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A zero-turn riding lawn mower (colloquially, a ''z-turn'') is a standard riding lawn mower with a turning radius that is effectively zero. Different brands and models achieve this in different ways, but hydraulic speed control of each drive wheel is the most common method. Both commercial duty and homeowner models exist, with varying engine power options, size of cutting decks, fuel type (gasoline or diesel), and prices. A z-turn mower typically drives faster and costs more than a similarly sized conventional riding mower that has steerable front wheels. Most current models have four wheels: two small swiveling front tires and two large drive tires in the back. Bush Hog mowers sometimes come with a small, pivoting fifth wheel mounted in the center behind the driver. Instead of controlling the swiveling tires to steer the machine, the large drive tires rotate independently of each other based on the driver's input. They may rotate in opposite directions. The mower can pivot around a point midway between the drive wheels (the classic z-turn), or it can pivot around either one of the drive wheels if one is stationary, or it can turn in a circle of any radius. Reversal of the direction of travel can be accomplished by causing both wheels to rotate in reverse. Steering controls differ on z-turn mowers. Instead of a steering wheel, most z-turns have two throttles that control the rotational speed and direction of each drive wheel. The throttles are typically moved by a seated driver who operates levers mounted waist to shoulder high. The mower's engine throttle is controlled separately, if at all. Some zero turn mowers are steered by a joystick or a steering wheel, the advantage of either one being the location of the hands may permit less fatigue during prolonged mowing and the use of a single hand for steering. ==History== In 1963, John Regier was an employee of the Hesston Corporation, a manufacturer of farm and agricultural equipment. The company had recently engineered a device called the swather, which, propelled by a series of belts, cut hay, alfalfa and other farming materials and laid them out in windrows. The way the belts and pulleys operated allowed for counter- rotation—a process which particularly struck Regier. An idea came to him one day: What if he could incorporate the same technology into lawnmowers? “So he went home and invented this thing that was able to operate on the zero-turn radius,” says Ken Raney, advertising manager at Hustler Turf. “He began selling them, but they weren’t really taking off the way he wanted them to. Nobody knew the technology then, so nobody wanted to buy it.” Regier’s patent was eventually sold to Hesston, which would eventually become Excel Industries—parent company of Hustler Turf. The mower was called—appropriately enough—the Hustler. “We were the first company to offer mowers with zero-turn technology,” says Paul Mullet, president of Excel Industries. “After Regier sold us the patent, he came to work for us and the rest is history.” (Excel Industries ) is the parent company of Hustler Turf Equipment, Inc., which manufacturers Hustler Turf and BigDog Mowers zero-turn mowers. In 1969, Grasshopper Mowers introduced the first commercially viable zero-turn mower, and in 1974, Dixon coined the term "zero-turn radius" with their entrance into the mower market.〔 In 1997, Robert D. Davis Jr. obtained United States Patent 5644903 for a new steering control he had invented for a zero turn radius mower, based on eight previous patents.〔 (more user-friendly presentation of the above)〕 Currently, there are more than three dozen zero-turn mower manufacturers offering a range of mid-mounted and out-front mowing deck options and accessories. 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「Zero-turn mower」の詳細全文を読む スポンサード リンク
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