Unless a belt breaks during the middle of the season, this is the time I’ll inspect and replace a brick saw’s belt. Just like with a car or truck, look for glazing of the belt (it’ll be shiny), or cracking that most likely comes from age and use. Also look for dust from the belt – there may be a fine coating of black dust inside the belt guard indicating the belt is getting rubbed the wrong way, possibly indicating some other problem.
A misaligned pulley or a burr on a pulley, given a little slippage, could gouge the belt and shorten it’s life. In the case of our Partner K950, we were burning through belts every 5-10 hours of use. Turned out the needle bearings in the clutch pulley were shot, making that pulley wobble. At 4,000+ RPM, the belt didn’t stand a chance.
I’ve tried a few things to address a slipping pulley – sometimes just tensioning the belt is enough. Other times I tried belt dressing, but that didn’t ever seem to work. The only thing that has been reliable to address slippage has been grinding the pulley groove with a rotary tool like a Dremel.
Depending on the amount of gunk on the pulley I’d use the wire brush wheel, the cutoff tool or one of the grinding wheels to clean them off – the trick is to put the Dremel at an angle where you can get a consistent cleaning around the entire pulley. Set the tool so that as it spins to clean the pulley, the pulley naturally wants to spin, too. You can provide some light resistance to the pulley with your finger to slow the rotation of the pulley, ensuring a good cleaning. Do this to both sides of the belt groove in the pulley. You might also consider removing each pulley and repacking the needle bearings with grease.
Lastly, check the clutch. Check to see that the springs still have a tight hold of the clutch pads. You might also start up the saw with the blade, blade guard, belt cover and belt off, so that just the clutch and pulley spin. The clutch should engage the pulley when throttled up and release it when throttled down.
I like to hit the clutch with compressed air. Sometimes I’ll use gas to clean caked brick dust out of the clutch. Don’t use a lubricant like WD-40 – you don’t want the clutch slipping any more than it was designed to. You might try a brake cleaner or carb and choke cleaner – whatever you choose make sure it doesn’t leave a residue behind that could cause slippage. In the picture you see I’ve removed the clutch using an impact wrench but this isn’t necessary to test it or clean it – the picture was taken during the repair of our K950 Partner brick saw.