PULLEY SIZE AND RPM

 

Supply any 3 of the following and calculate the fourth:

Pulley A Pulley B
SIZE SIZE
RPM RPM

Example:

On a ground driven planter unit, the drive wheel is 125 cm in circumference and turns a 13-tooth sprocket, driving a chain up to a 20-tooth sprocket. The 20-tooth sprocket is connected to a shaft which turns a 17-tooth sprocket that is connected to a 28-tooth sprocket which in turn spins the 45-cell planter plate. This is a compound drive system and will set the spacing of the seeds down the row.

 

Problem:

How many seeds will drop per revolution of the 125 cm drive wheel?

 

Calculation: (A compound drive is handled as 2 individual calculations)

 

Part #1:

Pulley A Pulley B

Size

13-tooth

Size

20-tooth

RPM

1

RPM

0.65

 

Part #2

Pulley A Pulley B

Size

17-tooth Size 28-tooth

RPM

0.65 RPM 0.395

 

Answer:

The Cell-plate (45 cell)   x    0.395 RPM   =   17.76 seeds drop in one revolution.

Seed spacing down the row then is:   125 cm / 17.76 seeds = 7.04 cm

 

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