Flail Mower Mott 72" Flail Mower bearing replacement & drive pulley spacing

[Zumdahl]

Good Evening. I have an old Mott 72 flail which needed to have the cutter shaft bearings replaced. I ordered a pair of the M-702408 bearing + housing combos from Flailmaster. Housing itself looks the very similar to the old one, with three bolt holes that line up great and grease zerks on the housing face. However, the face that mates with the pulley sits proud compared to the old bearing.

This first picture shows the original bearing & housing:


And the new one mounted to the flail on the drive pulley side.


And the step of the process where I realized I had a problem. The shaft itself no longer goes all the way through the pulley:


I'm sure it's something I've done. Before I took it apart the shaft was pretty much dead flush with the outer edge of the pulley.

The cutter shaft doesn't seem to be shifted left to right. The first set of knives on each side are spaced evenly from the mower sides.

The bearings are supposed to come fully pressed in, but I suppose I don't know if its actually bottomed out against something in the housing.
Really wrenching down the bolt that holds the pulley might gain me smidge, but I don't imagine it'll be enough for the shaft to go fully through the pulley.

Any advice is much appreciated!

 

[whirly]

Is it possible the housing is not seating in the frame? It looks like the distance for the shaft to be flush with the pulley is the same or greater than the amount of bearing that is sticking out of the housing.

Pics of both bearing unmounted, side by side,would help.

I have a Mott 72" I can look at in the morning.

 

[leonz]

Good morning Zumdal,


If you look very closely at the second image its either distorted or there is something wrong with the inner bore. you have a huge amount of metal shavings, and metal dust in and around the bearing housing and that is not good.

both bearings are locked with set screws and locking rings if I remember the sequence correctly and they should both be a slide fit never a press fit bearing set for the flail mower rotor.

Do you have fine emery paper of 400 grit or greater? the flail mower rotor stub shafts should just slide through the bores with no trouble.

You need to clean the bores with some isopropyl alcohol or hydrogen peroxide and a double thickness of the blue paper shop towels.

You have a fit problem of some kind that needs to be fixed.


I have a copy of the Mott mower manual I can email to you directly if you would like to have it. Please send me a PM for the manual at your convenience.

 

[Rocky Hoffler]

It seems your dealing with flailmaster they have been helpful to me about superced parts it’s worth a call also Mott was bought by Alamo there are part breakdowns available good luck

 

[Zumdahl]

Is it possible the housing is not seating in the frame? It looks like the distance for the shaft to be flush with the pulley is the same or greater than the amount of bearing that is sticking out of the housing.

Pics of both bearing unmounted, side by side,would help.

I have a Mott 72" I can look at in the morning.

The housing itself sits tight against the frame. The bolts that hold the housing on force it as tight as possible. You're right, that the distance the that the shaft is recessed is more than how proud the bearing stands.

I pulled the new housing off again, and took photos of it side by side with old.
From the outside of the mower:


Inside of the mower:


And from the side. This shows how far out the replacements stand.

 

[Zumdahl]

I just attached a handful of better pictures of the bearing. Do you still see the shavings you mention? I think it might have just been oily finger prints and a bad picture.

The stubs slide easily through the bores, though I didn't do anything with locking rings. The bearings were pressed into the housing when I received them. I literally just slid the entire assembly over the shaft and tightened the three bolts. The set screws were going to be next but I hadn't tightened them yet because of how out of place the shaft seemed.

In hindsight I'm realizing I should have fully replaced one side of the mower and tightened it down, then done the other. Is it possible I've just shifted the entire shaft a quarter inch to the side? The outermost knife stations really do look centered compared to each side.

Good morning Zumdal,

If you look very closely at the second image its either distorted or there is something wrong with the inner bore. you have a huge amount of metal shavings, and metal dust in and around the bearing housing and that is not good.

both bearings are locked with set screws and locking rings if I remember the sequence correctly and they should both be a slide fit never a press fit bearing set for the flail mower rotor.

Do you have fine emery paper of 400 grit or greater? the flail mower rotor stub shafts should just slide through the bores with no trouble.

