is a need for taking advantage of the cost benefits of using casting in manufacturing weights. There is also a need for a weight that is well-secured to the handle and has a tight tolerance fit with a handle. There is also a need for a weight for a barbell or dumbbell that will not wear down and wobble and rotate around the handle. In addition, there is a need for exercise devices such as these that do not require locking collars.