String trimmer also called as weed eater is available in several models provided by different manufacturers with battery-powered, gasoline and electric engines. Mostly battery-powered trimmers and electric trimmers are used for residential lawn care needs.
These String trimmers are very less weight tools. Mechanically, a string trimmer functions mostly like a handheld lawnmower.
The best cordless string trimmers work by the use of fastly spinning microfilament string that makes them be stiff enough to cut weeds and grass. Most of the string trimmer models automatically feed new string, when the old string wears out, allocating with the requirements for heavy metal blades that need sharpening.
Engine Operation Of String Trimmer
The best and powerful string trimmers mostly consist two-cycle gasoline engines that make use of both oil and gas. It is required to pull the chord to begin the trimmer engine. While it is pulled, the permanent magnet present on the flywheel makes ignition coil to get energized which in turn passes electric current to the spark plug.
It starts firing with each rotation of the flywheel, igniting fuel in the combustion chamber and then driving the crankshaft. If the string trimmer is of the battery-powered or electric model, then the electric current rotates the flywheel and drives the crankshaft.
For only gas-powered models, it is required to manually start by pulling the starter cord. The battery-powered and electric models start as soon as they have a power source.
Clutch, Drive Shaft and Trimmer Head
The engine crankshaft gets connected to a centrifugal clutch which in turn lead it to get connected to a drive shaft that extends to the trimmer head through the shaft of the machine.
When the engine is idling, the wings of the clutch stay retracted, and when you pull the trigger to engage the throttle, the clutch wings spread outward and engage the drive shaft, which in turn begin rotating the trimmer head.
The string move as quick as 29,000 feet per minute when trimmer head is turning at maximum speed, giving them enough force to slice easily through weeds and grass.
The Trimmer Head
The trimmer head that is bolted onto a spindle and is strongly connected to the drive shaft is one of the main parts of the string trimming machine that holds the string strong enough. It consists of a spool, and the string is wound around the cap with holes through which the string extends.
Some string trimmers automatically advance the string as it wears out, while the other string trimmers advance the string only when you manually bump the top of the cap on the ground. By removing the spool and cap from the head, you can wind new string or else you can just replace the whole head.
Most of the gasoline-powered string trimmers consist of a priming bulb or a choke or both of them to assist with cold starting. It is very important to follow and to use these string trimmers according to the instructions given in owner’s manual to avoid flooding the carburetor at start-up.
The string diameters generally would be around 0.065 inches to 0.090 inches. In particular, you should know what diameter your machine need because if you don’t use exact string diameters, then the trimmer won’t operate properly.
You can find this information also in the owner’s manual given to you along with trimmer. String trimmers come with a guard to prevent debris and stones from flying into the user’s eye or face, so make sure that guard is in place whenever the machine is operating so that you can avoid severe injuries.
For cutting, string trimmers mostly use monofilament nylon line for cutting. You can purchase this line in rolls or spools of different lengths and can cut them to your required size. Lower powered electric string trimmers use very light gage line of about 0.06 inch.
This is ideal for light grass trimming that grows around edges of your yards, flower beds, and curbs. Even higher gas powered string trimmers can also use this light gage line for cutting thick plants in the overgrown areas such as docks, nettles, long grass, other weeds.
However, the heavy gage line is best to avoid breaking the line, and you can buy this heavy gage line in size around 0.16 inches. Other than round profile, this line is also available in square profile which cuts corners in a perfect way.