Misplaced Pages

#740259

67-557: The Laverda 1200 is a 1,116 cc (68.1 cu in) air cooled DOHC triple motorcycle produced by the Italian manufacturer Laverda between 1977 and 1982. The model was developed from the Laverda 1000 . Austrian importer Werner Sulzbacher had had some success in production and endurance racing with triples over-bored to 1,172 cc (71.5 cu in) and 1,116 cc (68.1 cu in). Sulzbacher had put pressure on

134-418: A bicycle chain , but without rollers ) features small, sharp, cutting teeth. Each tooth takes the form of a folded tab of chromium-plated steel with a sharp angular or curved corner and two beveled cutting edges, one on the top plate and one on the side plate. Left-handed and right-handed teeth are alternated in the chain. Chains are made in varying pitch and gauge; the pitch of a chain is defined as half of

201-537: A two-stroke single-cylinder gasoline (petrol) internal combustion engine (usually with a cylinder volume of 30 to 120 cm ) or an electric motor driven by a battery or electric power cord. In a petrol chainsaw, fuel is generally supplied to the engine by a carburetor at the intake. Two-stroke engines have been preferred for chainsaws due to their higher power-to-weight ratio and simplicity. Hydraulic power may be used for chainsaws for underwater use. To allow use in any orientation, modern gas chainsaws use

268-523: A 2.5 gallon metal tank was fitted under the fibreglass. To celebrate 30 years of motorcycle production, Laverda announced in 1979 that they would produce a limited edition 30th Anniversary 1200 model. 200 of these were produced, although fewer than 50 were sold to the public. The remainder were sold to the Libya Police Force . A hydraulic clutch and drilled discs were fitted. This was the first Laverda to be fitted with these items. The engine

335-412: A closed circuit carrying liquid coolant through channels in the engine block and cylinder head. A fluid in these channels absorbs heat and then flows to a heat exchanger or radiator where the coolant releases heat into the air (or raw water , in the case of marine engines ). Thus, while they are not ultimately cooled by the liquid, as the heat is exchanged with some other fluid like air, because of

402-464: A cut is complete. The chainsaw operator may be trapped or crushed. Similarly, timber falling in an unplanned direction may harm the operator or other workers, or an operator working at a height may fall or be injured by falling timber. Like other hand-held machinery, the operation of chainsaws can cause vibration white finger , tinnitus , or industrial deafness . These symptoms were very common before vibration dampening using rubber or steel spring

469-443: A diaphragm carburetor, which draws fuel from the tank using the alternating pressure differential within the crankcase. Early engines used carburetors with gravity fed float chambers , which caused the engine to stall when tilted. The carburetor may need to be adjusted to maintain an appropriate idle speed and air-fuel ratio , such as when moving to a higher/lower altitude or as the air filter clogs. Carburetors are adjusted either by

536-576: A different colour to other 1200s, from July 1978 they were finished in metallic green. Universally known as the 'Green Mirage', this version has become the most sought-after 1200. A limited number (estimates vary between 14 and 17) of higher performance Formula Mirage models were built by the UK importer Slaters. These had a higher compression ratio and 7C endurance racing camshafts. A one-piece fibreglass seat and tank and matching fairing were fitted. As fibreglass petrol tanks were outlawed in some jurisdictions,

603-474: A drum. On this drum sits either a fixed sprocket or an exchangeable one. The clutch has three jobs: When the engine runs idle (typically 2500–2700 rpm) the chain does not move. When the clutch is engaged and the chain stops in the wood for another reason, it protects the engine. Most importantly, it protects the operator in case of a kickback. Here, the chain brake stops the drum, and the clutch releases immediately. A guide bar, typically an elongated bar with

670-430: A fluid is a function of its capacity and the difference in input and output temperatures. As the boiling point of water is reduced with lower pressure, and the water could not be efficiently pumped as steam, radiators had to have enough cooling power to account for the loss in cooling power as the aircraft climbed. The resulting radiators were quite large and caused a significant amount of aerodynamic drag . This placed

737-486: A great percentage of the heat generated, around 44%, escapes through the exhaust. Another 8% or so ends up in the oil , which itself has to be cooled in an oil cooler . This means less than half of the heat has to be removed through other systems. In an air-cooled engine, only about 12% of the heat flows out through the metal fins. Air cooled engines usually run noisier, however it provides more simplicity which gives benefits when it comes to servicing and part replacement and

