Flail Mower Let's talk flail mowers

[def38]

There seems to be some reluctance to use Chinese manufactured single row grooved ball bearings. I have used FAG, NTN, NSK as well as Chinese made ball bearings in a number of applications. I find little performance difference. The Chinese bearings are often lower in price. Am I missing something?

 

[leonz]

Hello Def38.

Some of the newer flail mowers have "sealed" one row ball bearings with two seals as they are packed with grease at the bearing factory..

Most flail mowers typically have a seal on one side to hold the grease in the bearing and allow the old dead grease a chance to melt out and
away over and be flushed out with new grease.

 

[Fallon]

When mentioning bearings, I am confused by the terms shielded and sealed. There is a major difference. Which style are used in our flail mowers? Are they interchangeable? Which one is better?

Shielded = washer or a shield of some that covers most of the balls & keeps some stuff out.

Sealed = plastic/rubber seal that keeps lube in & contaminatinants out.

Seals increase friction & wear faster than shields or nothing. But they keep lube in & grit out. If you pump lube into or outside of a sealed bearing the hydraulic pressure can blow the seal out or in.

There are 2 sides to a bearing so one side can be shielded & the other side sealed or any combination. You need to make sure you install the bearing in the correct orientation. Popping a seal or shield out will turn an sealed bearing into an unsealed one.

If you regularly lube the unsealed bearing to lubricate it & flush out contaminants the bearings should live a long life. Fail to lube them they will die prematurely. A sealed bearing will likely not last quite as long as an unsealed bearing that has been ideally maintained under harsh (tractor impliment) conditions. A sealed bearing has the advantage of not needing constant maintnance/lubrication. Industry is tipping towards sealed bearings as they are less maintnance, but may not be ideal for all instances. Historically most rotor & roller bearings on flails have not been sealed or only sealed on 1 side. Anything with a grease zerk on it is unsealed on at least 1 side.

You can usually put a sealed bearing into a greasable housing, but greasing it would probably cause problems. I've done that on my old 917 flail as sealed bearing were all Messicks had in stock as an OEM replacement. Putting an unsealed bearing into a place designed for a sealed one end up with a bearing you cant lube & dies a quick gritty death.

 

[troverman]

Good info Fallon, thanks.

 

[cscholz]

1) Those shackles look to be roughly the same cost as the ones I got from Flailmaster but have the advantage of not needing modification to install. Looks like they are the ones to get rather than the ones I got from Flailmaster. (GME Supply Co, SHA38LRBT 3/8" bolt type safety shackle for future reference). I presume there was no difficulty getting the blades over the ears. If the slight binding bothers anyone, a touch up with a grinder would only take a second or two.

IslandTractor, TDVT, Jelf (and anyone else who has them) - how have the GME Supply SHA38LRBT shackles held up? I'm about to buy a full set of clevis' and blades, and Flailmaster sent me a sample of their clevis. It took more bending and a bit of grinding than I expected to get it to fit. So I'm thinking of getting just the blades from them and getting the GME shackles. Any reason not to (other than more cost due to shipping mostly)?

Carl

 

[ericm979]

There seems to be some reluctance to use Chinese manufactured single row grooved ball bearings. I have used FAG, NTN, NSK as well as Chinese made ball bearings in a number of applications. I find little performance difference. The Chinese bearings are often lower in price. Am I missing something?

The chinese bearings can vary more in quality. I've had some that did not last long. If it's a lot of work to replace the bearings I tend to use the name brand ones; if it's easy and a failure won't be safety critical I'm ok with chinese.

 

[Eagleview]

Re: Flail mower basics and knife rotation

Hi guys, just called in, been a while .
Some flail mowers can cut cleanly with the rotor spinning in the same direction as the wheels . You will find that the flail stations on those rotors are attached to the rotor in straight rows along its length . There can be 3, 4, 5 or 6 rows .
Imagine a rotor with 4 rows, each row is mounted 90 degrees apart . As the mower moves forward, lets say a foot and the rotor has revolved twice in that foot of forward travel . The blades have struck the grass 8 times .
Now imagine a helical/spiral mounting arrangement that many mowers use now , and rotate in the opposite direction to the wheels and only have ONE cutter per spacing .
As our imaginary mower, now with a helical rotor (using the same blades)moves forward that same foot and the rotor has revolved the same two revolutions, the blade has only struck the grass twice . This is why people get crappy results when the try to cut going backwards with a helical rotor type flail (the roller also holds the grass down that makes it worse).
Gearing on helical rotor flails is tall to keep tip speed high which helps overcome the fact there is only one blade per position . The advantage of the helical design is that there are only 3 or 4 blades contacting the grass at a time, unlike a full row in the straight type rotor .

Also, helical rotors need big counterweights for balance, straight row rotors may just have a little one, as the straight rows at equal spacing balance themselves out .















.

 

[troverman]

I have an opportunity to buy a Ford 917 flail mower in working condition with a newer belt for $1000. It is 78 cut. Are these quality? Can parts still be had? What to look for that might be wrong?

 

[Fallon]

I have an opportunity to buy a Ford 917 flail mower in working condition with a newer belt for $1000. It is 78 cut. Are these quality? Can parts still be had? What to look for that might be wrong?

My decades old one is thrashed, but still holding together. I paid $100 for it & have $600 into it now. It was well worth it for my starter flail for a few years of side work. I replaced it but keep it around as a spare & have no plans to ever sell it. Flailmaster has knives. I got replacement bearings from Messicks. Make sure the gearbox is sound, the roller & rotor are round & it doesnt vibrate when you wind it up to PTO RPM. Cracks in the hood can probably be repaired, but may not be worth it. A tweaked roller rotor or gearbox will total most any used flail. Replacible or repairable, but not likely worth the cost or effort.

 

[Eagleview]

Re: Flail mower basics and knife rotation

Hi guys, just called in, been a while .
Some flail mowers can cut cleanly with the rotor spinning in the same direction as the wheels . You will find that the flail stations on those rotors are attached to the rotor in straight rows along its length . There can be 3, 4, 5 or 6 rows .
Imagine a rotor with 4 rows, each row is mounted 90 degrees apart . As the mower moves forward, lets say a foot and the rotor has revolved twice in that foot of forward travel . The blades have struck the grass 8 times .
Now imagine a helical/spiral mounting arrangement that many mowers use now , and rotate in the opposite direction to the wheels and only have ONE cutter per spacing .
As our imaginary mower, now with a helical rotor (using the same blades)moves forward that same foot and the rotor has revolved the same two revolutions, the blade has only struck the grass twice . This is why people get crappy results when the try to cut going backwards with a helical rotor type flail (the roller also holds the grass down that makes it worse).
Gearing on helical rotor flails is tall to keep tip speed high which helps overcome the fact there is only one blade per position . The advantage of the helical design is that there are only 3 or 4 blades contacting the grass at a time, unlike a full row in the straight type rotor .

Also, helical rotors need big counterweights for balance, straight row rotors may just have a little one, as the straight rows at equal spacing balance themselves out .

.

Straight rotor in red mower, helical rotor in orange mower .