DieselShip's Online Content Library

Q2. A. Explain the term Variable Injection Timing (VIT) when applied to fuel pumps and state why a change in timing of fuel injection may be required.;

B. Describe, with the aid of sketches a VIT fuel pump and explain how the change in timing is achieved whilst the pump is in operation

C. Explain how it may be determined that individual fuel pumps are injecting the correct quantity of fuel with the correct timing at a particular pump setting.

Q1. With reference to a particular make of main propulsion unit, describe how the engine is reversed manually and discuss the problems involved and the safety precautions which would be required if the control were operated remote from the machinery space.

Q2. Sketch a Main Engine air starting distributor and describe how it operates.

List the safety devices and interlocks incorporated in main engine air starting system and state the purpose of each.

Q2. During a routine crankcase inspection a main engine top end bearing is found to be wiped and subsequent inspection shows that the pin is badly scored.

A. Explain in detail the action which should be taken to enable the engine to be safety operated so that the vessel may reach a port where effective repair facilities are available.

B. State with reasons the factors which influence the speed at which the engine may be safely operated.

Q4. a) Describe, with the aid of a sketch, an external system for reducing engine NOx emission, explaining the chemistry of the process

b) Explain why Urea is used in the selective catalytic reduction process instead of ammonia.

(c) Explain why the exhaust gas quality must be monitored before and after the selective catalytic reduction unit, stating how such monitoring influences operation of the SCR unit.

Q6. What is "virtual tappet" in the hydraulically actuated air spring return exhaust valves, and how is it set. Explain why the damage occurs to the seats of the exhaust valves due to furrowing and cutting and how an incident of "valve drop" leading to extensive damage to running gear can occur.

Q5. With reference to the crankshaft and running gear of an engine, explain static balance, Dynamic balance, Torque reaction couple, and Critical speed

Q1. (a) Explain the factors you would consider in deciding whether to open up a cylinder unit for overhaul? After opening the unit and preparing for assembly, how would you decide whether to renew or re-use piston rings?

(b) List the causes of piston ring failure which may result in gas leakage or ring breakage.

Q4. How is fuel oil injected into the cylinder of a heavy oil two stroke cycle internal combustion engine and how is it ignited? Show by a timing diagram at what point of stroke injection of the fuel begins and ends. Name the engine to which your answer refers. Explain the effect of advancing the timing of injection on: i.  Fuel per brake horse power hour; ii. Exhaust temperature; iii. Cylinder maximum pressure