Getting the line on string trimmers

Given that one of this summer's biggest movie hits (Austin Powers) involves time travel, I thought I'd invite you to go back in time with me for a moment. On this particular trip, we are visiting the years 1968 to 1970 and observing how landscape-contracting companies perform trimming and edging work. Prior to 1970, there were no string trimmers as we know them today. Can you imagine edging sidewalks, driveways, parking lots and shrub beds with hand-held trimmers? Can you imagine how sore your back, arms and legs would be after a long day of pushing a manual edger along seemingly endless sidewalks and driveways? Can you imagine trimming any turf at all without a powered trimmer? Many of us take the advantages the string trimmer gives us for granted.

String trimmers are one of the most important pieces of equipment in your array of landscaping tools. Not only do they put an edge on sidewalks, shrub and flower beds and parking lots, they serve many other functions with dozens of available attachments. The time you save by using these tools is something you may take for granted these days. Since the early 1970s (when the first powered string trimmers appeared), the machines have improved with stronger string, more attachments and better engines. In fact, the string trimmer and its attachments have been the impetus for an entire industry. Designed not only to trim turf, machines of today perform hedge-trimming, pruning, sweeping, cultivating and blowing.

So mistreated Because modern-day string trimmers are so lightweight and easy to handle, they are among the most valuable pieces of equipment in your arsenal. However, they also are among the most abused pieces of equipment in most landscape-contracting firms. I've seen landscaping crew members toss them in the back of trucks without securing them. I've seen them dropped during the changing of spools or string. I've seen them bent because they were left on the ground behind vehicles. I've even seen them fall from inadequately designed racks in service garages. Suffice it to say that these little machines, although tough, are not invincible. As the owner of a landscape-consulting firm, I know that no one cares as much for the equipment as the person who owns it.

Heads and string feeds Four types of spin-trimmer heads are available and they are classified based on how they dispense string:

* Automatic heads feed the string automatically during operation when the throttle reaches a certain speed. * Semi-automatic heads require you to tap the spindle head on the ground (preferably not on concrete) during operation when the throttle is engaged. The tapping and open throttle causes the string to advance and feed out the guide holes in the spindle head. * Manual heads require you to stop the machine (turn it completely off) and manually pull or unwind the string that is wound inside the head. * Fixed-line heads do not hold additional string. You must use pre-cut lengths of string for replacements.

Statistically speaking, tap-and-go heads are the most popular variety. Most users view them as more convenient because you can control string length without stopping the machine. However, manual heads remain popular as well, and from my own experience, they are preferred by a growing number of landscape-company managers and owners. This growing preference stems from what we all have seen: crewmembers who don't care for the equipment and repeatedly bang the tap-and-go unit on hard surfaces to advance string. If this were a perfect world, string would effortlessly advance from the semi-automatic heads on the first, light tap. It's no secret that the string sometimes becomes stuck or tangled inside the heads of all trimmers and we must stop the machine and fix it. The important advantage of manual-feed heads is that they are damaged less often than automatic-feed heads because they don't endure such abuse.

String types String diameter varies greatly and comes in round-cut and edged varieties. Much debate occurs over which type and diameter trims turf the best. Unfortunately, there is no definitive answer to this debate. Diameter plays an important role in how long most string tends to last. Typically, the thicker the diameter, the longer the string will last. Diameters range from 0.066 mm to 0.160 mm. You must refer to the owner's manual to know what size of string will fit inside the trimmer's head.

Manufacturers market many different types of string. Some say that their string material is more durable, others propose the shape (smooth or edged) enables the string to trim turf more efficiently. You should keep in mind that some edged strings do not feed well in automatic-feed heads. Other types of string may "float" erratically while spinning, resulting in an uneven cut. Some string may cut extremely well, but also wear more quickly.

You must find a balance between the cost, effectiveness and efficiency of the string and find the type that fits your machine. Far too many specific brands of string are available to discuss them here, but you can readily find both original-manufacturer brands and after-market brands.

Maintenance In basic terms, string trimmers are simple machines. However, don't let their simplicity allow you to think that you can get away with irregular or infrequent maintenance. Most manufacturers supply trimmer users with standard checklists of preventative-maintenance schedules. Naturally, you must keep an eye on all of your equipment for possible problems and not let trivial matters worsen. Checking components such as air filters on a weekly basis can save you from downtime or costly repairs. Conversely, checking the spark plug and gear head can be done bi-monthly.

As a rule, you should plan to give your trimmers a thorough maintenance check-up after every 40 hours of use. This means inspecting the air filter, fuel system, ignition system, cutting head, gear head, shaft, muffler and spark arrestors, clutch wear and bolt tightness.

