The indexer was initially developed for bicycle gear shifting to keep rides within a predetermined pedaling cadence range.
A patented mechanical indexer indexes a fixed number of degrees when the motor input shaft reaches a preset speed. The initial 2.5-inch diameter model has five indexes and rotates through 17 degrees. For other models, the angle varies by the number of indices and size of the unit. When a preset speed is attained, a flyweight with a helical segment engages and interlocks with a helical thread on the inside bore of the housing. This action advances the output drum one index. If the input shaft drops a fixed amount below the present speed, the mechanism will index back to its original start position. If the input shaft speed drops to a speed between the advance and return speed, a ball-detent mechanism will stop indexing and hold position. The speed differential at which the indexer will advance, hold, or return is adjustable by changing the helix' circumferential position. Applications include advance or retard speed indexing such as on bicycle shift mechanisms.
Oliver Tysver, T DESIGN LTD, W76N1062 Hampton Ave; Cedarburg, WI 53012 Tel: (262) 375-8727; E-mail: email@example.com.
Science fiction author Isaac Asimov may have the best rules for effective brainstorming and creativity. His never-before-published essay, "On Creativity," recently made it to the Web pages of MIT Technology Review.
Much has been made over the potentially dangerous flammability of lithium-ion batteries after major companies like Boeing, Sony, and Tesla have grappled with well-publicized battery fires. Researchers at Stanford University may have come up with a solution to this problem with a smart sensor for lithium-ion batteries that provides a warning if the battery is about to overheat or catch fire.
In this new Design News feature, "How it Works," we’re starting off by examining the inner workings of the electronic cigarette. While e-cigarettes seemed like a gimmick just two or three years ago, they’re catching fire -- so to speak. Sales topped $1 billion last year and are set to hit $10 billion by 2017. Cigarette companies are fighting back by buying up e-cigarette manufacturers.
Advertised as the "Most Powerful Tablet Under $100," the Kindle Fire HD 6 was too tempting for the team at iFixit to pass up. Join us to find out if inexpensive means cheap, irreparable, or just down right economical. It's teardown time!
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.