Sheave/ pulley adjustment

[No1umfan]

I’ve got a 9 foot flail mower. Need to replace the belts. I found that the pulleys really are not in perfect alignment. So I’m trying to remove this top one to move it out about 3/16. But it won’t budge. I’m afraid of putting more force on the gear puller. Could it possibly bend the sheave out of alignment. Also I noticed there are extra holes after I removed all the bolts. I’ve seen this where you insert screws in there and screw those in to push the pulley off. Strange thing is is that the holes are smaller than the bolts. Usually they’re the same size. Any advice??

 

[nyone]

Yes on those you screw the bolt into the sheve to remove not the pully. That looks to be an old Alamo flail?
3/16 really isnt that much.

 

[No1umfan]

It’s a Ford 918 H. I put new belts on with that 3/16 misalignment. And I got a temperature reading up about 200° on the sheave after running the mower for about 15 minutes. The belts were 48 inch long whereas the OEM is 48.8. not sure if that would make a huge difference but that’s what happened.

 

[timbatrader]

using a puller will just tighten it on the shaft. The sheave is tapered you need to move the pully off the taper by using a hammer and drift to knock the pully back towards the mower and release the taper then remove the sheave. When you reassemble it consider putting back with the taper facing the other direction as long as you have room to access the retaining bolts it will make it easier to remove next time

 

[John0829]

Those smaller tapped holes are to push the sheave off of the taper lock hub. Use good bolts that will not mushroom as it could be really tight.

 

[ArlyA]

It’s a Ford 918 H. I put new belts on with that 3/16 misalignment. And I got a temperature reading up about 200° on the sheave after running the mower for about 15 minutes. The belts were 48 inch long whereas the OEM is 48.8. not sure if that would make a huge difference but that’s what happened.

If the sheves are 24" from each other, 3/16 out of plane is not worth messing with. Could they have been loose, slipping some and create that 200 degree heat? Could you have a bearing going out?

 

[No1umfan]

Those smaller tapped holes are to push the sheave off of the taper lock hub. Use good bolts that will not mushroom as it could be really tight.

Ugh. can’t find bolts to fit in those screw holes. They are really an odd size. 10-24 is too small and 1/4 - 20 is too big. In metric 5 mm is too small and six is too big.

 

[arto98607]

....................snip..................... When you reassemble it consider putting back with the taper facing the other direction as long as you have room to access the retaining bolts it will make it easier to remove next time

I disagree with this advice sir!

 

[arto98607]

I’ve got a 9 foot flail mower. Need to replace the belts. I found that the pulleys really are not in perfect alignment. So I’m trying to remove this top one to move it out about 3/16. But it won’t budge. I’m afraid of putting more force on the gear puller. Could it possibly bend the sheave out of alignment. Also I noticed there are extra holes after I removed all the bolts. I’ve seen this where you insert screws in there and screw those in to push the pulley off. Strange thing is is that the holes are smaller than the bolts. Usually they’re the same size. Any advice??

It's a cast iron pulley so it does not bend, instead it breaks if you apply too much force with a puller or hit in a wrong spot with a hammer!
Using a puller on the outer edge will be counterproductive and possibly just make the taper bushing grab on tighter to the shaft.

It looks like whomever installed it last time tightened the tapered bushing bolts all the way down so it may be in pretty tight.

Why not check if the smaller pulley comes loose easier and if there is enough room to move the smaller pulley 3/16" in the opposite direction?

By the way, in your second photo it looks like the smaller pulley has the extraction bolts you are looking for.
Or just keep looking until you find out what size bolts you will need?


Here is what the rest of a typical (much smaller) H-style tapered bushing looks like.

 

[K5lwq]

Ugh. can’t find bolts to fit in those screw holes. They are really an odd size. 10-24 is too small and 1/4 - 20 is too big. In metric 5 mm is too small and six is too big.

What about getting a 1/4-20 tap and resize the holes?

 

[timbatrader]

Hitting it with a hammer is not the correct way but if you don't have the right size bolts to break the taper using a block of hardwood and hammer to hit the pully close to the taper sheave but not on it generally works under absolutely no circumstances put pressure or hit the outer part of the pully that's what will break it

 

[No1umfan]

What about getting a 1/4-20 tap and resize the holes?

