I think that those that have experienced this problem will agree with me when I say that, there is nothing more frustrating than having to stop, unhook and untangle this grass or vines after it has stalled your brush. Because if it happens once, it will happen again every few minutes.
If you watch till the end of the video, you will see how effective the solution is at preventing this frustrating problem.
Cause
The reason why grass wraps around the brush cutter gear head is a result of the rotational cutting process and happens equally with a nylon line or steel blade. How much the grass wraps around the head depends on three things; the length, strength and stringiness of material being cut, the power of the brush cutter and the design of the gear head itself.
The design of the gear head itself is the biggest problem and is one that you have no control over. With all of the gear heads I have seen to date, not one has sort to address this problem. The main cause is the small diameter and the vee shape of the neck that allows grass and vines to wrap around and get pulled tighter and tighter so that it cannot fly free. The smaller the neck and the deeper the vee, the greater the problem, see the vee in the photo below.
Below is the high torque gear head of a high powered Echo brush cutter and even though it is brand new on the market it still has the same flawed design that allows stringy Kikuyu grass to wind around the gear head.
The good thing is that it had enough power not to stall, the bad this is that is had so much power that it ripped the nylon lines off. Now you not only have to stop and unhook the brush cutter to untangle the grass, you also have to pull the feed head apart to feed out the new line.
Solution
Is to prevent grass and vines from getting wrapped around the gearhead in the first place. By removing the vee and making the neck so large with a shield so that all material is deflected away and so cannot be dragged around the gear head.
I have succeeded in significantly reducing the problem with the Anti-Fouling blade on the BrushDestructor Blade, as you can see in the photo below. The blade is still free to rotate, even though the gearhead is all wrapped up. But leave this on the gearhead for any length of time, will cause it to get extra hot, thinning the grease and allowing it to escape past the seals.
I now intend to eliminate the problem completely by offering a bolt-on Anti-Fouling-Shield and eventually a specially designed gearhead that solves this and other issue.
In 2015 I will be offering a range of bolt on Anti-Fouling-Shields, (shown below) to fit most major brands of brush cutters that have a guard mounting plate as part of the gear head.
Below you can see the Anti-Fouling-Shield fitted to a 22cc Honda brush cutter.
The steel used in the shield will be the same as that used in the BrushDestructor Blade, so it will be super strong and be able to handle anything that is thrown at it.
Initial testing shows that it really works well, especially in conjunction with the Anti-Fouling Blades. It cuts long stringy grass at the base and spits it out with such ease, that is not matched by any other metal blade I have tried and I have tried most of them.
To be truthful, it is still possible to stall the blade if pushed hard enough, but all you have to do is wind the blade backwards against the ground half a turn and then give full throttle and the blade will clear itself of all tangled grass.
After several hours of testing I found that, grass started to wrap around the gear head again, although the Anti-Fouling-Blades did keep the blade free and running. But once the wrapped grass was there, it kept attracting more grass.
After closer inspection, I found that the stringy grass had wedged between the gear head and the Anti-Fouling-Shield, bending it up about 1mm.
This steel is 2mm thick and the hardest I could get, that could still be bent. I guess that if plant roots can apply enough force the blow apart concrete and rocks, they can apply enough force to bend steel. You can see the gap in the photo below, which allowed more and more grass fibre to wedged in, bending the steel shield up.
This means a slight redesign to the shield, to make it have an even closer fit to the gear head and stronger again to resist the forces that can be exerted on it.
Unfortunately, such a tight fit will mean it is going to be much more difficult to make this shield for all the different gear heads for all the different brands of brush cutters.
Below is a video showing how a newer version of the above easily clears itself of long grass wrapped around the gear head.
I am beginning to think that the only answer is to design my own gear hear and matching guard to go with my blade that can be sold as an after market add on to fit to all existing brush cutters.