Rex Linkbelt Roller Chain Catalog - Norfolkbearings.com

CDetermine the number of teeth for the large sprocket •Multiply the drive ration by the number of teeth in the smallsprocket.If the drive is to operate in a restricted location, check thesprocket radii against the space limitation. Radial clearancerequired for each sprocket is equal to one-half the sum of itspitch diameter and the chain pitch. Encased drives requirean additional 3" radial clearance. If sufficient space is notavailable, consider a smaller pitch, multiple strand drive.Calculate exact center distance and chain length •Formulas for these calculations are on page C-8.Lubrication • The methods of lubrication shown in thehorsepower rating tables are based primarily on chain speed;however, the relative position of driving and driven shafts ofteninfluence the method of lubrication. Recommendations andcomplete lubrication information are given on pages C-45and C-46.Drive selection exampleProblemSelect a roller chain drive for the following conditions:Source of powerGearmotorHorsepower to betransmitted10 HPSize of driving shaft 2.438" diameterSpeed of driving shaft 100 RPMDriven equipmentBucket elevator uniformly fedSize of driven shaft 2.938" diameterSpeed of driven shaft 42 RPMApproximate center distance 24.00"Relative position of shafts On same horizontal planeSpace limitationsNoneSolutionService factor • The service factor listed in Table 1 on pageC-7 for a uniformly fed bucket elevator driven by a gearmotoris 1.0.Material or design variation factor • Since the listedconditions do not indicate the need for a variation in chainmaterial or design, select a standard roller chain. Therefore, avariation factor does not apply.Equivalent horsepower • The equivalent horsepower equals:10 x 1.0 = 10 HPTrial Chain • From Chart C, page C-5, note that theintersection of the 100 RPM vertical line and the 10 HPhorizontal line falls in the area for No. 100 chain. Thus, the trialchain is No. 100 single strand.Small sprocket • In the No. 100 rating table, page C-23, the100 RPM column lists 10.3 horsepower which correspondsclosely to the equivalent horsepower of 10 required for thisapplication. This rating is for single strand chain when usedwith a 17-tooth sprocket.Check the small sprocket • As shown in the rating table,the maximum bore of a 17-tooth No. 100 sprocket is largerthan the 2.438" bore required; therefore, the selection issatisfactory. Stock sprockets are readily available and areoften more economical.Drive ratio • The drive ratio equals:100 RPM = 2.38 to 142 RPMNumber of teeth in large sprocket • The number of teethin the large sprocket equals: 2.38 x 17 = 40.4 teeth. Use a40-tooth sprocket.Center distance and chain length • Using the formula onpage C-8, calculate the chain length as follows:A = 15.932-6.803 = .190002 x 24From Table 4, page C-8, select the next higher listed valueof .19081 for A. Corresponding factors for B, C and D are1.9633, .4389, and .5611, respectively. The chain length inpitches equals:1.9633 x 24 + (.4389 x 17) + (.5611 x 40) x 1.25 = 67.6011.25Use 68 pitches, which is the nearest even number.Calculate the exact center distance, using 68 pitches:E = 68 -(.4389 x 17) – (.5611 x 40) x 1.25 = 24.254"1.9633Lubrication • The No. 100 rating table specifies Type B bathor disc lubrication. For lubrication and bathing details, seepages C-45 to C-46.The drive selected for this application consists of:17-tooth No. 100 driving sprocket40-tooth No. 100 driven sprocket68 pitches of No. 100 roller chain for 24.254” shaft centers,and an oil-retaining casing foroil bath lubrication.C - 4