Rights and Obligations Research Paper Example | Topics and Well Written Essays - 750 words

Rights and Obligations - Research Paper Example This is going to be done by analyzing a case study. There exists a difference between a contract and an agreement because they both have different ramifications for the parties involved. An agreement has the option of being legally binding, or it can be informal. An agreement becomes a contract when the parties involved conceptualize their agreement into a binding relationship. An agreement becomes a contract when it is made with a lawful consideration for a lawful entity. For an object to qualify to be included in a contract, it must not be forbidden by law or defeat the purpose of any laid down law. A contract should not be fraudulent in intent or imply injury and damage to a person or property of other individuals. A contract should not contravene societal morals either that can be deemed by a court of law as being opposed to public policy and interests (Miller, 2012). A contract should be agreed on based on free will and consent, and should not be realized through coercion. It sh ould not be accomplished through undue influence, misrepresentation or a mistake either. If a contract does not meet the aforementioned qualities, then it is null and void in the eyes of the law, and it cannot be enforced by law. Contracts have elements that define and validate their viability under the law, which makes them enforceable under the law. These main elements should be in a contract, or it would be invalid. The first element that constitutes a contract is an offer, agreement or a promise, which is the basis around which a contract is constructed. Without an offer, a contract cannot be actualized because it is the initial step that necessitates the drawing up of a contract (Helewitz, 2010). An offer in a contract should be between two or more individuals with one party making the offer and the other considering the same. The offer stipulates that there should be the fulfillment of duties and obligations by both parties for the offer to be constituted in a legally valid co ntract. There exists a difference between an offer in a contract and an advertisement. In an advertisement, the obligations and duties are fulfilled first before a contract is constructed. In an advertisement, one of the parties has no part to play in the setting up of terms and conditions required to fulfill the contractual obligations. Acceptance is an element that should be featured in a contract for it to be legally binding. Contractual acceptance is characterized by a party in the contract agreeing to the terms and conditions of the offer. A contract is not formalized until the party being proposed accepts the offer, and a contract is not legally binding if the requirements of an offer are under negotiation. Consideration in a contract is a vital element, and it means that the parties would be giving something back in return for the proposed offer. It is mostly characterized by a payment as consideration for the offer (Goldman & Sigismond, 2010). The parties involved in a contr act should make it clear to each other that the terms and conditions under which they are both entering into agreement are legally binding. This is an element in contracts that should be emphasized because it helps make the parties involved avoid the consequences of breach of contract. Certainty of the terms and conditions of a contract must be clearly stated and understandable to all parties. Lack of certainty of the regulations

Law and Legal Obligations Case Study Example | Topics and Well Written Essays - 2000 words

Law and Legal Obligations - Case Study Example The endorsing of the food by the celebrities, prominent personalities in visual media, The audio advertisements that tell about the taste and goodness of the junk food, The baseless topics that are publicised by the advertisements which do not have experimental proof, The instigating the children to eat junk food either by audio, visual, print media Can be considered as advertising the junk food under the criminalising of the sale of junk food to children and the ban of junk food vending machines in the schools and hostels Junk Food: The food that lacks nutrients and has more calories, The food that lack fibre and develops acidity The foods that have sugar content more than the prescribed level The foods that have less protein, fibre and that was replaced by starch and fats, The foods that have more fats than carbohydrates, The foods that have fat, carbohydrate, protein and fibre in disproportionate composition. (proportion is defined in the next section) The foods, which are not prescribed for good health of children. (health is defined in the next section) Vending Machines: The machine that supplies junk food without knowing to whom it is supplying. The machine which delivers junk food by taking the input of prescribed coins in to it. The machine which delivers junk food by taking the input of prescribed currency in to it. The vending machines which contain all the above three features and are installed in schools, hostels and the places where children buy the junk food directly without the consent of the adults. Section II In this section 'disproportion composition of the fats, carbohydrates, proteins, fibre, health of the children were defined. Disproportionate composition: the composition of fats, carbohydrates, proteins, fibre in a food substance was... In this paper a law about banning the junk food for children will be drafted and various terms will be defined. The definitions will be given according to the spirit of the law and the explanations for offences and defences will be incorporated. The sale of junk food to children will be considered as a crime. The sale of the same food for the adults is not in the purview of this act. For this purpose the sale