SECTION 10

#1732798351741

804-515: A guide frame was granted to Samuel J. Bens of San Francisco on January 17, 1905, his intent being to fell giant redwoods. The first portable chainsaw was developed and patented in 1918 by Canadian millwright James Shand. After he allowed his rights to lapse in 1930, his invention was further developed by what became the German company Festo in 1933. The company, now operating as Festool , produces portable power tools. Other important contributors to

871-440: A horizontal fashion as a Flat engine , while vertical Straight-four engine have been used. Examples of past air-cooled road vehicles, in roughly chronological order, include: During the 1920s and 30s there was a great debate in the aviation industry about the merits of air-cooled vs. liquid-cooled designs. At the beginning of this period, the liquid used for cooling was water at ambient pressure. The amount of heat carried away by

938-411: A round end of wear-resistant alloy steel typically 40 to 90 cm (16 to 36 in) in length, is used. An edge slot guides the cutting chain. Specialized, loop-style bars, called bow bars, were also used at one time for bucking logs and clearing brush, although they are now rarely encountered due to increased hazards of operation. All guide bars have some elements for operation: The lower part of

1005-472: A smaller wound and protect the adjacent muscles, nerves, and veins. While symphysiotomy had too many complications for most obstetricians, Jeffray's ideas about the excision of the ends of bones became more accepted, especially after the widespread adoption of anaesthetics. For much of the 19th century the chainsaw was a useful surgical instrument, but it was superseded in 1894 by the Gigli twisted-wire saw , which

1072-762: A wheeled power unit to drive the cutting bar. After World War II, improvements in aluminum and engine design lightened chainsaws to the point where one person could carry them. In some areas, the chainsaw and skidder crews have been replaced by the feller buncher and harvester . Chainsaws have almost entirely replaced simple man-powered saws in forestry. They are made in many sizes, from small electric saws intended for home and garden use, to large "lumberjack" saws. Members of military engineer units are trained to use chainsaws, as are firefighters to fight forest fires and to ventilate structure fires. Three main types of chainsaw sharpeners are used: handheld file, electric chainsaw, and bar-mounted. The first electric chainsaw

1139-399: Is a common source of damage to chainsaws, and tends to lead to rapid wear of the bar, or the chain seizing or coming off the bar. In addition to being quite thick, chain oil is particularly sticky (due to " tackifier " additives) to reduce the amount thrown off the chain. Although motor oil is a common emergency substitute, it is lost even faster, so leaves the chain under-lubricated. The oil

1206-532: Is a portable handheld power saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. Modern chainsaws are typically gasoline or electric and are used in activities such as tree felling , limbing , bucking , pruning , cutting firebreaks in wildland fire suppression , harvesting of firewood , for use in chainsaw art and chainsaw mills , for cutting concrete, and cutting ice. Precursors to modern chainsaws were first used in surgery, with patents for wood chainsaws beginning in

1273-411: Is adjusted so that it neither binds on nor comes loose from the guide bar. The tensioner for doing so is either operated by turning a screw or a manual wheel. The tensioner is either in a lateral position underneath the exhaust or integrated into the clutch cover. Lateral tensioners have the advantage that the clutch cover is easier to mount, but the disadvantage that it is more difficult to reach nearby

1340-430: Is normally lubricated for life. Most modern gasoline-operated saws today require a fuel mix of 2% (1:50). Gasoline that contains ethanol can result in problems for the equipment because ethanol dissolves plastic, rubber, and other material. This leads to problems, especially on older equipment. A workaround for this problem is to run fresh fuel only and run the saw dry at the end of the work. Separate chain oil or bar oil

1407-515: Is pumped from a small pump to a hole in the bar. From there, the lower ends of each chain drive link take a portion of the oil into the gauge towards the bar nose. The pump outlet and bar hole must be aligned. Since the bar is moving out and inwards depending on the chain length, the oil outlet on the saw side has a banana-style long shape. Chains must be kept sharp to perform well. They become blunt rapidly if they touch soil, metal, or stones. When blunt, they tend to produce powdery sawdust, rather than

SECTION 20

#1732798351741

1474-407: Is pumped, typically each tank filling to keep the nose sprocket well lubricated. Here, one or two bolts from the saw run through. The clutch cover is put on top of the bar and it is secured through these bolts. The number of bolts is determined by the size of the saw. Different bar types are available: Usually, each segment in a chain (which is constructed from riveted metal sections similar to

