Rocker Arm Ratio Calculator

Formula

The formula to calculate the Rocker Arm Ratio (RR) is:

\[ RR = \frac{Y}{X} \]

Where:

\(RR\) is the rocker arm ratio
\(Y\) is the distance from the center of the valve stem to the center of the pivot point
\(X\) is the distance from the center of the pushrod to the center of the pivot point

What is a Rocker Arm?

A rocker arm is a lever, typically an oscillating lever in a combustion engine, that converts radial movement from the cam into linear movement at the poppet valve.

What is a Rocker Arm Ratio?

The ratio of a rocker arm is a measure of the leverage or mechanical advantage that is achieved by the rocker arm due to its specific geometry. In general, rocker arm ratios are designed to be in the range of 1.5:1 to 1.8:1.

Example Calculation

Let's assume the following values:

Distance from Valve Stem to Pivot Point (Y) = 3 cm
Distance from Pushrod to Pivot Point (X) = 2 cm

Using the formula:

\[ RR = \frac{3}{2} = 1.5 \]

The Rocker Arm Ratio (RR) is 1.5.