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78-481: In 1988, the first Kawasaki MULE was introduced in the form of the MULE 1000; it featured a water-cooled 454 cc (27.70 cu in) twin-cylinder engine, which was fitted to an open-cab utility vehicle chassis. The MULE 1000 also featured a continuously variable transmission (CVT), independent suspension at the front and rear and a locking rear differential . The MULE 2010 was introduced in 1989, and featured

156-519: A radiator blind (or radiator shroud ) to the radiator that can be adjusted to partially or fully block the airflow through the radiator. At its simplest the blind is a roll of material such as canvas or rubber that is unfurled along the length of the radiator to cover the desired portion. Some older vehicles, like the World War I-era Royal Aircraft Factory S.E.5 and SPAD S.XIII single-engined fighters, have

234-407: A Spitfire . This is similar to Formula 1 cars of today, when stopped on the grid with engines running they require ducted air forced into their radiator pods to prevent overheating. Reducing drag is a major goal in aircraft design, including the design of cooling systems. An early technique was to take advantage of an aircraft's abundant airflow to replace the honeycomb core (many surfaces, with

312-406: A bellows type thermostat, which has corrugated bellows containing a volatile liquid such as alcohol or acetone. These types of thermostats do not work well at cooling system pressures above about 7 psi. Modern motor vehicles typically run at around 15 psi, which precludes the use of the bellows type thermostat. On direct air-cooled engines, this is not a concern for the bellows thermostat that controls

390-427: A flap valve in the air passages. Other factors influence the temperature of the engine, including radiator size and the type of radiator fan. The size of the radiator (and thus its cooling capacity ) is chosen such that it can keep the engine at the design temperature under the most extreme conditions a vehicle is likely to encounter (such as climbing a mountain whilst fully loaded on a hot day). Airflow speed through

468-536: A hammer. It was further investigated and described by Harry Ricardo during experiments carried out between 1916 and 1919 to discover the reason for failures in aircraft engines . Under ideal conditions the common internal combustion engine burns the fuel/air mixture in the cylinder in an orderly and controlled fashion. The combustion is started by the spark plug some 10 to 40 crankshaft degrees prior to top dead center (TDC), depending on many factors including engine speed and load. This ignition advance allows time for

546-422: A harmfully false reading. Opening a hot radiator drops the system pressure, which may cause it to boil and eject dangerously hot liquid and steam. Therefore, radiator caps often contain a mechanism that attempts to relieve the internal pressure before the cap can be fully opened. The invention of the automobile water radiator is attributed to Karl Benz . Wilhelm Maybach designed the first honeycomb radiator for

624-458: A high thermal efficiency . Since the onset of knock is sensitive to the in-cylinder pressure, temperature and autoignition chemistry associated with the local mixture compositions within the combustion chamber, simulations which account for all of these aspects have thus proven most effective in determining knock operating limits and enabling engineers to determine the most appropriate operating strategy. The objective of knock control strategies

702-476: A high ratio of surface to volume) by a surface-mounted radiator. This uses a single surface blended into the fuselage or wing skin, with the coolant flowing through pipes at the back of this surface. Such designs were seen mostly on World War I aircraft. As they are so dependent on airspeed, surface radiators are even more prone to overheating when ground-running. Racing aircraft such as the Supermarine S.6B ,

780-403: A larger 535 cc (32.65 cu in) engine, a high/low CVT transmission, selectable four-wheel-drive and a De Dion rear suspension. 1990 saw the introduction of three new MULEs; the 2020, which was designed for golf courses and used a fan-cooled single-cylinder engine , the 2030, which was designed for industrial work, and the compact 500 model with a single seat. The MULE 2500 series

858-458: A less efficient but simpler construction. Radiators first used downward vertical flow, driven solely by a thermosyphon effect. Coolant is heated in the engine, becomes less dense, and so rises. As the radiator cools the fluid, the coolant becomes denser and falls. This effect is sufficient for low-power stationary engines , but inadequate for all but the earliest automobiles. All automobiles for many years have used centrifugal pumps to circulate