1541-459: Is used for the lubrication of the bar and chain on all types of chainsaws. The chain oil is depleted quickly because it tends to be thrown off by chain centrifugal force , and it is soaked up by sawdust. On two-stroke chainsaws, the chain oil reservoir is usually filled up at the same time as refueling. The reservoir is normally large enough to provide sufficient chain oil between refueling. Lack of chain oil, or using an oil of incorrect viscosity ,

1608-418: Is usually cheaper to be maintained. Many motorcycles use air cooling for the sake of reducing weight and complexity. Few current production automobiles have air-cooled engines (such as Tatra 815 ), but historically it was common for many high-volume vehicles. The orientation of the engine cylinders is commonly found in either single-cylinder or coupled in groups of two, and cylinders are commonly oriented in

1675-619: The Gran Turismo concept, the 1200TS was introduced in 1979. It featured a handlebar fairing, engine-hugging fiberglass lowers and a new tail section on the seat. Most TS models were finished in silver with maroon coachlines. In 1980 larger inlet valves were fitted and in 1981 a larger Nippon Denso alternator was fitted and the ignition pick-ups moved to the primary side. For the American market softer touring cams were fitted along with more restrictive exhausts and noise-cancelling baffles in

1742-673: The 1,172 cc (71.5 cu in) 1200SC and 1,290 cc (79 cu in) 1300SC. Air cooled Air-cooled engines are widely seen in applications where weight or simplicity is the primary goal. Their simplicity makes them suited for uses in small applications like chainsaws and lawn mowers , as well as small generators and similar roles. These qualities also make them highly suitable for aviation use, where they are widely used in general aviation aircraft and as auxiliary power units on larger aircraft. Their simplicity, in particular, also makes them common on motorcycles . Most modern internal combustion engines are cooled by

1809-518: The 1200 instigated by the UK importers, Slater Bros. Following the success of the Jota , Richard Slater turned his attention to the 1200. 4C cams and a Jota exhaust was fitted. The name Mirage was suggested by Laverda's sales manager Luciano Zucarelli. Machines were shipped from the factory minus the exhaust and nameplates which were fitted in the UK. Following a request from Slater that the Mirage should be

1876-631: The 1900s. The first commercial production was by the New Way Motor Company of Lansing, Michigan, US. The company produced air-cooled engines in single and twin cylinders in both horizontal and vertical cylinder format. Subsequent to their initial production which was exported worldwide, other companies took up the advantages of this cooling method, especially in small portable engines. Applications include mowers, generators, outboard motors, pump sets, saw benches and auxiliary power plants and more. Chainsaw A chainsaw (or chain saw )

1943-576: The Ceriani items, a BTZ electronic ignition replaced the Bosch unit, and the petrol tank now carried badges instead of transfers. The 1200 Jota America was produced to comply with the US-DOT regulations . These included a left-side gearchange. The crossover linkage and rear brake master cylinder caused the footrests to be located in less than ideal positions. The Mirage was a higher performance version of

2010-690: The Light-Sport Aircraft ( LSA ) and ultralight aircraft market. Rotax uses a combination of air-cooled cylinders and liquid-cooled cylinder heads. Some small diesel engines, e.g. those made by Deutz AG and Lister Petter are air-cooled. Probably the only big Euro 5 truck air-cooled engine (V8 320 kW power 2100 N·m torque one) is being produced by Tatra . BOMAG part of the FAYAT group also utilizes an air cooled inline 6 cylinder motor, in many of their construction vehicles. Stationary or portable engines were commercially introduced early in

2077-573: The Navy underwriting air-cooled engine development at Pratt & Whitney and Wright Aeronautical . Most other groups, especially in Europe where aircraft performance was rapidly improving, were more concerned with the issue of drag. While air-cooled designs were common on light aircraft and trainers, as well as some transport aircraft and bombers , liquid-cooled designs remained much more common for fighters and high-performance bombers. The drag issue

Laverda 1200 - Misplaced Pages Continue

2144-421: The actual displacement was 1,116 cc (68.1 cu in). This was done by increasing the 1000's bore by 5 mm (0.20 in), from 75 to 80 mm (3.0 to 3.1 in), with the stroke remaining at 74 mm (2.9 in). The '1000' cast into the primary chaincase was machined off. The existing 3CL twin downtube frame was modified with the rear shock absorbers more forward leading. This frame

2211-454: The airbox. Slaters had agreed with the factory for the Mirage to be marketed worldwide. The model has been 'sanitised' by the factory to meet worldwide legislation. Whilst supposed to be a high-performance version of the TS, the differences were minor. Austrian Laverda importer Werner Sulzbacher, in conjunction with engineer Franz Laimboeck, produced a number of tuned cafe-racer versions, including

