Shuttle clutch…

Greetings Jeff, welcome!

If the left reservoir is used there will be a sight gauge on it and there will also be an accumulator used, also, the pump suction will go to that reservoir (this arrangement was used on later models). You have two hydraulic pumps mounted on the right front of the engine, the forward one is for the shuttle clutch and the rear one is for the tractor hydraulics. Curious what oil you are using in the clutch, it should be ISO AW 220 Machine Oil (or equivalent) for proper operation. Also curious if the dozer had proper pre-delivery service. Can I ask who you purchased it from? If purchased from a direct importer it most likely was not serviced. Will address your shifting issue next.

Just a note for clarification, my dozer (2002?) doesn't have a sight gauge on the left reservoir.  Wish it did.

Grizz,

If you pop out the fill/vent cap you can install on of these. I know there are some that don't require access to the reservoir but I ran out of time.

Hi, these older shuttle clutches were not built very well.  I have

taken mine apart and put it back together again.  I am currently

using Chevron ISO Rando 150 in my shuttle clutch.  If you over fill

the shuttle clutch reservoir the oil will get real hot and slipping of the

S.C. can occur.  You have a strange problem in that the shuttle clutch

is operated by a piston like device , one way or the other to engage

the front or rear clutch assemblies.  Sounds like your “rotate valve” has a problem and is not letting hydraulic fluid recirculate when you are in neutral.  Also install a water or oil pressure gauge, like rainbird, at the tap block next to the “rotate valve” underneath.  You can trouble shoot your shuttle clutch problem with this gauge.  40 PSI max. for the pressure relief valve adjustment.  A good system can engage the forward and reverse clutch packs at about 25 psi.

You should have near zero pressure reading when in neutral, because you are just recirculating and not engaging the clutch packs.  I actually made a movie how this whole system works with the clutch pack taken out of the machine and ran on water pressure with gauges.

So your problem is pretty simple compared to what I have had in the past.  There are so many places that S.C. hydraulic oil pressure can be lost in this system and seals that can leak, not including the distribution block on the main shaft (this shaft has holes in it and is hollow, etc., and receives the flow of hydraulic oil for forward or reverse operation).  A central, large piston in the middle of the shaft

moves forward or backwards engaging the clutch packs.

Al Lamore

nanapljr3@sbcglobal.net

Hi guys,

I have a 1993 Guilin 252L with 177 hours (according to the clock) on it, over here in NZ. This last week it developed shuttle issues.

I have only had it for a couple of months and have only done about 25 hours since I bought it. So very much still learning…

I think I got a bit low on oil in the shuttle clutch housing (I think she leaks and I hadn't noticed that she has a separate dip stick and fill to the gearbox, dou!) , and it is now working hard in forward and slipping a bit as it engages, but reverse is still working fine. I have taken of the lid of the shuttle clutch housing, and there is nothing obvious to see damaged. With Hi/Lo in neutral and 1/2/3 stick in neutral, reverse engages and the engine ticks over freely, but when I engage forward the engine labours and chuggs, suggesting that something somewhere is partially seized or something. Any suggestions?

Cheers,

Simeon

If I understand correctly, you're saying that with everything in neutral it shifts fine into reverse, but lugs the engine when you shift into forward. Correct?

What that tells me is that your reverse servo is not releasing fully and creating a drag. This could be caused by several things from plugged oil passages in the servo shaft, a bent shaft, wrong oil type, to a bad (by-passing, or plugged) selector valve. Does the system use an accumulator?

When is the last time the suction screen was cleaned?

What type of oil are you using?

Hi Bob, that's a lot of questions! 🙂 “If I understand correctly, you're saying that with everything in neutral it shifts fine into reverse, but lugs the engine when you shift into forward.” Yep that's right.

“What that tells me is that your reverse servo is not releasing fully and creating a drag.” Ok, sounds an interesting and logical idea…

Ok, so the 'servo' is the small hydraulic ram on the left side of the housing that activates the shuttle yoke?

I have not noticed an accumulator anywhere… I can see one would soften the shuttle engaging though, so it would be a good idea.

I haven't done a service yet, so no idea of it's service record… I did check what I thought was all the oils when I got it (but I hadn't realized that the shuttle clutch housing was separate from the gearbox). The hydraulics was low on oil, and as it turned out was the shuttle housing.

