OutdoorKing Repair Forum Forums Repairs and Maintenance Questions On Ride On Mowers Questions On Ride On Mowers Frames John Deere L110 Automatic

Just had my neighbour call in, his John Deere L110 Automatic just went bang in the rear.

Towed it to my place with the mighty Greenfield .

What he said happened, is that when he started it it didn't sound right, there was a strange noise coming from the rear and when he drove it, it sounded like a metal noise, when he drove it further he heard a bang from the rear and then the mower would not move.

The motor runs fine so it is not from there, the mower moves forward a little bit then goes no further.

That's all I know at the moment, will have a good look tomorrow but any thoughts suggestions on whre to start looking would be appreciated.




Regards
Rich

I'd Bet its the main drive gear....

Those JD Ride-ons Have a tendency to blow the drive gear...


Kori

The L110 Auto has the hydrostatic transmission and final drive all in one piece. This is what it looks like:


The unit is probably a TuffTorq K46 - this can be verified by looking at the unit's identification plate. I have read that another brand of transmission was also used as an alternative in that mower.

You can read the owner manual here:
http://manuals.deere.com/cceomview/OMGX21647_K3/Output/Index.html

The manual says the transmission is a sealed unit, not owner-serviceable. Various internet reports say that JD dealers simply replace them when they blow up, as your neighbour's seems to have done. (It seems this is not an uncommon event for K46 transmissions.) This is very expensive for any hydrostatic transmission, and for an 8 to 10 year old L110 will probably not be financially viable. If you or someone nearby really likes to get on the spanners, you might consider buying parts and rebuilding the unit. Here is some information on that approach, if it is a K46:
http://www.tractorbynet.com/forums/parts-repairs/164892-tufftorq-k46-repair-guide-pictures.html

You now see one of the reasons why I rather like the Greenfield's type of transmission, and generally regard hydrostatic units as best left for commercial operators. The L110 Automatic may have been an example of what happens when you try to make a consumer product with advanced features, and you do it by using short-life componentry.

No insult here Rich but you guys checked the lever at the back that engages drive? I forgot that on my dads.

I recently bought one of these for my ageing dad to make maintaining his block a bit easier. A second hand unit.

I had no idea about them and rang a John Deere dealer just to query spares prices. Apparently the price of these gearboxes has dropped to respectable levels recently and they are generally they only thing that causes too many issues. Don't quote me but $700 to 800 seems to ring a bell. All speculation I know as the problem hasn't been identified yet but just thought I would mention it.

How many hours on it Rich?

Hi grumpy,

Yep you are right about the Greenfield, I had great pleasure towing the neighbour JD from his place to mine, I even took a detour past some other neighbours just to rub it in .

Thanks very much for the info and pic & especially the link to tractorbynet, which then led me to a couple of ytube videos showing how to drop and repair the transmission.

I now have it out & sitting on the work bench ready to pull apart today to see what the damage is.

Will keep you updated as I go, I don't suppose you would happen to know off hand if Toughtorq in the USA will post parts to Aus.

If you don�t hear from me for a few days, it�s because I have changed ISP�s and cancelled the old one from the end of this month forgetting that Feb only has 28days & I am not expecting the new sim to arrive till early March

Regards
Rich

No insult taken mate, but yes I did check the lever and it was pushed in.

360hrs

Regards
Rich

Thanks for the heads up mate, much appreciated

Regards
Rich

Thanks for the update, Rich. We would certainly like you to continue this thread, with pictures, as you diagnose and perhaps repair that transmission. We do not have detailed repair threads on hydrostatic transmissions, and this one would be very useful for the archives. Of course we will help if we can.

From the thread on the transmission repair in that other forum, it sounds as if you need to make personal contact with the transmission manufacturer, and explain your problem (after you have found out pretty accurately what it is). Phone is best, but prohibitively expensive unless you have the right kind of phone plan. Most likely email is also possible, though. Whether TuffTorq will ship parts is one issue, but what they would have to charge for shipping is another.

