7RTA62
The Sulzer 7RTA62 is a low‑speed, two‑stroke marine diesel engine delivering 14 140 kW at 113 rpm, distinguished by its large bore (620 mm) and conventional camshaft design for robust, long‑life operation.
Engine Specifications
Inspector Detail
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Designation decoded
Sulzer 7RTA62 – 7-Zylinder, 620 mm Bohrung, 1976 mm Hub, Zweitakt-Kreuzkopfmotor mit zahnradgetriebenem Nockenwellen-Antrieb, Standard-Ausführung
Background
The 7RTA62 is a two-stroke crosshead marine diesel engine of the mid-power class from the Sulzer RTA series. With 620 mm bore and 1976 mm stroke, the engine offers a moderate stroke/bore ratio. The engine features a gear-driven camshaft, variable injection control (VIT), pulse lubrication and cylinder lubrication unit (CLU). The 7-cylinder configuration requires special attention with regard to torsional vibrations. The larger bore compared to the RTA48 and RTA52 types results in higher inertia forces and larger component dimensions.
Calculated metrics
Inspector checklist
- Measure and document gear backlash on the camshaft drive
- Inspect gears for pitting, spalling and wear patterns.
- Check lubrication oil supply and temperature at the gear drive.
- Check camshaft bearing clearance and condition.
- VIT-Funktion über gesamten Lastbereich verifizieren
- Pmax-Verteilung zwischen den 7 Zylindern auswerten
- Check fuel pumps for wear and correct timing.
- Test fuel injection nozzles for spray pattern, opening pressure and leakage.
- Measure cylinder oil dosage per stroke and per cylinder
- Check lubrication quills for patency and spray pattern
- Verify CLU control and load-dependent dosage
- BN-Zahl des Zylinderöls an Brennstoffschwefelgehalt anpassen
- Check torsional vibration damper for function, silicone oil level and tightness.
- Verify barred speed range compliance and documentation.
- Kurbelwellendurchbiegung an allen Lagerstellen messen
- Schwingungsmessungen mit historischen Referenzdaten vergleichen
- Laufbuchsenverschleiß an allen Messebenen dokumentieren
- Check piston rings for wear, breakage and correct end gaps.
- Inspect piston crown for cracks, thermal damage and deformation.
- Check scavenge ports for carbon deposits and edge damage.
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Zylinder-Abgastemperatur | 310–370 °C at rated load | Scatter >25 °C between cylinders indicates combustion or injection problems. |
| Spülluftdruck | 2.4–3.0 bar at rated load | Low pressure indicates turbocharger or charge air cooler fouling |
| Kühlwasser-Austrittstemperatur | 78–85 °C | Elevated temperature indicates deposits or faulty thermostat valves. |
| Kurbelwellendurchbiegung | ±0,05 mm (herstellerspezifisch) | Exceedance indicates bearing wear or foundation problems |
| Cylinder liner wear | ≤0,05 mm/1000 Bh | Increased wear indicates lubrication or fuel quality problems |
| Maximaler Zünddruck (Pmax) | Herstellervorgabe ±3 bar | Deviation indicates VIT malfunction or compression problems. |
| Schmieröltemperatur Nockenwellengetriebe | 45–60 °C | Elevated temperature indicates increased friction or lubrication deficiency. |
Common Failure Modes
Expert tips
- 💡 The moderate S/B ratio of 3.19 of the RTA62 offers comparatively low engine stress – nevertheless, focus inspections on the 7-cylinder-specific torsional vibration issue.
- 💡 With the larger bore of 620 mm, the piston rings and liners are dimensioned correspondingly larger – when assessing wear limits, consider the absolute limit values and not just the relative wear rates.
- 💡 Drain oil analysis is a valuable diagnostic tool for RTA62 engines – regular BN residue determination and iron content measurement provide early insight into wear and neutralization performance.
Related components
Classification & regulatory
IACS classification societies require a documented torsional vibration analysis with established barred speed range for 7-cylinder RTA engines. The torsional vibration damper is part of the periodic class survey. Liner wear and crankshaft deflection must be documented in the engine logbook and presented at class surveys. For fuel changeovers (HFO/VLSFO/ULSFO), the CLU settings must be adjusted and documented accordingly.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 50
Components & Design
Component data being added…
Technical Data
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Maritime Network →Manuals
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operating
Sulzer RTA Operating ManualWärtsilä Switzerland (historical Sulzer)
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maintenance
Sulzer RTA Maintenance ManualWärtsilä Switzerland (historical Sulzer)
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spare_parts
Sulzer RTA Spare Parts CatalogueWärtsilä Switzerland (historical Sulzer)