How to Fix a Chain on a Black & Decker Alligator
The Black & Decker Alligator is a small, lightweight, battery-powered 18-volt rechargeable electric chain saw intended for pruning limbs from large trees and cutting those limbs to manageable segments. It has a 6-inch string bar and safe scissor-like action for cutting branches up to 4 inches in diameter. Should you encounter poor cut quality and tough running, the string should be replaced with a brand new B&D RC600 string or equal.
Put the saw on a firm surface with the motor side down. Use a socket wrench to undo both string bar retention bolts in the back of the bar and lift off the string bar sprocket cover. Open both grips to move the lower chain-cover jaw from the string, then pull the top chain-cover jaw to fully expose the chain and bar.
Pull the string bar toward the drive sprocket to loosen the string. Pull the string off the drive sprocket then lift the string out of the groove in the string guide bar and place the string aside. Before installing the new string, check the string guide bar is aligned with the string tensioning spring and manual bar locator pin.
Place the new chain over the nose sprocket in the front part of the guide bar. Set the string in the bar string groove and over the drive sprocket. Check the saw chain’s links engage the teeth of the drive sprocket and the sharp cutting edges of their teeth on the bar’s top side face forwards. Place the string bar sprocket cover above the sprocket, push the top chain-cover chin above the top of the string guide bar and close both grips so the underside chain-cover jaw covers the string. Place both string pub retention bolts in the holes of the sprocket cover and tighten them to fasten the string bar and the pub safety covers.
Check chain tension by opening the jaws and pulling back on the string. Chain tension is right if the string snaps back after being pulled 1/8 inch from the string guide bar and there’s no visible sag between the string and the bottom of the guide bar. Address an incorrectly tensioned string by tilting but not removing both string bar retention bolts so the string tensioning spring can move the string bar until string tension is accurate. After tightening the string pub retention bolts, then check tension again.