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Sulzer
7RTA84C
The Sulzer 7RTA84C is a low‑speed, two‑stroke diesel main engine delivering 26 740 kW at 102 rpm, characterised by a conventional camshaft design and constant‑pressure turbocharging.
26740.0 kW
Power
Engine Specifications
7
Cylinders
840 mm
Bore
2400 mm
Stroke
26,740 kW
MCR Power
102.0 rpm
MCR RPM
2-stroke
Stroke Type
Family: Sulzer RTA
· Tier: IMO Tier I
· Fuel: HFO, MDO
Inspector Detail
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Designation decoded
7RTA84C: Sulzer RTA series, 7 cylinders, 840 mm bore, 2,400 mm stroke, C=container version. Gear-driven camshaft with VIT, pulse lubrication and CLU. Dry dock category (840 mm bore), individual component weights over 6 tonnes.
Background
The 7RTA84C is a large-bore two-stroke crosshead engine optimized for container ship propulsion (C suffix). With 840 mm bore and 2,400 mm stroke, it has a comparatively moderate stroke-to-bore ratio of 2.857, which permits higher speeds than ultra-long-stroke variants. The C variant is designed for dynamic container ship operation with frequent load changes. The 7-cylinder configuration requires torsional vibration monitoring. Falls into the dry dock category with individual component weights over 6 tonnes.
Calculated metrics
Stroke To Bore Ratio
2.857
Inspector checklist
Camshaft and gear drive
- Tooth flank clearance measure and document
- Kontaktbild auf gleichmaessigen Traganteil pruefen
- Nockenwellenlager-Zustand bewerten
- Inspect camshaft profiles for wear and pitting
VIT system and fuel injection
- Check VIT actuator function during rapid load changes
- Monitor injection timing at rated and part load
- Check fuel injectors for opening pressure and tightness
- Inspect high-pressure lines for fatigue in container operation
Zylinderschmierung CLU/Puls
- Puls-Schmierung Foerdermengen an allen Zylinderpunkten messen
- Review CLU regulation during load changes - container operation requires rapid adjustment
- BN-Zahl kontrollieren
- Schmierstellen auf gleichmaessige Verteilung pruefen
Piston and cylinder liner (drydock category)
- Kolbenzug erfordert Dockplanung - Gewichte ueber 6t
- Laufbuechsenmessung an drei Hoehen
- Check piston rings for wear and breakage
- Inspect piston crown for thermal damage from load changes
Torsionsschwingungen (7-Zylinder)
- Deflexionsmessungen an allen Kurbelwangen
- Check torsional damper for leakage and oil condition
- Test lockout range automation - frequently traversed in container operation
- Document and compare vibration measurement data
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Zuenddruck (Pmax) | 140–165 bar at rated load | Deviation indicates VIT misadjustment or compression loss |
| Exhaust gas temperature per cylinder | 340–395 degrees C at rated load | Cylinder deviation exceeding 30 °C indicates injection or valve problems. Consider load change influence in container operation |
| Kuehlwassertemperatur Zylinder | 78-88 Grad C | Temperature increase indicates cooling space fouling or hot corrosion |
| Spuelluftdruck | 2.8–3.8 bar at rated load | Pressure drop indicates turbocharger or air cooler efficiency reduction |
| Zylinderschmieroelverbrauch | 0.8-1.3 g/kWh | At 840 mm bore, increased consumption is cost-relevant and indicates wear |
| Kurbelwellen-Deflexion | Herstellerangaben je Zylinderposition | Grenzwertueberschreitung erfordert sofortige Lagerpruefung |
| Turbolader-Lagerschwingung | Unter 3 mm/s (abhaengig vom Turboladertyp) | Elevated vibration indicates bearing damage or imbalance |
Common Failure Modes
Torsionsschwingungsschaden (7-Zylinder-Containerbetrieb)
Symptoms: ['Abnormal vibrations at certain speeds', 'Kurbelwangen-Rissbildung', 'Torsionsdaempfer-Leckage', 'Erhoehte Deflexionswerte']
Causes: Frequent lockout range traversal in container operation, 7-Zylinder-Eigenfrequenz, Defekter Torsionsdaempfer, Rapid load changes in container operation
Preventive: Container ships traverse the lockout range more frequently than tankers - lockout range automation must function reliably. Inspect torsional damper every 4 years.
Fatigue damage from load changes
Symptoms: ['Rissbildung an hochbeanspruchten Stellen', 'Kolbenboden-Risse', 'Hochdruckleitungs-Brueche', 'Einspritzventil-Nadelbruch']
Causes: Haeufige Lastwechsel im Containerbetrieb, Thermische Wechselbelastung, Slow-Steaming-Phasen im Wechsel mit Volllast, Materialermuedung
Preventive: Containerbetrieb-spezifische Inspektionsintervalle beachten. Hochdruckleitungen regelmaessig ersetzen. Kolbenboden mit Risspruefsverfahren untersuchen.
Laufbuechsenverschleiss (840mm Grossbohrung)
Symptoms: ['Erhoehter Schmieroel-Verbrauch', 'Kompressionsdruckabfall', 'Blow-by', 'Laufflaechen-Beschaedigung']
Causes: Large running surface under load changes, Cat-Fines im Brennstoff, Thermische Wechselbelastung, CLU regulation not fast enough during load changes
Preventive: Measure cylinder liner at each piston stroke with trend analysis. Optimize CLU control behaviour during load changes. Monitor fuel cat-fines strictly.
