The present invention is related to a rock climbing apparatus, and more particularly to a lightweight rock climbing apparatus which has sufficient strength and can be easily assembled for personal or domestic rock climbing exercise.
Rock climbing has become a popular activity. However, natural outdoor rock field can be hardly found. Moreover, there is safety problem in real rock climbing. Therefore, many artificial rock fields have been built. However, the artificial rock field necessitates larger space and the equipments of the artificial rock field are expensive. Therefore, the cost for such rock climbing exercise is high.
U.S. Pat. Nos. 5,549,195, 5,125,877 and 5,919,117 disclose rock climbing apparatuses. In each of those rock climbing apparatuses, a caterpillar structure is arranged on a frame body. The caterpillar structure is connected with a transmission mechanism for restricting the rotational speed of the caterpillar structure. Two sides of the caterpillar structure are respectively disposed in the rails of the frame body via chains or rollers, whereby the caterpillar structure can circularly revolve along the rails. Multiple rocks are arranged on the caterpillar structure for a user to climb for rock climbing exercise.
In the caterpillar structure of the above rock climbing apparatus, simply two sides of the caterpillar structure bear the force, while the middle of the caterpillar structure totally lacks support structure. The rocks are positioned on the middle of the caterpillar structure. Therefore, when a user climbs the rocks, the application force will totally fall onto the middle of the caterpillar structure. In order to avoid swing or deformation of the caterpillar structure, the caterpillar structure is designed with quite strong structure for bearing all the application force in climbing.
For example, U.S. Pat. No. 5,549,195 discloses a caterpillar structure composed of multiple solid planks. U.S. Pat. No. 5,125,877 discloses a caterpillar structure composed of multiple metal frames pivotally connected with each other. A board body is inlaid in each metal frame. U.S. Pat. No. 5,919,117 discloses a caterpillar structure composed of multiple extruded board bodies pivotally connected with each other. In order to avoid deformation of the caterpillar structures, in all the above rock climbing apparatuses, the caterpillar structures are designed with quite strong and complicated structures. This results in that the rock climbing apparatus has a weight up to several hundred kilograms. Therefore, it is hard to move the rock climbing apparatus. In other words, such rock climbing apparatus is unsuitable for personal or domestic rock climbing exercise.
Furthermore, the frame body of the rock climbing apparatus is a huge and heavy structure for supporting the heavy caterpillar. Therefore, the rock climbing apparatus can be hardly assembled or transferred.
Besides, the caterpillar structure has gaps between the board bodies and the frames. These gaps are enlarged when the caterpillar is curved. A user's hairs, clothes, trousers or shoelaces may be chucked in the gaps to result in accident.
U.S. Pat. No. 6,860,836 of this applicant discloses a relatively lightweight rock climbing apparatus. A circularly rotating mechanism is mounted between two frames of a bed. The circularly rotating mechanism includes several sprockets. Each chain has multiple lugs arranged at intervals for mounting multiple transverse beams in parallel to the shaft. Two ends of each transverse beam are respectively inserted in open sides of the two frames. The transverse beams connected with the chains can be circularly revolved along the inner edges of the open sides of the frames. The chains and the transverse beams are wrapped with serially connected soft pads for shading the chains and the transverse beams. Multiple rocks are locked on outer sides of the soft pads corresponding to the lugs of the chains. Several U-shaped stopper boards are fixed between the frames corresponding to the chains, whereby the chains can lean on the stopper boards.
The chains can circularly revolve in a fixed path between the frames. The rocks are arranged on the chains which serve as the main supports for the rocks. Multiple transverse beams are arranged on the chains at intervals for bearing the outward pulling force exerted onto the rocks. The chains lean on the U-shaped seats for bearing the inward pushing force exerted onto the rocks. The above structure is simplified and the weight thereof is minified.
However, in practice, the above rock climbing apparatus still has some shortcomings. The rocks are fixed on the chains. When the rocks are forced inward, the lateral sides of two links of the chain abut against the U-shaped seat. When the chain revolves, the links and the U-shaped seat will abrade each other to produce noise. After a period of use, the links and the U-shaped seat will be worn out. This will affect the smoothness of the revolution and even the strength of the chain. In addition, when the rocks are forced outward, two ends of the transverse beam will abrade the open sides of the frames. Similarly, the transverse beam and the inner sides of the frames will be worn out and noise is produced.
Moreover, the above rock climbing apparatus is lightweight and suitable for personal or domestic use. However, the frames still have a considerable length exceeding the height of an adult for a user climb. The frames are divided into two segments. However, the segments can be hardly conveniently DIY assembled. Furthermore, there is no support structure between the frames. The entire structure is simply supported by the bed. Therefore, the strength of the rock climbing apparatus is still insufficient.
Besides, the transverse beams are arranged at intervals. Therefore, a gap is defined between two transverse beams. Although the transverse beams are wrapped with the soft pads, a user still often touches the gaps when climbing. At this time, the soft pads will be depressed to contact with the chains or the skeleton inside the frame. Under such circumstance, the inner faces of the soft pads will be abraded and worn out by the chains or the skeleton of the frame.
In addition, the soft pads must have a certain tightness to keep the surface smooth. However, the transverse beam is wrapped with the soft pad and fixed on the chain via the rock. When the transverse beam is revolved to the sprocket, the transverse beam will be tangential to the circumference of the sprocket. Accordingly, two ends of the transverse beam will lift the soft pad as shown in FIG. 12. At this time, the soft pad will be tensioned. In some cases, the soft pad will be broken in the position where the rock is fixed. In some serious cases, the chain will be unable to revolve. In the case that the soft pad is made of a resilient material, the inner face of the soft pad will be abraded by the chain or the skeleton of the frame. As a result, after a period of use, the soft pad will elastically fail due to the continuous tension.