Lawn mower centrifugal clutch. How Does A Weed Eater Clutch Work

9th August 2023

How Does A Weed Eater Clutch Work?

Weed eaters are essential tools for landscapers and gardeners. They are also useful for homeowners who want to trim their lawns or shrubs without using a power tool.

If you have a great gas-powered string trimmer, you’ll need to learn more about the clutch. It’s one of the most important components of your weed eater. In this article, we will teach you more about your weed eater clutch – both how it works and how you can tell if your trimmer clutch is starting to go bad.

Gas Weed Eaters Have A Centrifugal Clutch

Gas-powered weed whackers, chainsaws, and lawnmowers often use centrifugal clutches. These allow the engine to idle without engaging the output device, usually the drive train. The centrifugal clutch is one of the cheaper ways of providing a clutch to an engine – important for these 2 or 4-cycle engines. Engaging the clutch engages the engine, which allows the user to control its speed by disengaging the clutch when necessary.

Gas weedeaters usually use a centrifugal clutch (or “clutch”) to control the rotation of a blade or string. Centrifugal clutches operate by using centrifugal force. When the throttle is pressed on the trimmer, the external force of the motor causes the clutch to engage. When the throttle is released and the engine idles, the clutch disengages. Engaging the clutch causes the string trimmer to spin and cut weeds and grass, while disengaging the clutch allows the engine to run, but the string stops cutting.

While these weed eater clutches are essential, they do have a few problems.

If any of the parts that allow centrifugal clutches to operate are missing or damaged, they could cause a safety hazard As the internal shaft spins, springs push the weighted arms inward into the drum. If the drum were removed or damaged significantly, the weighted arms would not be able to spin against anything and could fly off, potentially injuring someone.

Centrifugal clutch systems are not as reliable as other clutch systems. Because it’s force comes from weighted arms pressing against an inner surface of a drum, it is limited by the torque and power of the weighted arms. If a stronger external force acts against the output, then no matter how fast the internal shaft is turning, the output will stop. An example would be a weed eater getting stuck in thick, heavy weeds. The trimmer stops even when the trigger is still pressed down.

How Do I Know If My Weed Eater Clutch Is Going Bad?

After you have your trimmer for a few years, it may begin to develop problems. It’s important to stay on top of these issues so they don’t develop into larger problems. Here’s some signs you weed whacker clutch is the problem:

The Weed Eater Doesn’t Start When Pressed Down

This is the most common symptom of a worn gas weed eater clutch. If the clutch isn’t working correctly, the engine won’t start. This happens because the arms inside the centrifugal clutch aren’t able to react to the spinning of the drive shaft, so the clutch can’t engage.

There are many reasons why a weed eater won’t turn over when you let go of the trigger:

The spring has become weak and needs replacing. Without a strong spring, the clutch can’t engage and your motor will simply rev in vain.

There is dirt or debris inside the clutch causing friction. Dirt builds up between the weights and the drum, reducing the ability of the weight to move. You may need to clean out the clutch.

The clutch was never installed properly. Make sure the clutch is in place before putting pressure on the throttle.

Your weed eater may need new spark plugs. Spark plug wires often wear out and break. Replacing them will ensure your weed eater starts right away.

String Trimmer Won’t Stop When Trigger is Released

A sign that your weed eater is running out of life is when the clutch doesn’t hold. Every time you press the button, the weed eater should start spinning. Likewise, the trimmer head should stop spinning when you release the throttle trigger.

If it doesn’t, then there’s probably something wrong with the clutch. It’s possible that the clutch has been damaged or broken. A cracked clutch drum will sometimes make the trimmer quit. In this case, the only solution is to replace the entire unit.

How To Avoid A Broken String Trimmer Clutch

It might seem counter-intuitive, but running your weed eater at low speeds for long times is one of the quickest ways to damage the clutch.