Turbolader-Surging
Symptoms: ['Pulsierendes Gerausch vom Turbolader', 'Spuelluftdruck-Schwankungen', 'Abgastemperatur-Instabilitaet', 'Turbolader-Drehzahlschwankungen']
Causes: Schnelle Lastwechsel im Containerbetrieb, Ladeluftkuehler-Verschmutzung, Turbocharger matching not optimal, Abgaskompensator-Undichtigkeit
Preventive: Turbolader-Abblaseventil auf Funktion pruefen. Ladeluftkuehler-Reinigungsintervalle einhalten. Bei Surging-Tendenz Turbolader-Matching ueberpruefen.
Expert tips
- 💡 C variant for container operation: The lower stroke-to-bore ratio of 2.857 permits higher speeds, but frequent load changes stress injection valves and pistons more severely than in tanker operation.
- 💡 840 mm bore with container operation: slow-steaming phases can lead to cold corrosion on cylinder liners - CLU BN number may need to be increased at part load.
- 💡 7-cylinder container engine: The barred speed range passage is particularly relevant with frequent speed changes - evaluate logbook entries on barred range events.
Related components
Turbocharger and charge air cooler (Container: increased cleaning frequency)
Exhaust valve and valve spindle rotation device
Kolbenstangenstopfbuchse
Crosshead bearing and guide
Fuel separators and fine filters
Anlassluftverteiler
Main and connecting rod bearing
Torsionsschwingungsdaempfer
Brennstoff-Viskositaetsregelung
Waste-Heat-Recovery-System (falls vorhanden)
Classification & regulatory
840 mm bore: Dry-dock-mandatory work to be coordinated with class. 7-cylinder: torsional vibration proof mandatory. Container operation (C-suffix): observe engine manufacturer operating limits during slow steaming. VIT calibration NOx-relevant per MARPOL Annex VI - EIAPP certificate must cover container operation profile. Deflection measurements at each intermediate and class survey. Container operation may require shorter inspection intervals.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 50
5RTA48T
5 cyl
· 6,600 kW
5RTA48T-B
5 cyl
· 7,150 kW
5RTA52
5 cyl
· 7,350 kW
5RTA52U
5 cyl
· 7,850 kW
5RTA58T
5 cyl
· 10,150 kW
5RTA58T-B
5 cyl
· 10,800 kW
5RTA62
5 cyl
· 10,100 kW
5RTA62U
5 cyl
· 11,000 kW
5RTA62U-B
5 cyl
· 12,000 kW
5RTA72
5 cyl
· 16,000 kW
5RTA72U
5 cyl
· 17,000 kW
5RTA72U-B
5 cyl
· 18,000 kW
5RTA82T
5 cyl
· 16,600 kW
5RTA84T
5 cyl
· 19,100 kW
5RTA84T-D
5 cyl
· 22,600 kW
6RTA48T
6 cyl
· 7,920 kW
6RTA48T-B
6 cyl
· 7,920 kW
6RTA52
6 cyl
· 8,820 kW
6RTA52U
6 cyl
· 9,420 kW
6RTA58T
6 cyl
· 12,180 kW
6RTA58T-B
6 cyl
· 12,960 kW
6RTA62
6 cyl
· 12,120 kW
6RTA62U
6 cyl
· 13,200 kW
6RTA62U-B
6 cyl
· 14,400 kW
6RTA72
6 cyl
· 19,200 kW
6RTA72U
6 cyl
· 20,400 kW
6RTA72U-B
6 cyl
· 21,600 kW
6RTA82T
6 cyl
· 19,920 kW
6RTA84C
6 cyl
· 22,920 kW
6RTA84T
6 cyl
· 22,920 kW
6RTA84T-D
6 cyl
· 27,120 kW
6RTA96C
6 cyl
· 32,940 kW
6RTA96C-B
6 cyl
· 34,320 kW
7RTA48T
7 cyl
· 9,240 kW
7RTA48T-B
7 cyl
· 10,010 kW
7RTA52
7 cyl
· 10,290 kW
7RTA52U
7 cyl
· 10,990 kW
7RTA58T
7 cyl
· 14,210 kW
7RTA58T-B
7 cyl
· 15,120 kW
7RTA62
7 cyl
· 14,140 kW
7RTA62U
7 cyl
· 15,400 kW
7RTA62U-B
7 cyl
· 16,800 kW
7RTA72
7 cyl
· 22,890 kW
7RTA72U
7 cyl
· 23,800 kW
7RTA72U-B
7 cyl
· 25,200 kW
7RTA82T
7 cyl
· 23,240 kW
7RTA84T
7 cyl
· 26,740 kW
7RTA84T-D
7 cyl
· 31,640 kW
7RTA96C
7 cyl
· 38,430 kW
7RTA96C-B
7 cyl
· 40,040 kW
Components & Design
Component data being added…
Technical Data
unified from engine model
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Maritime Network →Manuals
-
operating
Sulzer RTA Operating ManualWärtsilä Switzerland (historical Sulzer)
-
maintenance
Sulzer RTA Maintenance ManualWärtsilä Switzerland (historical Sulzer)
-
spare_parts
Sulzer RTA Spare Parts CatalogueWärtsilä Switzerland (historical Sulzer)
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Equipment Model #38669
· ✓ still in production