Type number selection calculation example 2: When selected by output torque1)Selection specificationInput shaft rotation speedn1=1800rpmOutput shaft rotation speedn2=180rpm24-hour continuous operationUniform loadingActual output torqueTa=200N・mAmbient temperature of the speed reducertr=20℃A 200mm diameter V-belt pulley is installed on theoutput shaft, and the overhang load acts inward10mm from the center of the output shaft.2)Determination of the reduction ratioR=n1n2=1800180=103)Equivalent output torque calculationBased on the load coefficient table, Sf=1.25 is foundfrom 24-hour continuous operation and uniform loadingTe=Sf・Ta=1.25×200=250N・m4)Provisional type number selectionFrom the performance table, first we temporarily select theMA80-10, which is the type that allows 250 N-m of torque.5)Thermal rating capacity check(1)Heat-transfer coefficientαk=29W/m2・℃(2)Upper limit lubricant temperaturete=95℃(3)Ambient temperature of the speed reducertr=20℃(from the specification)(4)Speed educer efficiencyη=93.3%(from the MA80-10 performance table)(5)Surface area of the gear caseSk=0.181m2(from the surface-area table)From the factors mentioned above,Pw=Sk・αK・(te-tr)10・(100-η)=0.181×29×(95-20)10×(100-93.3)=5.89kWThermal rating torque TwTw=974・Pw・η・9.8100・n2=974×5.89×93.3×9.8100×180=291N・mSince Te=250N・m, Tw≧Te. This is OK.6)Overhang load check(1)Actual overhang load calculationLr=Te・forHere, the radius (r) of the pulley=0.1m=250×1.5(fo is 1.5, from OHL coefficient table)0.1=3750N(2)The equivalent allowable overhang load is found.From the specification where the overhangload acts inward from the center of theoutput shaft,Le=LcRR-RxFrom the allowable OHL tableLc=7840NR=75.2㎜Rx=10㎜Le=7840× 75.275.2-10=9042NSince Lr=3750N, Le≧Lr. This is OK.According to the calculation above, theMA80-10 can be used.A-12MAKIACE