of junk food, where children will buy directly from the vendors will be banned and prominently the sale of junk food in schools and hostels was prohibited. This will be considered crime against the children and the society if it was observed to be done and the individuals or the organisations who are responsible for those acts will be prosecuted according to the clauses and provisions in the act. Disproportionate composition: the composition of fats, carbohydrates, proteins, fibre in a food substance was considered as disproportionate if they do not match with the composition of the food substances prescribed by Health department for the sake of health of children. The health of children can be defined according to the weight of them proportionate to their height, the extra fat they accumulate under their skin, the hip waist ratio of them, the good sight regarding their eyes, the accumul

Classic Airlines and Marketing Essay Example | Topics and Well Written Essays - 500 words - 1

Classic Airlines and Marketing - Essay Example irline is faced with the challenge of ensuring that they deliver quality services and at low costs so as to ensure they retain and acquire new customers (Lane & Kotler, 2006). In order for classic airlines to succeed in the market, it must foster forecasting of the market potential and demand for its products and establish long term marketing objectives. Classic airline aim is to marketing its fleet but is faced by organizational issues whereby its internal and external marketing strategies have not been able to live up to the expectations of its stakeholders. Due this, competition has undermined its profitability as customers are looking for other airlines that can satisfy their needs of lower travelling costs. This has had the effect of decreasing the lucrativeness of the company. Classic airlines needs to develop a marketing plan that will ensure that it attracts, retains customers and also boost its sales. A good marketing plan will lay down the strategies to be followed to ensure a company retains, attracts customers and also increases profitability. Classic airline has numerous challenges facing it due to the rising costs of operation and lack of innovation in the company that make it not to be able to meet consumer needs. The company is facing challenges that include decrease in its stock prices, its employee morale is low , and its loyal customers have been seeking services from other airlines. The airline needs to ensure it does environmental scanning as it will help in understanding the needs of its customers and this will further help in knowing how best to meet their needs by ascertaining that the services they offer are in line with the needs of those in need of the services (Lane & Kotler, 2006). Marketing management is required in Classic Airline as it will ensure that proper marketing strategies are put in place to ensure customers are acquired and retained. Classic Airlines should ascertain that they use marketing strategies to maximize profits

Gender criticism Essay Example | Topics and Well Written Essays - 1000 words - 1

Gender criticism - Essay Example Throughout the novel, disparities in gender roles emerge whereby the author depicts male characters as the superior sex compared to their female counterparts. Advancing this perception are traditions entrenched within the Victorian era, which influenced the author’s perception of gender. According to the author, females adulated the males regarding them as superior beings capable of making pivotal decisions despite females’ divergent perspectives. In addition, James’ description of females best exemplified real life Victorian women; however, his description of his male characters contrasted that of Victorian males. The Victorian zeitgeist regarded women as proper, docile beings preoccupied with safeguarding their reputations. For example, despite the Governess’ infatuation with her employer, she refrained from acting on her emotions, as she stood to soil her reputation. Conversely, the male characters in the novel were far from being chivalrous or moral me n, as were Victorian men. The master of Bly did not concern himself with matters pertaining to the two children left under his charge whereby he opted to hire governesses to take care of the children, as he engaged in selfish pursuits. In addition, a conversation between Mrs. Grose and the Governess revealed that an employee named Quint was sexually promiscuous, a behavior shunned by Victorian males. The author best exemplified disparities in gender roles through the Governess’s treatment of the children. She expects Flora to be courteous, flawless and conscious about her behaviors. However, she is less critical of Miles’ behaviors bordering on the extent that she encourages him to be a little naughty (James 12- 15). In addition, Miles takes offence when the Governess presumes to compare him to his little sister. He remarked: An analysis of the main female characters shows that there exist generational differences among the women, which were

Commercial bank of kuwait (CBK) Essay Example | Topics and Well Written Essays - 1000 words

