The New Way Things Work
This illustration-rich book provides a peek under the hood of the mechanized world we inhabit. David Macaulay, with tech writer Neil Ardley, has that rare gift of technical understanding paired with an ability to convey complex concepts through visual imagery. Kids, parents, Lit. majors, curious people – all can learn, and laugh, from the interpretive drawings that fill this wonderful tome, granting insight into the workings of everything from twin-rotor helicopters to printing presses to self-winding watches and even modems.
Remember floppy discs? The 1998 edition of this book (the most current) does feature some dated material regarding digital technology. Still, it’s an overwhelmingly relevant, educational reference — awe-inspiring because of Macaulay’s talents as well as the achievements of human ingenuity on which his pictures shed light.08/7/09
Inside the Mouse
The mouse rolls on a ball that turns two slotted wheels mounted at right angles. Each wheel has one or two pairs of light-emitting diodes and photodiodes. As the wheel turns, light shines through the slots and produces an electric signal in the photodiodes. The signals from the wheels give the changes in the mouse's position.
The Sewing Machine
The Feed-Dog: This moves the fabric forward. One train of cams and cranks moves the feed-dog forward and backward, while the other makes it rise and fall. Both are powered by a wheel driven by the electric motor, synchronizing their movements. The feed-dog rises and moves forward between stitches to shift the fabric and then dips and moves back.
The chuck of a power drill has to grip very strongly as it rotates the drill, yet it must be possible to loosen or tighten the chuck by hand. A compact arrangement of bevel gears and levers does the trick. The key pinion is turned to rotate the collar of the chuck, which turns the screw inside the chuck to move the jaws in or out. the screw is set at an angle so the the jaws open as they withdraw into the chuck, and close to grip the drill bit as they protrude from the chuck.
Changing Down: As the governor rotates more slowly or the accelerator pedal is pressed, the throttle valve pressure exceeds the governor pressure. The shift valve moves back, and the low-gear piston engages low gear while the high-gear piston disengages high gear.