Marine Engineers | Education
Marine Engineers
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24.01.2022 Lifeboat release gear
23.01.2022 Why shaft earthing is vital for ICCP????? The impressed current leaves the anode and passes into the surrounding seawater where it ‘looks’ for the least resistive path, taking it to the propeller and then down the shaft line. When the shaft rotates, the resistance in the bearings is variable and for split second it can change from very low to very high. When the resistance is low, current ‘jumps’ onto the bearings and it is this factor which causes damaging ‘spark erosion’. ...In the absence of a shaft earthing system, after the current has passed through the bearings there is still no easy way back to earth and therefore it travels back down the shaft line to the propeller blades. At the times of high resistance the seawater provides a less resistive path than through the bearings, so the current discharges into it from the tips of the propeller blades. This creates pitting in the blades as positively charged ions leave the surface of the metal. These pits enlarge as the propeller rotates, causing bubbles of oxygen to implode and create deeper cavities in the process known as the corrosion erosion cycle. All of these problems can be avoided by having a shaft earthing arrangement which is correctly positioned on the shaft line.
22.01.2022 Induction motor working principle
20.01.2022 What is Integrated Protection "IP" mentioned in the motor nameplate??? (For example IP 23) The first digit indicates how well protected the motor is against the entry of solid objects, the second digit refers to water entry. The two digit number is followed by letters IP. Here's what the first digit means: 0 - No protection ... 1 - Protection against objects larger than 50mm (about 2 in.) in diameter, like hands 2 - Protection against objects larger than 12mm (about 1/2 in.) in diameter, like fingers 4 - Protection against objects larger than 1mm (about 0.04 in.) in diameter, like small tools and wires 5 - Complete protection, including dust-tightness. The second digit signifies protection against water entry. Here are those ratings: 0 - No protection 1 - Protected from water falling straight down 2 - Protected from water falling as much as 15 deg from vertical 3 - Protected from spraying water as much as 60 deg from the vertical 4 - Protected from splashing water coming from any direction 5 - Protected against jets of water from all directions 6 - Protected from heavy seas 7 - Protected against the effects of immersion to depths of between 0.15 and 1.0m 8 - Protected against the effects of prolonged immersion at depth
19.01.2022 What is Hydraulic lock alarm in steering gear???????? Hydraulic lock alarm is activated when- Position of the variable displacement pump control system does not correspond to the given order, or ... Incorrect position of the 3-way full flow valve or similar in the constant delivery pump system is detected.
17.01.2022 Cylinder liner calibration Normal wear 0.1 mm / 1000 hrs Renew liner when bore exceeds 0.8 to 1.0 % of the original bore.... Liner calibration done between 6000 8000 hrs
16.01.2022 Lloyd’s Register Code for Lifting Appliances in the Marine Environment refer to the following formulae: SWL 10 t 2 x SWL 10 t < SWL 160 t (1.04 x SWL) + 9.6 SWL > 160 t 1.1 SWL... Once testing is completed successfully, the equipment will need to be permanently marked in figures >75mm with the following information: Safe working load in tonnes Certificate number(supplied by the surveyor) Quality grade mark for the type of steel Surveyor’s stamp (to be supplied) Tare weight in tonnes
16.01.2022 Common rail injector animation
15.01.2022 Aux boiler combustion control... increase in steam demand will increase air first then fuel only... and for decrease in demand vice versa.
14.01.2022 Fuel pump with punture v/v operation
10.01.2022 Lifeboat davit actuator Service
09.01.2022 What is the function of AVR? Automatic voltage regulator
08.01.2022 There are two Parker valves on ME-B engine. One is for hydraulic oil pressure control on HPS accumulator block. The other one is for fuel injection (and exhaust valve close timing control) on HCU ELFI (-V) valve.... Replacement procedures: Step1: Just take out the valve from HPS accumulator block or ELFI(-V) complete from HCU. In case of that not to forget to disconnect the cable from junction box. Step2: Install new Parker valve to HPS accumulator block or new ELFI(-V) with Parker valve to HCU NB: Don’t forget to connect the cable to junction box.
03.01.2022 Simple air start v/v
01.01.2022 The rudder carrier bearing takes the weight of the rudder on a grease lubricated thrust face. The rudder stock is located by the journal, also grease lubricated. Support for the bearing is provided by a doubler plate and steel chock. The base of the carrier bearing is located by wsdge type side chocks, welded to the deck stiffening. The carrier is of meehanite with a gunmetal thrust ring and bush. Carrier bearing components are split as necessary for removal or replacement. S...crew down lubricators are fitted, and the grease used for lubrication is of a water resistant type (calcium soap based with graphite). Weardown A small allowance is made for weardown, which must be periodically checked. This may be measured either between pads welded on top of the rudder and onto the rudder horn, or between the top of the rudder stock and a fixed mark on the inner structure of the steering gear flat. The latter generally involves the use of a 'Trammel gauge' which takes the form of a 'L' shaped rod ade to fit the new condition of the gear. As wear down occurs it can easily be checked with this gauge. The rudder is prevented from jumping by rudder stops welded onto the stern frame. Rudder movement stops Rudder stops are arranged as follows; Angle from centreline Position of stop Note 35o On telemotor system Normal limit 37o On steering gear Prevents rudder striking external stops 39o External, on stern frame emergency stop to protect propeller These limits refer to rudders of traditional design and is governed by both the physical layout of the rudder and actuator but also due to the stall angles of the rudder. i.e. the angle at which lift ( turning moment ) is reduced or lost with increasing angle of attack. There are designs of rudder such as becker flap which have increased stall angles up to 45o Reasons for critical contouring of thrust face; 1. for lubrication 2. conical in order to prevent side slip and centralise rudder 3. projected area gives greater bearing area allowing smaller diameter bearing See more