Commercial bank of kuwait (CBK) - Essay Example Characteristics of the industry in which the bank operates Commercial Bank of Kuwait operates in the Kuwait’s banking industries whose environmental features are identifiable. The industry is one of the strongest in the region and this identifies positive prospects such as sustainability and a business’ profit making interests. The industry is also free from unfavorable competition from international financial institutions. It comprises of about ten local banks and nine foreign banks, a number that identifies oligopolistic market. This means that the market players have significant potentials to dictate market factors but competitors can at the same time use such powers to gain competitive advantage over the firm. This further identifies banks’ fears of customer manipulation and leads to significant level of stability in the industry. The industry is also in its developmental stage in which competition is increasing as each bank seeks to expand its market control . Developments in the industry also identify diversification into new products and application of technology for developing new products as well as for efficiency. Innovation has been another characteristic feature of the industry and is a factor to increased level of competition. Favorable political environment has also been reported within the industry with policies that support commercial banks’ stability and operations. The policies indicate stability of the industry, regardless of possible entry by more foreign banks, because of the government policies that focuses on protecting the industry. Further, the minimal market size helps in protecting the industry from further venture by foreign banks because of risks of failing to reach breakeven points by new entrants and the country’s small population explains this (Capital Standards 1). The Industry however faces risks from volatility in two industries that are significant to its sustainability. The industriesâ€℠¢ dynamism affects performance and profitability of the banking industry that is also susceptible to threats of concentration. The role of Islamic banking that is gaining momentum in the country is another threat to the banking industry because of its ability to reduce the market base. Islamic banking is a significant threat because of the country’s dominant faith that is likely to induce bias towards the religious banks (Capital Standards 1). The Kuwait’s banking industry is also susceptible to global economic factors as global recession was witnessed during the global recession in the year 2009. Other significant sectors to the banking industry such as the construction sectors are also susceptible to the global economy and affect banks’ conditions. The industry’s financial indicators such as gross loans and non-performing loans also offer a basis for its analysis. Amount of gross loans has been increasing and this indicates increasing demand for financi al services. Increasing trend in nonperforming loans in the industry also indicates increasing advanced services to customers that culminates to increased defaults and threats of defaults. The increasing volume on non-performing loans is however, a threat to the industry as defaults constrains liquidity. Policies to improved asset quality have however promised to reduce the threats of growing volume of nonperforming loans with positive results being reported in the year 2010. The industry also relies on low cost deposits as sources

Marketing and Converse Question Essay Example for Free

Marketing and Converse Question Essay Need: Protection for the feet Wants: Cheap shoes which are comfortable and customizable. Demands: Emerging artists, designers and musicians wearing Chucks because of their affordability, simplicity and classic look. Now, anti-establishment rock fans beg Converse to feature a shoe by their favourite artist. Question 3 Production concept: The idea that consumers will favour the products those are available and highly affordable, and the idea that the company focus on improving production and distribution efficiency. Product Concept: Costumers will favour the products that offer the most quality, performance and features. Therefore the company should focus on making constant product improvements Selling Concept: The idea that consumers will not buy enough of the products unless it undertakes a large-scale selling and promotion effort. Marketing concept: The marketing philosophy that holds that achieving organizational goals depends on knowing the needs and wants of target markets and delivering that desired satisfaction better than competitors does. Almost every red Chuck converse sold goes to Global Fund. Question 4 Converse sees its role as one of making great products that its costumers want to wear. Beyond that it participates in consumers discussions rather that dictating them. Drawbacks: Converse rides a fine line: How many limited editions and upscale design can the brand produce without losing its image as a non marketing marketer. How popular can the brand become without losing the core costumers who love the precisely because it isn’t popular Question 5 Converse has been very careful in all that it does to remember on very important things for a brand like Converse, where authenticity is the most important trait, the costumer experience should be driven by the costumer.

Engine Cooling And Lubrication System

Engine Cooling And Lubrication System Cooling System: Despite the vast improvement in the basic internal combustion engines, around 70% of the energy from the gasoline is converted to heat. As it is not dissipated to the atmosphere on its own, a cooling system is employed for this purpose. Several purposes of the cooling system which it serves by cooling the engine include cooling the engine to keep it from overheating by transferring the heat to the air. This helps avoid the excessive wear and tear at high temperatures, auto-ignition due to hot cylinder which may result in knocking and hence, piston/cylinder failure. It may also incorporate thermal stresses which is not good for the engine itself. Figure . Cooling system and plumbing connection While it serves the purpose of cooling the engine, it also helps the engine to warm up quickly during cold start ups and then maintaining a constant temperature. When the engine is cold, components wear out faster too and the engine is less efficient, emitting more pollution. Types of Cooling System: There are two types of cooling systems found in cars: Air-cooled Liquid-Cooled Air-Cooled Engines: Many small and the medium-sized engines