Mowing large areas down to size
The versatility and productivity of large-area rotary mowers have typically made them a leading choice for the time-efficient maintenance of parks, sports complexes, golf courses or other large-acreage areas. Few would dispute their usefulness, yet the choices you face in selecting one of these highly productive giants depends on your location, climate and many other factors.
Considering the vast array of deck and engine sizes, blade configurations and optional accessories currently available from manufacturers, it's no small wonder that buying a large-area mower can seem to be a daunting task. To help see you safely through this process, following are some guidelines to keep in mind when adding or replacing one in your equipment lineup.
Questions, questions, questions... It's vitally important to enlist the expertise and experience of your turf-equipment dealer, especially if you have never previously purchased a large-area mower. The questions he or she asks, and vice versa, will help match engine and deck style to your workload and terrain. Be prepared to answer the following questions: * How and where will you use it and what types of demands will you place on it? * What turfgrass species will you cut and how often? * What type of "finish" do you expect from the cut? * What is your budget?
Likewise, you should ask: * What are the typical features of these units and what are their benefits? * Will the manufacturer or dealer provide you with a comprehensive maintenance schedule? * How easy is the unit to maintain? * What types of options are available? * How many years of service can you expect from it? Once your dealer establishes your maintenance needs, he or she can present you with appropriate engine, deck and blade choices.
Choosing the suitable engine Because the engine (or tractor unit) is the heart of any mower, choose it wisely. Most manufacturers offer a variety of models in a range of horsepowers and engine configurations: air-cooled or liquid-cooled, gas or diesel. Generally speaking, liquid-cooled and diesel engines are the most economical to operate, last longest and are best suited for heavy-use applications. However, air-cooled, gasoline-powered models have their advantages as well. The type and size of engine greatly depends on three factors: amount of use, terrain and cutting width. A general rule of thumb is to increase engine size by 5 hp for every additional foot of cutting width. For example: a 72-inch front-mounted cutting deck usually requires a 30-hp engine for optimal performance. Multi-deck, high-output "wing" models require horsepowers in excess of 50 hp.
* Air-cooled engines. Selecting an air-cooled gas engine isn't just a question of budget. Though typically the least expensive of engine choices, these units' lower horsepower-ranges of up to 25 hp-may be all you need. Particularly well-suited for single cutting-deck widths under 72 inches, a well-maintained 1- or 2-cylinder, air-cooled power plant can provide years of reliable service when used in a fairly light-duty application-that is, flat or slightly undulating terrain with dry turf.
If used in the off-season or for maintenance tasks, lower-horsepower air-cooled tractor units are usually robust enough to accommodate sweeper, aerator-core-destroyer and snow-removal accessories. However, such units do require more frequent maintenance inspections to ensure that grass and debris don't clog the air-intake fins. Also, you'll typically reduce these units' operating efficiency if you use them in high-heat conditions.
* Liquid-cooled engines. Available in either gas or diesel styles, liquid-cooled engines offer more consistent running temperatures and greater adaptability to wider cutting widths and multiple decks. Other advantages of these types of engines include improved fuel efficiency and a lower operating cost per acre.
Because liquid-cooled units contain either 3 or 4 cylinders, they are generally quieter and smoother-running than their air-cooled counterparts. Most liquid-cooled engines are available in the 28- to 50-hp range. However, some manufacturers do offer higher horsepowers.
The higher horsepower capacity of liquid-cooled engines makes them more appropriate for year-round cutting in a variety of terrain and weather conditions. The choice of 2- or 4-wheel power trains will also affect the engine's productivity.
The primary maintenance concern for liquid-cooled engines is in keeping a clear air flow to the radiator. When selecting one of these units, notice where the air-intake screen is positioned. Ideally, it should be located on top of the engine-away from the flow of grass clippings and other debris.
* Diesel engines. Despite their slightly higher up-front cost, diesel engines can be a better long-term investment than their gasoline-powered counterparts-both in terms of fuel consumption and operating costs. Their heavier construction helps them resist damage from impacts. Additionally, the cleaner-burning properties of diesel fuel could help you comply with today's growing number of municipal air-quality regulations.
Because higher-horsepower diesel models tend to use less fuel, they are particularly well-suited for handling multiple cutting decks. Provided that you perform regular maintenance and only use manufacturer-recommended fuels, a diesel engine can deliver many years of reliable service.
