Cutting Back on Moving Parts

Product designs are using fewer and fewer moving parts, and this is a trend that is sure to continue. Why? A device or component with no moving parts is simpler. Often, engineers can reduce the size, weight, noise, vibration, energy consumption, and price by replacing moving parts with something that doesn’t move. I will mention three areas where this is currently happening.

Flash Memory

Apple recently surprised many by replacing the iPod mini, its biggest-selling product ever, with the iPod nano. The biggest change was replacing the miniature hard disk drive with flash memory.

Flash memory costs more than hard disk storage, but it has important advantages. For the iPod, a portable music player, its biggest advantage is its lower power consumption.

A hard disk is an actual metal disk that has to spin around to function. That uses power. Flash memory has no moving parts, so it uses much less power. In a music player, this could translate into a smaller battery and longer battery life — obvious advantages in any portable device.

With no moving parts, flash memory is also more mechanically stable — not affected by movement, less likely to break when dropped, not much affected by extremes of temperature. And it is smaller and lighter, which is the first thing people notice about the iPod nano.

Flash memory prices have been falling faster than hard disk prices in recent years. If this continues, flash memory could completely replace hard disk drives in some portable computers and even audio recorders and camcorders, starting with applications where small size, light weight, and long battery life are important.

Powered Mixers

Live music is put together by the fingers of a mixing engineer on the knobs and sliders of a mixing board, or mixer. Over the past two decades, mixers have become gradually smaller — at first by making the knobs smaller, and more recently, by having fewer of them. When a mixer uses digital knobs, the same knob can control a whole array of functions at the press of a button, and this makes it possible to replace a whole bank of knobs with just one.

Mixers have become so small that powered mixers are making a comeback. Powered mixers became popular in the 1970s when someone got the idea of putting a power amplifier inside a mixer. Unfortunately, this made the mixer twice as heavy and hard to carry, so powered mixers had fallen out of favor by the 1990s.

Now powered mixers are back, but in a different format. Today’s mixers are so small that it would be impossible to put a power amplifier inside a mixer. Instead, the new powered mixer designs place a mixer on the front of a power amplifier. The mixer adds only a small amount of weight and bulk to the amplifier, and it can be a convenient way to set up a small-scale live performance.


Many in the automobile business believe hydrogen fuel cells will replace internal combustion engines in automobiles about ten years from now. Part of the appeal of hydrogen is the thought of reducing carbon monoxide and other airborne pollutants. It could also cut fuel costs, especially after the recent increases in petroleum prices.

Beyond that, though, fuel cells are expected to lead to much simpler car designs. With no need for a central engine, some of the biggest components that we take for granted in a car could be effectively eliminated, from the engine to the axles. This would make the whole car lighter, and that would allow the heaviest part of the car, the frame, to also be lighter. At the same time, taking away most of the large moving parts would also eliminate most of the need for repairs.

If batteries can be made lighter, the same kinds of advantages could come from an electric car design. Whatever design can combine low cost, low power consumption, and simplified maintenance will eventually claim the automotive market. Quite a bit is unknown about the cars of the future, but cars are under the same pressures as everything else to use simpler designs with fewer moving parts.

Fish Nation Information Station | Rick Aster’s World | Rick Aster