Environmental Engineering Reference
In-Depth Information
Fig. 6.6. A gang mower pulled by a tractor.
to mow golf course greens and tees and selected sport turfs. Golf course
fairways and large parks are often mowed with the so-called gang units
of reel mowers, which are pulled by tractors (Fig. 6.6). A gang unit
usually consists of 3-9 independent reel mowers and provides the fastest
way of mowing large areas. Reel mowers must be operated at a speed
that depends on the velocity of the spinning cylinder and the number of
blades attached to it. If the speed is too high, the cut becomes uneven.
Sharpness of the bed knife and spinning blades is of critical importance.
Reel mowers used to cut golf greens are sharpened at least weekly.
Despite their high quality of cut, reel mowers are not popular among
homeowners. A reliable engine-powered reel mower costs several times
as much as a rotary mower, requires considerable maintenance and does
not work well if the turf is overgrown, as residential lawns sometimes are.
Rotary mowers
The blade of a rotary mower is usually a single sharpened metal bar
suspended parallel to the ground at its centre point. It spins in a hori-
zontal plane, striking and severing vertically growing leaf blades
(Fig. 6.7). Rotary mowers do not provide an even cut, and they cause a
certain amount of mutilation to the leaf blade at the point of impact. For
the majority of turf-grasses rotary mowers provide a satisfactory cut, but
some turf-grasses with rigid leaves, such as zoysia, may sustain consid-
erable damage to the leaf tips, especially when the blade is not quite
sharp (Fig. 6.8). In general, rotary mowers are designed to mow grass
taller than 3 cm, so their operation is restricted to medium- and low-
quality turfs, and their primary users are homeowners. Rotary mowers,
usually powered by small engines, can cut a wide variety of grasses,
require little maintenance and need only periodical sharpening. The
shape of the mower blade can be varied to affect the mower's function
and the way grass clippings are disposed of. The spinning blade creates
air movement under the mower housing that may blow clippings to the
