机械零件 Mechanical Components

齿轮是直接接触、成对工作的实体，在称为齿的凸出物的连续啮合作用下，齿轮能将运动和力从一个旋转轴传递到另一个旋转轴，或从一个轴传递到一个滑块（齿条）。齿轮实质上是带有精确成型齿的轮子，这些齿与另一个齿轮的齿啮合，因而就提供了强制运动的驱动。装有一对齿轮的轴之间的转速比取决于齿轮的齿数。例如，如果一个20齿的齿轮驱动一个50齿的齿轮，较小的齿轮转2.5圈，可使较大的齿轮旋转1圈。

Gears are direct contact bodies,operating in pairs,that transmit motion and force from one rotating shaft to another,or from a shaft to a slide(rack),by means of successively engaging projections called teeth.A gear is virtually a wheel with very accurately shaped teeth.These teeth mesh with teeth of another gear,thus providing as positive-motion drive.The speed ratio between shafts carrying a pair of gears depends upon the numbers of teeth in the gears.For example,a 20-tooth gear drives a gear of 50 teeth,the smaller gear will have to turn 2.5 times to cause the larger one to make 1 turn.

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