Let's talk flail mowers

[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

[Iron Horse]

Originally Posted by 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

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]

Originally Posted by Reg

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]

Originally Posted by Iron Horse

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]

Originally Posted by 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?

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]

Originally Posted by DavesTractor

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.

[Iron Horse]

Originally Posted by 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?

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 .