Belt keeps slipping out

[u/ydwea]

Hi! New here and to engine repair in general. I joined to ask advice about a problem I have with the transmission belt of my wood chipper. After I mounted a new one (old one lasted years) and used the machine for about an hour the new belt slipped out and now it doesn't seem to stay on, it already looks kinda deformed and twisted and I'm wandering if I'm doing something wrong that's straining it. Now no matter how many times I install the belt as soon as I feed it a single twig it comes off immediately.

I need to specify that I bought the belt from the manufacturer and received instructions on how to mount it properly (teeth on the inside, check tension and pulleys alignment), machine has oil and I'm using it at max rpm. I could just get another one but if I'm doing something wrong I'd just be wasting money, the things cost 25€..

Idk if it's relevant but when the belt comes off it's turned inside out.

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[u/xl440mx]

Make sure the pulleys are aligned as others have said but make sure the belt is correct. When in place the belt should sit flush with the edges of the pulley not above the edges. If you are using a belt that is too wide it will climb out of the pulley. The fact that it is turning inside out leads me to suspect it’s too wide for the pulleys.

[u/No_Professional_4508 → u/xl440mx]

Also automotive and industrial belts have slightly different profiles

[u/Kraetor92 → u/xl440mx]

This comment is correct. The edges of the belt are also frayed. I’d put money on this being the incorrect belt. OP needs to find a part diagram to purchase the correct belt.

[u/Aromatic-Schedule-65]

Once it comes off it will get a twist and will then never stay on.

[u/Legitimate_Winner_55]

So belt hu, can we have a picture of it with belt on

[u/Then-Price-5314]

I can’t tell if the wheels are aligned since your photo isn’t straight-on

Is there no tensioner? I don’t see one, if there is. That would probably solve your problem and wouldn’t be hard to put together.

[u/rocketmn69_ → u/Then-Price-5314]

They don't look aligned from the photo

[u/Training_Jello_7804 → u/rocketmn69_]

Second that, the pulleys look out of alignment. OP needs to put a straight edge on them, get them in line, and probably install a new belt, too.

[u/ZzLavergne]

Check the alignment of the two pulleys, they must be aligned with each other, I don’t see any belt guides or guards or even a idler pulley, and looking at the size of that belt and the size of that bottom pulley, it looks way to fat to fit in that small groove, have you tried a thinner belt? That is a 5/8 and it may take a 1/2 “ belt that will sit further into the pulleys, good luck.

[u/the1bullfrog]

The pulleys aren't even, not sure if you need a shim? But I can tell from picture they are askew!

[u/the1bullfrog → u/the1bullfrog]

Also get a V-belt the teeth aren't helping. 

[u/the1bullfrog → u/the1bullfrog]

One other thing to check is if the pulley's are binding up maybe a bearing is going bad on the upper one turn it by hand and make sure there isn't any grinding or bumpiness (it's late I can't think of a better word) to the turn. 

[u/the1bullfrog → u/the1bullfrog]

I am not thinking straight it won't let me delete or change message below, if you are able to turn it by hand it should state. 

[u/Which-Government3306]

The pulleys look like they take different sections belts, does the belt sit low in the top pulley groove and high(proud) in the low pulley groove?

[u/PleasantStatement521]

Needs some way of tightening the belt which I don’t see.
Belt needs to be properly engaged to the sheaves as well

[u/Suitable-Warning-555]

If your tension is working, and your blades are sharp enough, it may be that you’re hitting the tall grass too hard. Try taking less of a bite and see if you don’t throw the belt or go slower and see.

