Gears (齿轮 Introduction to Engineering
1 Introduction to Engineering Gears （齿轮）
What are Gears? A wheel with teeth along its rim Used to transmit rotary motion from one shaft to another Introduction to Engineering
2 Introduction to Engineering What are Gears? • A wheel with teeth along its rim • Used to transmit rotary motion from one shaft to another
History of Gears Gears born with the invention of rotating machinery Early gears were made from wood and were often lubricated with animal fat grease Metal gearing became popular with the industrial revolution A science of gear design and manufacture rapidly developed through the nineteenth century Today,modern metallurgy(治金术)has greatly increased the useful life of gears Introduction to Engineering
3 Introduction to Engineering History of Gears Gears born with the invention of rotating machinery Early gears were made from wood and were often lubricated with animal fat grease Metal gearing became popular with the industrial revolution A science of gear design and manufacture rapidly developed through the nineteenth century Today, modern metallurgy（冶金术） has greatly increased the useful life of gears
Classification of Gears Spur(直齿) Helical(螺旋齿) Worm and worm gear pair Straight bevel Spiral bevel 直齿锥齿轮 蝶旋齿锥齿轮 M◆以 蜗杆和蜗轮对 Introduction to Engineering
4 Introduction to Engineering Classification of Gears Spur（直齿） Helical（螺旋齿） Straight bevel 直齿锥齿轮 Spiral bevel 螺旋齿锥齿轮 Worm and worm gear pair 蜗 杆 和 蜗 轮 对
What Is Spur Gears (直齿齿轮)？ >Teeth parallel to the shaft axes >The simplest and most common type of gears vuu >Used to transfer motion between parallel shafts Introduction to Engineering
5 Introduction to Engineering What Is Spur Gears（直齿齿轮）? Teeth parallel to the shaft axes The simplest and most common type of gears Used to transfer motion between parallel shafts
External and Ring Gears the external gears (外齿 轮)：the teeth are formed on the outside of the cylinder. internal or ring gears(内齿轮) the teeth are located on the inside. 6 Introduction to Engineering
6 Introduction to Engineering External and Ring Gears the external gears （外齿 轮） : the teeth are formed on the outside of the cylinder. internal or ring gears（内齿轮）: the teeth are located on the inside
Pinion, Gear and Mesh When two gears having complementary teeth engage and motion is fransmitted form one shaft to another,the two gears are said to form a gearset(齿轮对) Pinion(小齿轮)：the smaller (driving)gear in the gearset is called the pinion. Gear(大齿轮)：the other (driven)one. AAA-上AAAA The pinion and gear are said to mesh(啮合)at the point where the teeth approach,contact one another and then separate. pinion gear Pitch circles Introduction to Engineering
7 Introduction to Engineering Pinion, Gear and Mesh Pinion（小齿轮）: the smaller (driving) gear in the gearset is called the pinion. Gear（大齿轮）: the other (driven) one. The pinion and gear are said to mesh（啮合） at the point where the teeth approach, contact one another and then separate. pinion gear Pitch circles When two gears having complementary teeth engage and motion is transmitted form one shaft to another, the two gears are said to form a gearset（齿轮对）
Terms of Spur Gearset The pinion and gear are regarded as two cylinders that are pressed against one another and smoothly roll together. For two external gears,the cylinders roll on the outside of one another For one internal gear and one external gear,the cylinders roll within the other Introduction to Engineering
8 Introduction to Engineering Terms of Spur Gearset The pinion and gear are regarded as two cylinders that are pressed against one another and smoothly roll together. For one internal gear and one external gear, the cylinders roll within the other For two external gears, the cylinders roll on the outside of one another
Pitch Circle(节圆) Continuous contact between the pinion and gear is imagined to take place on the two pitch circles. Pitch circle 9 Introduction to Engineering
9 Introduction to Engineering Pitch Circle（节圆） Continuous contact between the pinion and gear is imagined to take place on the two pitch circles. Pitch circle
Pitch Radius(节圆半径) The radius of its Pitch radius conceptual rolling cylinder is called the pitch radius Not the distance from the gear's center to either the top or bottom lands of a tooth Introduction to Engineering
10 Introduction to Engineering Pitch Radius（节圆半径） The radius of its conceptual rolling cylinder is called the pitch radius Pitch radius Not the distance from the gear’s center to either the top or bottom lands of a tooth