Roller Chain - Tsubaki

British Standard/DIN ChainDrive SelectionTable III: BS Roller Chain Selection TableExampleData:1. Type of application: Centrifugal Blowers2. Source of power: Electric Motor3. HP to be transmitted: 40 hp4. Driving shaft: 600 rpm5. Driven shaft: 200 rpm6. Center distance: 19 inches7. Space limit: Max. 24 inchesStep 1 Use Table I and determine theservice factor.Service factor (SF) : 1.0Step 2 Obtain design HPDesign HP= HP to be transmitted X SF= 40 hp X 1.0= 40 hpStep 3 Obtain the chain size and thenumber of teeth of the small sprocket fromthe selection table for 40 hp and 600 rpm.Drive ChainDesign HP ValueRPM of Small SprocketThe selection table is based on the followingconditions:1) The chains are operated under ordinaryconditions. The ambient temperature range isbetween 15°F and 140°F. They are not to beused in an atmosphere where abrasive dust orcorrosive gas is present or when the humidity isexceptionally high.2) The two transmission shafts are in a horizontalposition and the chains are properly installed.3) The suggested lubrication system shown onTable IV is used.4) The load does not change significantly duringtransmission.The “Service Factors” given in Table I are usedwhen the chains are used under variousoperating conditions. The load conditions willaffect the life of the chain. The increase in thehorsepower rating of multiple-strand rollerchains cannot be calculated simply bymultiplying the horse-power rating of one strandby the total number of strands, since the loadon each strand is not exactly the same. In orderChain Speed (ft./min.)Table IV: Chain Speed andLubrication SystemChain No.to estimate the service life of a multiplestrandchain, the “Multiple-StrandFactor” given in Table II must be used.According to the selection table, the selectedchains and sprockets rpm are:(a) RS12B-3 chain and 25 tooth sprocket(b) RS16B-2 chain and 17 tooth sprocket(c) RS16B-1 chain and 25 tooth sprocket* For (a), the necessary number of teeth forboth small and large sprockets is 25 teethand 75 teeth respectively, since the speedratio is 1/3 (200/600 rpm). But the outsidediameter of both sprockets 6.3 inches for 25teeth and 18.3 inches for 75 teeth exceedsthe limitation (6.3 inches + 18.3 inches>24inches). Therefore, these sprockets cannot beinstalled.* For (b) the necessary number of teeth forboth the small and large sprocket is 17(outside dia: 5.9 inches) and 51 (outside dia:16.8 inches). It satisfies the space limitation(5.9 inches + 16.8 inches24 inches).Step 4 Use Table IV and determine thelubrication method.Chain speed (S) = P • N • n12= 1 X 600 X 17 = 850 ft./min.12System B is suggested.Step 5 Obtain the number of pitches ofchain (L).N 2 - N 2(1)= N1 + N2 + 2C +6.282 C251 - 17( )= 51 + 17 + 2 X 19 +6.282 1 191= 73.35 74 linksA-67