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936-437: A liquid called engine coolant through the engine block and cylinder head where it is heated, then through a radiator where it loses heat to the atmosphere, and then returned to the engine. Engine coolant is usually water-based, but may also be oil. It is common to employ a water pump to force the engine coolant to circulate, and also for an axial fan to force air through the radiator. In automobiles and motorcycles with

1014-444: A liquid-cooled internal combustion engine , a radiator is connected to channels running through the engine and cylinder head , through which a liquid ( coolant ) is pumped by a coolant pump. This liquid may be water (in climates where water is unlikely to freeze), but is more commonly a mixture of water and antifreeze in proportions appropriate to the climate. Antifreeze itself is usually ethylene glycol or propylene glycol (with

1092-447: A major area of research. The most obvious, and common, solution to this problem was to run the entire cooling system under pressure. This maintained the specific heat capacity at a constant value, while the outside air temperature continued to drop. Such systems thus improved cooling capability as they climbed. For most uses, this solved the problem of cooling high-performance piston engines, and almost all liquid-cooled aircraft engines of

1170-405: A more complete mixing of fuel and air. Diesels actually do not suffer exactly the same "knock" as gasoline engines since the cause is known to be only the very fast rate of pressure rise, not unstable combustion. Diesel fuels are actually very prone to knock in gasoline engines but in the diesel engine there is no time for knock to occur because the fuel is only oxidized during the expansion cycle. In

1248-472: A pair of metal or plastic header tanks, linked by a core with many narrow passageways, giving a high surface area relative to volume. This core is usually made of stacked layers of metal sheet, pressed to form channels and soldered or brazed together. For many years radiators were made from brass or copper cores soldered to brass headers. Modern radiators have aluminum cores, and often save money and weight by using plastic headers with gaskets. This construction

1326-408: A racing seaplane with radiators built into the upper surfaces of its floats, have been described as "being flown on the temperature gauge" as the main limit on their performance. Surface radiators have also been used by a few high-speed racing cars, such as Malcolm Campbell 's Blue Bird of 1928. It is generally a limitation of most cooling systems that the cooling fluid not be allowed to boil, as

1404-470: A radiator is a major influence on the heat it dissipates. Vehicle speed affects this, in rough proportion to the engine effort, thus giving crude self-regulatory feedback. Where an additional cooling fan is driven by the engine, this also tracks engine speed similarly. Engine-driven fans are often regulated by a fan clutch from the drivebelt, which slips and reduces the fan speed at low temperatures. This improves fuel efficiency by not wasting power on driving

1482-413: A separate small radiator to cool the engine oil . Cars with an automatic transmission often have extra connections to the radiator, allowing the transmission fluid to transfer its heat to the coolant in the radiator. These may be either oil-air radiators, as for a smaller version of the main radiator. More simply they may be oil-water coolers, where an oil pipe is inserted inside the water radiator. Though

1560-507: A series of shutters that can be adjusted from the driver's or pilot's seat to provide a degree of control. Some modern cars have a series of shutters that are automatically opened and closed by the engine control unit to provide a balance of cooling and aerodynamics as needed. Because the thermal efficiency of internal combustion engines increases with internal temperature, the coolant is kept at higher-than-atmospheric pressure to increase its boiling point . A calibrated pressure-relief valve

1638-405: A small amount of corrosion inhibitor ). A typical automotive cooling system comprises: The combustion process produces a large amount of heat. If heat were allowed to increase unchecked, detonation would occur, and components outside the engine would fail due to excessive temperature. To combat this effect, coolant is circulated through the engine where it absorbs heat. Once the coolant absorbs

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1716-432: Is a short lag between the fuel being injected and combustion starting. By this time there is already a quantity of fuel in the combustion chamber which will ignite first in areas of greater oxygen density prior to the combustion of the complete charge. This sudden increase in pressure and temperature causes the distinctive diesel 'knock' or 'clatter', some of which must be allowed for in the engine design. Careful design of

