Belt drive formula summary

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  • 1.BELT DRIVETerm & symbolNisbah halaju (velocity ratio) nSudut lekapan (angle of contact) Jarak antara pemacu & penurut (distance between driver & driven) xTegangan tali sawat (belt tension) F (sometimes T)Kesan empar terhadap tegangan talisawat (centrifugal effect on belt tension) FcKuasa terhantar (power transmitted) PSpeed ratio + tension, F1drivend2driverVelocity ratio; nN2 d1 N1 slack, F2Assuming no slip +v1 = 2v butv = rr1 r 21 =2and d=2rd1 d2 =1 2222 d1=1 d 2Therefore; halajudriven N2 2 d1n==== halajudriver N1 1 d2

2. Angle of contact For open drive: Mdrivendriver N1, r1N2, r2O2 x O1 Note: always measure angle of contact from smaller pulley O 2Mr 2 r1 sin = = O 2O1 x = (180 2)() , in radian 180 For cross drive:M Edriven driver O2 N2, r2 O1 N1, r1 O2M O 2 E +ME r 2 +r1 sin = = = O 2O1O 2 +O1x = (180 +2)() , in radian 180 Belt tension 3. F 2 < 1 < maxF F F1 - belt tension at tension side (N) F2 - belt tenson at slack side (N) Fmax max belt tension before fail For flat belt [flat belt, inelastic, friction theory] F1 Fc F 2 Fc e = F1 - belt tension at tension side (N) F2 - belt tenson at slack side (N) Fc tension due to centrifugal effect (N) coefficient of friction between belt & pulley angle of contact (rad) cross-section view side viewF1 F2 beltfriction pulley+ For V belt [flat belt, inelastic, friction theory]Fc F1 Fc F1 Fc ( csc )= e sin F 2 Fc e or = F 2 Fc F1 - belt tension at tension side (N) F2 - belt tenson at slack side (N) Fc tension due to centrifugal effect (N) coefficient of friction between belt & pulley angle of contact (rad)beltpulley frictionangle = 2 4. Where:Fc =mv 2andm = Am weight per unit length (kg/m)v velocity (m/s) belt material density (kg/m)belt initial tension F1 + F 2 + 2 FcFo = 2Power transmissionP = 1 2) v (FFP = TandT = 1 2) r(FFBelt creep (only for elastic belt) + tension, F1 drivenVelocity, v1Velocity, v2 driverd2N2d1When creep occur: N1slack, F2v2 1v +v2 F1 F 2 =1 ( )v1 AEThus, power:P = 1 2)v 2 (FF(use v2 for calculation)A cross-sectional area of belt (m2)E belt material modulus of elasticity (N/m2)