If you operate the trimmer at low speed, the shoes will slip against the clutch drum and wear down the friction coating. As you can imagine, this rubbing can generate A TON of heat. This stress can cause the drum to become deformed and bent out of shape.

In addition, you should use your trimmer only to cut grass and weeds. Using the weed eater as a poor man’s brush cutter will eventually catch up with you. Trying to cut a thick item will cause the clutch shoes to slip just as if you were running it intentionally at low speed. Once again, you’ll end up with a defective drum.

Conclusion

Hopefully, you’ve learned something from this article. If you notice your weed eater is experiencing any of these symptoms, take it in to an experience power tool repair shop or Big Box store to be looked at. Thanks for reading.

How to Create a Go Kart with a Lawnmower Engine

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Though go-karts traditionally use horizontal mount engines, with a little modification, you can install a vertical shaft lawnmower engine to be the driving force behind your homemade racing machine. Taste again the speed, freedom, and exhilaration of the open road when you convert your lawnmower engine into the go-kart you’ve always wanted.

Removing a Lawn Mower Engine

It’s best to drain the oil from an engine when it’s slightly warm, as the heat allows for a faster flow than when cold.

Drain the gas. Loosen the fuel hose clamp before you start draining your fuel. You can do so by tracing the route of the fuel hose from the engine to the base of the gas tank. Notice where the hose attaches to your lawn mowers carburetor. [2] X Research source Using your pliers, squeeze the clamp loose and slide it upwards on the hose. Now you can detach the hose and drain your fuel into a bucket.

Locate the throttle linkage. You can usually find the throttle linkage beneath the carburetor. There will be a cable that should connect to the throttle, and by removing the screw that holds the cable in place, you can easily remove the throttle linkage. [3] X Research source

Find the starter. This part is on the side of the engine and will have the shape of a small can. [4] X Research source Electric-start lawn mowers will have a red battery cabled attached. Use a wrench to unfasten the cable from the starter.

Remove necessary nuts and bolts. At the base of your mower engine is the mower house, which is where the engine is seated normally. Using your wrench on the bolt and another to hold still the nut below the mower house, unscrew the bolts holding your engine in place.

Take off the drive belt. You will find the drive belt on pulley on the crankshaft beneath the engine. Incline the engine slightly forward and pull the drive belt from its pulley. [5] X Research source

Remove the engine. Taking the engine firmly with both hands, lift the engine from the mower house and place it carefully off to the side in a safe place.

Preparing to Install

Larger engines in the 13 to 22 horsepower range, which you can find on riding mowers, may destroy the transmission or kart. [7] X Research source

Pick a suitable go-kart frame. You will want one that can support both your vertical shaft engine and lawnmower gearbox comfortably. Your gearbox should will need to have non-trans axle set-up.

Most frames have a width that varies between 1/3 and 2/3’s the wheelbase of your go-kart, with wider models giving better stability. [8] X Research source

Assembling the Frame

Always use proper protective gear when welding. Failing to do so can result in significant harm to yourself.

Put in a floor. A 16 gauge sheet metal piece should be sufficient for the floor of your kart. Using your plans from earlier, drill holes in the sheet for the fastening bolts for your seat.

Weld a brace for your seat. You should brace both outer sides of the go kart frame with flat, 3/16 gauge steel. This is where you will install the bench for your seat.

Assembling the Steering Column, Tabs, and Spindle Brackets

Cut and install you steering column. You should cut a section of 3/4 x 11 gauge tubing and weld it to your steering tabs. Insert an additional 1 spacer loosely by the shaft near the steering hoop, grinding the shaft slightly near the hoop if too tight. Drill a three hole pattern with the holes equidistant from the center of the washer at the end of your shaft.

Add resting tabs for brake and throttle. These 2 long 3/8 diameter tabs keep your pedals in their resting and full forward positions. The closest tab to the center of the frame should be fixed a max of 1/2 after the crosswise piece your to which your steering column is attached. The second tab should be installed 1 3/8 after the first tab.