are air-cooled. This category includes most small engines like lawn mowers, chain saws, model airplanes etc. Using the air-cooled system allows both the weight and price of the engine to be kept low, along with reduced complexity of the machine. The air-cooled system is still widely used on most of the motorcycles in use these days. This system utilizes the concept of heat transfer through fins to cool the engine. The cross-sectional area of the fin being larger closer to the head and a reduction in the area as we move further from the engine block. The basic principle on which the air-cooled engines rely on is the flow of air across their external surfaces to remove the excess heat to keep the engine from overheating. The airflow on machines like motorcycles and aircrafts is provided across the surface when the vehicle moves forward. Deflectors and ductwork is incorporated to direct the airflow to the critical locations where more cooling is required. The outer surface of the engine is made from a good conductor of heat and the surface is finned to promote maximum heat transfer, along with which an extra fan is used to increase the air-flow rate; whereas others use the concept of free-convection. These fins are to be properly designed for appropriate cooling effect which is required. Some automobile engines also use exposed flywheels with air-deflectors fastened to the surface. When the engine is in operation, these deflectors create air motion which increases the heat transfer on the finned surface. Even after considering and applying all the measures, the uniform cooling of cylinders is still difficult to achieve on air-cooled engines as compared to the liquid-cooled engines. The figure below shows that the cooling needs are not the same at all the locations. Figure . Variation of heat losses from the fins of an air-cooled aircraft engine. Seventy-one percent of the heat losses occur on the hotter side of the cylinder, containing the exhaust valve. The engine shown was used on a number of different aircrafts. Hotter areas, such as the ones around the exhaust valve and manifold need greater cooling and hence larger finned surface area. Cooling the front of an air-cooled engine which faces the forward motion of the vehicle is much easier and efficient as compared to the back surface of the engine. This may result in temperature differences and thermal expansion problems. Disadvantages: Disadvantages of air-cooled engines are that they: Are less efficient, Are noisier, with greater air flow requirements and no water jacket to dampen the noise, Need a directed air flow and finned surfaces. Advantages: When compared with liquid-cooled engines, air-cooled engines have the following advantages: They are lighter in weight, They cost less, No coolant system failures (e.g., water pump, hoses), No engine freeze-ups, and Faster engine warmup. Liquid-Cooled Engines: In a liquid or water-cooled engine, the engine block is surrounded by a water jacket through which the coolant flows. This allows for a better control of the heat removal from the engine, just by added weight and a more complex system. Very few water-cooled engines use just water as the cooling fluid in the water jackets; this is because the water has a freezing temperature of 0Â °C which is unacceptable as coolant in colder regions, so additives are usually used for better performance. Although water has very good heat transfer properties, but when used alone, it causes rust and corrosion in many of the pipes of the cooling system. Ethylene glycol (C2H6O2) is the antifreeze agent which acts as a rust inhibitor and a lubricant for the water pump. When added to water, it lowers the freezing temperature and raises the boiling temperature of the coolant. The properties of the mixture depend on the ratio in which water and the antifreeze agent are mixed. Pure ethylene glycol should not be used, and even at high concentrations the heat transfer properties of the water are lost as well. The properties of the ethylene glycol water mixture are shown in the table below. In addition to good thermal properties, a coolant should satisfy the following requirements: 1. Chemically stable under conditions of use 2. Non-foaming 3. Non-corrosive 4. Low toxicity 5. Non-flammable 6. Low cost Most commercial antifreezes satisfy these requirements. Many of them are basically ethylene glycol with small amounts of additives. Some commercial engine coolants use propylene glycol as the base ingredient. It is argued that when coolant systems leak or when the coolant becomes aged and is discarded, these products are less harmful to the environment than ethylene glycol. Basic Components: The basic components of a liquid-cooled system is shown below. Figure . Basic liquid-cooled system radiator radiator top hose radiator bottom hose water pump thermostat thermostat housing electric cooling fan thermo-time switch Radiator: The radiator is the part of the cooling system which is responsible for the heat rejection from the coolant and into the atmosphere. The radiator core is usually made up of flattened tubes with aluminum strips (fins) that zigzag between the tubes. These fins effectively transfer the heat contained in the coolant into the air stream to be lost into the atmosphere. On each end of the radiator is a tank made up of plastic to cover the ends. The tubes either run horizontally or vertically between the two tanks. The aluminum-plastic system is more efficient and cost effective. On radiators with plastic end caps, there are gaskets between the aluminum core and the plastic tanks to seal the system and keep the fluid from leaking out. The tanks have a large hose connection, one mounted towards the top of the radiator to let the coolant in, the other mounted at the bottom of the radiator on the other tank to let the coolant back out. On the top of the radiator is an