Flail Mower Let's talk flail mowers

[coastalguy]

500th post?

 

[Nuru]

Gents; Mowing with a flail on slopes, any suggestions? When i get my tractor back (very busy shop!), I want to avoid any issues just incase it was not just a weak valve that let go and the slope mowing with the flail (even though I really doubt it), contributed to the failure?

 

[Mike5252]

Yekrut,

The TL has a fixed offset of what appears to be about 9". I have about a 54" width and the mower extends from the right hand side of the tractor about 1 foot.

 

[IslandTractor]

Gents; Mowing with a flail on slopes, any suggestions? When i get my tractor back (very busy shop!), I want to avoid any issues just incase it was not just a weak valve that let go and the slope mowing with the flail (even though I really doubt it), contributed to the failure?

flails are used routinely by highway crews and they are often on big slopes so I would not worry.

 

[IslandTractor]

heads up. I posted about a week ago that I'd ordered 3/8 BSPP fittings for the Caroni dipstick fitting extender. I got a set but they are 2/100ths too big. Back to the drawing board.

I'll ask one of the moderators to let me add an edit to my earlier post so no one orders those fittings.

 

[Reg]

Something Iron Horse said about deliberately running universals out of line to avoid some sort of "in the middle" wear pattern - not verbatim, but close enough.
Maybe 100 posts or so back ?
I know it didn't make a whole lot of sense (to ME) at the time, but with a couple of dozen tabs usually open I don't always take up each point as it comes up.
Sometimes when I'm driving these things come back to me and I wish I could just log in and reply.

and so it was today.
OK, so maybe universals wear a bit more evenly if there is a slight bend in them, but I don't think I've ever seen one that was running dead straight in the vertical dimension, so why the need to off-set them in the horizontal dimension ?

Somewhere else there was mention of the speed fluctuation through a UJ, but that might have been a different thread. Anyway, sure the SHAFT goes through that, but doesn't the UJ at the other end cancel that out and the shaft as a WHOLE act like a CV joint ? (I said "act like").

Rzeppa joints aren't just a couple of UJs back to back, those are balls in spherical races (sorta).

Just thunkin' behind the wheel today.

 

[Builder]

Pretty impressive FX21

 

[Eagleview]

Reg.// This is a link to Dana Spicers facts on drive line angles , how a UJ speeds up and slows back down twice per revolution , etc . It is very good reading . Re. my statement on shaft angles to promote longevity in UJ'S . You are correct in saying the up and down angle does the same thing but many flails i have seen and owned have the gearbox high enough to make the shaft run straight so i offset the mower a little to counter this . I have replaced many Universal Joints in customers cars and trucks because the shafts were running to straight . As you can imagine , the rollers in such a shafts UJ are sitting static and the 2 or 3 rollers that are constantly taking all the thrust will burry themselves into the cups on the thrust side . A set of rollers that are twisting and rotating are spreading the load and wear amongst all of the rollers as well as the grease and increase the life span accordingly . It is espesially important in vehicles to shim the differential saddles when a vehicle height modification has been done to bring back the driveline angle to around 3 degrees .universal joints, dana spicer, drive shafts, Propeller Shafts, GWB - Machine Service, Inc

 

[SPYDERLK]

Reg.// This is a link to Dana Spicers facts on drive line angles , how a UJ speeds up and slows back down twice per revolution , etc . It is very good reading . Re. my statement on shaft angles to promote longevity in UJ'S . You are correct in saying the up and down angle does the same thing but many flails i have seen and owned have the gearbox high enough to make the shaft run straight so i offset the mower a little to counter this . I have replaced many Universal Joints in customers cars and trucks because the shafts were running to straight . [[[As you can imagine , the rollers in such a shafts UJ are sitting static and the 2 or 3 rollers that are constantly taking all the thrust will burry themselves into the cups on the thrust side.]]]

Couldnt find the link. Sounds good tho. [In your experience, is it the cups or the cross that detent more?] I would think it would be the cross due the the higher contact aspect between it and the rollers. The cup curvature would cause more load bearing area/ lower pressure in the contact region.
larry

 

[Eagleview]

Forgot to add the link , has been done now . Yes i meant to say the cross trunions as well as the cup races .

