Q7. What is Rocking test of Deck Crane? Explain the procedure of rocking test. Tabulate and indicate fault finding procedure. What is the action taken if deviation is out of limit?
Q1. Explain why auxiliary engine bottom-end bolts are prone to failure, even under normal running conditions. Identify those features, incorporated into the design of bottom-end bolts, to inhibit failure. Explain how this tendency is either aggravated or inhibited during maintenance and what checks are to be carried out.
Q3. 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. How an incident of "valve drop" leading to extensive damage to running gear can occur.
Q4. Many modern turbochargers use sleeve type bearings for rotor support.
A. Explain the reasons for their preference over the rolling contact bearings;
B. With a sketch describe the lubricating system provided for this type;
C. In a turbocharger with integral type of bearings, describe the procedure for renewing the bearings.
(i) Superheating at the compressor suction
(ii) Undercooling at the condenser outlet
(b) Describe, with the air of a pressure-enthalpy diagram, how the evaporator cooling load is affected by the conditions stated in Q5 (a)
Q6. With reference to main shaft bearings that are excessively loaded or very lightly loaded state for each condition what are the;
a) Indications of the fault,
b) Effects on adjacent bearings
c) Remedial steps.
Explain why load distribution on main shaft bearings changes in service.
Q7. (a) Specify with reasons those parts requiring particularly close scrutiny during internal and external examinations of independently fired auxiliary boilers.
(b) With reference to these examinations distinguish between metal fatigue due to caustic embrittlement, corrosion fatigue, overheating (plastic flow) and direct overpressure.
Q8. a) Discuss the Merits and demerits of a condition monitoring system compared to other maintenance regimes.
b) Describe how the data is gathered, stored and evaluated on a computer-based vibration analysis system
Q9. a) List the design problems associated with safety valves for high-pressure boilers.
b) State the factors that determine
(i) The relationship between the working pressure of the boiler and the setting pressure of the safety valve
(ii) The blow down setting of a safety valve
c) State what determines the settings of
(i) The super heater safety valve
(ii) The drum safety valve.
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