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Discussion Starter #1
I am getting a vibration on my set up. I have a horizontal engine with a 3" pulley,,and a forward reverse transmission with a 8" pulley.. They are sitting about a foot apart on the same level surface.
The engine pulley is not centered to the trans pulley. It is about a inch low from center.
I see the belt does not seem to run true,,it has some up/down movement.

Do I need to center the pulleys?? I think I know the answer,,but it is allot of work to lift this engine 1". And something I didn't give any thought to when I constructed this set-up.

Would have been easy before the paint job and assembly.
 

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shouldnt matter if the engine is above or below the gearbox, the relationship between them is the same, regardless of placement.

Vibration could come from a faulty belt that isnt sitting in the groove right, or has a t hin or fat spot...also it can be cause by a pulley issue, a narrow or wide spot in a pulley from removal or installation.

Personally, if it was me, id run a longer belt, and fab up a simple, spring loaded tensioner pulley to run on the back of the belt.
 

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Discussion Starter #4
Don't tell us you got rid of the original engine.
No not yet. It is a nice engine but being old and used I want a new engine on this. And the hand cord you have to wind around to start it,,is a step ahead of the horse and buggy days.
This little HF 7 hp is plenty of power, as a matter of fact,,I can't run it wide open.
But I do have a vibration I didn't have before.
 

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Discussion Starter #5
shouldnt matter if the engine is above or below the gearbox, the relationship between them is the same, regardless of placement.

Vibration could come from a faulty belt that isnt sitting in the groove right, or has a t hin or fat spot...also it can be cause by a pulley issue, a narrow or wide spot in a pulley from removal or installation.

Personally, if it was me, id run a longer belt, and fab up a simple, spring loaded tensioner pulley to run on the back of the belt.
I may just end up putting a tensioner on it. I did go tighten the belt a little and it helped. But vibration not completely gone.
It's good to know the pulley alignment should not matter.

I am going to re gear this soon,,to go a little faster,,so I might as well wait til then to modify it.
 

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Discussion Starter #8
If you remove the belt and run the motor at wot is the vibration there or not?
That is a great question. I just could have tried that had I thought of it!!! While I had all the bolts loose to tighten the belt!!DOH!!!
Maybe I can slip the belt on and off,,not sure. I'll try it either way!!
 

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blacktop roller...found the old thread.

Something to consider...the old engine may have turned 3600 rpms, like the new one, or whatever...BUT..the old engine had a TON more inertia in that big old engine than this new one. So its likely you are feeling this new engine's lack of inertia, which results in harmonic vibrations.
 

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Discussion Starter #11
blacktop roller...found the old thread.

Something to consider...the old engine may have turned 3600 rpms, like the new one, or whatever...BUT..the old engine had a TON more inertia in that big old engine than this new one. So its likely you are feeling this new engine's lack of inertia, which results in harmonic vibrations.
Well ,,the old engine is really only in need of a paint job. It starts first pull almost every time.

I really wanted to put a HF 10 hp engine on this,,and still could. But they have been out of stock in my area for months now.
 

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Its alot like, if you start a push mower with a blade on it...it runs smooth as silk. remove the blade, and start it...if you can, and it runs the same but is jerky, compared to before...as the energy that the engine was storing in the blade..to get it though exhaust stroke, intake stoke, and compression stroke...is no longer there, so when it makes power again, after 3 parasitic strokes..it jerks.
 

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Discussion Starter #13
Don't tell us you got rid of the original engine.
You and RED talked me into painting this old engine ,,and re-installing it!!lol

When I first got this roller,,,and was driving it around.I didn't like the feel of the engine,,but thinking about it. There was some serious problems with the roller. the rear drum was broke away from the axle,,and tilted in place.And broken bearings on it. rear drum was rubbing the frame ,,near wore right through 3/8" steel frame.

Besides,,I can use the HF engine for a tiller.

But I still need to change gears to speed it up some. It's at a crawl speed as fast as it can go.
Fun,fun!!
 

