# How to choose a splitter pulley for your engine?

When choosing pulleys for the engine, when building a drill splitter, we should be guided by the formulas below to calculate the ratio of pulleys and the choice of pulley diameter.

## Calculation of pulley gear ratio for a drill splitter

i = v1 / v2

where:
i - gear ratio
v1 - electric motor speed
v2 - target speed we want to achieve (on the drill splitter)

EXAMPLE:

For the 1400 rpm engine and the target speed we want to achieve for our drill splitter, i.e. 550 rpm, the ratio will be calculated as follows:

i = 1400/550 = 2.55

## Selection of pulley diameter for splitter

If we have already calculated the ratio we can adjust the pulleys.

If we know the diameter of a small pulley, we will calculate the large pulley as follows:

d2 = d1 * i

If we know the diameter of a large pulley, we calculate the small ones by transforming the previous formula, namely:

d1 = d2 / i

where:
d1 - small pulley (for engine)
d2 - large pulley (for drill)
i - gear ratio

EXAMPLE:

For example, suppose we have a small pulley with a diameter of 80mm on the engine, we calculate the large pulley as follows:

d2 = 80mm * 2.55 = 204mm

And vice versa, when we have a large pulley with a diameter of 204mm, we will calculate the small pulley using the second transformed formula:

d1 = 204mm / 2.55 = 80mm     