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Bicycle Adds Reliability With Second Chain

4 Febrero 2025 at 03:00

Ignoring the International Cycling Union‘s mostly arbitrary rules for what a bicycle is “supposed” to look like (at least if you want to race), there are actually reasons that the bicycling world has standardized around a few common parts and designs. Especially regarding the drivetrain, almost all bikes use a chain, a freewheel, and a derailleur if there are gears to shift because these parts are cheap, reliable, and easy to repair. But if you’re off grid in a place like Africa, even the most reliable bikes won’t quite cut it. That’s why a group called World Bicycle Relief designed and built the Buffalo bicycle, and the latest adds a second gear with a unique freewheel.

Bicycling YouTuber [Berm Peak] takes us through the design of this bike in his latest video which is also linked below. The original Buffalo bicycle was extremely rugged and durable, with a rear rack designed to carry up to 200 pounds and everything on the bike able to be repaired with little more than an adjustable wrench. The new freewheel adds a second gear to the bike which makes it easier to use it in hilly terrain, but rather than add a complicated and hard-to-repair derailleur the freewheel adds a second chain instead, and the rider can shift between the two gears by pedaling backwards slightly and then re-engaging the pedals.

Of course a few compromises had to be made here. While the new freewheel is nearly as rugged as the old one, it’s slightly more complex. However, they can be changed quite easily with simple tools and are small, affordable, and easy to ship as well. The bike also had to abandon the original coaster brake, but the new rim brakes are a style that are also easy to repair and also meant that the bike got a wheel upgrade as well. Bicycles like these are incredibly important in places where cars are rare or unaffordable, or where large infrastructure needed to support them is unreliable or nonexistent. We’ve seen other examples of bicycles like these being put to work in places like India as well.

Thanks to [Keith] for the tip!

Retrotechtacular: The Tyranny of Large Numbers

30 Enero 2025 at 19:30

Although much diminished now, the public switched telephone network was one of the largest machines ever constructed. To make good on its promise of instant communication across town or around the world, the network had to reach into every home and business, snake along poles to thousands of central offices, and hum through the ether on microwave links. In its heyday it was almost unfathomably complex, with calls potentially passing through thousands of electronic components, any of which failing could present anything from a minor annoyance to a matter of life or death.

The brief but very interesting film below deals with “The Tyranny of Large Numbers.” Produced sometime in the 1960s by Western Electric, the manufacturing arm of the Bell System, it takes a detailed look at the problems caused by scaling up systems. As an example, it focuses on the humble carbon film resistor, a component used by the millions in various pieces of telco gear. Getting the manufacturing of these simple but critical components right apparently took a lot of effort. Initially made by hand, a tedious and error-prone process briefly covered in the film, Western Electric looked for ways to scale up production significantly while simultaneously increasing quality.

While the equipment used by the Western engineers to automate the production of resistors, especially the Librascope LGP-30 computer that’s running the show, may look quaint, there’s a lot about the process that’s still used to this day. Vibratory bowl feeders for the ceramic cores, carbon deposition by hot methane, and an early version of a SCARA arm to sputter gold terminals on the core could all be used to produce precision resistors today. Even cutting the helical groove to trim the resistance is similar, although today it’s done with a laser instead of a grinding wheel. There are differences, of course; we doubt current resistor manufacturers look for leaks in the outer coating by submerging them in water and watching for bubbles, but that’s how they did it in the 60s.

The productivity results were impressive. Just replacing the silver paint used for terminal cups with sputtered gold terminals cut 16 hours of curing time out of the process. The overall throughput increased to 1,200 pieces per hour, an impressive number for such high-reliability precision components, some of which we’d wager were still in service well into the early 2000s. Most of them are likely long gone, but the shadows cast by these automated manufacturing processes stretch into our time, and probably far beyond.

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