Attach spindle brackets. You will weld these to the front axle of your go-kart. The spindle should have a 1 clearance above the front axle.

Give yourself a foot rest. Use a 3/8 rod in a vise to bend it with a hammer into the shape of your passenger footrest if applicable. This will keep your feet from resting on tie rods.

Centrifugal Clutch In Slow Motion (Pushed to Failure)

Don’t forget your brake Band stud. This stud will serve as the pivot for your brake Band. Weld a 3/8 round bar to the frame 1 1/2 after your axle.

Assembling Motor Mount, Brake Rod, and Accessories

The motor mount should be welded as the final step to building your kart.
Your mount should be able to hold your lawn mower engine in the horizontal position.

Attach the throttle cable guide tab. About 4 away from the middle of the throttle pedal bolt hole, weld this tab to your kart on a 45 degree angle.

Put in the brake rod guide tab. Take your brake rod and insert it through the tab, bending it to adjust it to the brake Band. Next, take the tab with the rod inserted and weld it to the kart.

Bend your brake rod into shape. Bend this 1/4 round rod so that it angles to meet your brake pedal assembly. Cut the length of your brake rod as needed, and weld eyelets to the rod with a return spring installed brake pedal.

Give yourself a seat. Many go-kart kits do not bolt seats directly to the kart. If this is the case for you, use a simple frame and bolt this into the seat braces. Your seat should be cut at a 37.5 degree angle for a 105 degree incline for your backrest.

Weld motor mount and attach accessory parts. Having finished with the body of your go-kart, you can now weld the mount to your frame. Upon completing your weld, you can add tires, seat padding, and all other necessary hardware to your vehicle.

Installing the Vertical Motor and Gearbox

Bolt down both motor and gearbox to the mount. The location of your motor is not as important as that of the gearbox. [9] X Research source To properly install your gearbox, align it with the gear on the rear axle, and then bolt it into place.

Change the sprocket size for the gearbox. A sprocket is a gear toothed wheel inside your gearbox that controls the gear ratio for your transmission, which is another name for the gearbox. Your target gear will be about 16 teeth.

Attach a throttle cable to throttle linkage on carburetor. Now you can clean off any residual oil from your kart, but do so with care. Always allow for sufficient time for the materials you are working on to cool, like the engine or solder, before using a cleaner.

Community QA

Speed mostly depends on three factors, engine RPM, tire size, and gear ratio. So that question is not easily answered. Most 5-7 HP yard go-karts go 17-35 mph, with 25 mph being common. 8-13 HP go-karts with torque converters and large tires top out at around 40 mph. Race karts can go much faster as they use modified or two stroke engines that rev higher, so you could see speeds of 50-60 mph in those. Enduro and high end race karts can go much much faster.

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As long as the engine is from a decent brand (and therefore good quality), it won’t explode out of nowhere. You’d really need to damage it to make it explode.

How to Install a Clutch on a Go-Kart: 4 Easy Steps

If you’re building your own go-kart or trying to replace a faulty clutch with a new one, you’ll most likely be confronted with the task of installing a go-kart clutch.

While it may seem like a daunting task, installing a clutch on a go-kart is a straightforward process and doesn’t require much. All you have to do is ensure that you have the right tools, understand the full process and make sure that your clutch is running optimally.

Here are the 4 steps to installing a clutch on a go-kart.

Slide the Clutch Onto the Crankshaft
Set the Clutch into Position
Align the Clutch Sprocket With the Rear Axle Sprocket
Do Final Preparations and Testing

This guide will show you a step-by-step process on how to install a clutch on your go-kart. We’ll also be discussing several important things that you should take care of before you start the installation.