1794-452: Is actually more efficient than deflagration, but is usually avoided due to its damaging effects on engine components.) If detonation is allowed to persist under extreme conditions or over many engine cycles, engine parts can be damaged or destroyed. The simplest deleterious effects are typically particle wear caused by moderate knocking, which may further ensue through the engine's oil system and cause wear on other parts before being trapped by

1872-437: Is due to the travel of the flame front through the combustible fuel–air mix itself, and due to Rayleigh–Taylor instability (resulting from the hot, low-density combustion gasses expanding into the relatively cold and dense unburnt fuel–air mix) which rapidly stretches the burning zone into a complex of fingers of burning gas that have a much greater surface area than a simple spherical ball of flame would have (this latter process

1950-408: Is enhanced and accelerated by any pre-existing turbulence in the fuel–air mixture). In normal combustion, this flame front moves throughout the fuel/air mixture at a rate characteristic for the particular mixture. Pressure rises smoothly to a peak, as nearly all the available fuel is consumed, then pressure falls as the piston descends. Maximum cylinder pressure is achieved a few crankshaft degrees after

2028-499: Is in turbocharged Saab H engines , where a system called Automatic Performance Control was used to reduce boost pressure if it caused the engine to knock. Since the avoidance of knocking combustion is so important to development engineers, a variety of simulation technologies have been developed which can identify engine design or operating conditions in which knock might be expected to occur. This then enables engineers to design ways to mitigate knocking combustion whilst maintaining

2106-441: Is less common in cold climates. As an aftermarket solution, a water injection system can be employed to reduce combustion chamber peak temperatures and thus suppress detonation. Steam (water vapor) will suppress knock even though no added cooling is supplied. Turbulence, as stated, has a very important effect on knock. Engines with good turbulence tend to knock less than engines with poor turbulence. Turbulence occurs not only while

2184-407: Is more difficult to build an aircraft radiator that is able to handle steam, it is by no means impossible. The key requirement is to provide a system that condenses the steam back into liquid before passing it back into the pumps and completing the cooling loop. Such a system can take advantage of the specific heat of vaporization , which in the case of water is five times the specific heat capacity in

2262-411: Is more prone to failure and less easily repaired than traditional materials. An earlier construction method was the honeycomb radiator. Round tubes were swaged into hexagons at their ends, then stacked together and soldered. As they only touched at their ends, this formed what became in effect a solid water tank with many air tubes through it. Some vintage cars use radiator cores made from coiled tube,

2340-423: Is permanently monitoring the signal of one or more knock sensors (commonly piezoelectric sensor which are able to translate vibrations into an electric signal). If the characteristic pressure peak of a knocking combustion is detected the ignition timing is retarded by steps of a few degrees. If the signal normalizes indicating a controlled combustion the ignition timing is advanced again in the same fashion keeping

2418-438: Is that the specific heat capacity changes and boiling point reduces with pressure, and this pressure changes more rapidly with altitude than the drop in temperature. Thus, generally, liquid cooling systems lose capacity as the aircraft climbs. This was a major limit on performance during the 1930s when the introduction of turbosuperchargers first allowed convenient travel at altitudes above 15,000 ft, and cooling design became

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2496-422: Is to attempt to optimize the trade-off between protecting the engine from damaging knock events and maximizing the engine's output torque. Knock events are an independent random process. It is impossible to design knock controllers in a deterministic platform. A single time history simulation or experiment of knock control methods are not able to provide a repeatable measurement of controller's performance because of

2574-437: Is usually incorporated in the radiator's fill cap. This pressure varies between models, but typically ranges from 4 to 30 psi (30 to 200 kPa). As the coolant system pressure increases with a rise in temperature, it will reach the point where the pressure relief valve allows excess pressure to escape. This will stop when the system temperature stops rising. In the case of an over-filled radiator (or header tank) pressure

