John Deere tractor X107 deck-belt problems

[foy9999]

Can anyone help?

We have a little-used (almost new) machine which keeps breaking belts.

Each time I change the belt I remove the deck completely and put it back on after double-checking the routing of the belt and that all the sheaves are moving freely and the tensioner is not seized.

It works for 5 minutes then you smell burning rubber and the belt snaps.

On closer examination today I found the main LHS pulley/sheave is rubbing slightly on the 'brake-pad' whilst the RHS one isn't

To explain how it works first: When the blades are not 'engaged' the drive from the engine still spins but the belt is loose and the brake pads are supposed to stop the sheaves spinning. This is a weird (but common) design which leaves the belt loose while parts are still in motion.

When a lever by the steering-wheel is pushed fwd (to start cutting) a cable pulls on a large spring attached to a metal arm on the deck. This is supposed to bring the movable sheave (on the end of the arm) into contact with the belt which tensions it and causes it to be tight round the other 4 sheaves plus it takes the brakes off.

So. With the deck off I noticed that there is a lot of slack in the arm-mechanism before it acts on the other components linked to it. The the range of the cable-movement is not sufficient to bring the brake pad fully off the LHS sheave as a lot of the movement takes up the aforementioned slack and when the lever is fully pushed forward the brake-pad is still on the LHS sheave. There is no means of adjusting the cable/spring/arm.

So I'm thinking there needs to be a way to tighten the cable so it pulls the arm further and fully releases the pad(s).

However increasing the pull on the arm increases the tension on the belt as well as moving the pads further and this would perhaps be a problem too. If the belt is too tight it would burn immediately I guess

It might be easier just to remove the brake pad. Why do you need them anyway?

All of this is perhaps a moot point as when we set off to test the machine today we could smell burning and hear clanking before the belt was even engaged,
This would be with the belt loose and the sheaves held stationary with the brake pads.

The clanking sound is probably the un-tensioned arm but I can't understand why the belt would be burning if it's routed correctly and not tight.

Any ideas, before the dealer needs to come and collect it for expensive examination?

Also is it correct to route the belt with the V-shape inwards round the drive pulley? Seems a crazy question but if you do it this way the flat face of the belt is running on the two small inner sheaves

 

[Guineafowl]

Can you see, from accumulated rubber debris, where the belt is rubbing?

Re: routing, have you got a diagram to ensure you’re doing it right? The groove of the pulley should reflect whether it contacts the V or flat side of the belt. Are you sure the belt is the right size?

If you suspect the brake pads, I’d certainly remove them, if only for diagnostics.

Have you checked every part of the drivetrain for excess friction? Do the blades spin freely?

 

[badabec]

Does this lady offer any insight?

John Deere 48 Inch Mower Deck Belt Diagram with Routing Guide

I have seen many people trying a DIY replacement of the deck belt on the John Deere 48-inch mower. And making things hard is very easy if you don't know your way around. The most

dillongarden.com

The flat back of the belt runs against the tensioners which have a flat groove, as guineafowl said.

 

[foy9999]

Can you see, from accumulated rubber debris, where the belt is rubbing?

Re: routing, have you got a diagram to ensure you’re doing it right? The groove of the pulley should reflect whether it contacts the V or flat side of the belt. Are you sure the belt is the right size?

If you suspect the brake pads, I’d certainly remove them, if only for diagnostics.

Have you checked every part of the drivetrain for excess friction? Do the blades spin freely?

Yes. Been through the manual very closely looking at the diagrams which aren't very clear and definitely have it routed correctly.

Thanks for confirming about the belt. I did notice the small sheaves (which touch the back of the belt aren't grooved.

The blades spin freely apart from the one with the binding pad. That's what I noticed the other day so took the deck off expecting to find a seized bearing on the spindle of that blade but then saw the pad had grooves in it where the wheel is rubbing.

If it was me I would take the pad off but the owner who doesn't know what the hell I'm on about has booked it in for a dealer to collect it. Las time he got a bill for £600

IO did quiz him about the belts (which he got from the dealer) as the packet didn't specifically say X107 on it but it did say 42" (deck) and that's what we have.

 

[foy9999]

I can't see specific rubber-debris, as the belt is burned all along its length, but I did see it has already melted the brand-new plastic guide which clips to the bottom of a guide at the drive-sheave

 

[badabec]

Side or rear discharge? Different belts apparently

 

[Nomad]

I have a 36" Murray ride on mower (similar layout as yours but only a single blade / pulley).
The drive/disengage lever throws an L-shaped arm, the arm has a roller at one end and a brake block at the other.
In drive - the idler tensions the drive belt, when disengaged the idler moves away and the brake block rests on the rim of the pulley connected to the blades.
It's crude but works well, it's designed so when the engine is running and disengaged the slack belt slips so sends no drive to the blades.

Suggestions :
Remove the belt and check none of the pulleys are seized (on mine the main shaft / bearing holding the blades sometimes needs lube - first time I noticed was when the belt started smoking)
Make sure you use a proper commercial belt (my local farmers merchant sells blue belts, stronger than typical black fanbelts)
Clear any grass around the edges of the deck, if I cut the grass when it's wet the cuttings build up under the deck - easy for a clump of something to jam the blade and let the magic smoke out..

 

[Nomad]

.... However increasing the pull on the arm increases the tension on the belt as well as moving the pads further and this would perhaps be a problem too. If the belt is too tight it would burn immediately I guess

It might be easier just to remove the brake pad. Why do you need them anyway?

All of this is perhaps a moot point as when we set off to test the machine today we could smell burning and hear clanking before the belt was even engaged,
This would be with the belt loose and the sheaves held stationary with the brake pads.

The clanking sound is probably the un-tensioned arm but I can't understand why the belt would be burning if it's routed correctly and not tight....

Also is it correct to route the belt with the V-shape inwards round the drive pulley? Seems a crazy question but if you do it this way the flat face of the belt is running on the two small inner sheaves

A late thought, on mine when disengaged the brake blocks stop the "blade pulley" from turning, they also stop the slack belt from moving. End result is the motor spins but the belts and pulleys don't.
Smoke suggests the belt is too tight and dragging even when disengaged. Check the pulley on the motor - if it has corrosion or crud in the "V" it could be casing friction rather than slipping freely.
Or could your belt be too lose when disengaged? Mine has the tension off but not enough for the idlers and pulleys to rattle (think of bringing a car clutch up until it just starts drag, not 100% disengaged).

When drive on mine is engaged the drive pulley is spring loaded so it will give the right tension even if an overlong or stretched belt is fitted.

It's also worth checking and greasing all moving parts from the lever by the steering wheel down to the final engage / disengage mechanism, also the pivots under the deck.
Mine are very worn so it's difficult to engage drive gently, nothing - nothing - *bang* and it's engaged

Disengaged should be the easy thing to sort out - suggest you look into that first before trying to sort "Drive" mode. Hope you get it sorted.

 

[foy9999]

Side or rear discharge? Different belts apparently

side discharge