2278-401: The bar. Tensioners through the clutch cover are easier to operate, but the clutch cover is more difficult to attach. When turning the screw, a hook in a bar hole moves the bar either out (tensioning) or in, making the chain loose. Tension is right when it can be moved easily by hand and not hanging loose from the bar. When tensioning, hold the bar nose up and pull the bar nuts tight. Otherwise,

2345-404: The chain breaks during operation due to poor maintenance or attempting to cut inappropriate materials. Gasoline-powered chainsaws expose operators to harmful carbon monoxide gas, especially indoors or in partially enclosed outdoor areas. Drop starting, or turning on a chainsaw by dropping it with one hand while pulling the starting cord with the other, is a safety violation in most states in

2412-422: The chain might derail. The underside of each link features a small, metal finger called a "drive link", which locates the chain on the bar, helps to carry lubricating oil around the bar, and engages with the engine's drive sprocket inside the body of the saw. The engine drives the chain around the track by a centrifugal clutch, engaging the chain as engine speed increases under power, but allowing it to stop as

2479-447: The chain runs in the gauge. Here, the lubrication oil is pulled by the chain to the nose. This is basically the thickness of the drive links. The end of the saw power head has two oil holes, one on each side. These holes must match with the outlet of the oil pump. The pump sends the oil through the hole in the lower part of the gauge. Saw bar producers provide a large variety of bars matching different saws. Through this hole, grease

2546-457: The edges set at an angle; the chain was moved around a guiding blade by turning the handle of a sprocket wheel. As the name implies, this was used to cut bone. One of the earliest patents for an "endless chain saw" comprising a chain of links carrying saw teeth was granted to Frederick L. Magaw of Flatlands, New York in 1883, apparently for the purpose of producing boards by stretching the chain between grooved drums. A later patent incorporating

2613-480: The engine speed slows to idle speed. Consistent improvement to overall chainsaw design, including adding safety features , has taken place over the years. These include chain-brake systems, better chain design, and lighter, more ergonomic saws, including fatigue-reducing antivibration systems. As chainsaw carving has become more popular, manufacturers are making special short, narrow-tipped bars (called "quarter-tipped" "nickel-tipped", or "dime-tipped" bars, based on

2680-453: The factory to produce a 1200 cc version. With increasing noise and pollution legislation in the 1970s, especially in the US, requiring restrictive inlet and exhausts, softer cams and lower compression ratios, Laverda sought to regain performance by increasing the triple's performance by increasing displacement. Based on the Laverda 3CL , the 1200T was introduced in 1977. Whilst marketed as a 1200,

2747-755: The forerunner of Pioneer Saws Ltd and part of Outboard Marine Corporation , the oldest manufacturer of chainsaws in North America. In 1944, Claude Poulan was supervising German prisoners cutting pulpwood in East Texas. Poulan used an old truck fender and fashioned it into a curved piece used to guide the chain. The "bow guide" now allowed the chainsaw to be used by a single operator. McCulloch in North America started to produce chainsaws in 1948. The early models were heavy, two-person devices with long bars. Often, chainsaws were so heavy that they had wheels like dragsaws . Other outfits used driven lines from

Laverda 1200 - Misplaced Pages Continue

2814-413: The idea of a saw "with joints like the chain of a watch" independently very soon after Park's original 1782 publication, but that he was not able to have it produced until 1790, after which it was used in the anatomy lab and occasionally lent out to surgeons. Park and Moreau described successful excision of diseased joints, particularly the knee and elbow, and Jeffray explained that the chainsaw would allow

2881-469: The large forces involved in the work, from the fast-moving, sharp chain, or the vibration and noise of the machinery. A common accident arises from "kickback" when a chain tooth at the tip of the guide bar catches on wood without cutting through it. This throws the bar (with its moving chain) in an upward arc toward the operator, which can cause serious injury or even death. Another dangerous situation occurs when heavy timber begins to fall or shift before

2948-557: The late 19th century. A chainsaw comprises an engine, a drive mechanism, a guide bar, a cutting chain, a tensioning mechanism, and safety features. Various safety practices and working techniques are used with chainsaws. The origin of chainsaws in surgery is debated. A "flexible saw", consisting of a fine serrated link chain held between two wooden handles, was pioneered in the late 18th century ( c.  1783 –1785) by two Scottish doctors, John Aitken and James Jeffray , for symphysiotomy and excision of diseased bone, respectively. It

