Straight Shaft vs. Curved Shaft: The Definitive Guide
Straight Shaft vs Curved Shaft String Trimmers
While shopping for a string trimmer, you'll probably consider many different factors:
- How much power the motor or engine provides
- How much the trimmer weighs
- How comfortable it is to hold
- How much it costs
But have you asked yourself, "Should I choose a curved or straight shaft trimmer?"
You’re not alone if your answer is no. It’s easy to think that a string trimmer’s shaft is nothing more than a pole that runs from one end to another.
However, even if that’s what you believe, you might notice that some string trimmers have a shaft that’s completely straight, while others have a curved one shaped like a hook or the letter J.
There are reasons for that.
It’s not just about aesthetics. It’s not even just about comfort, although that’s a big factor. The choice between a straight shaft and a curved shaft trimmer affects string trimmer usage and performance, all the way down how heavy-duty your string trimmer will be.
Why Is the String Trimmer Shaft Important?
The string trimmer’s shaft does more than give the handles a surface to attach to or allow you to trim hard-to-reach spaces of your lawn.
It also serves an incredibly important role: the shaft connects the power source at the top of the string trimmer (either a motor in an electric trimmer or an engine in a gas-powered tool) to the trimmer head and the string at the bottom.
Inside the shaft is a drive mechanism. The drive takes power from the motor or engine and uses it to rotate the head while you work.
Imagine a string trimmer with a head that couldn’t turn, and you’ll understand why the shaft and the drive mechanism inside of it are so vital!
All About Straight Shaft Trimmers
Straight shaft string trimmers are more common than curved shaft trimmers. One reason for that is the variety that’s possible with this trimmer style.
Straight Shaft String Trimmer Design
As mentioned earlier, the rod of a straight shaft string trimmer extends in a straight line from the power source to the head. Often, a straight shaft is longer than the one on a curved trimmer.
This design allows for more options when it comes to the type of drive mechanism inside the shaft. The drive inside a straight shaft can be a cable made from plastic or steel. Because it doesn’t have to bend to accommodate a curved design, it also can be a solid steel driveshaft – a typical option on commercial-grade trimmers.
Straight-shaft trimmers have gearboxes to help convert the rotational force of the motor or engine (also known as torque) into the speed of the head.
Pros and Cons of Straight Shafts
Engineers don’t add design features to a machine unless those features have some benefits. Each one of the design points mentioned above provides benefits for string trimmer users to enjoy:
- Better reach
- More torque
- Less wear and tear
It makes sense that a longer shaft would make it easier to trim areas that otherwise would be difficult to reach, like the space beneath a raised deck or patio. Not only that, they’re usually more comfortable for taller people to hold.
But as we said at the start of the article, it’s not just about comfort. A straight shaft trimmer with a solid steel driveshaft has a more durable construction than any trimmer with a plastic drive cable. It can use heavier-grade replacement string as well as optional cutting blade attachments in place of the string.
In fact, metal string trimmer blades are designed to work with straight shaft trimmers. Because of the gearbox inside a straight shaft trimmer, the shaft and the trimmer head always turn counterclockwise. You might not realize it by looking at them, but string trimmer blades are designed with counterclockwise rotation in mind.
Finally, it comes back to power. The straight-line design helps generate more torque, which translates into more cutting strength, with minimal vibration. Although straight shaft trimmers tend to be heavier, and the elongated shape can make them feel unbalanced, their ability to provide lots of power with less vibration ultimately makes them more comfortable for some users.
The Bottom Line
Straight shaft trimmers have features designed with greater durability, increased versatility, and higher power output in mind. Although anyone can use them, many straight shaft string trimmers are ideal for the long hours and demanding tasks that commercial users and people with large properties to care for often face.
All About Curved Shaft Trimmers
Straight shaft trimmers might be more common, but the ergonomics and the features of curved shaft string trimmers have a lot of appeal for the casual user.
Curved Shaft String Trimmer Design
On most curved trimmers, the curve is a hook-shaped bend in the shaft just above the powerhead. However, some trimmers have a pole that’s curved like an elongated letter S. In both cases, the shaft will typically be shorter than a straight-line shaft.
Inside the shaft is a drive cable that provides a direct connection from the power source to the trimmer head without a gearbox. This drive cable is made of a flexible plastic that will allow it to fit the bend of the shaft. Some drive cables might be braided so that they’re reinforced and more durable.
Pros and Cons of Curved Shaft Trimmers
The curved shaft represents an innovation in the realm of string trimmers, and innovations come with benefits:
- Better control
- Easier to carry
- Less expensive
Because the powerhead on a curved shaft trimmer points downward even when a user holds the trimmer straight in front, it’s easier to see and maneuver around objects in the yard like trees and flower beds. The trimmer head can be brought closer to ground level, and the curve gives the user greater leverage and a better sense of balance.
An improved sense of control also comes from the weight of the curved shaft trimmer. A shorter shaft is a lighter shaft that’s less of a burden to carry. The downside of this lightweight build is that curved shaft trimmers are limited to using light or low-gauge replacement line, but for most homeowners and casual users, this shouldn’t affect performance.
The other potential downsides of curved shaft trimmers come from the presence of the drive cable. The drive cable has to be flexible to accommodate the shaft’s curve. As a result, curved shaft trimmers are generally less durable and less suitable for long hours of use than straight shaft trimmers, though braided cables provide some reinforcement.
Also, all cable drives on curved string trimmers turn clockwise. Because metal trimmer blades are designed for counterclockwise rotation, they can’t be used with curved shaft string trimmers.
The Bottom Line
Curved shaft string trimmers are easy to use in tight spaces and yards with plenty of fixtures. Their low weight not only makes them more comfortable to carry but also places them at a lower price point. For homeowners and users who don’t need to run their string trimmers every day, a curved shaft string trimmer can be a logical choice.
Choosing a Shaft Style
The style of string trimmer shaft doesn’t just change the look of the machine. It also affects the tool’s durability, the power it puts out, and even the price you pay for it.
However, by having an idea of how often you plan to use your trimmer and what the grounds you want to maintain are like, the connection between you and your ideal string trimmer can be as straight and direct as the shaft on a straight shaft string trimmer.
NEXT: What Are 2-Cycle and 4-Cycle String Trimmers?