![Men_working_on_lawns_at_Ciudad_Universitaria,_Mexico_City](https://upload.wikimedia.org/wikipedia/commons/b/bf/Men_working_on_lawns_at_Ciudad_Universitaria%2C_Mexico_City.jpg)
A string trimmer, also known by the portmanteau strimmer and the trademarks Weedwacker, Weed eater and Whipper Snipper. is a
garden tool
A garden tool is any one of many tools made for gardening and landscaping, which overlap with the range of tools made for agriculture and horticulture. Garden tools can be divided into hand tools and power tools.
Hand tools
Today's garden tool ...
for cutting grass, small weeds, and
groundcover. It uses a whirling
monofilament line
Monofilament fishing line (shortened to just mono) is fishing line made from a single fiber of plastic material, as opposed to multifilament or braided fishing lines constructed from multiple strands of fibers. Most fishing lines are now nylon ...
instead of a blade, which protrudes from a rotating spindle at the end of a long shaft topped by a
gasoline engine
A petrol engine (gasoline engine in American English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends (such as ''E ...
or
electric motor
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate for ...
.
String trimmers are commonly used for cutting low foliage near obstacles or on steep or irregular terrain. Most professional-grade line trimmers can accept attachment blades to be used as brush cutters for more dense vegetation.
History
The first brush cutter was produced in Japan in 1960 by
Echo
In audio signal processing and acoustics, an echo is a reflection of sound that arrives at the listener with a delay after the direct sound. The delay is directly proportional to the distance of the reflecting surface from the source and the lis ...
. The U.S. string trimmer was invented in the early-1970s by
George Ballas
George Charles Ballas Sr. (June 28, 1925 – June 25, 2011) was an American entrepreneur. He invented the first string trimmer, known as the Weed Eater in 1971. He is the father of ballroom dancer, Corky Ballas, and grandfather of professional dan ...
of
Houston
Houston (; ) is the most populous city in Texas, the most populous city in the Southern United States, the fourth-most populous city in the United States, and the sixth-most populous city in North America, with a population of 2,304,580 i ...
,
Texas
Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...
,
who conceived the idea while watching the revolving action of the cleaning brushes in an automatic car wash. His first trimmer was made by attaching pieces of heavy duty fishing line to a tin can bolted to an
edger
An edge trimmer or lawn edger is a garden tool, either manual or motorised, to form distinct boundaries between a lawn, typically consisting of a grass, or other soft botanical ground cover, and another ground surface feature such as a paved, con ...
. Ballas developed this into what he called the "Weed Eater", since it chewed up the grass and weeds around trees.
The word "strimmer" is correctly a
trade name
A trade name, trading name, or business name, is a pseudonym used by companies that do not operate under their registered company name. The term for this type of alternative name is a "fictitious" business name. Registering the fictitious name w ...
for a particular make of string trimmer, but it is often used as a generic for any string trimmer. From it has been
backformed the colloquial verb "to
strim".
Terminology by country
The terminology used to refer to string trimmers varies by country and sometimes state:
* South Africa — Line trimmer or brushcutter
* Australia and Canada — whipper snippers
* UK / Ireland - Strimmer, Grass trimmer or brushcutters
Design
![Rasentrimmer String trimmer IMG 5522](https://upload.wikimedia.org/wikipedia/commons/c/c8/Rasentrimmer_String_trimmer_IMG_5522.JPG)
A string trimmer works on the principle that a line spun fast enough on its center stiffens by
centrifugal force
In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is parall ...
; the faster the hub turns, the more rigid the line. Even round-section nylon line is able to cut grass and slight,
woody plant
A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposite to herbaceous plants that die back to the ground until sp ...
s quite well. Some monofilament lines designed for more powerful cutters have an extruded shape, like a star, that helps the line slash the material being cut; the line is thus able to cut quite large woody plants (small shrubs) or at least
girdle
A belt, especially if a cord or rope, is called a girdle if it is worn as part of Christian liturgical vestments, or in certain historical, literary or sports contexts.
Girdles are used to close a cassock in Christian denominations, including th ...
them effectively. These lines make solid disks less necessary for tough jobs.
The line is hand-wound onto a reel before the job is started, leaving both ends extending from the reel housing. The motor turns the reel and the line extends horizontally while the operator swings the trimmer about where the plants are to be trimmed. The operator controls the height at which cutting takes place and can trim down to ground level quite easily.
As the line is worn, or breaks off, a bump feed string trimmer the operator knocks the reel on the ground so a release mechanism allows some of the line in the reel to replace the spent portion. Newer models "auto-feed", where a small cutter ensures the exposed length does not exceed what can be swung efficiently. Newly extended line operates more efficiently because of its heavier weight and surface effects. The speed of the spinning hub is controlled by a trigger activated
throttle
A throttle is the mechanism by which fluid flow is managed by constriction or obstruction.
An engine's power can be increased or decreased by the restriction of inlet gases (by the use of a throttle), but usually decreased. The term ''throttle'' ...
on the handle.
![String_trimmer_head-insert_style](https://upload.wikimedia.org/wikipedia/commons/2/2f/String_trimmer_head-insert_style.jpg)
A fixed line string trimmer has a trimmer head that takes pre-cut line inserts. There is no wound spool of line in the trimmer head, the user instead feeds the pre-cut line in to the appropriate slots, making the trimmer easier to feed line into and troubleshoot than a bump feed system.
For vertical cutting the whole machine can be tilted or some trimmers allow the head to be adjusted at different angles.
