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A hard hat is a type of helmet predominantly used in workplace environments such as industrial or construction sites to protect the head from injury due to falling objects, impact with other objects, debris, rain, and electric shock. Suspension bands inside the helmet spreads the helmet's weight and the force of any impact over the top of the head. A suspension also provides space of approximately 30 mm (1.2 inch) between the helmet's shell and the wearer's head, so that if an object strikes the shell, the impact is less likely to be transmitted directly to the skull. Some helmet shells have a mid-line reinforcement ridge to improve impact resistance. Blue-collar workers, especially union shop construction workers engaged in occupations that require protective equipment are sometimes referred to as "hard hats". A bump cap is a lightweight hard hat using a simplified suspension or padding and a chin strap. Bump caps are used where there is a possibility of scraping or bumping one's head on equipment or structure projections, but are not sufficient to absorb large impacts, such as that from a tool dropped from several stories. == History == In the early years of the ship building industry, workers covered their hats with pitch (tar), and set them in the sun to cure, a common practice for dock workers in constant danger of being hit on the head by objects dropped from ship decks. Management professor Peter Drucker credited writer Franz Kafka with developing the first civilian hard hat while employed at the Worker's Accident Insurance Institute for the Kingdom of Bohemia (1912), but this information is not supported by any document from his employer.〔Drucker, Peter. Managing in the Next Society. See: Franz Kafka, ''Amtliche Schriften''. Eds. K. Hermsdorf & B. Wagner (2004) (Engl. transl.: ''The Office Writings''. Eds. S. Corngold, J. Greenberg & B. Wagner. Transl. E. Patton with R. Hein (2008)); cf. H.-G. Koch & K. Wagenbach (eds.), ''Kafkas Fabriken'' (2002).〕 In the United States, the E.D. Bullard Company was a mining equipment firm in California created by Edward Dickinson Bullard in 1898, a veteran of the industrial safety business for 20 years. The company sold protective hats made of leather. His son, E. W. Bullard, returned home from World War I with a steel helmet that provided him with ideas to improve industrial safety. In 1919 Bullard patented a "hard-boiled hat" made of steamed canvas, glue and black paint. That same year, the U.S. Navy commissioned Bullard to create a shipyard protective cap that began the widespread use of hard hats. Not long after, Bullard developed an internal suspension to provide a more effective hat. These early designs bore a resemblance to the military M1917 "Brodie" helmet that served as their inspiration. On the Hoover Dam project in 1931, hard hat use was mandated by Six Companies, Inc. In 1933, construction began on the Golden Gate Bridge in San Francisco California. Construction workers were required to wear hard hats, by order of Joseph Strauss, project chief engineer. Strauss strove to create a safe workplace; hence, he installed safety nets and required hard hats to be worn while on the job site. Strauss also asked Bullard to create a hard hat to protect workers who performed sandblasting. Bullard produced a design that covered the worker's face, provided a window for vision and a supply of fresh air via a hose connected to an air compressor. In those times many workmen's safety helmets were made of steel. Aluminum became a standard for hard hats around 1938, except for electrical applications. MSA introduced the new plastic Skullgard® Helmet in 1930 for the metals industry to withstand radiant heat loads of up to 350 °F. New plastic Bakelite was used to provide protection rigid enough to withstand hard sudden impacts within a high-heat environment but still be light enough for practical use. Machinery of the times required that helmet materials used be electrically non-conducting. Bakelite resin compounded with wire screen and linen. The Skullgard Helmet is still manufactured. MSA also produced a low-crown version for coal miners known as Comfo-Cap® Headgear. Coal miners were quick to take up MSA’s low-crown version of the headwear called Comfo-Caps. Fiberglass came into use in the 1940s. Thermoplastics took over in the 1950s, as they are easy to mold and shape with heat and cost less to manufacture. Today, most hard hats are made from high-density polyethylene (HDPE) or advanced engineering resins, such as Ultem. In 1952, MSA offered the Shockgard Helmet to protect electrical linemen from electrical shock of up to 10,000 volts. In 1961, MSA released the Topgard® Helmet, the first polycarbonate hard hat. 1962 brought the V-Gard® Helmet that today is the most widely used hardhat in the United States. In 1997 ANSI allowed the development of a ventilated hard hat to keep wearers cooler. Accessories such as face shields, sun visors, earmuffs, and perspiration-absorbing lining cloths could also be used; today, attachments include radios, walkie-talkies, pagers, and cameras. Another milestone was reached in 2013 with production of the MSA V-Gard GREEN Helmet, the first industrial safety product produced from nearly 100 percent renewable resources. High-density polyethylene (HDPE) construction sourced entirely from sugarcane ethanol is recyclable, reducing the carbon footprint associated with this product type. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hard hat」の詳細全文を読む スポンサード リンク
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