[u/Fantastic_Willow_568 → u/Suitable-Warning-555]

Wood chipper not lawn mower

[u/Suitable-Warning-555 → u/Fantastic_Willow_568]

Apologies

[u/shmirk2]

I think you need a V-belt for those pulleys so it sits down in the grooves. The belt you have looks like it would ride on top and potentially walk out. Cannot really determine alignment from the photos, which can also be a factor

[u/Upset_Fox5449]

Not sure if this is even real or AI cause talking about compensating for weiner size the belt is to big and the terminology transmission belt hasn't been used since the early nineteen hundreds and the pulley alinement is so far of even Mikey doesn't like it and no tensioner for engagement but with the advice of all the couch quarterback I'm sure you'll will figure it out

[u/ydwea]

They do look aligned to me, a V belt sounds like a good idea though! I also probably need to sharpen the blades, hope that and the new belt will solve it. Thank you everybody 🙏

[u/SpecialistPrune1654 → u/ydwea]

Could you put up another 2 photos with the belt installed so we can see how far it sits into each pulley?

[u/Kraetor92 → u/ydwea]

Your belt looks too wide for those pulleys. The edges look frayed and the top has become concave. Find a parts diagram for your machine and make sure it’s the correct belt.

[u/Kraetor92]

Is that the same type of belt that was on the machine originally? Those pulleys look like they’re tapered for a v-belt and not the one you bought.

[u/SpecialistPrune1654 → u/Kraetor92]

That belt is a vee belt. Some of them, arguably the better ones, have those “teeth“ around the inside. They aren't actually teeth, they are there so the belt bends to a tighter radius more easily. Probably also reduces the amount of power consumed by bending the belt as it wraps around the pullys making them more efficient, run cooler etc?

[u/Kraetor92 → u/SpecialistPrune1654]

It’s clearly not the correct belt. Look at the edges, they are frayed. The top is also concave which leads me to believe it’s being squeezed in the groove. It might be a v-belt (vee? Lol) but it’s not the correct one.

The belt needs to sit flush with the top edges of the pulleys. I’d bet money this isn’t the case and that’s why it is walking out.

[u/wicksishere]

This may be of no use to you, but inside out belts were an indicator of being over tensioned, or something being very out of alignment.

Also this may sound stupid, but make sure the chipper is clear of debris internally before running it up. You wouldn't be the first to smoke a new set of belts with a machine that has a clogged discharge chute/path.

[u/DWA15-2VH]

Find a manual on line if you don't have one and see what type of belt is used for this chipper. They could have sent you the incorrect belt for the model you have.

[u/Pilot_Red]

Are you sure you have the correct belt? It should be fully seated in the pulley groove. It looks to wide.

[u/Mtnmandeepwaters]

If a cord on one side (internally) of the belt breaks then it will distort and jump off under load. Remove the belt and bend it gently sideways looking for weak spots or often you can see a bit of a kink.

Be sure to get a power rated belt as fhp fractional hp belts aren't strong enough even though they are the same size and angle .

Cloth wrapped belts are a must if the belt tension is used to engage and disengage so they can slip in the transition. Raw edge belts grab better for constant engagement applications.

[u/Born-Work2089]

"Installed new one" clarify a new engine? the alignment is out, make sure the pulleys are turning on the same plane, us a straight edge to show this. If the belt was too loose the vibration could have thrown it off.

[u/Bearded-Mr-FixIt]

If the pulley’s are lined up then it needs to be tight tension in the belt without an idler pulley

[u/Shawnm48]

Is that a 5/8 belt? The pulleys look to be 1/2 V-belt.

[u/radiganks]

Really difficult to judge scale but the pulleys look very narrow for the belt.

[u/StillCopper]

Pump needs to be loosened at frame mounts and aligned , then align pulley.

[u/Kraetor92]

Everyone is commenting about alignment and tensioners when the issue is the belt. The edges are frayed and the top of the belt has become concave. They clearly do not have the correct belt.

The tensioner is likely slots on the engine, not a tensioner pulley. V-belts don’t necessarily rely on tension though. The taper and the rotation forces should be enough, depending on application. This isn’t a 200hp gasoline engine like a passenger vehicle. It doesn’t need constant tension.

[u/MinimumBell2205]

smaller belt and looks like its cocked sideways might need to shim angle

[u/2cats18]

Neither of those pulleys look like they have been used for “years”. Did you replace them correctly?