3015-422: The length spanned by any three consecutive rivets (e.g., 8 mm, 0.325 inch), while the gauge is the thickness of the drive link where it fits into the guide bar (e.g., 1.5 mm, 0.05 inch). The conventional "full complement" chain has one tooth for every two drive links. "Full skip" chain has one tooth for every three drive links. Built into each tooth is a depth gauge or "raker", which rides ahead of

3082-575: The liquid-coolant circuit they are known as liquid-cooled . In contrast, heat generated by an air-cooled engine is released directly into the air. Typically this is facilitated with metal fins covering the outside of the Cylinder Head and cylinders which increase the surface area that air can act on. Air may be force fed with the use of a fan and shroud to achieve efficient cooling with high volumes of air or simply by natural air flow with well designed and angled fins. In all combustion engines,

3149-407: The longer, clean shavings characteristic of a sharp chain; a sharp saw also needs very little force from the operator to push it into the cut. Specially-hardened chains (made with tungsten carbide ) are used for applications where the soil is likely to contaminate the cut, such as for cutting through roots . A clear sign of a blunt chain is the vibrations of the saw. A sharp chain pulls itself into

3216-524: The modern chainsaw are Joseph Buford Cox and Andreas Stihl ; the latter patented and developed an electric chainsaw for use on bucking sites in 1926 and a gasoline-powered chainsaw in 1929, and founded a company to mass-produce them. In 1927, Emil Lerp , the founder of Dolmar , developed the world's first gasoline-powered chainsaw and mass-produced them. World War II interrupted the supply of German chainsaws to North America, so new manufacturers sprang up, including Industrial Engineering Ltd (IEL) in 1939,

3283-661: The most common type, but they faced competition from cordless lithium battery powered chainsaws from the late 2010s onwards. Although most cordless chainsaws are small and suitable only for hedge trimming and tree surgery , Husqvarna and Stihl began manufacturing full size chainsaws for cutting logs during the early 2020s. Battery powered chainsaws should eventually see increased market share in California due to state restrictions planned to take effect in 2024 on gas powered gardening equipment. A chainsaw consists of several parts: Chainsaw engines are traditionally either

3350-506: The much smaller radiators and less fluid in the system, the weight and drag of these designs was well below contemporary air-cooled designs. On a weight basis, these liquid-cooled designs offered as much as 30% better performance. In the late- and post-war era, the high-performance field quickly moved to jet engines . This took away the primary market for late-model liquid-cooled engines. Those roles that remained with piston power were mostly slower designs and civilian aircraft. In these roles,

3417-405: The operator or, in some saws, automatically by an electronic control unit . To prevent vibration induced injury and reduce user fatigue, saws generally have an anti-vibration system to physically decouple the handles from the engine and bar. This is achieved by constructing the saw in two pieces, connected by springs or rubber in the same way an automobile suspension isolates the chassis from

SECTION 50

#1732798351741

3484-481: The radiator size by 50% compared to water cooled designs. The experiments were extremely successful and by 1932 the company had switched all future designs to this coolant. At the time, Union Carbide held a monopoly on the industrial process to make glycol, so it was initially used only in the US, with Allison Engines picking it up soon after. It was not until the mid-1930s that Rolls-Royce adopted it as supplies improved, converting all of their engines to glycol. With

3551-454: The simplicity and reduction in servicing needs is far more important than drag, and from the end of the war on almost all piston aviation engines have been air-cooled, with few exceptions. As of 2020 , most of the engines manufactured by Lycoming and Continental are used by major manufacturers of light aircraft Cirrus , Cessna and so on. Other engine manufactures using air-cooled engine technology are ULPower and Jabiru , more active in

3618-417: The size of their tips). Some chainsaws are built specifically for carving applications. Echo sponsors a carving series. Today's chainsaws have multiple safety features to protect the operator. These include: ‹The template How-to is being considered for merging .›   Two-stroke chainsaws require about 2–5% of oil in the fuel to lubricate the engine, while the motor in electrical chain-saws

3685-458: The steam through tubes located just under the skin of the wings and fuselage, where the fast moving outside air condensed it back to water. While this concept was used on a number of record-setting aircraft in the late 1930s, it always proved impractical for production aircraft for a wide variety of reasons. In 1929, Curtiss began experiments replacing water with ethylene glycol in a Curtiss D-12 engine. Glycol could run up to 250 C and reduced

