齿轮GEARS

齿轮GEARS(中文4200字,英文2700字)
齿轮是成对运转的直接接触体，它们通过连续啮合的称作齿的突出物把运动和力从一根转轴传递带另一根转轴上，或从一根转轴传递到齿条上。图7所示是四种主要的齿轮（正齿轮、斜齿轮、蜗轮和锥齿轮）以及齿条小齿轮.
齿廓  齿轮齿的接触面必须排列得使传动是流畅的，即所传递的负载决不能依赖摩擦接触。正如在分析直接接触体时所指出的，这要求接触面上的公法线一定既不能通过主动轮的枢轴，也不能通过从动轮的枢轴。

GEARS
   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 . The four main types of gears ( spur , helical, worm ,and bevel) and a rack and pinon are shown in Figure 7.
Tooth profiles. The contacting surfaces of gear teeth must be aligned in such a way that the drive is positive ; the load transmitted must not depend on frictional contact . As shown in the treatment of direct-contact bodies , this requires that the common normal to the surfaces must not passs through the follower .

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Most gears are also required to hae tooth proflies of such a shape that the velocity ratio of the gears remains constant (unless otherwise noted ,this article will deal with such gears only ).thid requires that the common nomarl must cut the line between the pivots at a fixed point. [来源：http://Doc163.com]