Pole Saw: Can't Keep Chain Tensioned

The chain rotates along the channel of the bar on the bar rail. Over time, the chain will stretch from heat and wear to a point where you can no longer adjust it to pick up the slack. When this occurs, replacing the chain is a must. Remove the cover and separate the chain and bar from the pole saw. Remove the old chain and clean out the bar with a small screwdriver, this is a good time to inspect the bar for wear as well. Lubricate the bar with a bit of bar oil, then install a new chain around the bar, making sure the chain is installed around the drive sprocket. Install the cover and tighten the nut by hand. You might have to back off the tension screw for proper alignment into the hole in the chain bar, then adjust tension on the chain by rotating the adjuster screw clockwise. The chain should be tight enough to rotate with one hand and the drive links should not come out of the bar nose. Tighten down the cover then recheck the tension on chain, as it may have changed after final tightening of cover.

The bar provides the channel for the chain to rotate on. Over time, the inside of the bar will become worn and will need to be replaced. Remove the nut on the cover then pull the bar and chain off the pole saw, separating the chain from the bar. Inspect the bar for signs of wear such as loose nose wheel bearings, damaged chain rails, or anything else that looks out of the ordinary, and determine if it needs to be replaced or not. Lubricate the inside of the new bar with a bit of bar oil. Install the chain around the bar then back onto the pole saw. Make sure the chain is installed around the drive sprocket. For re-assembly and instructions for finishing your repair, see the “Adjuster” header elsewhere on this page for a detailed rundown.

The drive sprocket drives the chain around the bar. If the drive sprocket is worn, it can impact the tension on the chain. To inspect the drive sprocket, loosen the nut on the cover and remove the cover. With the cover off, inspect the drive sprocket for signs of wear such as worn-down teeth, damaged teeth, chips, or anything else you think is impacting its ability to keep tension on the chain. To replace, remove the E-clip, holding it in place and remove the sprocket before installing the new one. Re-install E-clip and cover with the nut hand tightened. For a full rundown on the process of re-installing everything as it needs to be, and getting your pole saw back to running order, see the “Adjusters” section elsewhere on this page.

The adjuster controls the tension on the chain, allowing you to set proper tension. If the adjuster screw has become stripped, damaged, or broken away, it will impact the operation of the adjuster. To replace the adjuster, remove the cover and the tensioner screw by rotating it with a screwdriver. Then remove the screw, tensioner, and retaining clip. Install the new retaining clip into the slot in the cover. Install the screw through the retaining slip and tensioner. Continue to thread until the retaining clip snaps over the hub on the screw. Rotate the screw counter clockwise to shift the tensioner towards the bottom half of the screw. Re-install the cover. You’ll probably need to turn the adjuster screw counter clockwise in order to correctly line the tensioner up with the hole in the chain bar. Tighten the nut on the cover by hand. Rotate the adjustment screw in a clockwise direction, to pick up the slack in the chain until it’s gone. Your chain should be sufficiently tight so as to rotate with one hand, but the drive links shouldn’t protrude from the bar nose. Tighten the nut on the cover and recheck the tension on the chain, as the final tightening process might have altered it.