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Open-Drive Compressor Belt Tension Incorrect — Belt Slipping or Bearing Overload

Likely causes

Insufficient belt tension — slipping reduces compressor RPM, generates high-pitched friction noise

Check: Apply 10N finger pressure at mid-span to check sag — normal: span length (mm) ÷ 100 mm. 1,000mm span: 10mm sag (acceptable 8~12mm). Visually inspect belt surface for cracks or glazing

What to do: Adjust tension via motor base slide then re-tighten lock bolts → if cracks or glazing found, replace entire set (multi-V-belt: always replace as complete set). Pulley alignment: lateral deviation ≤ 2mm over 2m

Excessive belt tension — radial overload on shaft and bearings

Check: Excessive tension: bearing temperature rises (too hot to touch, above 70°C). Sag is less than reference (8mm)

What to do: Adjust motor position to restore sag to normal range (8~12mm) → monitor for 10~15 minutes until bearing temperature normalizes

Field tip

Sag formula: span (mm) ÷ 100 = target sag (mm). Can be calculated on-site without a tension gauge. Multi-V-belts must always be replaced as a complete set — replacing just one causes uneven tension and rapid re-failure.

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