| 摘要 |
Adjustable-drive-ratio multiple-step transmission wherein a multiple-v belt passes around driving and driven pulleys each including movable sheave elements individually shiftable in discrete steps along respective trackways away from or toward the pulley axis for changing effective diameters for changing driving ratio (rotational speed relationship) between the two pulleys. In the appropriate rotation direction, either pulley can be driving or driven. Advantageously, the individual sheave elements are one-piece belt-load-locked units engaged with saw-toothed shaped steps along their respective individual trackways by action of belt force applied off-set to torque each sheave element in the plane of the pulley forcing its saw-toothed shaped gripping teeth into engagement with steps along one side of the trackway automatically retaining each sheave element in its shifted position when under belt loading. Trunnion-like projections extend from its opposite sides for shifting each sheave element by applying balanced forces to its opposite sides by a first pair of inner and outer shift cams on one side of each pulley and a second pair of inner and outer shift cams on the other side. When these cams are shifting sheave elements outwardly on one pulley they are simultaneously shifting sheave elements inwardly on the other pulley. These cams move parallel with the pulley plane for shifting the one-piece sheave elements in the pulley plane. A thin, compact belt transmission having numerous predetermined drive-ratios, involves few components, with all sheave elements economically injection molded.
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