Timing Belts Catalogue

154Calculation ExamplesCalculation ExamplesCalculation ExamplesStep h: Checking all calculated dataThe tensile strength of the jointed timing belt can be checkedas follows:3) Timing belt for a linear drive (rack feeder)given data:• Gear motor with nominal torque of 350 Nm• Relationship nominal torque to starting torque 1 : 1.5• Gear output speed: 400 1/min• Velocity: 4 m/s• Open length timing belt, fixed ends• Drive pulley/deflection pulleys designed as Omegadrive (W)Pre-calculation2872 N = F < Fal = 4750NResult step 8:2 timing belts 40 HTD 14 M V 20608 mmSince the speed of the rack feeder is known (v = 4 m/s) thenecessary pulley diameter is calculated as follows:v 4 m/s sv = π * D*n => D = =*60 = 0, 191mπ * n 3,14*400 1/ min minThe circumference of the pulley (U = π * D) is 600 mm.Step a: Calculation of present torque T and the force FThe maximum torque is 350 Nm * 1,5 = 525 Nm.This torque results in a force which has to be transmitted by theteeth of the timing belt:Step b: Select Torque, moulded, jointedor open length materialAccording to given data an open lengthbelt is suitable.Result step 2:Select open length materialStep c: Select profile form and pitchBuild the intersection point of “speed”and “force” in the diagram, „force openlength material/Torque“. The grey line ofthe XH/T20 timing belts is the next oneabove this point. A T20 timing belt isselected because inch pitch belts like theXH (imperial), should generally not beused for new designs.Result step 3:Selected timing belt T 20 StahlStep d: Calculation of pulley sizesThe circumference of the drive pulleyalready was calculated with 600 mm.Since the pitch is 20 mm, the number ofteeth results in 30. The working diameteris 190.99 mm (see pulley table of T20timing belt).Result step 4:pulley with 30 teethT 2T2*525NmF = = = = 5497NR D 0,191mCopyright © Ammeraal Beltech 2006Result step 1:T = 525 Nm, F = 5497 N