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The ones that Ive seen, only went about 15-20 feet per minute, very very slow, got to keep in mind..its meant for rolling and compacting blacktop and driveways, not joyriding or running out to the mailbox. Its made for a flat, uniform surface, every time.

Speeding it up, would make it less effective and work the engine harder. But its simple to do, in theory...just take the pulley off the engine, its a 3"..and go to a 4". This will effectively make it go 25% faster.
 

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Discussion Starter #15
The ones that Ive seen, only went about 15-20 feet per minute, very very slow, got to keep in mind..its meant for rolling and compacting blacktop and driveways, not joyriding or running out to the mailbox. Its made for a flat, uniform surface, every time.

Speeding it up, would make it less effective and work the engine harder. But its simple to do, in theory...just take the pulley off the engine, its a 3"..and go to a 4". This will effectively make it go 25% faster.
If I increase the size of the drive pulley ,,yes it will speed it up,,but also speed up the transmission. Which is rated for 2000 rpms. I'm guessing where it is now.
I want to change the gear size on the other side of trans to achieve more speed. There are 4 gears/sprockets and 2 chains.
One chain/gear on output of engine going to a slave(not sure what to call this). Other side of slave ,,another small gear that is going to a large gear on rear roller.

Yes I will need to lengthen the chain,,no fun. But I am thinking of changing the gear just above the rear roller. The last in line,,this will not increase the speed of the slave, only the rear drum.

Torque now comes into effect. Which I am not familiar with. But this change is not going to be drastic. Shouldn't mean much as I only want a small increase in speed.

Pictures would explain this very much more. Soon!! I have covers on everything now.
 

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Discussion Starter #16
Here is what I am calling a slave. lol
The lower chain is off in picture but it goes to a large gear mounted on rear roller. The small gear (with no chain in pic) is the one I want to change.

These are pictures I already have from previous. If you look at the pic above (about belt )you can kinda see the set up also.
 

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Discussion Starter #17
I was rolling a lawn ,,,and blew that HF engine up!! lol
It had about 6 hours of run time,,,let out a puff or two of smoke,,did some spit n and sputtering and quit!!
It would still turn over but it would not start again.

I think the little 212cc(7 hp) had a issue from the start and was the cause of my vibration.

I took it back ans upgraded to a 346cc(10hp) engine,from HF.

I installed the new engine in the field,,had to drill new holes to mount it. Since they are not slotted,,I could not tighten the belt enough. Although I could rig it enough to move,,it's not operational yet. But it seemed much smoother.

I will be putting a tensioner on it soon!!! It's easier than slotting the holes,,and it will take any belt vibration away. (if there is any)
 

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V-belts are flexible and vibrate as a matter of course. In one of the seminars that I attended, they had a video of a multi v-belt industrial drive in slow motion. The belts were doing a dance and none were in step with any of the others.

How to correctly tension a v-belt.


The older, much heavier engines of days gone by had a very distinct advantage over the lighter, higher horsepower newer engines. That is stored energy. A heavy flywheel stores more energy for starting a heavy machine into motion. The new engines rely on horsepower to do the same job, and it takes a substantially more horsepower to equal the stored energy in a heavy flywheel for startups.

That's why walk behind lawnmowers need the blade attached. The flywheel is too light to run the engine properly without the added flywheel effect of the mass of the blade to help it through the parasitic strokes.

If you look at an old GT, you will find a heavy cast iron flywheel and heavy cast iron pulleys on an engine with half the horsepower of the new GTs with a much lighter flywheel and stamped metal pulleys. That flywheel effect smooths out the engine horsepower requirement for sudden short term power demands without losing very much in rpm with the older engines, while a new engine with the same horsepower will bog badly giving the appearance that it is not making the same power.

Did you ever watch an old movie showing 2 guys turning a crank on the side of a WWII fighter? They are winding up a flywheel and in a couple of minutes will store enough energy in that flywheel to turn a 1500 hp radial engine fast enough and long enough for it to fire up on the flywheel inertia alone.
 
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