The transmission alternatives A 2-wheel-drive transmission offers the dual advantages of reduced cost and maintenance. If used in the correct conditions (that is, generally flat terrain, dry to moderately damp turf that you cut frequently), it can perform as well as a 4-wheel-drive model. However, if you plan to use a unit with 2-wheel drive in hilly, damp conditions or a unit with a deck that is too large, you'll lose any initial savings to decreased fuel efficiency and shorter overall unit life. Whether manual or automatic, 4-wheel-drive tractor units tend to be the most versatile and efficient, especially when used in the Northeast and Northwest United States' damp, hilly terrain. Most manufacturers also offer models with "on-demand" or "full-time" transmissions. While cutting, such units should always be in 4-wheel drive.
As mentioned, terrain, turf type and climate conditions are only a few of the factors to consider when determining whether to purchase a unit with 4-wheel-drive transmission. Another aspect to contemplate is how much turf do you want to cut in one pass? Generally, if the width of your cutting swath dictates that you should choose a horsepower in excess of 30 hp, then-once again-choose a 4-wheel-drive unit.
Contrasts in cutting decks and blades Just as you should match your engines and transmissions to your rotary mower's workload, so should you match cutting decks and blades. Look for high-quality construction: heavy-gauge steel, sealed blade-drive spindles and tough belts. These parts should be able to deliver quality results even when you operate your mower at a reasonably fast ground speed.
Because large-area mowing usually requires you to raise and lower the deck-or decks-around curbs, trees and other obstacles, examine the deck-lift mechanism on units you consider to make sure it's durable. The front and rear of the deck should be able to clear the same-size obstacle. Hydraulic hoses and connections should be robust and positioned clear of any ground obstructions; some models also now have on-board leak-detection systems.
Consider the contours, turf variety and landscaping at your site when selecting a deck. After all, you'll lose the productivity of a "wing" mower's wide cutting swath if you must constantly raise and lower decks to mow around trees. Likewise, a 60-inch deck won't be very time efficient if you're maintaining large, obstacle-free tracks of green space.
Since scalping is a problem as cutting width increases, most decks feature anti-scalp rollers. These allow decks to closely follow ground contours and deliver an even cut and finish across the entire swath. Your choice in decks varies between deep-draft decks, side-discharge decks, rear-discharge decks and mulching decks.
* Deep-draft decks. This deck option helps provide a quality cut in wet, dense-turf conditions. Usually combined with high- or semi-lift blades, these decks are designed to create a "turbulence" that moves a large amount of air across the width of cut. Under normal cutting conditions, they perform especially well on bluegrass and fescue turf. The decks are also ideal for areas that you cut less frequently. Usually available in 60-, 72- and 80-inch widths, most deep-draft decks feature a side-discharge configuration. The side-discharge creates windrows of cut grass-a factor you should consider if after-mowing site cleanup is not possible.
If you do choose a deep-draft deck for regular use in heavy turf conditions, you may need slightly more tractor unit horsepower. Consider too, if your site is located near a residential area, that high- and semi-lift blades create a certain amount of noise.
* Side-discharge decks. These decks, which have a lower profile than their deep-draft cousins, are often used where you want a lower height of cut. Designed for regular use, these decks perform well on turf varieties such as St. Augustinegrass and Bermudagrass. However, they are also adequate for most other mowing conditions.
The best choice for multiple-deck mowers, side-discharge mowers usually employ either flat or semi-lift blades. The semi-lift blade works well on fine-textured turf. Side-discharge decks are available in a wide range of widths, from 30 to 72 inches.
* Rear-discharge decks. This deck choice, which evenly disperses grass clippings to the rear of the mower, is best suited for high-traffic areas. Because they don't create windrows, you can use these decks on or near narrow medians and sidewalks, flower beds and buildings. Their primary advantage is reduced cleanup.
* Mulching decks. Mulching decks were born out of concern over landfill restrictions and increased education about the agronomic benefits of grass clippings. Because the deck design on mulching units finely chops clippings and forces them down to the soil level, you eliminate the need for cleanup. Additionally, the turf receives a healthy dose of nitrogen from the decomposing clippings.
Most mulching decks rely on a twin-blade design to lift and cut the grass. Provided you don't cut off more than one-third of the grass on a single pass, this type of deck delivers a clean finish almost every time. Because of their closed configuration, however, mulching decks are not recommended for heavy turf conditions.
Peter Whurr is director of marketing for Ransomes America Corp. (Lincoln, Neb.).
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