additional opening that is capped off by the radiator cap. Another component in the radiator for vehicles with an automatic transmission is a separate tank mounted inside one of the tanks. Fittings connect this inner tank through steel tubes to the automatic transmission. Transmission fluid is piped through this tank inside a tank to be cooled by the coolant flowing past it before returning to the transmission. Radiator Fans: One or two electric fans are mounted on the back of the radiator close to the engine. These fans used the concept of forced convection to cool the heated coolant going through the pipes in the radiator core. If noticed, this fan starts working once the engine reaches a predefined temperature, after which the cooling by just natural convection during the forward motion of the car cannot be achieved. In the cars with air conditioning, there is an additional radiator mounted in front of the normal radiator. This radiator is called the air conditioner condenser, which also needs to be cooled by the air flow entering the engine compartment. As long as the air conditioning is turned on, the system will keep the fan running, even if the engine is not running hot. This is because if there is no air flow through the air conditioning condenser, the air conditioner will not be able to cool the air entering the interior. Pressure cap reserve tank: The pressure cap is simply a cap which maintains the pressure in the cooling system up to a certain point. If the pressure builds up higher than the set pressure point, the spring loaded valve releases the pressure. Figure . Pressure cap When the pressure in the cooling system reaches the point when the cap needs to release this excess pressure, some amount of coolant is bled off. The coolant which is bled off goes into the reserve tank which is not pressurized, which causes a partial vacuum in the cooling system. The radiator cap on these closed systems has a secondary valve which allows the vacuum in the cooling system to draw the coolant back from the reserve tank into the radiator. Coolant Pump: It is a simple pump which helps in circulation of the coolant around the system. This pump is run using one of the following: A fan belt that will also be responsible for driving an additional component like an alternator or power steering pump A serpentine belt, which also drives the alternator, power steering pump and AC compressor among other things. The timing belt that is also responsible for driving one or more camshafts. The impeller of the pump uses centrifugal force to draw the coolant in from the lower radiator hose and send it under pressure to the engine block. A gasket seals the water pump to the engine block and prevents the flowing coolant from leaking out where the pump is attached to the block. Thermostat: The thermostat is simply a valve that measures the temperature of the coolant, and if the coolant is hot enough it opens to allow the coolant to flow through the radiator otherwise the flow to the radiator is blocked and the fluid is directed to a bypass system that returns the coolant to the engine. Figure . Thermostat The engine is at times allowed to run at higher temperatures of 190-195Â °C; this reduces emissions, moisture condensation inside the engine is quickly burned off improving engine life, and a more complete combustion improving fuel economy. Oil as a Coolant: The oil when used to lubricate the engine also helps to cool the engine. The piston for example gets very little cooling from the coolant in the water jacket or the externally finned surface, so when the back surface of the piston crown is subjected to the oil splash or flow the piston is cooled to some extent. This is very necessary as the piston is one of the hottest elements in the engine. Usually, the oil is sprayed in pressurized systems, and splashed in non-pressurized systems. The oil acts as the coolant on the back face of the piston crown as it absorbs energy and then runs back into the larger reservoir where it mixes with the cooler oil and dissipates this energy into the other engine parts. This splash cooling of the piston is extremely important in small air-cooled engines as well as in automobile engines. A few other engine components other than the piston are also cooled by oil circulation, either by splash or by the pressurized flow from the oil pump. Oil passages through internal components like the camshaft and connecting rods offer the only major cooling these parts are subjected to. As the oil cools the various components, it absorbs energy and its temperature rises. This energy is then dissipated to the rest of the engine by circulation and eventually gets absorbed in the engine coolant flow. Some high-performance engines have an oil cooler in their lubricant circulation system. The energy absorbed by the oil as it cools the engine components is dissipated in the oil cooler, which is a heat exchanger cooled by either engine coolant flow or external air flow. Oil Pump: The gear-type oil pump has a pair of meshing gears. The spaces between the teeth are filled with oil when the gears unmesh. The oil pump obtains oil from the oil pan and sends oil through the oil filter to the oil galleries and main bearings. Some oil passes from the holes in the crankshaft to the rod bearings. Main bearings and rod bearings are lubricated adequately to achieve their desired objectives. In the rotor type oil pump, the inner rotor is driven and drives the outer rotor. As the rotor revolves, the gaps between the lobes are filled with oil. When the lobes of the inner rotor move into the gaps in the outer rotor, oil is forced out through the outlet of pump. An oil pump can also be driven by a camshaft gear that drives the ignition distributor or by the crankshaft. Oil Pan: Oil also flows to the cylinder head through drilled passages that make up the oil gallery, lubricates