Never done that before but I guess there’s always YouTube

 

[No1umfan]

If the sheves are 24" from each other, 3/16 out of plane is not worth messing with. Could they have been loose, slipping some and create that 200 degree heat? Could you have a bearing going out?

I’m just an amateur hobbiest farmer so I didn’t think about getting 3 v belts that were from the same lot. Went to tractor supply and they only had two of the belts. So I went down the road and got a third one from family farm and home. Figured they’re all 48 inch what’s the difference. But I think one of them might’ve been just very slightly bigger because it was definitely looser. Maybe that was the one that was slipping and causing the heat. So I just took that one off and kept the other two on. Do I actually even need the three belts. Is there any major detriment to running this with just the two belts. I hate to take it all apart and have to put a third belt back on.

 

[K5lwq]

I would put 3 belts on and they need to be the same. However, the bigger belt was not slipping as the other two belts would have to slip as well. They need to match in order to keep the work load even for each belt. With one bigger it will not help much and the other two will be doing all the work.

 

[timbatrader]

in the old days it was always a thing to order belts that were going to be used together as a matched set. These days if from the same manufacturer and batch it doesn't seem to matter but if from different manufacturers or batch not only can they be a different length to start with they can stretch differently over time.
If it is only going to get light use two belts probably ok they will wear quicker and if if you work it hard will slip which will kill them quick If I were in your shoes I would probably run it with two belts but have a matched set on hand for when it does fail I mean what else are you going to use those two belts for you may as well get some use out of them it might surprise you how long they last

 

[WranglerX]

This video show the "concept " of how a sheave and tapered bushing assembles and disassembles....

 

[John0829]

What about getting a 1/4-20 tap and resize the holes?

Tapping is NOT an option at this time, the threads MUST go completely though the hub so the bolts can push against the pulley. With it assembled the tap will stop short of completely passing through the hub. However I would re-tap to a common thread after it is off.

Hitting it with a hammer is not the correct way but if you don't have the right size bolts to break the taper using a block of hardwood and hammer to hit the pully close to the taper sheave but not on it generally works under absolutely no circumstances put pressure or hit the outer part of the pully that's what will break it

Using a hammer is a risky option but IF you were to try a hammer find a punch that will fit freely inside the pusher holes and hammer against the pulley where it was designed to handle the pressure. Don't go gorilla on it just good wacks while moving from opposite hole to opposite hole.

Also if you are not using matched belts do not expect them to give the service you expect. Non matched belts will vary in length slightly and each belt will stretch at a different rate. When buying belts purchase good ones from a source that KNOWS what matched belts are, all the numbers and codes on a properly matched set will all be the same. Or better yet use a 3 in 1 belt (can't remember the proper name, to early in the morning) it looks like one wide belt with the 3 V's molded in.

 

[Michael In Tennessee]

Ugh. can’t find bolts to fit in those screw holes. They are really an odd size. 10-24 is too small and 1/4 - 20 is too big. In metric 5 mm is too small and six is too big.

Have you tried a 1/4" - 28 fine thread? Fine threads would provide more pushing power for the same torque. The other possibility is a #12 in fine or coarse.

Check the attach bolts and see if they are inch or metric. That way, you can eliminate half the choices anyway. In those sizes, there are no metric fine pitch nor is there a 5.5mm thread, so I think you have inch threads, you just got to find the right bolt.

I would not re-tap those holes. When you figure it out, use a paint pen and write the bolt size someplace on the machine. Inside the cover if that is a clean place. I do that often.

 

[arto98607]

....................snip................... In those sizes, there are no metric fine pitch nor is there a 5.5mm thread, so I think you have inch threads, you just got to find the right bolt...snip..

I agree with everything else you said, but there is M5.5 and there are fine pitch metric treads "In those sizes".
Please see the enclosed table for metric threads, but they are not likely metric in this tapered bushing.


I think he already has the correct "pusher bolts" on hand - they are still screwed in the smaller pulley in his second photo of post #1

 

[Tinhack]

Ugh. can’t find bolts to fit in those screw holes. They are really an odd size. 10-24 is too small and 1/4 - 20 is too big. In metric 5 mm is too small and six is too big.

They could be #12-24.