You need to clean the bores with some isopropyl alcohol or hydrogen peroxide and a double thickness of the blue paper shop towels.

You have a fit problem of some kind that needs to be fixed.


I have a copy of the Mott mower manual I can email to you directly if you would like to have it. Please send me a PM for the manual at your convenience.

 

[Zumdahl]

Since I already had it apart, i tossed the old housing & bearing back on to check fit. Shaft is still recessed a bit, but not nearly as much as with the new bearings. Spacing it hard to see here, but its 3.25mm in.

I assume I can shift the shaft a bit before tightening the set screws. The new assembly sits another 7mm proud of the surface. If I tried to shift shaft that far, I'm almost positive the the outer blades would hit.

 

[whirly]

As you can see the bearing sticking out on the outboard side is half the problem. You might mic the thickness of the housing to see if that is the other half of the problem.



The real issue is the sheave. If it sticks that far out it won't line up with the drive sheave.

If this was my problem and the only issue was the one in the attached pic, I'd assemble it and measure how far off the 2 sheaves are then take it to a machine shop and have them remove the excess.

[Edit] you may just need to remove the excess.

 

[Zumdahl]

The housing themselves are identical as far as I can tell. It does seem like the new sheaves are just 6-7mm longer. The sheave is inserted to be flush with the inner side of the housing. I do have space between the mating surface of the flail drum at the back of the sheave. Is it possible to press the sheave further in so that it sticks out the back of the assembly instead of the front?

 

[whirly]

... Is it possible to press the sheave further in so that it sticks out the back of the assembly instead of the front?

Do you mean the Bearing?

 

[leonz]

Don't hate me, but I need pictures of the interior of the side weldments of the flail mower please

I would love to see more pictures of the bearings and housings facing the same direction also so I can be of more help.

My soap opera is on so I will be back in a while.

 

[Zumdahl]

Do you mean the Bearing?

Sorry, I'm really not sure on the language here. The hole through the center of the new bearing/housing assembly which resembles a ~2" long pipe. I'm not sure if this is actually part of the bearing, or basically a pipe that rides inside a bearing. If for instance, I inserted the assembly and then set the pulley on the shaft could I use the bolt which secures the pulley to really press against that proud metal surface? I don't know if that 'pipe' bottoms out on something, or if it could go as far 'into' the mower as necessary.

 

[Zumdahl]

Don't hate me, but I need pictures of the interior of the side weldments of the flail mower please

I would love to see more pictures of the bearings and housings facing the same direction also so I can be of more help.

My soap opera is on so I will be back in a while.

You're here spending your free time helping someone you've never met out. I'll be out there with a camera all night if it makes this easier to resolve.
This is with the old assembly, and is the inside of the mower, the 1/2" metal piece that sticks through the side of the mower is part of the bearing assembly.


And facing the same direction if that's what you meant:

 

[leonz]

Hello Zumdahl,

By now you should have the Mott manual that covers the entire Mott flail mower line in your mailbox.

If the original bearing for the driven side of the flail mower was a flush mount face without a shoulder
they sent you the wrong bearing.

If they sent you two of the same bearing it does not take into account the fact that the driven pulley MUST be mated flush with the Flail Mower Rotor Stub Shaft on that side as the bolt will not have the holding power as the bolt threads will not be fully bottomed out and you cannot be expected to run your mower like that.

Give me a couple more minutes here.

 

[leonz]

Fixing my post here;


The bearing with the hub faces inward not outward according to the old manual, that would explain the issues your having. Do you have the washer which is part number 57 in the manual?


I will be back a bit later -my favorite attorney is on now :^0.

 

[Zumdahl]

I do have two identical housing+bearing assemblies. Thank you for the manual. Am I reading the parts diagram included incorrectly? It seems like it calls for duplicates of everything bearing cage/bearing related. The part I ordered two of from Flailmaster was the "M-702408", which references the same '700736' as the manual. Did I order the wrong part?

