Tall grass (and other stuff) wraps around the "mushroom" bushing & stalls the trimmer

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  • Updated 4 years ago
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Using our new 12" string trimmer in green grass and weeds found the motor stalling after a short time.  Investigated.  Fine fibers of grass were wrapped around the "mushroom bushing" and jamming (very) tightly against the thin thrush washer next to the motor.  Moved into dry grass, and it became much worse, often cutting only a few moments before jamming on a mass of grass.  This may be unavoidable given the need for the cooling air to pass through that space, but if the mushroom bushing were something like an eighth shorter the cooling fan blades would at least be close enough to the motor housing that stalks of tall grass could not readily get through to get wrapped around the bushing and jam.  Failing that, teardown needs to be "field friendly".  The present stack of small pieces (bushings, washers, the nut) is too vulnerable to falling into the grass and running off.  A redesign might have the cooling fan fins located on the top of the motor, away from the cutting action, with the cooling air discharging out the bottom. . .reverse the flow.  As is the machine is of very limited use for us.  
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Ken Preston

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Posted 5 years ago

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Blue Angel, Champion

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Are you using the trimmer to clear very thick tall weeds and overgrowth? This is the first time I've seen this issue brought up.
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Ken Preston

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It's primarily field grass that I normally keep mown, but around the edges of the meadow and the well house it was getting tall enough to want to use the string trimmer to take it down a notch.  The first bit was on the edge of the garden where it got some water (overspray) but the rest had browned out for the summer and was dry and tough.  I tried a couple of different attacks trying to get it neatly cut without giving it a chance to get swallowed, but the machine pulled it in quickly no matter.  Look at a few of the trimmers and see if there is any variability in the gap between the lower face of the motor and cooling fan blades.  I will probably take the mushroom bushing to a machine shop and get the small end faced off a bit. . .something more than an eighth, but nowhere near a quarter.  I'll try to mike the gap somehow first.  Thanks, kp
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Official Response
I have taken my old 12" trimmer apart and know what your talking about. So if you have that piece machined down, id use a grinder on the small diameter face as it is hitting the bearing so its not as critical to be perfectly square, along with that, still try to make it as square as possible. BUT before you do that take a look at the motor fans, push and pull the trimmer head, you will notice some play. This is because the armature has the ability to move in and out slightly. All motors do this. MAKE sure that the fan blades wont hit the gray plastic housing when you modify this piece.
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What about a redesign that includes stainless steel screen. This way the grasses won't get lodged and air flow is sufficient?