For a pair of engaging gears, A pair of Gears 01 m1=m2,Pal Pd2,1=d2 Conulton iol engaying. Pat =Pn2 then: P1=P2 πdh= nd dp d a2 02 =p cos a =πm·COS O: π cos a Pa 上游文通大 A pair of Gears Contact Ratio(重合度) 0 口Contact line:NN2 Common normal of Ks:N N2 Common tangent of base circles:N N2 Contact forces'direction:N,N2 4 lines in 1 023 O1 O2 1 2 N2 N1 B2 B1 K ra2 ra1 rb1 rb2 O1 O2 N2 N1 B1 P i i j Condition for engaging: Pn1  Pn 2 Pb1  Pb 2 then: d d N d N d P b b b      p c  cos   m  cos      cos pd 1 2 d1 d2 1 2 m m , p p , For a pair of engaging gears,      A pair of Gears Contact Ratio(重合度) rb2 O2 1 2 N2 O1 rb1 P N1 K K’ 4 lines in 1  Contact line: N1N2  Common normal of Ks：N1N2  Common tangent of base circles： N1N2  Contact forces’ direction：N1N2 A pair of Gears