A little Machinist advice please

[AndyM]

I know we have some very talented machinists on this site and I would appreciate your opinons.

My 25 year old JD lawn mower has a habit of eating the self propelled drive pulley. This is number 2. I see it might be available on the JD website but but the time I add the cost, exchange and shipping I could likely buy a mower.

So, my question - any hope of fixing this? Alas I did not buy that metal lathe 10 years ago so I am limited in my fabrication abilities but I can get pretty creative. Any hope here or just chin up and buy a new one?

 

[North Idaho Wolfman]

First: I don't think we have any little machinists on here, I think they are all full sized.

I don't see what the issues is?
If it's the wear on the faces of the pulley shaft, I'm not understanding how that's impeding use?

 

[Old Machinist]

A new pulley or pulley repair in itself will not fix your problems. You will need to replace the pulley AND shaft and determine why it is working lose to begin with.

 

[Runs With Scissors]

Hmmm.

I am not a machinist, but I have a decent amount of experience with machines/engines in general.

I have never seen a pulley that has been "wallowed out" like that.



I cant imagine a keyed pulley doing that if it is a "proper snug fit".



Was it a "snug fit" when you put it on last time?

 

[JimDeL]

Seems like the only way the pulley would be "wallowed out" like that would be if it was spinning on the shaft. That shouldn't be possible unless the woodruff key is either missing or sheared.

You did put a new key in when you replaced the pulley, didn't you?

 

[AndyM]

First, I take the point on the little machinist - that could have been phrased better...

To better describe the issue the bore is no longer true , the slot for the key worn (at an angle) to the point the shaft slips when it tries to engage. The 10 mm shaft looks ok to me and the key itself is ok but would no doubt be better replaced.

The design is at fault I am guessing - a lever on the handle raises the transmission (and pulley) to engage the belt. It's likely not spinning on a perfect plane a good part of the time causing uneven wear on the pulley. The fit was snug to start but as I have a lot of hill work, it gets torqued out of shape over time.

I did actually buy the whole transmission unit the last time (and yes it was expensive 10+ years ago). The pulley seems to be reasonably robustly made but not robust enough I guess. Not sure if it could be trued up by drilling it out and welding in a ring with a key slot (sounds dicey) but I can't think of anything else (short of buying a new pulley).

 

[Hoserman]

I would say the shaft has been wore down to where the pulley is no longer kept tight to it'. Have you inspected the shaft/spindle to see if it has stepped on you. And like JimDel said; it looks like the key came out and the pully spun on the shaft. Sorry, I wish I could give you more info.

 

[chim]

If the shaft is OK, I'd do some Googling and look for a sheave with matching dimensions. It's possible you can find a stock one that works. I sometimes had good luck finding what seemed to be proprietary parts online.

 

[lynnmor]

The hole could be bored to a much larger size and then a piece of bar stock welded in. Then a hole of proper size could be drilled and bored on location. Last, a keyway will be broached in.

A better solution might be to find a quality pulley the correct size, or at least one that can be easily modified, at a place like Surplus Center. That piece of tin from JD is something that should be upgraded.

 

[North Idaho Wolfman]

Yea I would be doing a cast pulley!
There is no fixing that one.

 

[AndyM]

Thanks all.

I did take a picture of the shaft and key; it looks good - I would show you but without too much digression, the cell world is a bizarre place sometimes.

Appreciate the lead on alternatives - sounds like finding stronger pulley will be a better way to go in any event or I will be back at his again in a few years (with any luck). That will be my plan.

Cheers
Andy

 

[Old Machinist]

You might could drill it out and bush it. Are you sure the shaft is metric?

I would first measure the shaft and pulley diameter and try to find a generic replacement. Without seeing the design and parts list it's difficult to give good advice.

Grainger sells some inexpensive shaft reducer bushings in inch sizes.

Whoops, we couldn't find that.

 

[AndyM]

You might could drill it out and bush it. Are you sure the shaft is metric?

