Gear-drive, hydrostatic, zero-turn, stand-on, riding, walk-behind – contractors’ choices when purchasing lawn mowers have never before been so varied. Whether you’re looking for high speed, comfort or compact size, mower styles offer something for everyone.
Ultimately, these options are merely fancy packaging for what is truly important: the components that will get the job done. Underneath it all, mower blades determine whether a machine will be a dream or a dud when cutting the grass. Choosing the appropriate blade for the application, inspecting the blades for wear and tear, and following safety precautions ensure a quality cut. In addition, familiarity with mower blade types and uses allows contractors to avoid frequent blade replacement – and thus cut down costs. “The blade is what the lawn mower is all about,” said Paul Jurgens, director of customer service, Exmark, Beatrice, Neb. “Consider the blade a necessary evil to generate revenue with the unit.”
SHOPPING AROUND. Of course, mower type cannot be ignored when selecting the correct mower blade, suggested John Kuhn, senior engineer, commercial mower development, John Deere, Horicon, Wis. “Buy blades that have been designed to perform for the specific mower in question,” Kuhn said. “A mower blade design that works well on one mower will not necessarily be optimal for another mower.”
Blades are tested for specific applications, so using them for alternate uses or equipment other than those suggested may actually weaken the effectiveness of the blade, Kuhn continued. Ken Day, president, Frederick Manufacturing, Kansas City, Mo., also warned against choosing generic blades. “Universal blades are compromises that a professional should not choose if specific fit blades are available.”
| HONING IN |
Since costs can add up when purchasing several blades throughout the year, proper mower blade care is also an economical consideration. Damaged and bent blades are inevitable occurrences, so it is important to have extra sets of blades available. "It is a good idea to always have a spare set of blades on hand that can be resharpened when the other set is being used," said John Kuhn, senior engineer, commercial mower development, John Deere, Horicon, Wis. Blades can become excessively worn through resharpening or sandblasting in sandy areas. Kuhn said certain regions' soil types may wear out a blade's airlift portion more quickly, but be aware that over-sharpening can be detrimental to the blade effectiveness. "I believe if the cutting edge has been sharpened enough to move it back more than ¼ inch to 3/8 inch, it should be replaced," he said, adding that when sharpening the blade contractors should blend the sharpened area into the rest of the blade to avoid creating a notch. Kuhn cautioned against blades with a notch between the flat portion and the airlift portion, which makes the blade more prone to fatigue breakage. Breakage also can be exacerbated with double blades, or placing two blades on each spindle in a cross-configuration, said Bill Wright, president, Wright Manufacturing, Frederick, Md. "Doubling of the mass creates a far greater time delay on clutch slippage on blade start-up and on the blade brake on blade shut-down, which would reduce both of these components' life expectancy," he said. When replacing blades, balance the blade carefully, stated Jaret Bishop, president, Custom Lawn Care & Landscaping, Washington Court House, Ohio. Unbalanced blades cause vibration of the entire system, resulting in the wear of other components. Paul Jurgens, director of customer service, Exmark, Beatrice, Neb., offered some additional pointers for replacing mower blades. "After you have removed the blade from the unit that needs to be sharpened, carefully inspect the air foil of the blade to make sure that sand or dirt has not undercut the airfoil," he said. "If the airfoil were to break free during mowing, it could do considerable damage to whatever it hits. "You also need to be careful when installing a sharpened blade to make sure it is secured properly while tightening the blade bolt," he continued. "There have been lots of nasty cuts inflicted by a non-moving mower blade." Kuhn added that blades must be fed properly onto the spindle so they are centered. Some spindles offer pilot mechanisms that guide the blade into place, he added. Further, he stressed that contractors should always wear gloves when handling blades. - Kristin Mohn |
Next, contractors must decide between the two main categories of mower blades: side- or rear-discharging and mulching. Discharge blades offer notches in the air foil that help chop grass and leaves into small pieces, Jurgens offered. “The high-lift blade provides for the most efficient means of discharging grass from the deck,” he said. These features also help with bagging applications, Kuhn noted. “Typically a higher airlift will create more airflow for better dispersion or bagging,” he said. “It is sometimes, but not always, the case that higher airlift improves cut quality.”