camshaft bearings and valves, and then returns to oil pan. Some engines have grooves or holes in connecting rods, which provide extra lubrication to pistons and walls of cylinders. Oil Cooler: Oil cooler prevents overheating of oil, by flow of engine coolant past tubes carrying hot oil. The coolant picks excess heat and carries it to the radiator. Oil Filter: The oil from oil pump flows through oil filter before reaching the engine bearings. The oil filter retains the dirt particles and allows only clean filtered oil to pass. The Lubrication system and its types: There are three basic types of oil distribution systems used in engines: Splash, Pressurized, or A combination of these. The crankcase is used as the oil sump (reservoir) in a splash system, and the crankshaft rotating at high speed in the oil distributes it to the various moving parts by splash; no oil pump is used. All components, including the valve train and camshaft, must be open to the crankcase. Oil is splashed into the cylinders behind the pistons and onto the back of the piston crowns, acting both as a lubricant and a coolant. Many small four-stroke cycle engines (lawn mowers, golf carts, etc.) use splash distribution of oil. An engine with a pressurized oil distribution system uses an oil pump to supply lubrication to the moving parts through passages built into the components. A typical automobile engine has oil passages built into the connecting rods, valve stems, push rods, rocker arms, valve seats, engine block, and many other moving components. These make up a circulation network through which oil is distributed by the oil pump. In addition, oil is sprayed under pressure onto the cylinder walls and onto the back of the piston crowns. Most automobiles actually use dual distribution systems, relying on splash within the crankcase in addition to the pressurized flow from the oil pump. Most large stationary engines also use this kind of dual system. Most aircraft engines and a few automobile engines use a total pressurized system with the oil reservoir located separate from the crankcase. These are often called dry sump systems (i.e., the crankcase sump is dry of excess oil). Aircraft do not always fly level, and uncontrolled oil in the crankcase may not supply proper lubrication or oil pump input when the plane banks or turns. A diaphragm controls the oil level in the reservoir of a dry sump system, assuring a continuous flow into the oil pump and throughout the engine. Figure . Lubrication of an engine consisting of a combination of a pressurized system and splash system Oil pumps can be electric or mechanically driven off the engine. Pressure at the pump exit is typically about 300 to 400 kPa. If an oil pump is driven directly off the engine, some means should be built into the system to keep the exit pressure and flow rate from becoming excessive at high engine speeds. A time of excess wear is at engine startup before the oil pump can distribute proper lubrication. It takes a few engine cycles before the flow of oil is fully established, and during this time, many parts are not properly lubricated. Adding to the problem is the fact that often the oil is cold at engine startup. Cold oil has much higher viscosity, which further delays proper circulation. A few engines have oil preheaters which electrically heat the oil before startup. Some engines have pre-oilers that heat and circulate the oil before engine startup. An electric pump lubricates all components by distributing oil throughout the engine. It is recommended that turbocharged engines be allowed to idle for a few seconds before they are turned off. This is because of the very high speeds at which the turbocharger operates. When the engine is turned off, oil circulation stops and lubricated surfaces begin to lose oil. Stopping the oil supply to a turbocharger operating at high speed invites poor lubrication and high wear. To minimize this problem, the engine and turbocharger should be allowed to return to low speed (idle) before the lubrication supply is stopped. Lubrication system in 2-stroke engines: Many small engines and some experimental two-stroke cycle automobile engines use the crankcase as a compressor for the inlet air. Automobile engines which do this generally have the crankcase divided into several compartments, with each cylinder having its own separate compressor. These engines cannot use the crankcase as an oil sump, and an alternate method must be used to lubricate the crankshaft and other components in the crankcase. In these engines, oil is carried into the engine with the inlet air in much the same way as the fuel. When the fuel is added to the inlet air, usually with a carburetor, oil particles as well as fuel particles are distributed into the flow. The air flow then enters the crankcase, where it is compressed. Oil particles carried with the air lubricate the surfaces they come in contact with, first in the crankcase and then in the intake runner and cylinder. In some systems (model airplane engines, marine outboard motors, etc.), the oil is premixed with the fuel in the fuel tank. In other engines (automobiles, some golf carts, etc.), there is a separate oil reservoir that feeds a metered flow of oil into the fuel supply line or directly into the inlet air flow. Fuel-to-oil ratio ranges from 30:1 to 400:1, depending on the engine. Some modern high-performance engines have controls which regulate the fuel-oil ratio, depending on engine speed and load. Under conditions of high oil input, oil sometimes condenses in the crankcase. Up to 30% of the oil is recirculated from the crankcase in some automobile engines. It is desirable to get at least 3000 miles per liter of oil used. Most small lower cost engines have a single average oil input setting. If too much oil is supplied, deposits form on the combustion chamber walls and valves will stick (if