Lawn mower and Lawn mower racing Info

Two cutting mechanisms in common use

reel or cylinder mowers, those with a set of spiral cylindrical blades spinning on a horizontal axis. Cutting is by a scissor-like action between moving spiral blades and a single stationary horizontal blade, or bed knife. The axle is attached to a gear mounted on one of the wheels in order to spin the blades rapidly for good grass cutting action even when the mower is moving slowly.
rotary mowers, those whose blades spin horizontally on a vertical driveshaft. Cutting is due to a horizontal blade striking the grass at high speed.
The two cutting mechanisms can lead to different results. On rotary mowers, the blade is usually not sharp enough to cut grass cleanly. The speed of the blade simply tears the grass resulting in ragged tips. By contrast, the cylinder type reel lawn mowers and manual lawn mowers usually work by scissor action on blades and a cleaner cut is achieved.

Rotary lawn mowers allow the height of the lawn mower to be adjusted to control the height of cut grass. On older or less expensive lawn mowers, this is accomplished by manually moving each wheel to different slot on the chassis. A more recent innovation in rotary mowers is a one touch height adjust mechanism where the blades are mounted on a frame separate from the rest of the lawn mower and the frame can be raised and lowered.

Lawn mowers need power for two purposes: to cut and to move. The act of pushing or pulling a reel mower provides power for cutting and moving at the same time. For rotary mowers, the power sources may vary: grass cutting may be powered by either an internal combustion engine or an electric motor, while propulsion may share power source or be supplied by the user or another external source such as a tractor. Wheel-driven gear systems allow for cutting to be powered by the same external source as used to propel the mower.

Reel mowers
There are four major types of reel mower: push, walk behind power, riding power, and tow behind gang mower.

Push mowers are powered by people pushing them and are usually used on very small lawns. The walk power reel mower can be divided into two types: a largely obsolete powered version of the push mower, used for residential lawns and a 'greens mower used for the precision cutting of golf greens. Riding power reel mowers can also be divided into two types: the triplex which has three hydraulically driven independent cutting heads and is used for golf greens, and the larger 'fairway' machine that has five or seven hydraulically driven cutting heads. Gang reel mowers are towed behind a tractor in sets (gangs) of three, five, or seven. They are ground-powered that is, the tires of each cutting unit are geared to drive the reel. Gang mowers are used to mow large areas of turf such as sports fields or parks.

Presently several companies are producing cordless electric reel mowers. The performance of the batteries vary in terms of how long the batteries can power mowers and the recharging cycles. An hour and a quarter (75 minutes) to half an hour (30 minutes) is the range of running time. Six hours to twenty-four hours is the range of time required to fully recharge batteries. Most batteries can be recharged several hundred times. Cordless electric reel mowers weigh 30 – 35 pounds.

The cutting action of the reel mower requires contact between the spinning reel and the stationary bed knife. The reel is first adjusted until it spins free. It is then adjusted back until it barely touches the bed knife on one side. The other side is then adjusted until it too makes contact with the bed knife. Contact is judged by cutting strips of slick magazine paper. The machine should be gradually adjusted until it is able to cut paper all along the bed knife. If the machine is too tight to be easily pushed, the left and right sides should be loosened slightly, by the same amount on each side, until loose enough to push. It is sometimes helpful to spray the reel with oil or silicone lubricant to allow it to turn freely.

The scissor-like action of a reel mower provides a much cleaner cut on the blades of grass than a rotary mower, avoiding brown ends that result from tearing or bruising of the remaining portion of the blade of grass.

Rotary mowers

Electric rotary lawn mower with rear grass catcher.
A mulching blade.Rotary mowers are often powered by internal combustion engines. Such engines can be either two stroke or four-stroke cycle engines, running on gasoline or other liquid fuels. Internal combustion engines used with lawn mowers normally have only one cylinder. Power generally ranges from two - seven horsepower (1.5 to 5.25 kW). The engines are usually carbureted and require a manual pull crank to start them, although an electric start is becoming a sales feature in some countries.