 

[Reg]

Thanks for the link.
Clarification;
They seem to say that the ideal is 1 degree and that 3 degrees shouldn't be exceeded.

"Parallel at each end" is something that bears some thought in this (flail mower) context.
I doubt that most of us are thinking much about it when messing with the rear roller, top link, skid shoes and lift arm height to get the desired cutting height.

I don't particularly like their example of wheel/tire balance. Sure the mass of some shafts can be greater than that of some tires, but the mass of a tire is much farther from the axis, balancing is therefore more important due to the moment of inertia. I don't think I've seen band clamps around drive shafts in several decades, it used to be standard practice to balance a truck drive shaft with a couple of those.

Yes, yes, yes to phasing. I'm not sure if the "triangular" cardan shaft permits or disallows 120 degree screw ups, but it is certainly something to watch for when cutting shafts.

 

[SPYDERLK]

Thanks for the link. Most of it I get, but what are they getting at in the description of cross breakage at the lube hole. Keep it under compression makes perfect sense and I looked forward to their explanation, but "Heres what we mean" leaves me confused. The frames of reference arent clear to me.
larry

 

[Eagleview]

Thanks for the link. Most of it I get, but what are they getting at in the description of cross breakage at the lube hole. Keep it under compression makes perfect sense and I looked forward to their explanation, but "Heres what we mean" leaves me confused. The frames of reference arent clear to me.
larry

Larry.// I did'nt have time to read their comments again as i'm about to head off in my truck but from what i know about UJ'S i'd say this is what they mean .There are 2 positions you can fit a universal joint . If you can imagine looking at a UJ cross from front on , with one trunion vertical and the grease hole at 10 o'clock and the tailshaft bearing eyes attached to that vertical trunion and the diff attached to the horizontal trunion . Now apply clockwise thrust to the shaft and you will see that the hole is being torn apart . But if you attached the shaft to the horizontal trunion and the diff to the vertical trunion and apply that same clockwise thrust to the shaft you will see that the grease hole is now being compressed and impossible to collapse . Hope this is clear enough . Reg.// A drive shaft with a center bearing should have the angle of the shaft at the center bearing around 1.5 degrees but the angle at the differential drive flange should be around 3 degrees . Also with flails it is very easy to have the universal joint at the gearbox running straight when the front of the mower is elevated for preffered cut height and at the same time the UJ at the tractor end can be running at an angle , thats why i run mine a little off center , to make sure both are running at a small angle .

 

[sunspot]

Yes, yes, yes to phasing. I'm not sure if the "triangular" cardan shaft permits or disallows 120 degree screw ups, but it is certainly something to watch for when cutting shafts.

The Cardan shaft DISallows putting it together
wrong. One of the triangles of the shaft is made different from the other two.

 

[scuvnut]

This is a followup to my earlier postings where I was having trouble with going over hills and into dips. IronHorse provided some great replies and the bottom line is that the slot where I attach the toplink needed to be expanded. Thick metal! Well, I got the job done and figured I post a followup in case it may help someone else in the future. The slot was only 1.5 inches and its been expanded to about 3.5 inches. This did the trick. Anyway, here are the pics.

The far right pic is obviously the flail where the middle pic is prior to expanding the slot. The left pic is the post expansion. I just need to clean the area up and apply some paint!

 

[SPYDERLK]

Larry.// I did'nt have time to read their comments again as i'm about to head off in my truck but from what i know about UJ'S i'd say this is what they mean .There are 2 positions you can fit a universal joint . If you can imagine looking at a UJ cross from front on , with one trunion vertical and the grease hole at 10 o'clock and the tailshaft bearing eyes attached to that vertical trunion and the diff attached to the horizontal trunion . Now apply clockwise thrust to the shaft and you will see that the hole is being torn apart . But if you attached the shaft to the horizontal trunion and the diff to the vertical trunion and apply that same clockwise thrust to the shaft you will see that the grease hole is now being compressed and impossible to collapse . Hope this is clear enough .