there are valves). If too little oil is supplied, excess wear will occur and the piston can freez e in the cylinder. Engines that add oil to the inlet fuel obviously are designed to use up oil during operation. This oil also contributes to HC emissions in the exhaust due to valve overlap and poor combustion of the oil vapor in the cylinders. New oils that also burn better as fuel are being developed for two-stroke cycle engines. Some two-stroke cycle automobile engines and other medium- and large-size engines use an external supercharger to compress inlet air. These engines use pressurized/ splash lubrication systems similar to those on four-stroke cycle engines with the crankcase also serving as the oil sump. Lubricating Oil: The oil used in an engine must serve as a lubricant, a coolant, and a vehicle for removing impurities. It must be able to withstand high temperatures without breaking down and must have a long working life. The development trend in engines is toward higher operating temperatures, higher speeds, closer tolerances, and smaller oil sump capacity. All of these require improved oils compared to those used just a few years ago. Certainly, the technology of the oil industry has to continue to improve along with the technology growth of engines and fuel. Early engines and other mechanical systems were often designed to use up the lubricating oil as it was used, requiring a continuous input of fresh oil. The used oil was either burned up in the combustion chamber or allowed to fall to the ground. Just a couple of decades back, the tolerances between pistons and cylinder walls was such that engines burned some oil that seeped past the pistons from the crankcase. This required a periodic need t o add oil and a frequent oil change due to blowby contamination of the remaining oil. HC levels in the exhaust were high because of the oil in the combustion chamber. Modern engines run hotter, have closer tolerances which keep oil consumption down, and have smaller oil sumps due to space limitations. They generate more power with smaller engines by running faster and with higher compression ratios. This means higher forces and a greater need for good lubrication. At the same time, many manufacturers now suggest changing the oil every 6000 miles. Not only must the oil last longer under much more severe conditions, but new oil is not added between oil changes. Engines of the past that consumed some oil required periodic makeup oil to be added. This makeup oil mixed with the remaining used oil and improved the overall lubrication properties within the engine. The oils in modern engines must operate over an extreme temperature range. They must lubricate properly from the starting temperature of a cold engine to beyond the extreme steady-state temperatures that occur within the engine cylinders. They must not oxidize on the combustion chamber walls or at other hot spots such as the center crown of the piston or at the top piston ring. Oil should adhere to surfaces so that they always lubricate and provide a protective covering against corrosion. This is often called oiliness. Oil should have high film strength to assure no metal-to-metal contact even under extreme loads. Oils should be non-toxic and non-explosive. Some desired qualities of Lubrication oil: Lubricating oil must satisfy the following needs: Lubrication. It must reduce friction and wear within the engine. It improves efficiency by reducing the friction forces between moving parts. Coolant Removal of contaminants Enhancement of ring seal and reduction of blowby Slow corrosion Stability over a large temperature range Long life span Low cost Hydrocarbon Components in Lubricating oil: The basic ingredients in most lubricating oils are hydrocarbon components made from crude oil. These are larger molecular weight species obtained from the distillation process. Additives: Various other components are added to create a lubricant that will allow for the maximum performance and life span of the engine. These additives include: Antifoam agents: These reduce the foaming that would result when the crankshaft and other components rotate at high speed in the crankcase oil sump. Oxidation inhibitors: Oxygen is trapped in the oil when foaming occurs, and this leads to possible oxidation of engine components. One such additive is zinc dithiophosphate Pour-point depressant Antirust agents Detergents: These are made from organic salts and metallic salts. They help keep deposits and impurities in suspension and stop reactions that form varnish and other surface deposits. They help neutralize acid formed from sulfur in the fuel. Anti-wear agents Friction reducers Viscosity index improvers Rating of Lubricating Oils and grades: Lubricating oils are generally rated using a viscosity scale established by the Society of Automotive Engineering (SAE). The higher the viscosity value, the greater is the force needed to move adjacent surfaces or to pump oil through a passage. Viscosity is highly dependent on temperature, increasing with decreasing temperature. In the temperature range of engine operation, the dynamic viscosity of the oil can change by more than an order of magnitude. Oil viscosity also changes with shear, decreasing with increasing shear. Shear rates within an engine range from very low values to extremely high values in the bearings and between piston and cylinder walls. The change of viscosity over these extremes can be several orders of magnitude. Common viscosity grades used in engines are: SAE 5 SAE 10 SAE 20 SAE 30 SAE 40 SAE 45 SAE 50 Common oils available include: SAE 5W-20 SAE 10W-40 SAE 5W-30 SAE 10W-50 SAE 5W-40 SAE 15W-40 SAE 5W-50 SAE 15W-50 SAE 10W-30 SAE 20W-50 Synthetic Oils: A number of synthetically made oils are available that give better performance than those made from crude oil. They are better at reducing friction and engine wear, have