>> P.26
T=9550000 ……………………………(14)HnBearing loads in case of belt or chain transmissionKt= ……………………………………(15)TRKs=Kttan θ ………………………………(16)Kc= Kt +Ks =Kt22 sec θ…………………(17) where, T:Torque applied to gear,N-mm Kt:Tangential force acting on gear,N Ks:Radial force acting on gear,N Kc:Resultant normal force on gear tooth surface,N H:Transmitting power,kW n:Rotational speed,min-1 R:Pitch circle radius of drive gear,mm θ:Pressure angle of gear,deg.KtKsRFig. 6 In this case, the resultant normal force on the tooth surface acts as the radial force to the shaft and the magnitude of vibration or shocks varies depending on wheel, N-mm Kt Effective transmitting force of belt or chain,N H Transmitting power,kW:Rotational speed,min-1 n R ffective radius of pulley or sprocket wheel,mmWhen power is transmitted by a belt or chain, the load acting on the pulley or sprocket wheel is obtained from the following equations: T=9550000 ……………………………(11)HnKt= ……………………………………(12)TRwhere, T: orque acting on pulley or sprocket For belt transmission, the load Kr acting on the pulley shaft is obtained from the following equation, multiply-ing the effective transmitting force Kt by the belt factor fb shown in Table 7.Kr =fb Kt ………………………………………(13)Table 7 Belt factorType of beltV-beltsTiming beltsPlain belts (with tension pulley)Plain beltsfb2 〜2.51.3〜22.5〜34 〜5In the case of chain transmission, a value of 1.2 to 1.5 the accuracy and surface nish of the gear. Therefore, is taken as the chain factor corresponding to fb. The the sprocket wheel shaft is obtained load acting on from equation (13) in the same manner as the belt transmission.the radial load Kr applied to the shaft is obtained from the following equation, multiplying the resultant normal force Kc on gear tooth surface by the gear factor fz shown in Table 8.Bearing loads in case of gear transmissionKr=fz Kc ……………………………………(18)When power is transmitted by gears, the force acting Table 8 Gear factoron the gears varies according to the type of gear. Spur gears produce radial loads only, but helical gears, bevel gears and worm gears produce axial loads in addition to radial loads. Taking the simplest case of spur gears as an example, the bearing load is obtained from the following equations:Type of gearfzPrecision gears (Pitch error and form error: Less than 0.02mm)Ordinary machined gears(Pitch error and form error: 0.02 〜0.1mm)1.05〜1.11.1〜1.3A23
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