These are the tools you’ll need:

1 x Centrifugal Clutch
1 x Set Screw (sometimes not included)
1 x Allen Key (for set screw)
1 x Washer (sometimes not included)
1 x Key
1 x Wrench

Before you start with the first step, you’ll want to ensure that the engine you are working on is easily accessible to you and that you have all the required tools prepared. You may also want to oil your go-kart clutch first, before you actually start the installation process.

Slide the Clutch Onto the Crankshaft

Now that the preparation is out of the way, you can proceed to slot the clutch onto the crankshaft of the engine. Ensure that the crankshaft is clean (you can wipe it down with a dry cloth) and slot the clutch into position.

Quick Guide:

Slot the clutch onto the crankshaft (indicated with a red arrow in the illustration)
Sprocket of clutch should face outward
Don’t tighten the set screw yet

When you place the clutch onto the crankshaft, ensure that the key of the clutch is aligned with the keyway on the crankshaft. They should fit perfectly. Once aligned you can proceed to push the clutch all the way through.

You’ll want to make sure that you are installing the clutch outboard, as opposed to inboard. To install a clutch outboard, the sprocket of the clutch should be facing outward – pointing towards you, not towards the engine. You should only consider an inboard setup if you have space limitations on your go-kart.

After you have completed this, it’s time to move onto the next step!

Set the Clutch into Position

The next step involves setting the clutch in place so that it’s firmly secured. In order to do this you’ll need to make sure that you have the following parts in front of you:

Quick Guide:

The set screw is located on the back of the clutch (facing the engine)
Set the screw in place firmly
Then, tighten the washer and bolt to the front of the crankshaft

Husqvarna String Trimmer Clutch Replacement #530055122

Setting the Set Screw

You’ll want to secure the go-kart clutch in place by tightening the set screw in the set screw hole, which is located at the back of the clutch – facing the go-kart engine.

Simply place it in, and screw until it’s reasonably tight. You’ll need a right-sized Allen/Hex key for this. Take note that some go-kart clutches do not come with set screws. In that event, you’ll need to source one independently.

Setting the Bolt and Washer

Now you’ll need to secure the clutch on the crankshaft by placing the bolt into the bolt hole located in the front of the crankshaft (it’s the large opening facing you).

Before slotting in the bolt, ensure that you have a washer in place, as the bolt is usually too small. Tighten it using a wrench and ensure that the clutch is firmly held in place.

Align the Clutch Sprocket With the Rear Axle Sprocket

Now that the clutch is on the crankshaft of the go-kart engine it’s time to align the clutch sprocket with the rear axle sprocket. There are several ways to do this.

Quick Guide:

Loosen the rear axle sprocket, move the kart or rear axle back and forth to automatically align the clutch
Tighten rear axle sprocket once aligned

The easiest way to align the rear axle sprocket with the clutch is to loosen the sprocket on the rear axle and connect the drive chain to the clutch sprocket and rear axle sprocket. If the go-kart is on the floor, simply move it back and forth and you’ll see that the go-kart chain automatically places the rear axle sprocket into alignment.

If your go-kart is on a stand, you can simply turn the wheels or rear axle back and forth to achieve the same thing. If you want to be more accurate, you can use a large rod or a laser tool to align the clutch sprocket and the rear axle sprocket.

Don’t forget to properly tighten the rear axle sprocket and ensure it’s firmly held in place. As you can see, there are several ways to achieve this. Check out this detailed guide on ways to align go-kart sprockets.

Do Final Preparations and Testing

Now, this part is easy! All you have to do is test your setup to ensure that all components are working as intended. Before you take your go-kart for a spin, it’s best to inspect the rear axle sprocket, drive chain and go-kart clutch to make sure that all are in place and set properly.

After you have done this, take your go-kart out for a ride to see if the new clutch is functioning properly.

Sources:

https://www.backyardworkshop.com/how-does-a-weed-eater-clutch-work/
https://www.wikihow.com/Create-a-Go-Kart-with-a-Lawnmower-Engine
https://www.gokartguide.com/how-to-install-a-go-kart-clutch/

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