DieselShip's Online Content Library

Q1. a) Explain why pilot injection is required for a Dual fuel engine when burning natural gas. (2)

b) Describe, with the aid of a sketch, the arrangements for a dual fuel engine which is capable of burning natural gas on;

          a) The otto cycle (7)

          b) The Diesel cycle (7)

Q2. (A) Explain why crankshaft deflections are taken. (4)

(b) Write a procedure for the taking of main engine crankshaft deflections. (8)

(c) Explain the action to be taken if some crankshaft deflection readings are outside acceptable limits. (4)

Q3. With reference to engine fuel injector nozzle cooling;

(a) Explain why fuel injector nozzle cooling is necessary (4)

(b) Describe, with the aid of a sketch, the operation of a nozzle cooling system for a generator engine; (8)

(c) Explain how fuel injector nozzles are cooled on engines which are not fitted with a separate nozzle cooling system (4)

Q4.a) Describe the procedure for entry into, and inspection of, the inside of a starting air bottle,

stating the types of defects which may be present with their possible causes. (12)

b) Describe the procedure of closing up the bottle and the initial pressurisation to working

pressure. (4)

Q9. (a) Explain why variable exhaust valve closing can be advantageous in the operation of large slow speed main engines.

(b) Explain, with the aid of a sketch, how variable exhaust valve closing is achieved.

(c) Explain how high impact is avoided as the valve closes. (2)

Q6. (a) Explain why highly efficient diesel engines tend to produce more NOx than low performance diesel engines.

(b) Describe, with the aid of a sketch, a Selective Catalytic Reduction (SCR) unit for a marine propulsion diesel engine.

(c) Explain why accurate monitoring of the exhaust gas flows entering and leaving a Selective Catalytic Reduction unit are required and how these readings are used to control the reduction chemical supplied to the SCR unit.

Q7. Analyse the problem of cylinder liner lubrication with reference to oil injection timing relative to piston position, speed and direction of motion. Describe the worst effects of inaccurate lubricant injection timing and how it can have a detrimental effect on developed power in the cylinder. Describe with sketches the arrangement for conveying the oil through the cylinder jacket. (16)

Q8. With reference to solid propellers state:

a) how badly damaged blade tips are restored? (6)

b) why propellers need balancing from time to time. (5)

c) why intense concentrated heat should not be applied to bosses. (5)

Q9. a) Describe with the aid of a simple labelled sketch the important features of a reduction gearbox suitable for installation with medium speed engines. (6)

b) State the materials used for gears and briefly explain how the gears are manufactured (5)

(c) As Second Engineer describe how you would conduct an inspection of the gearing and at the

same time give instruction to a cadet on the type of damage most likely to be found. (5)