I would first measure the shaft and pulley diameter and try to find a generic replacement. Without seeing the design and parts list it's difficult to give good advice.

Grainger sells some inexpensive shaft reducer bushings in inch sizes.

Whoops, we couldn't find that.

When I measured the shaft the first time it was 25/64 or some such as I assumed the JD would be US. Dawned on me to try metric and it was an exact 10mm.

I will try to find a cast unit that fits but I may just play with welding in a plug as Lynmorr suggested just for fun.

I did look on Grainger at one point but didn't see the size I needed. I will have a closer look.

 

[Hugo Habicht]

So, my question - any hope of fixing this?

Hello Andy,

of course there is hope

The original design is flawed, you saw that yourself already, so no point in buying original spare parts again. What I would do is fit a locking assembly, something like this:

https://www.maedler.de/product/1643/spannsaetze-spannbuchsen-taperbuchsen

Since you do not own a lathe you could find a machine shop that modifies the pulley so that it can be fitted.

Kind regards,
Hugo

p.s.: you could also consider buying a Kubota lawn mower

 

[jaxs]

I could be mistaken but if shaft,bore and key fit snug you might be able to salvage and reuse the whole assembly without need for parts or precision machining.
It looks like keyed sleeve has a disc attached and relies on friction from being trapped between 2 piece pully that was spot welded together. Visualize sleeve w/disc assembly looking like cutter wheel of a plumber's pipe cutter. As that disc slipped under load it progressivly became loose,slipping.wearing then wobbling. The problem could easily been averted by spot welding pully halves to disc at same time pulley halves were spot welded together. At this point if bore can be aligned with pulley then 2-3 holes drilled through disc and both halves of pulley,tapped with threads then secured with screws. If screw heads and/or nuts cause interference, grind flush with pulley, weld,braze,solder or JB Weld tips of screws to prevent them working themselves out. Alternately if you have a spot welder, forgo screws and spot weld instead. Or if screw heads must be ground off to prevent interference, forgo screws, drill threw pully halves enough to expose disc then hit each hole with tiny rod in conventional arc welder/tig or mig.
The only challenge will be holding alignment throughout drilling,screwing , welding.

I hope all that is clear as muddy water since I was making it up as I went along.

 

[Lil Foot]

With the experience, equipment, & supplies I have, I would repair that pulley better than new, just as an exercise to keep my hand in, if nothing else.
But without those things, a new (probably cast) pulley would seem to be the way to go.

 

[Yooper]

What Lil Foot said plus I would make it a slight press fit on the shaft. Also would make sure that shaft isn’t bent.

 

[PoTreeBoy]

How about something like this? A little cutting and welding required.

 

[AndyM]

Hugo
It always amazes what you can learn from a simple question - locking assemblies - who knew. As to the Kubota mower, we did buy a Ryobi battery unit a while ago, so I am not without (as long as the grass is not too long it works).

Jaxs
That sounds like a bigger project I am up for - buying a cast pulley is more likely for more me.

Lil Foot / Yooper
Yes this would be nothing to fix for you two - alas developing the skills and buying a bunch of equipment is not in the cards at this point. (I did look for a lathe a few years back but decided it was a bigger undertaking than I was up for). Shaft appears true as near as I can tell.

PoTreeBoy
I will have a closer look at that, thanks. Again, it's amazing the options that exist if you know about them.

Cheers
Andy

 

[lugbolt]

Is that a JS or JA 65 series mower? If so, just get rid of it. Deere's venture into mass marketing, and they failed with those too.

The JX/JE series and 14SB mowers, however, have been awesome, just expensive. I buy them from time to time and give them to folks who need them. I used to make a good bit of money on them, because a lot of people were still paying top dollar for clean ones. That kind of sunsetted and I generally just give them away now. Always get to work on them, though...general servicing is about all they ever need. Blade here and there and an occasional blade brake clutch on the rougher used ones. I still have two of them, I keep the bad one and my mom is getting the other one which looks cuts runs like a brand new one.