How To Repair A Brush Cutter When Blade Does Not Turn

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If your brush cutter engine is running normally, but the saw blade does not spin when the throttle is engaged, there may be an issue with the clutch. The clutch is attached to the crankshaft, and engages the drive shaft to start rotating once a certain rotational speed is reached. The clutch allows the engine to run without always rotating the drive shaft. If the clutch is broken or the springs are not tensioned properly, the clutch may not engage at all. A broken clutch is easy to replace once the engine housing has been disassembled to allow for access to the clutch. It is a good idea to remove the spark plug and feed a piece of scrap starter rope into the combustion chamber, as this will stop the piston from moving while the clutch is removed.


Some saws employ a gearbox to transfer the motion of the drive shaft into motion that spins the saw blade. If your saw is equipped with a gearbox (refer to your user manual for more information on your particular model), and the saw blade will not spin, the gearbox may be broken or jammed. Gearboxes can become clogged with grass and debris, or seize due to lack of lubrication. Remove the engine cover to access the gearbox. If it is clogged, try to unclog it by cleaning it thoroughly. If the gearbox is broken and still will not function properly, it will need to be replaced. The gearbox life can be extended by ensuring that it is lubricated on a regular basis.

Cable or Shaft

If your saw blade will not spin and the engine is running normally, there may be an issue with the drive cable or shaft that connects the crankshaft from the engine at the back end of the unit to the saw blade at the opposite side. The clutch drum attaches to the drive shaft and connects to a gearbox which spins the saw blade. If the drive cable breaks or becomes detached, the saw blade will no longer spin. You can inspect the drive cable by removing the engine assembly from the shaft and checking to see if the cable is still in place. If the cable has slipped out of place, it will need to be reinstalled firmly. If the cable has snapped, it will need to be replaced altogether.

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