MEOclassIIexamnotes

 Loaded operation :  A rise in suction pressure causes needle valve to close. Oil pressure in the power element increase as the oil enters capacity control circuit from the oil pump. Power  element piston is forced upwards , pivoting lifting fork downwards .  Lifter pins drop  allowing suction valve to  seat & load control the cylinder. Unloaded operation  :  A drop in suction pressure causes the needle valve to open. Oil bleeds through the valve to the crank case decrease the oil pressure in the power  element, hence the piston moves downwards. lifting fork is pivoted upwards moving the lifting pin upwards. Suction valve is raised from its seat & controlled cylinder is unloaded. 

The power generated by the piston in the combustion chamber of marine engine is transferred to the crankshaft using the connecting rod. While transferring this tremendous power, the connecting rod itself is subjected to different stresses, which makes is vulnerable to damage. For this reason connecting rod bolts are used to join the connecting rod and con-rod bearing cover under the tremendous stresses generated by the running engine. The most common type of connecting rod that is used in the ship’s auxiliary engine is oblique or cross-cut connecting rod which is made of two parts. The connecting rod of the engine must be inspected at regular intervals of time to ensure there is no defect or problem to avoid any future accidents/emergency. It’s the knowledge and skills of the engineer that decides whether to use the same connecting rod or to renew it with the spare one. Following points ...

This refers to the measurements taken generally during a docking period to indicate excessive wear in the steering gear system particularly the rudder carrier. The significance of this is that for ram systems excessive wear can lead to bending moments on the rams. For rotary vane systems it can lead to vane edge loading.The readings taken are offered for recording by the classification society. TrammelThis takes the form of an 'L' shape bar of suitable construction. When the vessel is built a distinct centrepunch mark is placed onto the ruder stock and onto a suitable location on the vessels structure, here given as a girder which is typical. The trammel is manufactured to suit these marks As the carrier wears the upper pointer will fall below the centrepunch mark by an amount equal to the wear down.

Babbitt metal, is an antifriction metal alloy first produced by Isaac Babbitt in 1839. In present-day usage the term is applied to a whole class of silver-white bearing metals, or “white metals.” These alloys usually consist of relatively hard crystals embedded in a softer matrix, a structure important for machine bearings. They are composed primarily of tin, copper, and antimony, with traces of other metals added in some cases and lead substituted for tin in others. Bearings used in large marine diesel engines are tin based babbitt metals. Lead content is a minimum. Tin based white metals have 4 times the load bearing characteristics and two and a half times the maximum surface speed of lead based white metals. Tin-based white metal is an alloy with minimum 88% tin (Sn), the rest of the alloy composition is antimony (Sb), copper (Cu), cadmium (Cd) and small amounts of other elements that are added to improve the fineness of the grain structure and homogeneity during the solidificatio...

Interpretion of ignition quality of fuel from the fuel analysis report. CCAI is an empirical attempt to estimate how long the fuel will take from injection to ignition and by implication the likelihood of engine damage. Knowing the CCAI, the operator must then judge the acceptability of that fuel for effective operation in the engine. Ignition quality can to some extent be predicted by calculations based on viscosity and density, using formulas or graphs issued by the oil industry (CCAI by Shell or CII by BP).

    ➢    Machinery spaces are particularly vulnerable to fire hazards and casualties when large number of shore workers and their equipment are on board.     ➢    Temporary electric connections ( like, lighting and power cable ) if not in proper order ( say, improperly connected or fused, having deteriorated insulation or being subjected to chafing from port holes or doorways ) can cause hazards.     ➢    Air hoses passing through port holes and doors prevent them closing incase of emergency.     ➢    Carelessness during welding or gas cutting operations may cause shower of sparks, resulting ignition of oily waste and oil.     ➢    Minor or serious fires originate in oily rags and waste, rope and rubbish, lagging etc. in insulated spaces which may have smouldered for hours following ignition from cigarette end or sparks from electrodes or...

The difference between the set pressure at which relief valve starts lifting and at the pressure it reseats is known as blown down of relief valve . Suppose relief valve set pressure is 30 bar At 30 bar it starts opening as pressure increases valve opening increases . When it drops to 28 bar valve reseats so blowdown is 2 bar. The blowdown ring on a relief valve is adjusted to set te reseat pressure of the valve The spring pressure determines the pressure at which valve coil lift , where as blowdown ring determines when it will reseats.