Flail Mower Let's talk flail mowers

[threeoranges]

And by the way, the drivetrain is nearly horizontal, just as the mower is perfectly level. So there can't be much stress in the U-joints.

The belt tension is the only explanation.

 

[arto98607]

Couple of photos showing how I had to add shims on my mower, in order to get the two pulleys line up properly with each other.

I doubt it left the factory with misalignment like that - who knows what the previous owner did with it during the 20 - 30 years he had it?

It was an easy fix.

 

[Menagerie-Manor]

Sorry to rain on an interesting discussion (I've only been through 1/10 of it!!!).

I am having a frustrating problem with my Betstco flail mower belts repeatedly failing.

(I hope links to pertinent outside images and videos is acceptable -- no ads.)

My email to Betstco (I've heard about Keith but I don't know if he's there anymore):

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I am having frequent belt breakages with my EF125 flail mower.

It happened first with the OEM belts last week, and again with the new belts I got today, which were A38/4L400 (1/2" by 40" outer circumference).

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.

The video below is with the PTO at its slowest speed (not 540 RPM) and the flail mower raised off the ground.

https://1drv.ms/v/s!Ar2wgEZy_jHyoeQW7Gjat-dQ0qGQ1g

Something was striking the gear box when it was raised too high to increase the belt tension.

I loosened the tension bolt until that striking sound went away, but then the belts felt loose and very flabby.

I used them anyway to mow with, until one of them burned out about 25 minutes into mowing:

https://1drv.ms/i/s!Ar2wgEZy_jHyoeQXMA4IU8SwnuJyOg

I am next going to try A37 ( 1/2" x 39" OC).

I do not know if am overloading it (EF125). It seems to mow okay but there is a slight smell of burning rubber until the belt breaks. I have removed all grease residue from the pulleys using a rag and a strong cleaner like acetone.

I could try raising the flail mower higher off the ground. Right now the roller sits gently on the ground and a level shows that the mower is balanced front-to-back by the adjustment of the top pin. There are no obstructions except thick grass, and the ground is mostly flat.

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Have the same mower and experience with the belts, my original set didn't last but a few days even after adjusting each time before using. Hit up napa for a set of Kevlar belts and have not touched them in almost 3 years since. I did a lot of power transmission work back in the day and never experienced belts melting and smelling like they did, total garbage.

 

[threeoranges]

I have ordered 38" and 39" outer circumference Kevlar belts.

Apparently the U-Joint on the implement side is striking the top of the gearbox when it is raised up too high.

With the original nut still included, it is tighter at the tension bolt's tightest position, but still gives too much:

If I remove the nut and increase the tension all the way, it has much less give:

Apparently this is a problem with this model, since a 40" outer circumference belt requires raising the gearbox so high that it is being struck by the implement-side U-Joint.

I checked the gearbox and there were no metal filings, dark oil, or damage visible through the fill hole with a flashlight, and the gear oil level was good. There is no sound when the gearbox is lowered by easing the tension bolt, but then the belts are too loose and burn up.

I am going to try the 39" and 38" belts, but they may be hard to install without removing the pulleys, since the 40" belt already requires a screwdriver to guide it onto the pulleys when the tension bolt is totally retracted.

 

[threeoranges]

Have the same mower and experience with the belts, my original set didn't last but a few days even after adjusting each time before using. Hit up napa for a set of Kevlar belts and have not touched them in almost 3 years since. I did a lot of power transmission work back in the day and never experienced belts melting and smelling like they did, total garbage.

I have been using Kevlar belts. The nearest NAPA store is 50 miles away, so I've been using Tractor Supply and O'Reilly for belts.

Any belt, even Kevlar, will burn up if not properly tensioned.

I'll try shorter belts which don't require raising the gearbox so high that it gets struck by the U-Joint.

 

[threeoranges]

Here are more videos showing the U-Joint hitting the top of the gearbox:

https://1drv.ms/v/s!Ar2wgEZy_jHyoeQ21FQls37Zkp0a-g

https://1drv.ms/v/s!Ar2wgEZy_jHyoeQ304hxPWR1w42L6Q

A shorter belt than the A38 (1/2" x 40" OC) would seem to be necessary.

Betstco was on the phone with me for almost an hour today and was thinking of sending me a new gearbox, but I don't think that's necessary. The U-Joint strikes the gearbox when it's raised too high, so shorter belts to not require raising it too high would seem to be in order.

 

[threeoranges]

Is it clear to anyone what the striking noise is?

It seems to be the U-Joint on the implement side striking the gearbox when the gearbox is raised too high to increase the belt tension. If the belt tension is lowered to get rid of the noise, the belts are not tensioned enough and will burn up. I plan to use smaller belts to avoid having to raise the gearbox that high and causing the U-Joint to strike.

 

[threeoranges]

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 ?

See my earlier post, where I hand-tested it and you can see the deflection. I still think it was too loose even in the best case. Shorter belts is indeed the plan.

I am not mowing fast -- I am going very slow (Kubota turtle speed or less). The belts were slipping because they did not have enough tension, even for the lightest load.

 

[threeoranges]

One problem is that 38" and 39" outer circumference belts are much harder to obtain than 40" OC belts. I've had two orders for them canceled because of lack of supplies.

 

[TractorNoob85]

One problem is that 38" and 39" outer circumference belts are much harder to obtain than 40" OC belts. I've had two orders for them canceled because of lack of supplies.

From the design of the mower, it looks like the deck that the gearbox is mounted to raises with the long adjuster bolt. Loosen the deck bolts and as the adjuster bolt gets screwed in, the deck raises which raises the pulley, tightening the belt. Is this correct?