Flail Mower Let's talk flail mowers

[dadohead]

I could not tighten the belts as much as I wanted to, because raising the gearbox too high to tighten the belts caused it to strike something. The belts were loose but not loose enough to fall off the pulleys.

You could have multiple issues going on here.... low belt tension for sure. If the belt tension seems too low, don't mow with it until you get things figured out.... you'll just smoke belts.

The belts are tensioned by raising the gear box (and I assume an outboard carrier bearing) to raise the driver sheave? Could you be imparting a weird twist into the gearbox by not raising them equally? I'd disconnect the pto from the tractor and turn by hand to diagnose further.

BTW- the NAPA A40 belt specs are published online: wrap molded/polyester cord made by Gates. This is not a robust drive. If you bought the mower new the manufacturer should be helping you through this or take it back.

 

[TractorNoob85]

What happened after that? Did it eventually get normal?

I tried increasing the tension of the belts, but the gearbox had a loud striking noise and I reduced the tension just enough to remove the striking noise. The belts still felt too loose. I couldn't increase the tension anymore without creating the striking noise.

The belts broke midway through my 3rd mow and I had about 4 acres left. Luckily I ordered a spare set of China belts with the mower so I put them on to finish up. No issues the rest of the job. I haven't had to mow since. The Goodyear belts are sitting on my workbench for next year.

I cant think of what could be hitting. When you adjust the belt tension, are you loosening the bolts at the gearbox too?

 

[dieselscout80]

The belts broke midway through my 3rd mow and I had about 4 acres left. Luckily I ordered a spare set of China belts with the mower so I put them on to finish up. No issues the rest of the job. I haven't had to mow since. The Goodyear belts are sitting on my workbench for next year.

I cant think of what could be hitting. When you adjust the belt tension, are you loosening the bolts at the gearbox too?

I think I’d be tempted to design a idler/tensioner pulley to make it easier to maintain the correct belt tension.

 

[threeoranges]

I have a bestco flail HD 7 ft. I burnt up my first set. Salesperson said every new flail operator burns up the first set because they cut too short allowing the hammers to engage the earth...2nd set, I started cutting a couple inches taller with the front of the mower higher than the rear for better feed. And I put belt dressing on liberally. So far so good. There is tension instruction inside the cover, 3/4" deflection I believe. Check your manual.

I did follow the manual as far as leveling the mower with the top pin. I actually glued a level onto the side of the mower. It is totally level front-to-back.

There are four bolts which hold the gearbox onto the mower, and a tension bolt a few inches right of the back left side. I raised the gearbox using the tension bolt, but when it was set to where the belts felt like they had the right tension (I didn't have a tension measuring device), there was a striking sound in the gearbox when the PTO was activated, as my video shows. I reduced the tension bolt slowly until the sound went away, but then the belts seemed too loose. I tightened the 4 bolts holding the gearbox to the mower before operating it.

I set the back roller gently (not crushingly) on the ground using the 3-point. There are no rocks, stumps, or uneven ground. I have not played with the flail height adjustment, since I just need a mow, and any height is better than not mowing at all.

 

[threeoranges]

One thing I've considered, is that the striking sound could be being caused by a misalignment which is possible to correct by adjusting the position of the gearbox before the 4 retainer bolts are tightened, while leaving the tension bolt extended to tighten the belts.

Oh, and I'm using the highest quality V-Belts with Kevlar/Aramid, and they are still burning up.

 

[TractorNoob85]

I think I’d be tempted to design a idler/tensioner pulley to make it easier to maintain the correct belt tension.

100% with you on that. A spring-loaded tensioner would resolve the belt issues.

 

[dadohead]

Oh, and I'm using the highest quality V-Belts with Kevlar/Aramid, and they are still burning up.

Any belt will slip and burn if the tension starts out low.

If you can resolve the tension issue and the stock belts still slip, installing raw edge belts will be a noticeable improvement without reworking your mower... they really hook up.

 

[scootr]

Not saying you are doing this because it sounds like you have a belt tension issue? But mowing too fast in too thick material will cause the belts to slip. Spray on belt dressing helps. Shorter belts may be exactly what you need. How much deflection is there in the belt when it is tightened ?

 

[threeoranges]

When you adjust the belt tension, are you loosening the bolts at the gearbox too?

Yes, I release the 4 bolts holding the gearbox before adjusting the tension bolt, and then tighten them back up before operating the mower.

As I said in another message, maybe adjusting the position of the gearbox before tightening the 4 bolts might be able to stop the striking.

 

[threeoranges]

I agree that this is a belt tension issue.

When I increase the belt tension so that it's tight, I get grinding noises in the gearbox which I am not able to accept.

As per the manual, I release the 4 bolts holding the gearbox to the mower, adjust the tension bolt, and then tighten the 4 bolts back.

I am going to try to adjust the position of the gearbox to avoid the grinding noises, if possible, while keeping the belts tight with the tension bolt. There are 4 bolts which hold the gearbox to the mower, and there might be some wiggle room.

I am not mowing too close or forcefully into the ground, nor am I mowing too fast.