Full definition
The measurable difference between pulley peripheral speed and actual belt speed, expressed as a percentage. Normal operating slip due to elastic creep: 1-2%. Slip exceeding 3% indicates under-tensioning, overload, worn pulleys, or oil contamination and leads to heat buildup, glazed sidewalls, belt squeal, and accelerated wear. Measured using tachometer on driver and driven shafts. For V-belts, slip above 5% causes rapid temperature rise (rubber degrades above 60°C ambient plus friction heat). Correction: verify tension with a frequency meter or deflection gauge, inspect groove wear with a groove gauge, and confirm alignment. Per ISO 5292. Excessive slip can reduce belt life by 50-80%.