This may be a secondary issue, but I didn't order new bearing washers. I didn't actually see those when I removed the old pieces either. It's possible they're buried under wound grass and grease. I'll go poke at the old piece and see.
[edit] Nope, there doesn't look to be a washer on either side. I don't think the manual references a size. Is it just based on the ID (1-3/16") of the bearing?

 

[leonz]

I am pretty sure they sent the right bearing now as item 56 is the bearing with the shoulder that protrudes into the interior of the mower.

The washer on the hub side nests against the shoulder of the stub shaft of the flail mower rotor.

 

[leonz]

Good morning,

I realize that its 7:10 AM in gods country and I hope that you did not lose any sleep.

Did you have the opportunity to rotate the bearing housing 180 degrees to see how well the fit
is in relation to the driven V pulley fit-It has to be flush with the stub shaft.

Are you on the desert side of Wenatchee, Wa. or on the western side of Skykomish Wa.?

I have been an amateur historian of the Great Northern Railroad from 1890-1929 when the GNRR
crossed the cascades from Skykomish to Wenatchee using the old switchbacks from Skykomish to
Corea to Elba then on to Wellington and then across the mountains to Cascade Tunnel Station and
then on to Wenatchee and points east.


The Railroad town of Wellington, Washington was named after Arthur Mellon Wellington who was a brilliant Civil Engineer who built railroads in Mexico and South America and he was also a Member of the Board of Directors of the Great Northern Railway



We will get you through this.


Leon

 

[Zumdahl]

Sorry for the radio silence, I've been busy at work and just had a chance to get back out to the garage now. We're on the western side of the state, but further south than Skykomish. More along the I-90 corridor. Ever been to the Northwest Railway Museum? Its in right at the base of Snoqualmie Pass. One of those restored train stations, rides for the kids etc. Neat place if you're into trains and in the area.

As it stands now with the new assemblies I can't get the pulley to fully seat, and because of that it's quite out of alignment with the idle and input pulleys.
Rotating the bearing housing doesn't seem to change anything in relation to how far the shaft protrudes. The bearing assembly snugs up to is shoulder against the mower and I can't see any way to make it tighter or sit further in.

 

[leonz]

Hello Zumdahl,

The railroad museum is on my wish list when I am able to travel west as I plan on walking across Windy and Cowboy mountain on the old switchbacks with a guide after I have my knees replaced.

I have always felt that the GN made a huge mistake when they built the new tunnel as its been proven they would have gone bankrupt if it was not for the CB&Q's hauling iron ore from the Mesabi range to their docks at Allouez.

They had been upgrading the line for years before Ralph Budd pushed the new tunnel on the board and they took him at his word.

They could have kept everything intact and just improved the line every year with more modern equipment. The electric locomotives that were used until 1956 were the same ones that were used when the line from Skykomish to Wentachee in 1909.
These locomotives were salvaged after the avalanche in 1910 and upgraded to a more efficient electric locomotive after that and the ones that were sold to the Pennsylvania railroad were practically brand new and the Pennsy folks were shocked as they were practically brand new when they recieved them from the Great Northern Railroad.
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There is no need to apologize for the radio silence at all Zumdahl, At this point I will be candid and tell you that you need to call flailmaster on Monday if possible and explain this to them as the bearings and housings are the wrong ones.


At this time:

1. If possible remove the flail mower rotor and put it on a bench or saw horses and take pictures of both end of the flail mower rotor.

2. take pictures of both sides of the interior and exterior of the side weldments with all the holes exposed and clean.

3. take pictures of both sides of the old bearings and bearing housings.


At worst they may ask you to send the old bearings and the new bearings back as they sold you the wrong bearings and bearing housings and be sure to ask them to send back the old bearings and housings to you.

That way they can send you the correct bearings and bearing housings and also the bearing washers which you need anyway.


I would if at all possible send pictures of both ends of the the flail mower rotor to them and the shaft stub diameters and lengths of the stub shafts. You need to also send a picture of the mower knife mounts as well.


Leon


I am so sorry that I am not closer to you to help.