String trimmers powered by an
internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal c ...
have the engine on the opposite end of the shaft from the cutting head, while electric string trimmers typically have an electric motor in the cutting head, but there are other arrangements such as where the trimmer is connected to heavy machinery and powered by a
hydraulic motor
A hydraulic motor is a mechanical actuator that converts hydraulic pressure and flow into torque and angular displacement (rotation). The hydraulic motor is the rotary counterpart of the hydraulic cylinder as a linear actuator. Most broadly, ...
.
The head contains a safety shield on the user side and a rotating hub which may also be called a head or spool. Disadvantages of a gasoline-powered string trimmer include its greater weight, the need to refuel, and the significant vibration that carries throughout the device, both of which interfere with its maneuverability and contribute to muscle fatigue. Advantages include complete mobility and higher maximum power.
Large trimmers, used for cutting thick roadside grass and weeds in large areas, are both heavier and more powerful. Some are fitted with a harness to spread weight onto the shoulders. Often referred to as brush cutters, these often mount straight or circular metal blades instead of monofilament line.
Accessories
![Bruschcutter and line trimmer and tools](https://upload.wikimedia.org/wikipedia/commons/8/85/Bruschcutter_and_line_trimmer_and_tools.jpg)
Many string trimmers allow the hub, the head or the lower part of the shaft to be replaced with accessories. Common accessories include:
* metal or plastic blades
* a small
chain saw
A chainsaw (or chain saw) is a portable gasoline-, electric-, or battery-powered saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. It is used in activities such as tree felling, limbing, bucking, pruning, ...
* a toothed
hedge trimmer
A hedge trimmer, shrub trimmer, or bush trimmerAs with the term ''scissors'', the plural terms "hedge trimmers" + c. are often used for individual trimming tools. is a gardening tool or machine used for trimming (cutting, pruning) hedges or so ...
* a
cultivator
A cultivator is a piece of agricultural equipment used for secondary tillage. One sense of the name refers to frames with ''teeth'' (also called ''shanks'') that pierce the soil as they are dragged through it linearly. It also refers to ...
Quick-release shafts are offered on many newer models which do not require any tools to switch in accessories.
Power and emissions
Gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organi ...
-engine powered trimmers usually have a minimum of displacement motors. At this size they can easily turn line and some have nylon blades as accessories to the line-reel. A engine can swing a line and often has metal-blade accessories. Most trimmers use
two stroke engine
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of t ...
s and require gasoline mixed with oil. Due to pollution laws
four stroke engine
A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...
s are becoming more popular, particularly in the commercial market. Manufacturers include
Honda
is a Japanese public multinational conglomerate manufacturer of automobiles, motorcycles, and power equipment, headquartered in Minato, Tokyo, Japan.
Honda has been the world's largest motorcycle manufacturer since 1959, reaching a producti ...
,
MTD and
Craftsman. Companies such as
John Deere carry low-emission two-stroke engine trimmers.
Stihl manufactures a hybrid four stroke engine trimmer that still requires oil to be pre-mixed into the fuel. Battery powered models should eventually see increased market share in California due to state restrictions planned to take effect in 2024 on gas-powered gardening equipment.
Electric edge trimmers have the advantage of being very light, easy to maneuver and easy-to-operate. However, both the power cord and total cord length limit them. Typically less powerful and robust than gasoline-powered units, they are normally are limited to maximum diameter nylon because of their lower power output (400 to about 1200 watts). Recharge time for a battery model using small or large sealed lead acid, nickel metal hydride, or lithium ion batteries is typically several hours; some models offer a quick-charge option of as little as half an hour, or a removable battery pack.
Propane-powered string trimmers were also manufactured by Lehr.
Plastic pollution
''
Earth Island Journal
The Earth Island Institute is a non-profit environmental group founded in 1982 by David Brower. Located in Berkeley, California, it supports activism around environmental issues through fiscal sponsorship that provides the administrative and org ...
'' criticised string trimmers as a source of
plastic pollution
Plastic pollution is the accumulation of plastic objects and particles (e.g. plastic bottles, bags and microbeads) in the Earth's environment that adversely affects humans, wildlife and their habitat. Plastics that act as pollutants are catego ...
due to the string being shredded while in use.
Safety concerns
String trimmers can send
debris
Debris (, ) is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, as in geology, large rock fragments left by a melting glacier, etc. Depending on context, ''debris'' can refer to ...
flying randomly at high speed. It is typical for the user to wear either
safety glasses
Glasses, also known as eyeglasses or spectacles, are vision eyewear, with lenses (clear or tinted) mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known as temples or ...
or a suitable
visor
A visor (also spelled vizor) is a surface that protects the eyes, such as shading them from the sun or other bright light or protecting them from objects.
Nowadays many visors are transparent, but before strong transparent substances such a ...
to protect their eyes, but passersby are still at risk. The debris can even damage cars and buildings, with a particularly high risk of broken glass.
Chain-link flail rotors, and any other trimmer head with linked metal parts, were prohibited from sale in the EU after a fatal accident in 2010.
See also
*
Brushcutter (garden tool)
A brushcutter (also called a brush saw or clearing saw) is a powered garden or agricultural tool used to trim weeds, small trees, and other foliage not accessible by a lawn mower or rotary mower. Various blades or trimmer heads can be attached to ...
, a heavy duty tool which may take a line trimmer head or various other blades
*
Leaf blower
A leaf blower, commonly known as a blower, is a device that propels air out of a nozzle to move debris such as leaves and grass cuttings. Leaf blowers are powered by electric or gasoline motors. Gasoline models have traditionally been two-str ...
References
Notes
{{Garden tools
Gardening tools
Lawn care
Habitat management equipment and methods
American inventions