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How to Fix a Chain on a Black & Decker Alligator

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Battery-powered tree limb loppers like the Black & Decker Alligator make quick work of removing smaller limbs on trees with minimal effort and no contending with cumbersome electrical cords. It's designed to cut limbs no larger than 4 inches in diameter. Putting the proper amount of tension on your Alligator chain prevents the chain from accidentally and dangerously sliding off, or binding and overheating the engine.

Close the two handles on your Black & Decker Alligator and slide the latch inside the bottom handle forward to the lock position to turn off the tool and lock the handles closed.

Place your Alligator electric lopper on a flat level surface and allow it to cool completely. Remove the battery pack from the rear of the tool by pressing the release button on its rear and sliding it out of the tool.

Insert your Alligator wrench that is included in the purchase or an adjustable wrench on the two chain cover bolts on the right side of the tool from the operator's position. Turn the bolts counterclockwise to loosen them about two revolutions. The automatic chain-tensioning device underneath the bolts pushes the chain bar out to the correct position to tension the chain. Tighten the two bolts clockwise.

Pull the chain lightly about 1/8 inch from the bar and release it. The chain should snap back into the bar groove and there should be no slack between the chain bottom and the bar. If there is slack in the bottom of the chain, repeat the tensioning process.


Dull chains require removal and need to be either sharpened or replaced when they do not perform correctly and only fine sawdust is removed from a limb, rather than small chips of wood.

Do not overtighten the tension on the chain, as it will lead to poor performance and reduces the life of both the chain and bar.

The manufacturer suggests checking the chain's tension after the first two hours of use because chains have a tendency to loosen up with prolonged use.

Wear leather gloves when working on the chain saw's chain to keep from cutting your hands on the sharp teeth.

If you are unable to apply the correct amount of tension on the chain it needs to be replaced with a new one.


Always wear protective eyewear when using a chain saw and do not wear loose clothing that can get caught in the chain saw.

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