Crank gear

Crank gear
Crank gear: mechanism comprised mainly of pedals, cranks and a chain wheel that drives a bicycle.
Frame: chassis of a bicycle.
Cone: roller bearing.
Fixed cup: metal plate covering the ball bearings.
Chain wheel: support that holds a disk clutch.
Pedal: foot-operated system used to propel a bicycle.
Crank arm: arm perpendicular to an axle, used to give it circular motion.
Ball bearings: ball-bearing mechanism used to reduce friction between pieces rolling on each other.

Photo :

EN : Bridge structure
FR : Structure de pont
ES : Estructura del puente


A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle. Designs of bridges vary depending on the function of the bridge and the nature of the terrain where the bridge is to be constructed.

Animation : Quadribent