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Sulzer

12RTA84C

Name: Sulzer 12RTA84C
Brand: Sulzer
SKU: OSE-38710

The Sulzer 12RTA84C is a low‑speed, two‑stroke marine diesel main engine delivering 45,840 kW at 102 rpm, known for its high power output per cylinder and proven reliability in large vessels.

45840.0 kW

Power

Engine Specifications

Cylinders

840 mm

Bore

2400 mm

Stroke

45,840 kW

MCR Power

102.0 rpm

MCR RPM

2-stroke

Stroke Type

Family: Sulzer RTA · Tier: IMO Tier I · Fuel: HFO, MDO

Inspector Detail ✓ verified

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Designation decoded

Sulzer 12RTA84C – 12-Zylinder-Reihen-Zweitakt-Kreuzkopf-Dieselmotor, Bohrung 840 mm, Hub 2400 mm, zahnradgetriebene Nockenwelle, Baureihe C (Container-Optimierung). Sulzer/Wärtsilä-Lizenzfertigung für Großcontainerschiffe.

Background

The RTA84C series was designed for fast container ships with high power demand at moderate speed. 12-cylinder configuration already represents considerable engine length (~22 m engine length), bringing foundation and alignment issues to the fore. Gear-driven camshaft with conventional VIT (Variable Injection Timing) and pulse lubrication system. Cylinder output approx. 3820 kW at 102 rpm. CLU (Cylinder Liner Unit) as maintenance concept with dry-docked liner removal for weights >8 t per unit.

Calculated metrics

Stroke To Bore Ratio

2.857

Inspector checklist

Logbook reference values

Parameter	Expected	Deviation means
Maximaler Zünddruck (Pmax)	140–155 bar (lastabhängig, VIT-korrigiert)	Deviation >5 bar between cylinders: VIT mis-adjustment, fuel injector coking or compression deficiency. Systematic deviation: check fuel quality or turbocharger efficiency.
Exhaust gas temperature per cylinder	340–400 °C at rated load	Individual cylinder >30 °C above average: fuel injector defect, valve leakage or unequal air distribution. With 12 cylinders, pay particular attention to flow distribution in scavenge air box.
Kühlwassertemperatur Laufbuchse	75–85 °C Eintritt / max. 95 °C Austritt	Elevated outlet temperature: scale deposits, thermostat failure or cylinder liner crack. Analyze cooling water for oil traces and pH value.
Zylinderschmieröl-Verbrauch	0,9–1,3 g/kWh (Pulse-System)	Increased consumption: piston ring wear or faulty metering. Reduced consumption: plugged lubrication holes – risk of increased cylinder liner wear.
Spülluftdruck	2.8–3.5 bar abs. at rated load	Low pressure: turbocharger fouling, charge air cooler fouling or scavenge port narrowing. Check air filter and compressor wheel.
Kurbelwellen-Deflexion	±0.05 mm (depending on crank and manufacturer specification)	Exceedance: foundation settlement, bearing wear or uneven loading/ballasting. With 12 cylinders, particularly middle bearings and end cylinders are critical.
Turbolader-Drehzahl	Depending on turbocharger type, typically 8000–12000 rpm at rated load	Deviation >5 %: fouling on turbine or compressor side, bearing wear. With multi-turbocharger arrangement, check load distribution.
Steuerluftdruck Auslassventil	7–9 bar	Low pressure: leakage in control line, valve stem seal or actuator failure. Valve closing time extends – increased thermal load.

Common Failure Modes

Camshaft gear drive wear

Symptoms: ['Ungewöhnliche Geräusche aus dem Getriebekasten', 'Changed fuel injection and valve timing', 'Metallpartikel im Schmierölfilter']

Causes: Mangelhafte Schmierung des Zahnradgetriebes, Material fatigue at high operating hours, Misalignment after foundation settlement

Preventive: Regular flank clearance measurement, lubricating oil analysis for wear metals, vibration monitoring on gear housing. Document tooth flank contact pattern every 8000 operating hours.

CLU-Laufbuchsenriss

Symptoms: ['Kühlwasserverlust ohne äußere Leckage', 'Ölfilm auf Kühlwasseroberfläche', 'Erhöhte Laufbuchsentemperatur einzelner Zylinder', 'Weißrauch im Abgas']

Causes: Thermal fatigue due to uneven cooling, Corrosion from inadequate cooling water treatment, Mechanical overstress from piston ring blowby

Preventive: Monitor cooling water quality strictly (pH, inhibitor concentration). Monitor cylinder liner temperatures continuously. When replacing CLU, inspect seating surfaces and O-rings carefully.

Fundament-Chocking-Degradation

Symptoms: ['Zunehmende Deflexionswerte über Zeit', 'Vibrationserhöhung am Motorblock', 'Rissbildung an Chocking-Material (Epoxidharz)', 'Lockere Fundamentbolzen']

Causes: Aging and shrinkage of epoxy resin, Thermische Wechselbelastung, Hull deformation at 12-cylinder design length

Preventive: Check foundation bolt preload at every dock visit. Monitor chocking condition visually and by tap test. Deflection measurements as trend monitoring at least twice yearly.

Pulse-Schmiersystem-Fehlfunktion

Symptoms: ['Erhöhter Laufbuchsenverschleiß', 'Piston ring failure', 'Uneven oil distribution visible during scavenge port inspection']

Causes: Verstopfte Schmierölbohrungen in der Laufbuchse, Dosierventil-Defekt, Akkumulator-Druckverlust, Steuerelektronik-Fehler

Preventive: Regular function test of all 12 cylinder lubrication points. Monitor accumulator pressure. Scavenge port inspection for uniform oil film every 4,000–6,000 operating hours.

Expert tips

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Related components

C r a n k s h a f t b e a r i n g s , m a i n b e a r i n g s , c r o s s h e a d g u i d e s , t u r b o c h a r g e r ( t y p e a n d n u m b e r t o b e o b s e r v e d ) , c h a r g e a i r c o o l e r , e x h a u s t g a s b o i l e r , s h a f t a l i g n m e n t , p r o p e l l e r s h a f t , f o u n d a t i o n b o l t s , v i b r a t i o n d a m p e r ( a x i a l a n d t o r s i o n a l d a m p e r s ) , a u x i l i a r y b l o w e r , c o n t r o l a i r c o m p r e s s o r s

Classification & regulatory

Class survey: crankshaft bearings and crosshead bearings in accordance with classification society (DNV, LR, BV etc.) every 5 years or as required. Deflection measurement at every intermediate and renewal survey. Engine performance measurement (indication) in accordance with MARPOL Annex VI / EEXI requirements. NOx Technical Code compliance for Tier I/II depending on year of build. Cylinder lubrication in accordance with manufacturer specification and IACS UR M68.

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

unified from engine model True

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Manuals

operating
Sulzer RTA Operating Manual
Wärtsilä Switzerland (historical Sulzer)
maintenance
Sulzer RTA Maintenance Manual
Wärtsilä Switzerland (historical Sulzer)
spare_parts
Sulzer RTA Spare Parts Catalogue
Wärtsilä Switzerland (historical Sulzer)

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Equipment Model #38710 · ✓ still in production