What do you need to look for when you buy a string trimmer? With so many options for heads, engines, and handles, it can get pretty confusing. Here’s how these differences affect performance.
Handles and Harnesses: Wide Sweeps or Small Areas
A harness spreads the weight of the trimmer over your shoulders. It connects to the trimmer at its balance point, making it easy to move around. This leaves your hands free to move the trimmer head without the fatigue of carrying it. Harness mounts are a great choice for heavier commercial trimmers, but they can interfere with maneuverability.
A loop handle lets you hold the trimmer near the center of the shaft with one hand, while the other hand operates the trigger near the engine. This is common on lightweight trimmers that are hand-carried. This setup lets the operator reach into tight spaces, trimming around fences, planters, and other landscape obstacles.
A bicycle handle has two vertical grips spaced far apart. This gives you more leverage and control, making it ideal for cutting large swaths through thick vegetation. This type of handle is only found on trimmers with harnesses. The harness supports the trimmer, while the handles are only used to control direction.
Engines: Two-Stroke, Four-Stroke and Somewhere In Between
Two-stroke engines use a sealed crankshaft to push fuel and air into the engine at the bottom of the piston stroke, while simultaneously pushing exhaust out. This lets the engine fire on every rotation and eliminates the need for a valvetrain. The result is more power and less weight than equivalent four-stroke engines. To keep everything lubricated, oil is mixed with the fuel and burned during the combustion cycle. This lets the engine work at any angle. Two strokes seem ideal for string trimmers, but there are some disadvantages.
Power delivery is concentrated at the top of the RPM range. If the trimmer bogs down, it can move out of the power band and stall. These engines are also sensitive to stale fuel. Manufacturers recommend using fuel treatment and disposing of fuel that’s over one month old. Some unburnt gas leaves the cylinder during the intake/exhaust stroke, which increases fuel consumption and emissions. Two strokes also don’t last as long as four-stroke engines, so it’s not unusual to wear out a trimmer after a couple seasons.
There are two alternatives on the market today. Honda’s small-displacement four-stroke has baffles to control oil flow, keeping the engine lubricated, no matter its position. The “2/4 stroke” or “Hybrid 4” engine (used in some Shindaiwa and Echo products) is a four-stroke engine with a two-stroke oiling system. You still need to mix oil with the fuel, but the engine is far less sensitive to stale fuel. With both engines, you get more torque, better fuel efficiency, and a longer engine life at the expense of weight.
Trimmer Heads
There are seemingly endless varieties of shapes and sizes of lines. However, you will generally get the best performance by matching the line with the size and density of the grass. Thin lines have no trouble with trimming around lawns, while thick lines and blades work best on overgrown areas.
Head designs can be divided into three main categories:
- Bump heads have a button on the bottom of the head that releases a little bit of line every time it’s hit. This mechanism is cheap and reliable.
- Automatic heads have a motor that spins the spool, releasing the line. While not as reliable as a bump head, you never have to stop to release line while trimming.
Fixed-line heads use pre-cut lengths of line. Once the line wears down, the trimmer has to be shut off, and a new line threaded through the holes. This is used almost exclusively with heavy gauge lines, which can’t be wrapped around a spool. Nylon and metal blades slice through thick vegetation with ease, offering similar performance.
Some trimmers can be fitted with brushcutter blades. These blades have sharp tips that slice through woody vegetation and saplings. This might be great for ripping through unkempt land and wilderness, but they’re hopeless at cutting regular grass.
From Home Lawn Care to Professional Landscaping, Shank’s Has the Equipment You Need
If you need a new string trimmer, talk to the experts at Shank’s Lawn Equipment. We have helped local residential and commercial customers with their outdoor equipment for 35 years. We’re also an authorized dealer for several major trimmer brands, including Honda and Echo. Our shop is at 4900 Molly Pitcher Highway in Chambersburg, PA. To get here, take Exit 10 from I-81.
Need parts to fix your trimmer? We can ship what you need to any address in the USA or Canada. To order, visit us online at www.shankslawn.com.