Serviced belt-drive speed calculator

The diameter ratio sets ideal driven speed; measured belt slip reduces that speed. Verify restored mechanical service after pulley or belt changes.

Units

N_{\text{driven}} = \frac{N_{\text{driver}} \times D_{\text{driver}}}{D_{\text{driven}}} \times \left(1 - s\right)

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

N_{\text{driven}} = \frac{1760 \times 5}{12} \times \left(1 - 0.06\right) \approx 689.3

Symbol	Meaning	Unit
$N_{\text{driven}}$	driven pulley speed	rpm
$N_{\text{driver}}$	driver pulley speed	rpm
$D_{\text{driver}}$	driver pitch diameter	in
$D_{\text{driven}}$	driven pitch diameter	in
$s$	fractional belt slip relative to ideal driven speed	fraction

Symbol	Meaning	Unit
$N_{\text{driven}}$	driven pulley speed	rpm
$N_{\text{driver}}$	driver pulley speed	rpm
$D_{\text{driver}}$	driver pitch diameter	m
$D_{\text{driven}}$	driven pitch diameter	m
$s$	fractional belt slip relative to ideal driven speed	fraction

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.