Rotary mowers powered by electric motors are increasingly popular. Usually, these mowers are moved by manual motive power— the on-board engine or motor only spins the blades. These have the disadvantage of requiring a trailing power cord that limits range and so these are only useful for relatively small lawns, close to a power socket. There is the obvious hazard with these machines of mowing over the power cable, which stops the mower and may put users at risk of electrocution. Installing a residual-current device (GFCI) on the outlet can reduce the risk of electrocution. Cordless (battery powered) electric lawn mowers are also available for small lawns. Electric rotary mowers weigh 45-50 pounds.

Rotary mowers typically have an opening in the side or rear of the housing where the cut grass is expelled. Some have a grass catcher attachment at the opening to bag grass clippings. Special mulching blades are available for rotary mowers. The blade is designed to keep the clippings circulating underneath the mower until the clippings are chopped small. Some designs have twin blades to mulch the clippings to small pieces. This avoids a need for bagging the clippings or raking the clippings. Not only does this save labor, as no organics are removed from the lawn, less fertilizer is needed.

A dead man's switch is required in some places so that the operator must hold a switch to keep the engine running. Typically, this is an extra bar that is held against the handle. Should the operator lose control of, or contact with, the lawn mower and release the bar, either the engine is turned off or the blade is disconnected by disengaging a clutch.

Riding mowers

A riding mower on the campus of Harvard Business School.A popular alternative for larger lawns is the riding mower. These often resemble small tractors, with the cutting deck mounted amidships between the front and rear axles. An alternative layout for a ride on is a rear-mounted engine with rear wheel steering, and a front mounted deck.

Hover mowers
Hover mowers are powered rotary push mowers that use a turbine above spinning blades to drive air downwards, thereby creating an air cushion lifts the mower off the ground like a hovercraft. The operator can easily move the mower as it floats over grass. Hover mowers are necessarily light in order to achieve the air cushion and typically have plastic bodies with an electric motor, although small petrol engines have been used. A different style of movement is often employed with hover mowers whereby operators swing the mower in an arc around themselves because there are no wheels touching the ground to impede movement in sideways directions.

Robotic mowers
Robotic lawn mowers represented the second largest category of household autonomous robots used by the end of 2005. A typical robotic lawn mower requires a user to set up a border wire around the lawn that defines the area to be mowed. The robot uses the wire to trim and in some cases to locate a recharging dock. Robotic mowers are capable of maintaining up to 5 acres of grass. Electricity usage varies from about 100 watts for 1/2 acre to 500 watts to maintain 5 acres.

Pull mowers

A bull drawn pull mower on the lawns of Taj Mahal.A pull mower is essentially the same as a manually pushed mower but the propulsion unit pulls the mowing unit instead of pushing it.

Professional mowers
Professional grass cutting equipment (used by large establishments such as universities, sports stadiums or local authorities and suchlike) usually take the form of much larger, dedicated, ride on platforms or attachments that can be mounted on, or behind, a standard tractor unit (gang-mower). Either type may use rotating-blade or cylindrical-blade type cutters, although good quality mown surfaces demand the latter.

Clippers
Hand-powered or battery-powered grass clippers can used for the tightest spots, for example around flowers, however one has to be on their knees a lot (though they may be attached to a long handle to give you the opportunity to work in an up-right position, saving your knees and back). The simplest forms of these are shears, which are like scissors with long blades.

A string trimmer, also called a line trimmer, edge trimmer, Weedeater, Weedwhacker, whipper snipper, strimmer, garden strimmer, or bush cutter is a powered handheld device which uses a flexible monofilament line instead of a blade for cutting grass and other plants near objects. It consists of a cutting head at the end of a long shaft with a handle or handles and sometimes a shoulder strap. String trimmers powered by an internal combustion engine 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.

Lawn mower racing is a form of motorsport where competitors race modified lawn mowers, usually of the ride on or self-propelled variety. Original mower engines are retained but blades are removed for safety. The sport attracts all ages, and is usually entered into in a spirit of fun rather than extreme competitiveness, though many do take it quite seriously. The pastime of Lawnmower racing was featured in the American Sitcom Home Improvement.

http://www.blmra.co.uk/ British Lawn Mower Racing Association

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