I notice that the repair manual for a Poulan ride-on that uses the K46 transmission, says "Order parts from transaxle manufacturer", so my guess would be that TuffTorq is experienced in dealing with this kind of customer enquiry.

Well it has got me stumped.

Opened the transmission up, and pulled every thing out and checked it and can't find a thing wrong with it, no broken bits - no siezed bits & only a few light shavings on the magnet, oil looked fine.

Remembering that there was a big bang and then it just stopped, it wouldn't go forward or reverse but the motor was running normally.

Just to be sure I went and started the motor to make sure the drive & cutter pulleys were working/spinning and they were fine.

When you hear a bang you expect to find broken bits but there is nothing and nothing to suggest that it may have jumped a cog or similar.

So is it possible that nothing broke but the cylinder block pump or the cylinder block motor have just given up the ghost and the bang was a last gasp.

ps: Neighbour called in so I did not get any photo's done yet but will when I put it back together.

Very confused
Rich

Rich, I suggest you take a bunch of pictures before you put it back together. We probably won't learn much from what it looks like assembled.

The failures for which the K46 is notable usually seem to be hydraulic failures, not gear or shaft failures. It may be that the transmission's hydraulics do not usually last long enough for the gears to fail. I am doubtful that an internal hydraulic failure would happen with a bang, though, unless a pipe or hose burst or a gasket blew. Typically the hydraulics wear out, creating leakage paths, and the transmission is then unable to pump enough oil to generate much torque. However any leakage path, including a single major leak, would stop the music. I suggest you carefully inspect the interior for leaks, especially ones that might have happened suddenly. Also, was the transmission full of oil when you dismantled it? If it lost its oil (either gradually or suddenly), it would lose its drive.

Was the transmission losing performance (i.e., slower than it used to be when climbing hills) before the loss of drive? This would signify wear. If it was still bounding up hills like a mountain goat, and there were no metal particles in the transmission (especially its oil filter) we would seem to be looking for a sudden failure, not a wear-out failure.

The alternative to a sudden hydraulic failure is a sudden mechanical failure. Have you checked for stripped internal splines, keys etc, as well as gears that have lost teeth or shafts/axles that have broken in invisible places? I've seen pictures of mower transmissions that lost just one or two teeth from a driven gear, and the damage was relatively difficult to see, but there was no drive. Also, I notice that the axles drive the mower's hubs with keys. When a hub drive key shears there is likely to be something of a bang, followed by little or no drive, so please report on the condition of the keys and keyways.

Sorry grumpy but for some reason when replying to your post it jumps straight back to the top after the text goes below the scroll bars and I can't see what I am typing.

It seemed to have plenty of oil and there was very little discolouring.

The neighbour is not sure but does say that his is not as fast as his work one (same model & a year older)the oil filter was dirty but no metal particles in it & there were only a few fine metal shavings on the drain magnet.

I can't see any teeth missing or stripped splines, the hubdrive keys & keyways are fine.
I am assuming that the axles are meant to be independant in that you can turn one side clockwise & the other anti clockwise and are not both meant to only turn either back or forward together as a pair??

Sorry grumby but I am still having problems when typing, I can't see the text as I type as it scrolls back toward the top of the box.

Rich

We still need pictures, while it is in pieces, and in stages when you reassemble it. Also, which model of K46 is it? There will be one or two letters after K46 in its identification number.

You said you have inspected the axles and hubs, and you don't have a broken axle or a sheared key or a stripped keyway in a hub (things which have been known to happen to K46s it seems).

If it didn't drive, but it was full of oil, and its hydraulic system was primed, something is broken. Unless the oil level was well below full, it can't have lost prime, because it had been working previously and the mower hadn't been turned upside down. (Fill means 1.85 litres of multigrade engine oil, reaching well up into the neck of the filler tube on top - initial fill is 10W-30, but they now recommend 5W-50 synthetic.) Note that on the K46 there is a single filler for the hydraulic system and the mechanical part of the transmission, but the two lots of identical fluid are kept separate inside the transmission. Did you find a total of nearly 2 litres of very light engine oil in the transmission?

