齒輪原理(急~)

如果將齒輪的輪齒做為正方形，
齒輪將無法運轉 。

將齒輪改窄，則齒輪可運轉，但接觸點滑動產生時快時慢的現象，並會引起振動及噪音 。

要改善從動輪時快時慢的缺點，齒輪的外緣必須做成特殊的曲線，以滿足齒輪傳動的基本定律 。

只要齒形符合齒輪傳動基本定律，則從動輪的轉速就會固定，而不會有時快時慢的現象。


圓柱體或圓椎體的外線，製成適當的齒形，藉以傳遞較大的動力，此種機件即為—齒輪。

A gear is a wheel with teeth around its circumference, the purpose of the teeth being to mesh with similar teeth on another mechanical device -- possibly another gear wheel -- so that force can be transmitted between the two devices in a direction tangential to their surfaces. A non-toothed wheel can transmit some tangential force but will slip if the force is large; teeth prevent slippage and allow the transmission of large forces.

A gear can mesh with any device having teeth compatible with the gear's teeth. Such devices include racks and other non-rotating devices; however, the most common situation is for a gear to be in mesh with another gear. In this case rotation of one of the gears necessarily causes the other gear to rotate. In this way, rotational motion can be transferred from one location to another (that is, from one shaft to another). While gears are sometimes used simply for this reason -- to transmit rotation to another shaft -- perhaps their most important feature is that, if the gears are of unequal sizes (diameters), a mechanical advantage is also achieved, so that the rotational speed, and torque (rotational force), of the second gear are different from that of the first. In this way, gears provide a means of increasing or decreasing a rotational speed, or a torque. This is a highly useful property.


pic

http://upload.wikimedia.org/wikipedia/commons/thumb/4/42/Gears_large.jpg/200px-Gears_large.jpg