2652-434: Is vented by allowing a little liquid to escape. This may simply drain onto the ground or be collected in a vented container which remains at atmospheric pressure. When the engine is switched off, the cooling system cools and liquid level drops. In some cases where excess liquid has been collected in a bottle, this may be 'sucked' back into the main coolant circuit. In other cases, it is not. Before World War II, engine coolant

2730-560: The Mercedes 35hp . It is sometimes necessary for a car to be equipped with a second, or auxiliary, radiator to increase the cooling capacity, when the size of the original radiator cannot be increased. The second radiator is plumbed in series with the main radiator in the circuit. This was the case when the Audi 100 was first turbocharged creating the 200. These are not to be confused with intercoolers . Some engines have an oil cooler,

2808-554: The P-51 Mustang ) derive thrust from it. The thrust was significant enough to offset the drag of the duct the radiator was enclosed in and allowed the aircraft to achieve zero cooling drag. At one point, there were even plans to equip the Supermarine Spitfire with an afterburner , by injecting fuel into the exhaust duct after the radiator and igniting it . Afterburning is achieved by injecting additional fuel into

2886-416: The air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug , but when one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel–air charge is meant to be ignited by the spark plug only, and at a precise point in the piston's stroke. Knock occurs when the peak of the combustion process no longer occurs at

2964-469: The flame front is subjected to a combination of heat and pressure for a certain duration (beyond the delay period of the fuel used), detonation may occur. Detonation is characterized by an almost instantaneous, explosive ignition of at least one pocket of fuel/air mixture outside of the flame front. A local shockwave is created around each pocket, and the cylinder pressure will rise sharply – and possibly beyond its design limits – causing damage. (Detonation

3042-399: The 520, followed in 1999. The first diesel MULE with a 953 cc (58.2 cu in) three-cylinder engine was introduced in 1999 as part of the 2500 series. The MULE 3000 series arrived the following year, combining the 2500 series' V-twin petrol engines with a new continuously variable transmission and featuring new "pick-up truck" styling incorporating a storage compartment under

3120-473: The World War II period used this solution. However, pressurized systems were also more complex, and far more susceptible to damage - as the cooling fluid was under pressure, even minor damage in the cooling system like a single rifle-calibre bullet hole, would cause the liquid to rapidly spray out of the hole. Failures of the cooling systems were, by far, the leading cause of engine failures. Although it

3198-413: The adoption of glycol or water-glycol mixtures. These led to the adoption of glycols for their antifreeze properties. Since the development of aluminium alloy or mixed-metal engines, corrosion inhibition has become even more important than antifreeze, and in all regions and seasons. An overflow tank that runs dry may result in the coolant vaporizing, which can cause localized or general overheating of

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3276-555: The aircraft wings, fuselage and even the rudder. Several aircraft were built using their design and set numerous performance records, notably the Heinkel He 119 and Heinkel He 100 . However, these systems required numerous pumps to return the liquid from the spread-out radiators and proved to be extremely difficult to keep running properly, and were much more susceptible to battle damage. Efforts to develop this system had generally been abandoned by 1940. The need for evaporative cooling

3354-403: The combustion process to develop peak pressure at the ideal time for maximum recovery of work from the expanding gases. The spark across the spark plug's electrodes forms a small kernel of flame approximately the size of the spark plug gap. As it grows in size, its heat output increases, which allows it to grow at an accelerating rate, expanding rapidly through the combustion chamber. This growth

3432-472: The coolant temperature as the engine warms up. Engine coolant is directed by the thermostat to the inlet of the circulating pump and is returned directly to the engine, bypassing the radiator. Directing water to circulate only through the engine allows the engine to reach optimum operating temperature as quickly as possible whilst avoiding localized "hot spots." Once the coolant reaches the thermostat's activation temperature, it opens, allowing water to flow through

3510-437: The correct clearances. Another side effect of over-cooling is reduced performance of the cabin heater, though in typical cases it still blows air at a considerably higher temperature than ambient. The thermostat is therefore constantly moving throughout its range, responding to changes in vehicle operating load, speed, and external temperature, to keep the engine at its optimum operating temperature. On vintage cars you may find