You can get some information on the oil system here:
http://www.mytractorforum.com/showthread.php?t=161413

You need to check the drive pulleys (both engine and top of transmission) and the belt of course. However a high speed, low torque drive doesn't usually emit a bang when it fails unless some part comes off and hits something. It is surprising how loud a broken V belt can be when it hits a guard or some other stationary part. Serious bangs, though, usually come from a high pressure seal or gasket blowing, or a geared-down part, probably the final drive area, fracturing. As it happens, I cannot see a high pressure seal or gasket in the hydraulic part of the K46, so a pressure failure does not seem a plausible cause.

The sudden failure is an important diagnostic feature, especially when combined with the oil not being discoloured, the main filter (the large round one under the hydraulic pump) not having metal swarf in it, and it having full drive capability immediately before the bang. Since there does not seem to be a high pressure pipe, hydraulic coupling or gasket in there, it seems like it must have been a mechanical failure. Incidentally the hydraulic part does not seem to have done much serious work, from your description of the state of the fluid and the main filter. You referred to just one magnet in the transmission: I believe there are actually three, one of them being just under the filler cap, and the others lower down inside the transmission.

Along with the suddenness of the drive failure, the accompanying bang is very important. If it were not for the bang, a simple loss of connection between the drive pedal and the tiltable swashplate inside the hydraulic pump would account for what happened. The disconnection could have been anywhere along the pedal linkage and the transmission's control linkage. However I can't imagine a linkage disconnection being accompanied by a bang (there might be a bit of a clunk perhaps, as the swashplate suddenly centered itself at zero pump output). I suggest that you carefully check the drive pedal linkage and the transmission linkage, ensuring that the swashplate is actually tilting when the pedal is moved.

I have only encountered exactly the symptoms reported in this case (sudden complete loss of drive accompanied by a bang) twice before, but in both instances the cause was exactly the same: a single tooth broken off the large final drive gear on the rear axle. It is interesting that this was Kori's diagnosis right at the beginning of this thread.

In reply to your question about turning one of the axles by hand, the final drive part of the transmission has a differential in its center. It is the differential that allows one axle to turn very easily, as long as the other axle is able to turn in the opposite direction by rotating the differential's planet gears. If you hold the other axle, or turn it in the same direction as the one you were turning in the first place, the whole final drive has to turn over and there will be a little more resistance. Aside from visual inspection of the parts, you can't learn about the condition of the transmission except by making the final drive turn over. When it turns, if nothing is broken it will rotate the whole gear train smoothly, right back to the hydraulic motor part of the central hydraulic unit. If a tooth is missing from the axle's final drive gear, the rest of the transmission will turn intermittently due to the gap in the large gear on the axle.

This unit, like most small hydrostatic units, has a multi-cylinder hydraulic pump with a vertical axis, driven by the input shaft. The oil pumped flows directly into a multi-cylinder hydraulic motor with a horizontal axis, driving a shaft with a small pinion on the end of it. The connections between the pump and the motor are completely internal to the single aluminium casting on which both the pump and the motor are mounted. Internal oil leakage does occur due to wear on the port-plates at the ends of the pump and motor cylinders, but this is something that happens gradually and is normally associated with high-temperature degradation (i.e. oxidation) of the hydraulic oil - the oxidised material in the degraded oil is abrasive. In my experience, oxidised oil is always brown and has a distinctive odour. You have reported that in this transmission the oil is in good condition, and the transmission has not been progressively losing speed or gradability.

When you test the gears by rotating the axle be sure the gears have some oil on them, and especially, be sure there is a bit of light engine oil in the hydraulic motor part to ensure it does not scuff or seize. Of course the transit bypass must be pushed in to allow the motor to rotate.