Fuel mix With 2-cycle machines, such as string trimmers, most manufacturers recommend using the highest-quality gasoline and oil in the proper ratio. However, it is also important to use only those products specified for trimmers and 2-cycle engines. For example, although there are high-quality oils designed for outboard engines, you shouldn't use those oils for 2-cycle engines. Another thing you should be aware of is that some manufacturers double the life of their warranties if you use oil that they sell or produce.

Another benefit of higher-grade oil is that it produces fewer emissions. This issue certainly will affect all of us before the end of the next decade as new regulations take effect.

With regards to fuel, some manufacturers believe that you should stay away from alcohol-based gas. They argue that this type of gasoline is hard on fuel systems and disintegrates fuel lines and gas-cap lids. It causes engines to run hotter and causes vapor locking. When oil is added to such fuel in 2-cycle engines, they don't stay mixed as well and tend to separate over time. When deciding which is best for your equipment, consult your owner's manual.

Safety matters Before you do anything else, read the operator's manual for your string trimmer. You must know what you're doing before you start a string trimmer. Untrained operators are more likely to cause accidents. There are several important safety factors involved in the operation of these machines:

* Untrained operators and power equipment do not mix. Don't let untrained personnel use string trimmers. * Never operate a string trimmer when there are people within 50 feet of you. * Always wear complete eye and hearing protection when operating a string trimmer. * Wear protective clothing such as long pants, closed-toe shoes and gloves. Don't wear loose clothing. * Make sure operators who have long hair keep it secured above their shoulders while using the trimmer. * Keep your footing firm and don't overreach with a trimmer. * Operate the trimmer only during times of adequate daylight. * Keep the string head below waist level at all times during operation. * String trimmers are meant only for trimming turf and weeds. Never use them to trim ivy or shrubbery. * Before each use, inspect the trimmer for loose fasteners, fuel leaks and cracked or chipped string heads. * Never operate a trimmer inside a closed room.

General advice When making string-purchasing decisions, most manufacturers recommend buying a high-quality string-specifically an anti-weld or anti-fuse line. Because the string pulls when it hits vegetation, heat builds up inside the head and less-expensive string may fuse together and clog the unit. If you must use a softer string, spray it with a silicone spray after you've re-loaded the spool. This, although not a complete solution to the fusing problem, helps reduce string fusion.

Shafts are a major component of the trimmer and you must pay particular attention to their durability. Flex shafts generally have been ignored by our industry because of their high proliferation and low-end reputation in the consumer market. As long as the shaft is labeled as a strong, reinforced unit, you should have no problems with breakage. Benefits you gain with flex shafts are the anti-vibration and shock-absorption characteristics that offer you comfort and help prevent gear and clutch wear and damage. In addition, if a drive housing on a flex shaft is bent, you can continue to operate it. However, if the drive housing gets bent on a solid-shaft unit, you must immediately replace it.

Don't over-grease the gearbox. Too much grease causes the seals to blow out or leak. When you are running your trimmer, the grease heats up and expands. Seals can't handle the expansion if there is too much grease.

Trimmers will serve you and your crews for many years if treated and maintained properly. Install carrying racks in your trucks with Velcro straps to hold the trimmers in place while in route to various job sites. Again, one of the most common causes of trimmer damage is the negligent crewmember who simply lays the trimmer in the back of a truck and drives from site to site. No trimmer can take the constant bouncing and tossing it endures when not securely fastened down during travel.

1. Use a high-quality air-cooled 2-cycle oil. Low-grade 2-cycle oils have a high ash content that will increase carbon deposits. Carbon deposits foul spark plugs and can damage the cylinder, piston and rings. In addition, carbon deposits in the muffler restrict exhaust flow and cause the engine to overheat. Outboard-motor 2-cycle oils are designed for liquid-cooled applications. The temperatures sustained in air-cooled engines are much higher, and the oil must be formulated to operate under these conditions.

2. Lubricate the unit according to the recommendations in the operator's manual. Lubricate more often under severe operating conditions. Lack of lubrication causes parts to overheat and fail prematurely.

3. Make sure all bolts, fasteners and fittings are tight and in good condition. Components that are not securely attached to the machine present a real danger to the operator and any bystanders. In additions, loose components cause excessive vibration and premature wear to the machine.

4. Keep the machine clean. Excessive oil, dirt and debris on the engine cause overheating and engine failure. A dirty air filter creates a rich fuel mix. This rich fuel mix causes spark-plug fouling and carbon deposits. Carbon deposits in the combustion chamber damage the cylinder, piston and piston rings. Deposits in the muffler restrict exhaust flow and cause overheating.

5.Operate the machine at full throttle. Low engine RPM causes premature wear to the clutch components due to slippage and heat. In addition, the engine may overheat due to high load and low RPM (lugging). Technical credit: Hoffco Inc.

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