The Engineering Diary

Maintenance Running checks should include: Gear box - oil level; inspect for leaks around casing; ensure pins and bolts in mechanical linkages are secure. Shaft bearings - check oil level in bearing sump; leakage through end seals; temperature of bearing. Stern gland - a leaking stern gland is a normal routine and is adjusted as a matter of course. See stern tubes in section above. Propeller shaft - check noise level to determine whether it is increasing. Regular maintenance schedules will include: Gearboxes - Adjust clutches and operating mechanism, clean filters and clean oil coolers. Drive train  Engine and shaft bearing moutings, loose shaft coupling bolts (perhaps due to mis-alignment) may need to be tightened. Mis-alignment of intermediate bearings will show up by overheating of the bearing. Survey servicing and repair schedules will include: Weardown survey- Allowance is determined by the manufacturer, but rules of thumb range from 3% of diameter as due for replacement to 6% bei

Diesel fuel systems Direct supply The fuel tank with filler cap and venting breather is measurable by a sight gauge. Fuel is directed to the mechanical fuel pump through the supply line, along which primary and secondary filters ensure clean fuel only reaches the mechanical pump. Additional water separators are often fitted at the primary filter position. A manual lift pump is provided to assist bleeding (priming) the fuel line of trapped air after servicing the fuel filters. The cam driven mechanical pump forces the fuel to the injectors when it is required for combustion. Other fuel line components include: Baffle - They are fitted to prevent free surface effect. This affects the stability of the vessel and in extreme cases can cause vessels to capsize. Drain valve - is fitted to the lowest part of the tank. Its purpose is to drain water or sediment from the tank. A plug or cap is fitted so, if the valve vibrates open, the fuel is not lost or causes a fire risk. Water can be in the t

Quick closing valves: What are Quick Closing Valves? On ships, marine diesel engines draw fuel from reservoirs or storage tanks which are also known as service tanks. All these tanks are provided with a specific valve known as quick closing valve, in order to shut the fuel supply in case of emergency such as fire. The closing of the valve can be done either manually, hydraulically or even by using compressed air. A typical arrangement consists of wire operated valves with wire pull livers located externally to the machinery space. If you want to know more about other types of valves, read these articles about gate valves, globe valves and butterfly valves. Construction and Working Quick closing valve is a kind of pressure reducing valve in which the an automatic process control valve for fluid pressure control is used for unmanned machinery spaces. This can be done by careful selection of valve trim, i.e. the parts of the valve that come in contact with the controlled fluid and form an

What is a Ship's Stern Tube? Everyone knows that a ship is propelled with the help of a propeller located at the aft of the ship. However, they may not know how the propeller is connected to the engine located inside the ship. A stern tube, situated at the aft of the ship, helps in this purpose. The propeller is the only part of ships machinery, apart from the rudder, that is located outside the ships engine room. Have you ever seen the propeller of a ship and wondered how it is connected to the inside of the ship? Have you ever wondered where the shaft holding the propeller goes when it vanishes into the ships hull? If so, then you have come to the right place. The propeller, a part of the propulsion system of the ship, needs a power source to rotate it. A marine diesel engine located inside the ship supplies the power to the propeller. Both the diesel engine and propeller are very heavy: locating them both at the same place inside the ship would disturb the ships stability. It is

Principles of internal combustion engines Operating principles Combustion is the process in which fuel heated beyond its flash point ignites and gives off energy and the waste products as exhaust gasses (carbon dioxide, carbon monoxide and water). The three elements necessary for combustion (or fire) are: Oxygen + Heat + Fuel = Explosion or Fire Internal combustion engines suck in air to access the oxygen and use hydrocarbon fuels including petrol, diesel and liquid propane gas. The internal combustion process Internal combustion engines use successive explosions of atomised air and fuel mix to force a piston down a gas tight internal cylinder. The piston is connected through a big end bearing to a cranked shaft that is weighted by a flywheel to assist its rotary momentum. Thus with three primary moving parts (piston, connecting rod and crankshaft) the pistons reciprocating motion drives the crankshafts rotary motion. A sturdy metal casting of an engine block holds the internal parts a

How Does a Diesel Engine Work? When people think of a diesel engine, they often think of a big truck which hauls a lot of items. Although diesel engines are commonly found in bigger vehicles, they can really be in any size vehicle. The benefit of a diesel engine is getting better miles per gallon. Since truck drivers are constantly on the road for most of the day, it is more economical for them to drive a diesel-powered vehicle versus a petrol-powered vehicle. The reason that diesel engines provide better gas mileage is because they have fewer revolutions per minute. Unlike with a petrol engine, the air is the only thing that gets compressed in the chamber. This highly compressed air is then used to ignite the diesel fuel. This differs from the petrol engine which requires separate spark plugs to generate a spark for ignition. The diesel engine does not require such a spark. It relies solely on the highly compressed air to generate enough heat for a proper ignition of its fuel. The Fou

Nonrenewable Resources What Are Nonrenewable Resources? A nonrenewable resource is a natural substance that is not replenished with the speed at which it is consumed. It is a finite resource. Fossil fuels such as oil, natural gas, and coal are examples of nonrenewable resources. Humans constantly draw on the reserves of these substances while the formation of new supplies takes eons. Renewable resources are the opposite: Their supply replenishes naturally or can be sustained. The sunlight used in solar power and the wind used to power wind turbines replenish themselves. Timber reserves can be sustained through replanting. Understanding Nonrenewable Resources Nonrenewable resources come from the Earth. Humans extract them in gas, liquid, or solid form and then convert them for their use, mainly related to energy. The reserves of these substances took billions of years to form, and it will take billions of years to replace the supplies used. In economic terms, nonrenewables are resources

Types of Renewable Energy Sources Solar Energy Humans have been harnessing solar energy for thousands of yearsto grow crops, stay warm, and dry foods. According to the National Renewable Energy Laboratory, more energy from the sun falls on the earth in one hour than is used by everyone in the world in one year. Today, we use the suns rays in many waysto heat homes and businesses, to warm water, or power devices. Solar, or photovoltaic (PV), cells are made from silicon or other materials that transform sunlight directly into electricity. Distributed solar systems generate electricity locally for homes and businesses, either through rooftop panels or community projects that power entire neighborhoods. Solar farms can generate power for thousands of homes, using mirrors to concentrate sunlight across acres of solar cells. Floating solar farmsor floatovoltaicscan be an effective use of wastewater facilities and bodies of water that arent ecologically sensitive.   Solar supplies a little mo

Problems with low pH pH that is too high or too low will have negative effects on the fish. Low pH can cause damage to the gills, skin and eyes. Higher H+ concentrations will also increase the permeability of the gills, leading to leakage of Na+ and Cl which creates osmotic problems. First, the effects can be regis-tered as a reduction in growth; too low a pH will kill the fish. In natural populations, the pH may vary from 5 to 9, but for aquaculture facilities it is rec-ommended to be in the range 6.59. Problems with metals in the water are best avoided; tolerance may vary with fish species and life stage, with newly hatched fry being especially sensitive. For crayfish, for example, the pH and alkalinity must be high because they utilize Ca2+ in the water for shell synthesis. The solubility of metal ions in the water will increase with reduction in pH. There have been particular problems with the concentrations of aluminium (Al+ + +) in fish farming; this metal leaches from the soil o