⚓ Working on this equipment?
Ask the AI troubleshooter, log your hours on board and turn them into invoice-ready service reports — for this exact model.
Start free — 14 days →
No credit card required
🔧 24 verified suppliers & service companies for Sulzer in the Maritime Network
Find suppliers →
Sulzer
9RTA72
The Sulzer 9RTA72 is a medium‑speed, 9‑cylinder two‑stroke diesel main engine delivering 28.8 MW at 91 rpm, known for its robust camshaft design and constant‑pressure turbocharging.
28800.0 kW
Power
Engine Specifications
9
Cylinders
720 mm
Bore
2500 mm
Stroke
28,800 kW
MCR Power
91.0 rpm
MCR RPM
2-stroke
Stroke Type
Family: Sulzer RTA
· Tier: IMO Tier I
· Fuel: HFO, MDO
Inspector Detail
✓ verified
▸
Designation decoded
9RTA72: 9 cylinders, Sulzer RTA series, 72 cm bore, standard design. Two-stroke crosshead slow-speed engine with gear-driven camshaft. 9-cylinder configuration requires special attention to engine length and alignment.
Background
The 9RTA72 is a proven two-stroke slow-speed engine of the Sulzer RTA series with 720 mm bore and 2500 mm stroke. The 9-cylinder configuration is the most critical arrangement with regard to engine length and alignment problems. The extreme overall length places high demands on hull girder stiffness and thermal expansion of the engine. Equipped with VIT (Variable Injection Timing), Pulse Lubrication System and CLU (Cylinder Liner Unit). The gear-driven camshaft is particularly dependent on correct alignment and synchronization in 9-cylinder configuration.
Calculated metrics
Stroke To Bore Ratio
3.472
Inspector checklist
Engine alignment and foundation
- Kurbelwellen-Deflexionsmessung an allen 9 Lagerstellen durchführen
- Check foundation bolt preload (critical due to 9-cylinder length)
- Document thermal expansion at operating temperature
- Check chock condition and side supports for looseness
Camshaft and gear drive
- Zahnflankenspiel an allen Antriebspunkten messen
- Inspect camshaft bearings for wear (9 bearings = increased number of inspection points)
- Nockenwellen-Ausrichtung über Gesamtlänge kontrollieren
- Torsionsschwingungsverhalten am Nockenwellenantrieb überwachen
VIT system and fuel injection
- VIT-Aktuator Funktionsprüfung an jedem Zylinder
- Check injection nozzle opening pressure and spray pattern
- Kraftstoffpumpen-Verschleißzustand bewerten
- Ensure uniform fuel injection across all 9 cylinders
Cylinders and cylinder liners
- Determine cylinder liner wear by micrometer measurement
- Inspect surface for scoring, cloverleafing and corrosion
- Inspect CLU seals and cooling water spaces
- Check cylinder cover valves for leakage and wear
Pulse Lubrication System
- Dosierventile an allen 9 Zylindern auf Funktion testen
- Zylinderölverbrauch pro Zylinder vergleichen
- Oil quality and BN value to check
- Schmierkanäle auf Verstopfung prüfen
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Maximaler Zünddruck (Pmax) | 135–150 bar | Scatter >5 bar between cylinders indicates VIT misadjustment or fuel injection system problems |
| Exhaust gas temperature per cylinder | 340–410 °C | Elevated values indicate combustion disturbance or worn fuel injection nozzles |
| Kurbelwellen-Deflexion | According to manufacturer specification (typically ±0.05 mm at cold measurement) | Exceedance of limit values indicates foundation displacement or bearing wear – particularly critical at 9 cylinders |
| Cylinder liner wear | 0,05–0,15 mm/1000 Bh | Excessive wear indicates lubrication problems or unsuitable cylinder oil |
| Spülluftdruck | 2,2–3,5 bar (lastabhängig) | Deviations cause combustion deterioration and temperature rise |
| Kühlwassertemperatur Austritt | 80–95 °C | Exceedance may indicate deposits in cooling channels or thermostat defects |
Common Failure Modes