3588-439: The engine at its best possible operating point - the so-called ″knock limit″. Modern knock control-loop systems are able to adjust ignition timings for every cylinder individually. Depending on the specific engine the boost pressure is regulated simultaneously. This way performance is kept at its optimum while mostly eliminating the risk of engine damage caused by knock (e.g. when running on low octane fuel). An early example of this

3666-472: The engine coolant because natural circulation has very low flow rates. A system of valves or baffles, or both, is usually incorporated to simultaneously operate a small radiator inside the vehicle. This small radiator, and the associated blower fan, is called the heater core , and serves to warm the cabin interior. Like the radiator, the heater core acts by removing heat from the engine. For this reason, automotive technicians often advise operators to turn on

3744-611: The engine downstream of the main combustion cycle. Engines for stationary plant are normally cooled by radiators in the same way as automobile engines. There are some unique differences, depending on the stationary plant – careful planning must be taken to ensure proper air flow across the radiator to ensure proper cooling. In some cases, evaporative cooling is used via a cooling tower . Detonation internal combustion engine In spark-ignition internal combustion engines , knocking (also knock , detonation , spark knock , pinging or pinking ) occurs when combustion of some of

3822-435: The engine is inhaling but also when the mixture is compressed and burned. Many pistons are designed to use "squish" turbulence to violently mix the air and fuel together as they are ignited and burned, which reduces knock greatly by speeding up burning and cooling the unburnt mixture. One example of this is all modern side valve or flathead engines . A considerable portion of the head space is made to come in close proximity to

3900-459: The engine is producing. Allowing too much flow of coolant to the radiator would result in the engine being over-cooled and operating at lower than optimum temperature, resulting in decreased fuel efficiency and increased exhaust emissions. Furthermore, engine durability, reliability, and longevity are sometimes compromised, if any components (such as the crankshaft bearings) are engineered to take thermal expansion into account to fit together with

3978-442: The engine's combustion chambers and cooling system as well as controlling the initial air intake temperature. The addition of tetraethyl lead (TEL), a soluble organolead compound added to gasoline, was common until it was discontinued for reasons of toxic pollution. Lead dust added to the intake charge will also reduce knock with various hydrocarbon fuels. Manganese compounds are also used to reduce knock with petrol fuel. Knock

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4056-410: The engine. Severe damage may result if the vehicle is allowed to run over temperature. Failures such as blown head gaskets, and warped or cracked cylinder heads or cylinder blocks may be the result. Sometimes there will be no warning, because the temperature sensor that provides data for the temperature gauge (either mechanical or electrical) is exposed to water vapor, not the liquid coolant, providing

4134-405: The enormous amount of heat energy soaked up during the generation of steam, equivalent to 500 °C. In effect, the evaporative version is operating between 80 °C and 560 °C, a 480 °C effective temperature difference. Such a system can be effective even with much smaller amounts of water. The downside to the evaporative cooling system is the area of the condensers required to cool

4212-494: The fan unnecessarily. On modern vehicles, further regulation of cooling rate is provided by either variable speed or cycling radiator fans. Electric fans are controlled by a thermostatic switch or the engine control unit . Electric fans also have the advantage of giving good airflow and cooling at low engine revs or when stationary, such as in slow-moving traffic. Before the development of viscous-drive and electric fans, engines were fitted with simple fixed fans that drew air through

4290-481: The gasoline engine the fuel is slowly oxidizing all the time while it is being compressed before the spark. This allows for changes to occur in the structure/makeup of the molecules before the very critical period of high temperature/pressure. Due to the large variation in fuel quality, atmospheric pressure and ambient temperature as well as the possibility of a malfunction, every modern combustion engine contains mechanisms to detect and prevent knocking. A control loop

4368-404: The heat from the engine it continues its flow to the radiator. The radiator transfers heat from the coolant to the passing air. Radiators are also used to cool automatic transmission fluids , air conditioner refrigerant , intake air , and sometimes to cool motor oil or power steering fluid . A radiator is typically mounted in a position where it receives airflow from the forward movement of

