The lawn mower is a mechanical device that literally shaves the surface of the grass by using a rapidly rotating blade or blades.
For centuries, grass was cut by workers who walked through pastures or fields wielding small, sharp scythes. In addition to being tiring and slow, manual cutting was ineffective—the scythes worked well only when the grass was wet. The first mechanical grass-cutting device appeared in 1830, when an English textile worker named Edwin Budding developed a mower allegedly based on a textile machine used to shear the nap off of cloth. Budding's cylindrical mower was attached to a rear roller that propelled it with a chain drive, and it shaved grass with a curved cutting edge attached to the cylinder. He created two sizes, large and small. The large mower had to be drawn by horses, whose hooves were temporarily shod with rubber boots to prevent them from damaging the turf; the head gardener at the London Zoo was among the first to purchase this model. Budding marketed the smaller mower to country gentlemen, who would, he claimed, "find in [his] machine an amusing, useful and healthful exercise."
Mechanized grass cutting was evidently slow to catch on, perhaps because Budding's mower was quite heavy in addition to being inefficiently geared. Only two lawn mower manufacturers exhibited their machines at England's Great Exhibition in 1851. However, several decades later the new machines experienced a surge in popularity due to the interest in lawn tennis that arose in England during the late Victorian period. Before the turn of the century, Budding's initial designs were improved. Weighing considerably less than their predecessors and based on the side wheel design still used in today's most popular mowers, these refined machines were soon visible in yards throughout England.
The earliest gas-driven lawn mowers were designed in 1897 by the Benz Company of Germany and the Coldwell Lawn Mower Company of New York. Two years later an English company developed its own model; however, none of these companies mass produced their designs. In 1902 the first commercially produced power mower, designed by James Edward Ransome, was manufactured and sold. Although Ransome's mower featured a passenger seat, most early mowers did not, and even today the most popular models are pushed from behind.
Power mowers are presently available in four basic designs: the rotary mower, the power reel mower, the riding mower, and the tractor. Because the rotary mower is by far the most common, it is the focus of this entry. Pushed from behind, rotary mowers feature a single rotating blade enclosed in a case and supported by wheels. As the engine turns, it spins the blade. The blade whirls at 3,000 revolutions per minute, virtually 19,000 feet (5,800 meters) per minute at the tip of the blade where the cutting actually occurs. The best rotaries feature a horn of plenty (cornucopia) or wind tunnel shape curving around the front of the housing and ending at the discharge chute through which the mown grass flies out. Self-propelled models are driven by a chain or belt connected to the engine's drive shaft. A gearbox usually turns a horizontal axle which in turn rotates the wheels. Some models have a big chain- or belt-driven movable unit that rises up off and settles down on the wheels.
The power reel mower features several blades attached at both ends to drums that are attached to wheels. The coupled engine drive shaft that spins the reel can also be rigged to propel the mower, if desired. Overlapping the grass, this machine's five to seven blades pull it against a cutting bar at the bottom of the mower. Then one or more rollers smooth and compact the clippings as the mower goes over them. Reel mowers are more efficient than rotary mowers because the latter actually use only the end of the blade to do most of the cutting, whereas the fixed blades in a reel mower cut with the entire length of both edges. However, rotary mowers are easier to manufacture because the basic design is simpler, and they are also favored over reel mowers on most types of turf. By industry estimates, most of the 40 million mowers in use on any given summer Saturday are rotary mowers.
The typical gas-powered walk-behind mower may have as many as 270 individual parts, including a technologically advanced two- or four-cycle engine, a variety of machined and formed parts, various subassemblies purchased from outside contractors, and many pieces of standard hardware. Most of these pieces are metal, including the major components: mower pan, handlebar, engine, and blades. A few, however, are made of plastic, such as side discharge chutes, covers, and plugs.
Manufacturing the conventional rotary lawn mower requires precision inventory control, strategic placement of parts and personnel, and synchronization of people and tasks. In some instances, robotic cells are used in conjunction with a trained labor force.
Inspectors monitor the manufacturing process throughout the production run, checking fits, seams, tolerances, and finishes. In particular, the paint operation is scrutinized. Samples of each painted part are regularly pulled off the line for ultrasonic testing, a process that utilizes the corrosion activity created in a salt bath to simulate 450 hours of continuous exposure to the natural environment. Painted parts are also scribed and the deterioration of the exposed surface watched for tell-tale signs of rust. If needed, the paint or cleaning cycles are adjusted to assure high quality and durable finishes.
Final performance testing—the last step in the assembly sequence—guarantees reliability and safety for users. A small quantity of a gas/oil mixture is added to each engine. A technician cranks the engine and checks its rpm with a gauge; drive elements and safety switches are also checked. As required by current Consumer Product Safety Commission regulations, the mower blade, when running, must stop within three seconds after the control handle is released.
Like many other machines, the lawn mower will benefit from the development of new and more efficient power sources. A recent invention is the solar-powered lawn mower, which uses energy from the sun rather than gasoline as fuel. It needs no tuneups or oil changes, and it operates very quietly. Perhaps its biggest drawback is the amount of energy its battery can store: only enough for two hours of cutting, which must be followed by three days of charging. However, as batteries with more storage capabilities are developed, this drawback will disappear.
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— Peter Toeg