Select chain drive components for 31 reduction 100 hp input

Solution

GIVEN

3:1 REDUCTION

100HP input

500 RPM

C/P =30

C is the centre to centre distance and P the pitch

The centre to centre distance, the number of teeth on the sprockets and the dia of the sprockets are variables.

If the reduction ratio is 3:1 then the dia ratio of the gear sprockets is the same.. FOr speed reduction, the smaller sprocket (driver) must turn 3 times for one rev of the big sprocket (driven). The dia of the big sprocket is 3 times the dia of the small sprocket.

The sprocket pitch dia (PD) is calculated as   PD = P/(sin180/N) where P = chain pitch in inches,

N = no of teeth on sprocket.

Once the chain is chosen, the distance between the sprockets is determined from C/P =30

By geometrical calculations can now calculate the total chain length.

However this is not the main design limitation, one must select a chain that can transmit a 100HP at 500rpm

100 HP = 55000 ftlp/sec which must equal the torque in ft lb X he speed in rps, which works out to

55000 = Torque* N/60 , = Torque* 500/60

Torque = 6600 ftlb.

The small the dia of the sprocket, the larger the tension.

SO this limits the size of any of the sprockets. The characteristics of the chain need to be known.

This is a design problem with many variables, so the choice depends on size, cost and availability of parts.