Mulching blades, on the other hand, offer features that direct the mowed material back into the grass. “Mulching blades typically have a downdraft feature inboard from the airlift that directs cut material back into the turf,” Kuhn said. Another type of mulching blade features projections or vanes above the cutting edge, Day noted. “After the grass is cut it flows over the top of the blade and impacts the vanes,” he described. “This tends to pulverize the clippings. The vanes are formed so they direct this same blade of grass toward the center of the blade where it falls through and is cut and pulverized again. The blade results in a reduction of clipping volume by 30 to 50 percent.”
However, when cut quality is the main issue, high-lift blades offer better results, said Jaret Bishop, president, Custom Lawn Care & Landscaping, Washington Court House, Ohio. “High-lift blades offer better quality, where I haven’t had as good results with the mulching blades.” Day continued that the success of mulching blades depends on grass conditions like moisture or height.
Other mower blade considerations include the length of the sharpened edge and blade thickness. Jurgens related that the norm has generally been to sharpen only the outer 4- or 5-inch portion of the blade, but fully-sharpened blades may improve cut quality. In terms of thickness, commercial blades should be at least ¼-inch thick, suggested Bill Wright, president, Wright Manufacturing, Frederick, Md. “All else being equal, a thicker blade will usually last longer and be less prone to bending,” Kuhn related.
Mower blades generally can be bought in retail stores for approximately $9 to $20 a piece, depending on type and manufacturer. Mulching blades tend to cost more because they require more attention and take longer to manufacture, offered Mike Seaford, product development manager, Stens, Brillion, Wis. Although purchasing mower blades one by one requires a relatively low investment, it may be more economical to purchase them in bulk, Bishop said. This reduces overhead and allows contractors to always have blades on hand should one break or bend.
Choosing the correct mower blade also requires regional knowledge of soil conditions and grass types. “A solid air foil blade may work better in the wide blade fescue, bahaia and St. Augustine-type grasses where a notched air foil blade seems to perform better in fine blade fescues and bluegrass lawns,” Jurgens said. Jurgens warned that lower-lift blades create less turbulence under the deck, which may reduce blowout in dry areas with little grass. However, “low-lift blades also tend to pick up less sand in sandy areas, which can reduce the sandblasting effect that can be detrimental to deck and blade life,” he added.
| BUYING THE RIGHT BLADE |
When a person looks at buying a blade for his mower, he should understand what it is designed to do. Contractors have many different blades to choose from: notched airfoil, solid airfoil, low airfoil and mulch. All of these blades act differently for different conditions. With the availability of different design and functions, a person can change the type of blades he or she is using to better suit his or her mowing conditions. A notched airfoil is Exmark's standard blade. This blade produces a lot of lift and moves a lot of air. The notched airfoil blade produces maximum discharge velocity and is ideal for heavy, thick, hard-to-lift grasses. With the high lift of the blade and cutting conditions, the blade takes full advantages of a unit's horsepower. Some of the negative effects we see with this blade can be build-up on the underside of the deck (with certain grasses) and blowout in areas where the grass is thin. The solid airfoil is a high-lift blade without the notch in it. This blade produces a strong lift and it is a step down from the amount of air movement that the notched airfoil produces. The solid airfoil will have slightly less discharge velocity, blowout and can help with build-up problems under the deck. This blade works well in drier grass conditions in the summer, fall or in the southern region grasses of the United States. These blades are also used more by state, park, recreational and municipality concerns with rougher mowing conditions. These blades tend to be tougher by design. Low-lift blades are very similar to the solid airfoil blades. The low-lift blades are as the name state - they produce a much lower amount of lift. With low-lift blades you will see substantial reduction in any blowout and less discharge velocity. Low-lift blades are a good choice for thin, dry or stiff grasses. These blades are great for the contractor in sandy areas of the county. They increase the life on the bottom of the deck and the discharge