Continuous duty, scarce maintenance windows and salt fog push marine and offshore sets to direct drive; belt suits small intermittent duty, gear suits high-speed centrifugal.
- Direct drive: 98–99% transmission efficiency, one coupling element every 3–5 years.
- Belt: 1–3% lower efficiency; at 200 kW / 8,000 h that is real money.
- Dry oil-free rotors need synchronising gears — belt slip is not acceptable.
- Verify alignment after transport (≤0.05 mm radial).
- VSD direct drive needs shaft grounding or insulated bearings.
Full comparison article in Chinese; we size the drive by your duty curve.