Lawn Care/Maintenance/Mowing/Lawn Mowers
Lawn mowing is a partial defoliation of the turfgrass plant. The blades (leaves) of the grass plant are cut with mechanical machines called mowers.
The primary type of mower used on most lawns is the rotary mower. This mower
uses a gas or electric powered engine to rotate a cutting blade horizontally.
The blades create a vacuum lifting and then cutting the grass. Height adjustments
of rotary mowers is relatively easy.
One of the most recent advances in rotary mowers is the refinement in mulching mower design. Recently, a number of manufacturers have introduced mulching mowers in response to the recycle (i.e. "Don't Bag It") programs. In general, the mulching lawn mowers are standard rotary mowers modified to cut and then re-cut the clippings several times to allow the the finely grass to fall into the canopy of the lawn and not remain on the surface. The design modifications intended to assist in this recutting includes the use of high lift blades with expanded cutting edges and restrictions on the grass discharge ports.
Push-type reel mowers are making a comeback because they are quiet, non-polluting, inexpensive and are good exercise. These mowers do a good job of chopping and distributing clippings over the lawn. Their disadvantage is that clippings are not blown down into the turf as with a power mulching mower.
If
properly adjusted, they provide a higher quality cut than rotary mowers, particularly
at close mowing heights. A study conducted at The Ohio State University, comparing
reel and rotary mowers on Kentucky bluegrass at a 1 and 2 inch mowing height,
found consistently higher quality cuts with the reel unit. A reel mower is also
better at following the contour and giving a uniform height of cut. Reel mowers
have limited popularity today due to the inability of some models to adjust
mowing heights, difficulty in sharpening, and poorer performance at higher mowing
heights.
A reel mower consists of a rotating cylinder with attached blades and the stationary bed knife. The reel blade guides grass toward the bed knife. This creates a shearing action as with a scissors. When these surfaces are not sharp, grass is not cleanly cut, but may be torn, leaving a jagged edge. Mowing quality is affected by mowing height (MH) and the clip of the reel (CR). CR is defined as the forward distance traveled between successive clips. The MH is measured from a flat surface to the bottom of the bed knife. The CR is determined by the number of blades on the reel, the rotational velocity of the reel blade, and the forward operating speed of the mower. The most uniform cut occurs when CR = MH.
Because of the metal-to-metal contact between the reel blade and bed knife, regular lubrication is necessary to reduce wear of the two cutting surfaces. During mowing, this is accomplished with fluids from the plants that are cut. When a reel mower is operated on a non-grass surface, the reel should be disengaged to prevent unnecessary wear.
In contrast to the reel mower are rotary or flail impact mowers. A rotary mower is more versatile in mowing tall grass, seed heads and changing the height of cut. Rotary mowers are also relatively inexpensive to maintain with simpler maintenance requirements.
A number of materials are used for the cutting action on rotary mowers. Nylon cord is often used in string trimmers or similar devices to mow turf through an impact. In addition to nylon string, many other types of materials are used such as plastic strips, fiber wheels, etc.
The second type of impact mower is the flail mower, which has small knives attached to a horizontal shaft. When the shaft rotates, the knives extend the centrifugal force and clip the grass. Because they are not fixed, there is less danger of hard objects being thrown with this type of a mower. Flail mowers are generally used for roadsides and in other areas where hidden objects could damage a conventional mower.
Basic considerations for selecting the specific type of mower are the size of the area to be mowed, mowing height, and interfering features in the landscape. Some examples of this would be trees, fences or sloped areas. Other variables include desired height, frequency, and the mowing pattern.