4446-407: The heater and set it to high if the engine is overheating , to assist the main radiator. The engine temperature on modern cars is primarily controlled by a wax-pellet type of thermostat , a valve that opens once the engine has reached its optimum operating temperature . When the engine is cold, the thermostat is closed except for a small bypass flow so that the thermostat experiences changes to

4524-405: The hood; a diesel version followed in 2003. 2005 saw the introduction of a four-seat version of the 3000 series and the compact 600 series, which featured an upgraded suspension, a 401 cc (24.47 cu in) engine, and new "high volume" bodywork similar to the 3000 series. In 2009, the 4000 series followed, with both petrol and diesel versions being available. In 2014, the new MULE PRO-FXT

4602-422: The incoming air charge—not to cool the engine. Aircraft with liquid-cooled piston engines (usually inline engines rather than radial) also require radiators. As airspeed is higher than for cars, these are efficiently cooled in flight, and so do not require large areas or cooling fans. Many high-performance aircraft however suffer extreme overheating problems when idling on the ground - a mere seven minutes for

4680-414: The injector pump, fuel injector, combustion chamber, piston crown and cylinder head can reduce knocking greatly, and modern engines using electronic common rail injection have very low levels of knock. Engines using indirect injection generally have lower levels of knock than direct injection engines, due to the greater dispersal of oxygen in the combustion chamber and lower injection pressures providing

4758-616: The liquid form. Additional gains may be had by allowing the steam to become superheated. Such systems, known as evaporative coolers , were the topic of considerable research in the 1930s. Consider two cooling systems that are otherwise similar, operating at an ambient air temperature of 20 °C. An all-liquid design might operate between 30 °C and 90 °C, offering 60 °C of temperature difference to carry away heat. An evaporative cooling system might operate between 80 °C and 110 °C. At first glance this appears to be much less temperature difference, but this analysis overlooks

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4836-433: The need to handle gas in the flow greatly complicates design. For a water cooled system, this means that the maximum amount of heat transfer is limited by the specific heat capacity of water and the difference in temperature between ambient and 100 °C. This provides more effective cooling in the winter, or at higher altitudes where the temperatures are low. Another effect that is especially important in aircraft cooling

4914-455: The oil filter. Such wear gives the appearance of erosion, abrasion, or a "sandblasted" look, similar to the damage caused by hydraulic cavitation . Severe knocking can lead to catastrophic failure in the form of physical holes melted and pushed through the piston or cylinder head (i.e. rupture of the combustion chamber ), either of which depressurizes the affected cylinder and introduces large metal fragments, fuel, and combustion products into

4992-452: The oil system. Hypereutectic pistons are known to break easily from such shock waves. Detonation can be prevented by any or all of the following techniques: Because pressure and temperature are strongly linked, knock can also be attenuated by controlling peak combustion chamber temperatures by compression ratio reduction, exhaust gas recirculation , appropriate calibration of the engine's ignition timing schedule, and careful design of

5070-408: The optimum moment for the four-stroke cycle . The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive. Knocking should not be confused with pre-ignition —they are two separate events. However, pre-ignition can be followed by knocking. The phenomenon of detonation

5148-413: The piston crown, making for much turbulence near TDC. In the early days of side valve heads this was not done and a much lower compression ratio had to be used for any given fuel. Also such engines were sensitive to ignition advance and had less power. Knocking is more or less unavoidable in diesel engines , where fuel is injected into highly compressed air towards the end of the compression stroke. There

5226-409: The piston passes TDC, so that the force applied on the piston (from the increasing pressure applied to the top surface of the piston) can give its hardest push precisely when the piston's speed and mechanical advantage on the crank shaft gives the best recovery of force from the expanding gases, thus maximizing torque transferred to the crankshaft. When unburned fuel–air mixture beyond the boundary of

