What am I missing? (leaf blower problem)

I have a self-propelled leaf blower/vac. The wheels are driven by a belt that goes down from the horizontal shaft of the engine, turns
horizontal to go under the deck, and turns vertical again to drive the axle. All that turning is problematic and the belt keeps coming off.
This is a blower that I reconstructed from the parts of 2 scrapped ones. Same model, so no fabrication involved, just bolting together. At first I thought that I had gotten something oriented wrong, but I've ruled that out (most parts only go one way and I have a parts diagram that agrees).
Here is a picture of the underside. The arrow points to the spot on a pulley where the belt "enters" it at an angle. Of course, the belt wants to climb up the side of the pulley and come off.
http://home.comcast.net/~bobengelhardt/DSCF1179.jpg
I just don't get how this can work. My first impulse is to fix it by changing something. But this is the way that it came from the factory and it should work. What am I missing?
Thanks, Bob
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On 01/03/2015 9:20 AM, Bob Engelhardt wrote:

Not seen that particular one before, but all pieces of gear have seen/had that used such an arrangement had some additional guides to restrict the belt from side movement.
I notice some holes in the above bracket at about the right position; wonder if there aren't some missing such pieces here...
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On 1/3/2015 10:50 AM, dpb wrote:

Those holes are for the motor bolts. And the parts diagram doesn't show belt guides. But it's a good idea - I was considering changing the pulley orientation, but I think that a guide would be easier.
Thanks, Bob
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On 1/3/2015 9:20 AM, Bob Engelhardt wrote:

Two things I think I see in the picture.
1) The pulley on the left side is wider than the one on the right side. Swap them and see if the problem moves with the pulley.
2) The pulley on the right side seems to have a slightly different angle than the left side. Not perpendicular with the frame.
3) On the axle, can you slide the assembly with pulley and sprocket to the right a bit? You will need to move the sprocket at the other end to. Mikek
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On 1/3/2015 11:14 AM, amdx wrote:

One of the first things that I tried was swapping the pulleys. But one is a flat pulley, riding on the back of the belt & the other a vee. Swapping them and keeping the front-back right didn't work.
> > 2) The pulley on the right side seems to have a slightly different > angle than the left side. Not perpendicular with the frame.
The angles are slightly different & the right one is nearly perpendicular, but needs to be "tilted" quite a bit (clockwise). If it pointed in the direction that the belt was coming from, it would work. That's the big question in my mind: why doesn't it point that way?
> > 3) On the axle, can you slide the assembly with pulley and sprocket > to the right a bit? You will need to move the sprocket at the other > end to.
The unseen sprocket is welded to a shaft and that determines the alignment of the rest. I thought of an end-over-end swap, but the belt pulley is centered & swapping wouldn't change anything.
Thanks, Bob
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Bob Engelhardt wrote:

The right hand pulley needs to be angled in at the bottom so the belt enters straight.
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On 1/3/2015 2:51 PM, Steve W. wrote:

It does. I was about to change it so that it would when I thought I might be missing something and posted.
I still can't answer why it was made that way. And it's not been damaged so that the alignment has changed.
Thanks, Bob
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Bob Engelhardt wrote:

Some of the outdoor stuff I have worked on defies logic. Bending that into alignment will decrease the belt wear as well as keep the belt on.
One of my old Power King mower decks will make you scratch your head. It uses a LONG belt. Comes off the engine back to the deck, then wraps around and goes over itself to drive one spindle then back across to drive the two on the other side. Sort of looks like those W shaped paper clips!
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"Bob Engelhardt" wrote in message
I have a self-propelled leaf blower/vac. The wheels are driven by a belt that goes down from the horizontal shaft of the engine, turns horizontal to go under the deck, and turns vertical again to drive the axle. All that turning is problematic and the belt keeps coming off.
This is a blower that I reconstructed from the parts of 2 scrapped ones. Same model, so no fabrication involved, just bolting together. At first I thought that I had gotten something oriented wrong, but I've ruled that out (most parts only go one way and I have a parts diagram that agrees).
Here is a picture of the underside. The arrow points to the spot on a pulley where the belt "enters" it at an angle. Of course, the belt wants to climb up the side of the pulley and come off.
http://home.comcast.net/~bobengelhardt/DSCF1179.jpg
I just don't get how this can work. My first impulse is to fix it by changing something. But this is the way that it came from the factory and it should work. What am I missing?
Thanks, Bob
What direction is the geared shaft supposed to turn?
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"Rick" wrote in message
I have a self-propelled leaf blower/vac. The wheels are driven by a belt that goes down from the horizontal shaft of the engine, turns horizontal to go under the deck, and turns vertical again to drive the axle. All that turning is problematic and the belt keeps coming off.
This is a blower that I reconstructed from the parts of 2 scrapped ones. Same model, so no fabrication involved, just bolting together. At first I thought that I had gotten something oriented wrong, but I've ruled that out (most parts only go one way and I have a parts diagram that agrees).
Here is a picture of the underside. The arrow points to the spot on a pulley where the belt "enters" it at an angle. Of course, the belt wants to climb up the side of the pulley and come off.
http://home.comcast.net/~bobengelhardt/DSCF1179.jpg
I just don't get how this can work. My first impulse is to fix it by changing something. But this is the way that it came from the factory and it should work. What am I missing?
Thanks, Bob
What direction is the geared shaft supposed to turn?
Sorry, meant "sprocket".........
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On 1/3/2015 3:53 PM, Rick wrote:

Such that the chain and belt sections in the foreground move upward. Given CCW engine rotation and forward movement of wheels.
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It appears to have two different width pulleys, so I'm wondering if the righthand pulley had been replaced at some point (or originally) with the narrow one, causing the problem. One fix I can think of, having dealt with quite a few mower deck pulleys myself, is to add a 1/4" or 3/8" rod guide. It would keep the belt from trying to hop the left sheave. You have 4 existing holes to mount it between.
http://manuals.deere.com/cceomview/OMM152793_H4/Output/images/OMM152793_H4a18.jpg

Yes.
Um, what direction is the belt moving? My guess is that the righthand side moves up toward the pulley it tries to jump, correct? In that case, the geared shaft moves thattaway! (counterclockwise if looking from the end the gear is on) I love these quick quizzes based on a single, incomplete picture of a complex mechanism, where entire drive and driven mechanisms are hidden! Do post more. ;)
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On 1/3/2015 5:13 PM, Larry Jaques wrote:

The pulleys are as shown on the parts diagram. And were the same on both of the donor machines. So I think they're OK.
"dpb" mentioned a guide, but your picture of the Deere arrangement convinces me that it's the way to fix it.

Yes. It is the critical point. The belt is entering the pulley under tension and wants to climb the side. All other points are either aligned properly, or the belt is exiting a pulley, or it is entering "slack" (return path).
> I love these quick quizzes based on a > single, incomplete picture of a complex mechanism, where entire drive > and driven mechanisms are hidden! Do post more. ;)
Well, the engine is off, so there's nothing to show there. The chain goes to sprocket - that's no help. There's really nothing to add.
Thanks, Bob
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Perhaps you have the belt running backwards on the drive pulley?
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On 1/3/2015 6:25 PM, Jim Wilkins wrote:

No - the direction of the wheel rotation determines the direction of the sprocket, hence belt. And the direction of rotation of the engine determines how the belt rides on it's pulley. The belt could ride in reverse on the left-right pulleys and the cross over itself going to the engine, but, seriously!
Bob
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On Sat, 3 Jan 2015 18:25:45 -0500, "Jim Wilkins"

(Palm hits forehead) Yeah, flip the belt at the chain end and it will track the other way, running just fine onto the wider pulley. I'm sure that's how it was designed, if no pulleys have been changed.
(That said, how could it have worked the opposite direction?)
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I helped rebuild an old riding mower for a community park committee which had a convoluted belt arrangement that could easily be routed incorrectly. It may have been discarded after being reassembled wrong in a previous repair.
The blades spin backwards just fine, but they don't cut very well. -jsw
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On Sun, 4 Jan 2015 07:28:39 -0500, "Jim Wilkins"

Ditto those great stories. My $5-fix golf cart was my best repair. I've cleaned plugged-up vacuum cleaners found in the junk pile at garage sales and they worked perfectly; it sold for $10 at my next gar(b)age sale.

Funny how that works.
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I'm thinking that this was much ado about nothing!
I went to the cellar to put a guide on the belt. I took the pulley bracket off & thought "Why don't I try to bend it?". Well, it bent really easily, much to my surprise! Here's the fixed pulley (the full picture for you, Larry :-)
http://home.comcast.net/~bobengelhardt/DSCF1184.jpg
The pulley is held by an L-shaped bracket & I just twisted the upright leg. Now I'm thinking that it might have been damaged, given how easy it was to twist and how little twist it took.
Bob
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I see that you have the problem fixed, but just in case, here's another tho ught: I have several old Cub Cadet garden tractors that turn a belt 90 degrees to move power from the horizontal engine shaft to vertical driven pulley on the mower deck. Most of the time when a belt comes off it's because the b elt itself is bad. Sometimes I have to look closely to find the defect. I have learned over the years that all vee belts are not created equal, b y a long shot. Especially when subjected to this kind of twisting. Some o f them take a permanent or semi-permanent set when sitting for a long time. Not a problem in "normal" service, but not good here.
(There ARE other belt-retention problems with these old Cub Cadets, which I detail at: http://www.spaco.org/CubCadet/MowerBeltComeOff.htm
Pete Stanaitis ---------------
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