SCIENCE AND TECHNOLOGY ENGLIAH FOR MECHANICAL ENGINEERING Gearing A friction drive consists of two cylindersgear齿轮 rolling together under some pressure. When no slipping occurs, the tangential velocity V attangential the line of contact of the two cylinders is, of‖正切的,切线的 course, the same for each. From physics we know that v= o X r in which v is the tangential velocity (in /sec),o is the rotational velocity(rad/sec), and I is the radius of radius +12 rotation. Since V=0,r, and also V=O,I,,we can equate both equations. Thus 6.8 Dividing both sides by O2X I, we get O1/(,=r2/r where o, /0, is the speed ratio(mo) speed ratio速比SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING A friction drive consists of two cylinders rolling together under some pressure. When no slipping occurs, the tangential velocity V at the line of contact of the two cylinders is, of course, the same for each. From physics we know that V= ω × r, in which V is the tangential velocity (in./sec), ω is the rotational velocity (rad/sec), and r is the radius of rotation. Since V= ω1 r 1 and also V= ω2 r 2 , we can equate both equations. Thus, ω1 × r 1 = ω2× r 2 6.8 Dividing both sides by ω2× r 1 , we get ω1 /ω2 = r2 / r1 6.9 where ω1 /ω2 is the speed ratio (mω ). Gearing gear 齿轮 tangential 正切的，切线的 radius 半径 speed ratio 速比