Four-Stroke Operation — Alternator Duty
Learn alternator-engine operation: LO, jacket-water and overspeed trips, OMD, pre-op checks, start-run-stop drill and gearbox coupling watch.
1. Protection & Plant Map
Low LO pressure and high jacket temperature trips each alarm then fuel-cut the engine; overspeed kills fuel to a standstill. The crankcase breathes through a flame-trapped breather, relieves through door valves against explosion, and watches itself through the mist detector — alarm always, auto slow-down on propulsion, breaker trip and off-load on generators.
2. Pre-Op & Start
Prove before starting:
- Header and sump, turbocharger, governor and bearing levels correct.
- Jacket-water and injector-cooling heaters on with valves correctly set.
- Racks and plungers moving free; liners hand-lubricated without force.
- Every system valve in position; separator run as needed (sump-to-sump purifying hours before, unlike main-engine practice).
- Pre-lube running.
- Cylinders barred dry through open cocks.
- Heaters and circulating pumps off.
- Gear out with lever locked.
Start sequence:
- Alarms live; pre-lube, transfer, booster, nozzle-cooling, jacket and service pumps up.
- Gear confirmed out and locked.
- Indicator cocks open.
- 25–30 bar air proved.
- Governor at zero with knob wound five turns.
- Racks stroked free.
- Main air valve open.
- Clearance and GO from the duty staff — then start.
3. Run & Stop by the Clock
Cocks shut, ten minutes at speed warming, RPM eased up, load only on warm metal — then pressures to spec, per-unit jacket/LO/exhaust and turbo temperatures, turbo oil, filter differentials, service-tank water drains with positive head, header levels, sump trends (fast moves mean trouble), and ears open for knocks. Stop: load across first, breaker under ~50 kW, 10–15 minutes cooling running, speed down, stop button, cocks open, air valve shut, pre-lube off, slow barring over.
4. Gearbox & Coupling Watch
Single-reduction usually single-helical gearing with elastic couplings absorbing misalignment and torque ripple (clutch-combined where fitted, mechanical excluded from easy clutch duty). Watch sump level and oil state, pressures with filter differentials, temperature trends, vibration and noise — maker instructions overrule any generic list.
Practise this in the question bank
- Auxiliary Engine / Generator — 24 questions
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- Two-Stroke Main Engine Standby & Start Preparation: Preheating, Turning Gear, Blow-Through & Bridge Control Changeover
- Starting & Reversing the Two-Stroke
- Manoeuvring, Port Ops & Engine Vigilance
- Four-Stroke Operation — Alternator Duty
- Starting Air System Physics, Explosions & Air Distributor