chute. These blades use very little horsepower to run and greatly reduce any grass build-up under the deck. Mulch blades are designed to cut clippings and put them back into the lawn. The Exmark mulching blade has a medium amount of lift airfoil at the tip. They also have an airfoil to force the clippings back into the lawn; this is noted by the wavy design of the blade. This blade works great in all types of grasses and light to medium leaf build-up. Heavy build-up of leaves or overgrown grass will often require double cutting with any mulching application. The operator also needs to take into consideration the season of the year and the moisture content of the grass. Let's say that you have thick bluegrass and it is springtime. This would be where a notched airfoil would be a good choice or a solid airfoil if build-up becomes an issue. If you are cutting centipede or zoysia grasses in the southern regions, or in sandy conditions, a low-lift blade would be a very good choice. The last bit of information everyone should keep in mind is nine times out of 10, slowing down slightly can help more than anything. When mowing at full speeds conditions and consistency change rapidly in the turf. Slowing down may do more for you than any blade you may find. -Paul Jurgens The author is director of customer service, Exmark, Beatrice, Neb. |
Kuhn also identified region as a factor in blade replacement. “In northern parts of the country where the soils are more of a clay, you are not picking up as much soil and the blade might last for the better part of a season,” he said. On the other hand, in southern regions such as Florida, which feature sandy conditions and sparse grass, a blade may need to be replaced after only 30 to 50 hours of mowing. Yet, Kuhn warned against regional generalizations, as grass type and condition can vary from property to property.
BLADE TLC. After finding a mower blade that fits the application and mower type, contractors can extend blade life with proper care and safety. Kuhn identified blade sharpness and damage inspection as the two main components of blade care. “Sharp blades require less power, give a cleaner cut and do not fray the end of the grass blade, which results in grass tips browning,” he said.
Since honed blades cut grass more cleanly and efficiently than dull blades, Jurgens suggested sharpening mower blades frequently. “In many cases it would be ideal to start each day with a freshly sharpened set of blades; it makes it easier and quicker to sharpen the blades that were removed if they are not run until they are extremely dull,” he said. “The load on the engine, the belts and the bearings in the cutting housings is significantly reduced when the blades are sharp vs. dull.” Day added that frequently sharpening blades actually removes less material over time, thus allowing more efficient mower operation and a better cut.
When sharpening blades, contractors can expect the best results from a blade grinder, Day continued. “[Grinders] will pay back quickly in longer blade life, improved lawn cut, and extended engine and mower deck life,” he said. For increased blade life, remove nicks that lead to cracking and balance the blade when finished sharpening, Day said. “Inexpensive balance testers are available from most dealers,” he stated. “An out-of-balance blade will result in premature wear of the mower deck.”
Continuously inspecting mowers and blades for damage also ensures maximum efficiency. At his company, Bishop insists that a mechanic examine all mowers at the end of the day and change out blades as needed. For damage control, he advises contractors to do a “trash run” on properties before starting the mowers. Removing rocks and debris from the lawn lessens the chance of mower blade damage – and damage to the operator.
When mowers do hit hidden objects, Kuhn suggested examining the mower immediately for bent blades and other damage. “A quick method for checking to see if the blade is bent is to check all combinations of tip alignment,” he said. “The tips should align within 1/8 inch. If a blade is bent, it should not be straightened, it should be replaced.”
On the other hand, Jurgens maintained blades must be checked and changed daily. In dry conditions this frequency may increase to more than once a day, he added. “Dust, dirt and sand are more easily drawn into the cutting chamber in dry conditions, thus causing increased wear to the blades and underside of the deck,” he said.
Ultimately, a mower blade can only be maintained for so long before wearing out its welcome, Jurgens said. “It should be considered as a normal wear part that will need to be replaced on an as-needed basis,” he commented.
The author is Assistant Editor of Lawn & Landscape magazine.