3752-411: The tooth and limits the depth of cut, typically to around 0.5 mm (0.025"). Depth gauges are critical to safe chain operation. If left too high, they cause very slow cutting; if filed too low, the chain becomes more prone to kick back. Low depth gauges also cause the saw to vibrate excessively. Vibration is uncomfortable for the operator and is detrimental to the saw. The tension of the cutting chain

3819-459: The two designs roughly equal in terms of power to drag, but the air-cooled designs were almost always lighter and simpler. In 1921, the US Navy , largely due to the efforts of Commander Bruce G. Leighton , decided that the simplicity of the air-cooled design would result in less maintenance workload, which was paramount given the limited working area of aircraft carriers . Leighton's efforts led to

3886-590: The volume of water required and the size of the radiator by as much as 30%, which opened the way to a new generation of high-powered, relatively low-drag liquid cooled inline engines such as the Rolls-Royce Merlin and Daimler-Benz DB601 , which had an advantage over the unpressurized early versions of the Jumo 211 . This also led to development work attempting to eliminate the radiator entirely using evaporative cooling , allowing it to turn to steam and running

3953-482: The wheels and road. In cold weather, carburetor icing can occur, so many saws have a vent between the cylinders and carburetor which may be opened to allow hot air to pass. Cold temperature can also contribute to vibration-induced injury, and some saws have a small alternator connected to resistive heating elements in the handles and/or carburetor. Typically, a centrifugal clutch and sprocket are used. The centrifugal clutch expands with increasing speed, engaging

4020-485: The wood without pressing on the saw. Since the air intake filter tends to clog up with sawdust, it must be cleaned from time to time but is not a problem during normal operation. Protective clothing is designed to protect operators in the event of a moving chain touching their clothing by snarling the chain and sprocket, by using special synthetic fibers woven into the garment. Despite safety features and protective clothing, injuries can still arise from chainsaw use, from

4087-462: Was also adopted on the 1000 cc models. Ceriani 38 mm (1.5 in) front forks were fitted. Twin 280 mm (11 in) Brembo discs were fitted on the front with a single disc of the same size on the rear. The cast wheels were of Laverda's own manufacture. The model was initially finished in red or blue with orange flashes. In early 1978, a number of changes were made. 38 mm (1.5 in) Marzocchi front forks and yokes replaced

SECTION 60

#1732798351741

4154-497: Was fitted with larger inlet valves, as used on the Jota . The model was finished in Black and gold with the chrome parts finished black chrome , the engine covers were also finished in black. A handle bar fairing and seat cover that were unique to this model. The steering nut was gold plated. Every bike was supplied with a personalised letter from Massimo Laverda and a gold medal with the owner's picture etched on it. Carrying on with

4221-491: Was illustrated in the second edition of Aitken's Principles of Midwifery, or Puerperal Medicine (1785) in the context of a pelviotomy . In 1806, Jeffray published Cases of the Excision of Carious Joints , which collected a paper previously published by H. Park in 1782 and a translation of an 1803 paper by French physician P. F. Moreau, with additional observations by Park and Jeffray. In it, Jeffray reported having conceived

4288-520: Was introduced. Heated handles are additional help. Newer, lighter, and easier to wield cordless electric chainsaws use brushless motors, which further decrease noise and vibration compared to traditional petroleum-powered models. The risks associated with chainsaw use mean that protective clothing such as chainsaw boots , chaps, and hearing protectors are normally worn while operating them, and many jurisdictions require that operators be certified or licensed to work with chainsaws. Injury can also result if

4355-415: Was invented by Stihl in 1926. Corded chainsaws became available for sale to the public from the 1960s onwards, but these were never as successful commercially as the older gas-powered type due to limited range, dependency upon the presence of an electrical socket , plus the health and safety risk of the blade's proximity to the cable. For most of the early 21st century petrol driven chainsaws remained

4422-415: Was substantially cheaper to manufacture, and gave a quicker, narrower cut, without risk of breaking and being entrapped in the bone. A precursor of the chainsaw familiar today in the timber industry was another medical instrument developed around 1830, by German precision mechanic and orthopaedist Bernhard Heine . This instrument, the osteotome , had links of a chain carrying small cutting teeth with

4489-493: Was upset by the 1929 introduction of the NACA cowl , which greatly reduced the drag of air-cooled engines in spite of their larger frontal area, and the drag related to cooling was at this point largely even. In the late 1920s into the 1930s, a number of European companies introduced cooling system that kept the water under pressure allowed it to reach much higher temperatures without boiling, carrying away more heat and thus reducing

#740259