Clear, yes. Thanks. I guess I have seen those type of grease hole arrangements and had forgotten about them. Ill have to be on the lookout for them. All my UJ crosses have a lube hole that exits straight out in the dead center. An angle fitting brings out the nipple at the chosen quadrant. I thot they were implying that that orientation mattered. It would have been good if the link had distinguished between the 2 types of cross. I guess they were totally focused on automotive applications which may use the angled/offset hole.
Thx,larry

 

[bucmeister]

Not sure if this has been discussed in this or another flail mower thread, but here goes.

Do any of you experienced flail users have any knowledge about whether or not they can be "geared up" by changing the pulleys? The reason I ask is because my JD5300 pulls a Bush Hog 287 and a RDTH84 finish mower just fine. In fact if it were not for trying to get the tip speed up enough for a better cut 1700-1800 engine rpm will pull just fine with the finish mower. If I could get a flail geared up so that I could drop the engine down from 2400 to 1800 while keeping the rotor speed in the correct range I figure the fuel savings would be worth the effort.

What say you? Can it be done?

 

[DavesTractor]

Not sure if this has been discussed in this or another flail mower thread, but here goes.

Do any of you experienced flail users have any knowledge about whether or not they can be "geared up" by changing the pulleys? The reason I ask is because my JD5300 pulls a Bush Hog 287 and a RDTH84 finish mower just fine. In fact if it were not for trying to get the tip speed up enough for a better cut 1700-1800 engine rpm will pull just fine with the finish mower. If I could get a flail geared up so that I could drop the engine down from 2400 to 1800 while keeping the rotor speed in the correct range I figure the fuel savings would be worth the effort.

What say you? Can it be done?

Not that this helps you, but some tractors have an economy mode on the PTO. Branson does this now, so if you do not need the HP, but still need to spin 540, you put it in economy mode on the PTO lever and run the engine about 1700rpm. In 540E at 2400, it is spinning about 750 rpm, which would be a real no-no as most mower gearboxes will overheat and be toast after a while.

 

[bucmeister]

Not that this helps you, but some tractors have an economy mode on the PTO. Branson does this now, so if you do not need the HP, but still need to spin 540, you put it in economy mode on the PTO lever and run the engine about 1700rpm. In 540E at 2400, it is spinning about 750 rpm, which would be a real no-no as most mower gearboxes will overheat and be toast after a while.

I would have to get a new unit to get the economy mode. What really burns is that the tach has the 540E marking on it so I knew it was an eventuality, sure wish it was offered at that time. Just can't justify trading in a perfectly good, paid for unit in an effort to save one or two gallons of fuel per grass cut.

 

[Eagleview]

Not sure if this has been discussed in this or another flail mower thread, but here goes.

Do any of you experienced flail users have any knowledge about whether or not they can be "geared up" by changing the pulleys? The reason I ask is because my JD5300 pulls a Bush Hog 287 and a RDTH84 finish mower just fine. In fact if it were not for trying to get the tip speed up enough for a better cut 1700-1800 engine rpm will pull just fine with the finish mower. If I could get a flail geared up so that I could drop the engine down from 2400 to 1800 while keeping the rotor speed in the correct range I figure the fuel savings would be worth the effort.

What say you? Can it be done?

Even though the pullies will inter change , the bottom one is always smaller than the top so swapping them will only slow the rotor down (you could purchase a larger top pulley if it was worthwhile and if it would fit into the housing) . If you have a 1000 PTO speed and you only have light mowing to do you can use this setting and then bring your engine revs down by nearly half . This will NOT hurt your engine as an engine runs at peak efficiency at it's torque band (this is why trucks that are governed at 2100rpm run at 1400 at 60mph in top gear). It will NOT glaze your engine as the combustion process is working at it's optimum . You will however find the engine will run at a higher temp but still within it's working range . If it's a very hot day you may need to slow your travel speed to limit the amount of material being processed to keep within it's temp range .

scuvnut.// Thanks for telling us how you went , i'm glad slotting the hole has helped .

SPYDERLK.// Yes , some time ago the engineers moved the grease hole to the center of the cross into a more neutral area where they are less prone to cracking .

Another tip on flails i have not mentioned is to get the mower warm before adjusting the belts . As they stretch when hot they will become loose if adjusted cold and will glaze , causing slippage and breakage .