Please post the pictures, and let's talk about what is going on step by step through the gear train.

How can the two lots of identical fluid be kept seperate if you fill them from the one filler, surely the fluid must flow between the two to keep the levels equal.

I filled it from number 7 in the photo from your first post.
Moderator edit: I have replaced the original illustration with a different one. The oil filler cap is number 15 in the new one.

I have taken lots of pics but have to wait till my new internet package arrives next, I hope.

Rich

Rich, I agree that there is a small amount of mixing over time. With thermal expansion while the tractor is in use, the fluid is expected to climb up the riser pretty much up to the filler cap. That results in there being maybe an inch and a half of about one inch diameter riser in which the two lots of fluid mix. However there should not be any flow through that riser, so the amount of mixing should be very limited.

Bigger, better hydro transmissions have two separate fillers, and perhaps two different lubricants. The K46 is not only made to be cheap, it is also made to be very small so it will fit small tractors. I don't actually hate the design of the transmission, the problem seems to be tractor manufacturers who put it in situations where it will be overheated and overloaded.

I'm really looking forward to seeing the pictures. Right now it looks like the first couple of chapters of a murder mystery.

Then how do you know if you have enough fluid in both chambers??.

The reason I ask is I have put it back together, (I also replaced both the small idler pullies and
the belt to be on the safe side)jacked it up und done the air purging, got the wheels to go forward & back
then lowered it and tried it out.

It goes forward ok for a little bit then very slowly, in reverse some times it works then the next time it won't
I done the air purge 3 or 4 times for the same results.
When it does go it makes a howling type sound when under pressure, so that is why I queried the oil bit as I am wondering
if there is enough in each chamber - I put exactly 1.8L of 5w50 syn oil.

Or is it a matter of continuing the air purging.

Rich

Rich, the air purging will only succeed if the transmission is full of oil throughout the process. Tuff Torq says it may take up to 2.2 litres of oil. Item 7 of this page describes the purging:
http://www.mytractorforum.com/showthread.php?t=161413

Note the reference to it taking up to 10 minutes of purging at idle before you lower the wheels to the ground.

The symptoms you describe sound as if there is air in the hydraulic circuit. There are several things that could cause this - in particular, aerated oil at the end of the purging process. Because the L110 does not have a proper oil reservoir, de-aeration of the oil may be a protracted process. FWIW, my approach would be to let the machine idle with the rear wheels elevated while alternating between forward and reverse, until I had clear oil in the filler: no signs of aeration. It is usually recommended that you switch the motor bypass valve on and off (i.e. operate the transit lever) a number of times while you are doing this. Of course some topping up along the way is likely to be required, due to the L110 not having a reservoir.

Please do not run the machine above idle, or lower the wheels to the ground, until you have all of the air out. The howl you described is a cavitation sound, and it is accompanied by cavitation damage to the pump and motor.

If it makes you feel any better, you are not the first person to go through this personally-unsettling process. You may find this description hauntingly familiar:
http://dir.groups.yahoo.com/group/John_Deere_L100_Club/message/1473

Just imagine how much easier this would be if JD had bought the optional oil reservoir and transmission drain plugs:

Thanks grunpy, I will rip it out again and try purging it on the bench with a power drill.

When I filled it up I done it with a pump and I may have got a lot of air in it as the as the oil got to the bottom of the container.

Last question where do I hook the drill up to, to drive the motor, is it the spindle that holds the pulley and fan.

Rich

Yes, the vertical shaft is the pump spindle. If you rotate the shaft at around 500 rpm or so with a drill (in the normal drilling direction, clockwise when viewed from above), and keep reversing the direction of the transmission, while watching the oil in the filler neck, you should get this sorted out easily. Do not reverse the drill, of course: just switch the transmission between forward and reverse. Aerated oil looks foamy-white. When you get all the air out the oil should look just as clear as when it's in the can. Remember, the oil has to be continuously clear: the odd clear patch does not mean all the air is out.