Mechanical Concepts

Every so often, I get into these Wikipedia binges where I start looking up random things. A little while back, I got into reading on various on mechanical devices. Maybe one day I will build one of these.

Hoberman Sphere

A Hoberman sphere is an isokinetic structure patented by Chuck Hoberman that resembles a geodesic dome, but is capable of folding down to a fraction of its normal size by the scissor-like action of its joints. Colorful plastic versions have become popular as children's toys: several toy sizes exist, with the original design capable of expanding from 5.9 inches (15 cm) in diameter to 30 inches (76 cm).

A Hoberman sphere typically consists of six great circles corresponding to the edges of an icosidodecahedron. The Hoberman sphere can be unfolded by allowing certain members to spread apart. The operation of each joint is linked to all the others in a scissors mechanism like those used to mount pantograph mirrors, or how a folding chair operates. In larger models, this can be accomplished by feeding out a string or cable instead.


Kinematic Synthesis
Kinematic synthesis, also known as mechanism synthesis, determines the size and configuration of mechanisms that shape the flow of power through a mechanical system, or machine, to achieve a desired performance.

Hartenberg and Denavit describe kinematic synthesis as

...it is design, the creation of something new. Kinematically, it is the conversion of a motion idea into hardware.

The earliest machines were designed to amplify human and animal effort. Later, gear trains and linkage systems captured wind and flowing water to rotate millstones and pumps. Now machines use chemical and electric power to manufacture, transport, and process items of all types. Kinematic synthesis is the collection of techniques for designing those elements of these machines that achieve required output forces and movement for a given input.

Wenkel Engine

The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion.

All parts of a rotary engine rotate in one direction. This is opposed to the common reciprocating piston engine, which has pistons instantly and rapidly changing direction 180 degrees. In contrast to the reciprocating piston designs, the Wankel engine delivers advantages of simplicity, smoothness, compactness, high revolutions per minute, and a high power-to-weight ratio.