Calculate sheave ratio, driven speed from sheave diameters, and belt speed from pitch diameter and RPM in inches, mm, ft/min, m/min, or m/s.
Sheave Ratio Formula
The following formula is used to calculate the Sheave Ratio.
SHR = MS / OS
- Where SHR is the Sheave Ratio (dimensionless)
- MS is the motor (driver) speed (RPM)
- OS is the driven (output) speed (RPM)
To calculate the sheave ratio, divide the motor (driver) speed by the driven (output) speed. For a belt-and-sheave (pulley) drive with negligible slip, this speed ratio also equals (driven sheave pitch diameter) ÷ (driver sheave pitch diameter).
How to Calculate Sheave Ratio?
The following example problems outline how to calculate Sheave Ratio.
Example Problem #1:
- First, determine the motor (driver) speed (RPM).
- The motor speed (RPM) is given as: 50.
- Next, determine the driven (output) speed (RPM).
- The driven (output) speed (RPM) is provided as: 20.
- Finally, calculate the Sheave Ratio using the equation above:
SHR = MS / OS
The values given above are inserted into the equation below and the solution is calculated:
SHR = 50 / 20 = 2.5
Example Problem #2:
For this problem, the variables required are provided below:
motor speed (RPM) = 60
driven (output) speed (RPM) = 10
Test your knowledge using the equation and check your answer with the calculator above.
SHR = MS / OS = ?
