7S50ME-B9.5
The MAN Energy Solutions 7S50ME-B9.5 is a 7‑cylinder, low‑speed two‑stroke main engine delivering up to 26 110 kW at 127 rpm, featuring camshaft‑driven exhaust valves and electronic fuel injection for Tier III emissions compliance.
Engine Specifications
Inspector Detail
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Designation decoded
7 stands for 7 cylinders, S for Super-Long-Stroke, 50 for 500 mm bore, ME-B for electronically controlled fuel injection with camshaft-controlled exhaust valve, 9.5 for Mark 9.5.
Background
The S50ME-B9.5 with 7 cylinders is a widely used configuration for Supramax bulkers and MR tankers. S/B 4.0 as a proven compromise. ME-B technology. 7 cylinders for the typical power range of mid-size merchant vessels.
Calculated metrics
Inspector checklist
- Cylinder liners: S/B 4.0 — significant side forces, document wear
- Piston rings: Butt clearance and height wear
- Alpha Lubricator: Dosing and timing
- Crosshead bearing: Temperature across 7 cylinders
- Stuffing box: Check drainage
- Piston rod: Deflection and run-out
- ME-B control: Sensors and EICU
- Camshaft: Chain elongation
- SaCoSone software
- Scavenge air box: Inspection openings
- Turbocharger: Single TC
- Exhaust temperature across 7 cylinders
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Exhaust temperature by cylinder | 350–420 °C at MCR | Spread >15 °C → check injection |
| Scavenge air pressure | 2.3–3.0 bar | Drop → TC/cooler |
| Pmax | ±2 bar cylinder balance | Deviation → control system |
| Cylinder oil feed rate | 0.5–0.8 g/kWh | Calibrate Alpha Lubricator |
Common Failure Modes
Expert tips
- 💡 7×S50ME-B9.5 is one of the most popular ME-B configurations worldwide — broad experience base, good service network, spare parts readily available
- 💡 ME-B allows variable injection timing — optimize injection profiles for efficiency during slow steaming, for emissions at full load
- 💡 7-cylinder S50: Torsional vibrations possible at certain speeds — verify Barred Speed Range in the control system
Related components
Classification & regulatory
IMO Tier II compliant. Tier III with EGR/SCR. EEDI-optimized. MARPOL Annex VI — VLSFO.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 23
Components & Design
Component data being added…
Technical Data
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