good detergency properties which keep the engine cleaner, offer less resistance for moving parts, and require less pumping power for distribution. With good thermal properties, they provide better engine cooling and less variation in viscosity. Because of this, they contribute to better cold-weather starting and can reduce fuel consumption by as much as 15%. These oils cost several times as much as those made from crude oil. However, they can be used longer in an engine, with 24,000 km (15,000 miles) being the oil change period suggested by most manufacturers. Available on the market are various oil additives and special oils that can be added in small quantities to standard oils in the engine. These claim, with some justification, to improve the viscous and wear resistance properties of normal oils. One major improvement that some of them provide is that they stick to metal surfaces and do not drain off when the engine is stopped, as most standard oils do. The surfaces are thus lubricated immediately when the engine is next started. With standard oils it takes several engine rotations before proper lubrication occurs, a major source of wear. Oil filters: Included in most pressurized oil systems is a filtration system to remove impurities from the engine oil. One of the duties of engine oil is to clean the engine by carrying contaminant impurities in suspension as it circulates. As the oil passes through filters that are part of the flow passage system these impurities are removed, cleaning the oil and allowing it to be used for a greater length of time. Contaminants get into an engine in the incoming air or fuel or can be generated within the combustion chamber when other than ideal stoichiometric combustion occurs. Dust and other impurities are carried by the incoming air. Some, but not all, of these are removed by an air filter. Fuels have trace amounts of impurities like sulfur, which create contaminants during the combustion process. Even pure fuel components form some contaminants, like solid carbon in some engines under some conditions. Many engine impurities are carried away with the engine exhaust, but some get into the interior of the engine, mainly in the blowby process. During blowby, fuel, air, and combustion products are forced past the pistons into the crankcase, where they mix with the engine oil. Some of the water vapor in the exhaust products condenses in the crankcase, and the resulting liquid water adds to the contaminants. The gases of blowby pass through the crankcase and are routed back into the air intake. Ideally, most of the contaminants are trapped in the oil, which then contains dust, carbon, fuel particles, sulfur, water droplets, and many other impurities. If these were not filtered out of the oil, they would be spread throughout the engine by the oil distribution system. Also, the oil would quickly become dirty and lose its lubricating properties, resulting in greater engine wear. Figure . Oil Filter Flow passages in a filter are not all the same size but usually exist in a normal bell-shaped size distribution. This means that most larger particles will be filtered out as the oil passes through the filter, but a few as large as the largest passages will get through. The choice of filter pore size is a compromise. Better filtration will be obtained with smaller filter pores, but this requires a much greater flow pressure to push the oil through the filter. This also results in the filter becoming clogged quicker and requiring earlier filter cartridge change. Some filter materials and/or material of too small a pore size can even remove some additives from the oil. Filters are made from cotton, paper, cellulose, and a number of different synthetic materials. Filters are usually located just downstream from the oil pump exit. As a filter is used, it slowly becomes saturated with trapped impurities. As these impurities fill the filter pores, a greater pressure differential is needed to keep the same flow rate. When this needed pressure differential gets too high, the oil pump limit is reached and oil flow through the engine is slowed. The filter cartridge should be replaced before this happens. Figure . Exploded view of an Oil Filter Figure . Pore size distribution for common filters Sometimes, when the pressure differential across a filter gets high enough, the cartridge structure will collapse and a hole will develop through the cartridge wall. Most of the oil pumped through the filter will then follow the path of least resistance and flow through the hole. This short circuit will reduce the pressure drop across the filter, but the oil does not get filtered. There are several ways in which the oil circulation system can be filtered: 1. Full-flow oil filtration. All oil flows through the filter. The filter pore size must be fairly large to avoid extreme pressures in the resulting large flow rate. This results in some larger impurities in the oil. 2. Bypass oil filtration. Only part of the oil leaving the pump flows through the filter, the rest bypassing it without being filtered. This system allows the use of a much finer filter, but only a percentage of the oil gets filtered during each circulation loop. 3. Combination. Some systems use a combination of full-flow and bypass. All the oil first flows through a filter with large pores and then some of it flows through a second filter with small pores. 4. Shunt filtration. This is a system using a full-flow filter and a bypass valve. All oil at first flows through the filter. As the filter cartridge dirties with age, the pressure differential across it needed to keep the oil flowing increases. When this pressure differential gets above a predetermined value, the bypass valve opens and the oil flows around the filter. The filter cartridge must then be replaced before filtering will again occur. Solid lubricants, such as powd