Kurbelwellen-Ausrichtungsprobleme
Symptoms: ['Erhöhte Deflexionswerte', 'Ungleichmäßiger Lagerverschleiß', 'Vibrationen im Maschinenraum']
Causes: Extreme engine length at 9-cylinder configuration, Hull deformation due to cargo loading, Foundation settlement or chock failure
Preventive: Deflection measurements at every class survey, install bearing temperature monitoring, document loading conditions during measurements
Nockenwellen-Torsionsschwingungsschäden
Symptoms: ['Geräuschentwicklung am Zahnradantrieb', 'Nockenprofil-Beschädigungen', 'Unregelmäßiges Einspritz-Timing']
Causes: Resonance excitation by 9-cylinder ignition sequence, Unzureichende Torsionsdämpfung, Wear on tooth flanks
Preventive: Torsionsschwingungsmessungen durchführen, Zahnflankenspiel regelmäßig kontrollieren, Schwingungsdämpfer auf Funktion prüfen
Zylinderlaufbuchsenrisse
Symptoms: ['Kühlwasserverlust', 'Druckabfall im Kühlsystem', 'Wassereinbruch in Spülluftkasten']
Causes: Thermische Wechselbelastung, Kavitationskorrosion, CLU-Montagefehler
Preventive: Druckprüfungen in regelmäßigen Intervallen, Kühlwasserchemie überwachen, CLU-Einbauanweisungen strikt befolgen
VIT-Regelung Fehlfunktion
Symptoms: ['Ungleiche Zylinderdrücke', 'Erhöhter Kraftstoffverbrauch', 'Abgastemperatur-Streuung']
Causes: Hydraulik-Leckagen am Aktuator, Mechanical wear of control rods, Kontamination des Hydrauliköls
Preventive: Completely overhaul VIT system at overhauls, filter and analyse hydraulic oil
Expert tips
- 💡 9-cylinder configuration is the most critical arrangement: the extreme engine length makes alignment problems more likely than with any other cylinder count. Always perform deflection measurements in both warm AND cold condition and correlate with loading condition.
- 💡 When inspecting the camshaft, definitely account for the entire length – at 9 cylinders the camshaft can expand thermally significantly. Document end clearances at camshaft bearings.
- 💡 Pay special attention to even power distribution across all 9 cylinders – deviations accumulate at this cylinder count and place additional load on the crankshaft.
Related components
Turbocharger and charge air cooler
Crankshaft bearing and main bearing
Stern tube seal and thrust bearing
Fuel treatment and separators
Anlassluftsystem
Abgaskessel
Classification & regulatory
Comply with MARPOL Annex VI emission regulations. Ensure NOx Technical Code compliance through VIT calibration. Classification society requires extended deflection measurements and alignment protocols for 9-cylinder engines. Camshaft gear drive is subject to special test requirements.
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
7RTA84C
7 cyl
· 26,740 kW
7RTA84T
7 cyl
· 26,740 kW
7RTA84T-D
7 cyl
· 31,640 kW
7RTA96C
7 cyl
· 38,430 kW
Components & Design
Component data being added…
Technical Data
unified from engine model
True
🤖 Ask about this model
One free question — answered like a marine engineer. No account needed.
Suppliers & Spare Parts
Direct links to manufacturer, datasheet, spare-parts portal and dealers — request access below.
📄 Request sourcing links & documents🛠 Manage this equipment in your fleet
Cases, daily reports, timesheets and AI troubleshooting in the OceanSphere Marine app — free for 14 days.
Start free trial →🔎 Suppliers & service for this equipment
Find manufacturers, repair shops and spare-part dealers in the Maritime Network — our global company directory.
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)
Working on this unit?
Log hours, photos and findings into an invoice-ready service report — OceanSphere Marine, 14-day free trial.
Need a service partner for Sulzer?
114,000+ shipyards, suppliers and service companies in the Maritime Network directory.
Equipment Model #38691
· ✓ still in production