5304-450: The radiator at all times. Vehicles whose design required the installation of a large radiator to cope with heavy work at high temperatures, such as commercial vehicles and tractors would often run cool in cold weather under light loads, even with the presence of a thermostat , as the large radiator and fixed fan caused a rapid and significant drop in coolant temperature as soon as the thermostat opened. This problem can be solved by fitting

5382-431: The radiator to prevent the temperature from rising higher. Once at optimum temperature, the thermostat controls the flow of engine coolant to the radiator so that the engine continues to operate at optimum temperature. Under peak load conditions, such as driving slowly up a steep hill whilst heavily laden on a hot day, the thermostat will be approaching fully open because the engine will be producing near maximum power while

5460-509: The steam back below the boiling point. As steam is much less dense than water, a correspondingly larger surface area is needed to provide enough airflow to cool the steam back down. The Rolls-Royce Goshawk design of 1933 used conventional radiator-like condensers and this design proved to be a serious problem for drag. In Germany, the Günter brothers developed an alternative design combining evaporative cooling and surface radiators spread all over

5538-527: The vehicle, such as behind a front grill. Where engines are mid- or rear-mounted, it is common to mount the radiator behind a front grill to achieve sufficient airflow, even though this requires long coolant pipes. Alternatively, the radiator may draw air from the flow over the top of the vehicle or from a side-mounted grill. For long vehicles, such as buses, side airflow is most common for engine and transmission cooling and top airflow most common for air conditioner cooling. Automobile radiators are constructed of

5616-407: The velocity of airflow across the radiator is low. (Being a heat exchanger, the velocity of air flow across the radiator has a major effect on its ability to dissipate heat.) Conversely, when cruising fast downhill on a motorway on a cold night on a light throttle, the thermostat will be nearly closed because the engine is producing little power, and the radiator is able to dissipate much more heat than

5694-447: The water is hotter than the ambient air, its higher thermal conductivity offers comparable cooling (within limits) from a less complex and thus cheaper and more reliable oil cooler. Less commonly, power steering fluid, brake fluid, and other hydraulic fluids may be cooled by an auxiliary radiator on a vehicle. Turbo charged or supercharged engines may have an intercooler , which is an air-to-air or air-to-water radiator used to cool

5772-483: Was described in November 1914 in a letter from Lodge Brothers (spark plug manufacturers, and sons of Sir Oliver Lodge ) settling a discussion regarding the cause of "knocking" or "pinging" in motorcycles. In the letter they stated that an early ignition can give rise to the gas detonating instead of the usual expansion, and the sound that is produced by the detonation is the same as if the metal parts had been tapped with

5850-409: Was introduced in 1992 and featured a new 617 cc (37.65 cu in) V-twin engine with a fan cooled CVT. The 2500 series also featured four wheel self-adjusting hydraulic brakes and introduced a high mounted air intake system for the engine and transmission that drew air through the rear cab frame tubes. The two-seat compact model 550 followed in 1996 and a turf version of that model, known as

5928-525: Was introduced, featuring a fuel-injected 812 cc (49.55 cu in) straight-three engine , a CVT transmission, and a cab that could seat up to six people. Radiator (engine cooling) Radiators are heat exchangers used for cooling internal combustion engines , mainly in automobiles but also in piston-engined aircraft , railway locomotives , motorcycles , stationary generating plants or any similar use of such an engine. Internal combustion engines are often cooled by circulating

6006-467: Was soon to be negated by the widespread availability of ethylene glycol based coolants, which had a lower specific heat , but a much higher boiling point than water. An aircraft radiator contained in a duct heats the air passing through, causing the air to expand and gain velocity. This is called the Meredith effect , and high-performance piston aircraft with well-designed low-drag radiators (notably

6084-417: Was usually plain water. Antifreeze was used solely to control freezing, and this was often only done in cold weather. If plain water is left to freeze in the block of an engine the water can expand as it freezes. This effect can cause severe internal engine damage due to the expanding of the ice. Development in high-performance aircraft engines required improved coolants with higher boiling points, leading to

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