The manual suggests “#20 gear oil or diesel engine oil grade T14” for the clutch housing… I have used 15W-40, is that ok?

I going to attach a pic of the exploded diagram of the shuttle assembly, in case my old machine if different to the more modern ones.

For the hydraulics I used the hydraulic oil as I use in our excavator.

Cheers

Having problems posting.

Tame wrote:

Ok, so the 'servo' is the small hydraulic ram on the left side of the housing that activates the shuttle yoke?

No. The servos I was referring to are found inside the larger model shuttle clutches and operate spring loaded forward and reverse friction disc clutch packs through a planetary gear drive. I would call your clutch a hydraulic “reverser”.

I have not noticed an accumulator anywhere… I can see one would soften the shuttle engaging though, so it would be a good idea.

Accumulators are found on the later model shuttle clutches.

I haven't done a service yet, so no idea of it's service record… I did check what I thought was all the oils when I got it (but I hadn't realized that the shuttle clutch housing was separate from the gearbox). The hydraulics was low on oil, and as it turned out was the shuttle housing.

Does your tractor have two separate hydraulic pumps or does the clutch get it's pressure through the tractor hydraulics?

The manual suggests “#20 gear oil or diesel engine oil grade T14” for the clutch housing… I have used 15W-40, is that ok?

I wouldn't use engine oil in the clutch hydraulic system at all. In the later shuttle clutches I recommend ISO AW 220 Machine Oil, mainly because it is rated for geared friction drives and has an AGMA 4 rating.

I going to attach a pic of the exploded diagram of the shuttle assembly, in case my old machine if different to the more modern ones.

Yes, it is totally different, and I beleive it is only found on the two cylinder tractors.

For the hydraulics I used the hydraulic oil as I use in our excavator.

I assume that is ISO AW 32 or 46 hydraulic oil, and that's ok.

I believe Greg's dozer has the same type of clutch yours does.

Jolly good. I still think there is a possibility that it is something to do with the clutches fight against each other… Humm, is Greg the only guy on here that has the older 2cyl 252 Dozer or is there a few of us?

Seems I need to learn a bit more about different oils…

Well I better clear out a shed and get her in and see if I can figure out what the story is… got rather a lot of work lined up for her, and the weather is drying out, so the sooner I get her back into action the better.

I presume I have to remove the engine to dismantle the shuttle clutch, is that correct?

Tame wrote:

I presume I have to remove the engine to dismantle the shuttle clutch, is that correct?

Correct.

One thought is that it might be just a simple adjustment to that hydraulic cylinder not travelling far enough in one direction, however I don't have that spec. Could be in your manuals somewhere.

You also need to determine where that clutch cylinder is getting it's pressure from.

There is one other fellow with a two cylinder dozer but he hasn't been around for a long time.

Hey Bob thanks for your help.

In the manual it does talk of adjusting the clutch… but I can't say it is over clear what it expects one to do!

It does imply that there should be 2.5mm-9.2mm gap with the pressure plate released on each clutch pack, with should equate to a max travel of the pressure plate from reverse to forward of 18.4mm (should be only 5mm with the clutches in new condition) so I think that is the first thing I will check. It tells one that if it is greater than this to adjust it, but as far as I can tell, not how to adjust it!

It would appear that it runs of the same hydraulic system, but at a different pressure (500 psi as opposed to 2000 psi), so there must be a pressure regulator somewhere.

It's interesting to note that your clutch operating principles are exactly opposite of the newer models, where the servos in the newer models are used to separate the clutch packs against the spring pressure that keeps them engaged (much like the operating principles of the steering clutches). The problem with that system is that if the engine quits while you are in gear, you can't get it back into neutral. Hence I believe the reason for the accumulator. At least in your case you could un-link the hydraulic cylinder and disengage it manually.

Just to update, I had a bit of a go at working through the possible issues.

The actuating cylinder has 40 mm of travel, 20 mm each way, and with it disconnected from the crank it appears to move smoothly both ways and returns to center as it should. So that suggests that the hydraulics and ram all works fine.

With the cylinder attached it appear to move about 10 mm for reverse and about 6 mm for forward… Look at the yoke inside the housing the movement seemed a bit odd. In reverse the yoke moved maybe 5 mm but forward it seemed to barely move, though I could see the shaft turn slightly.

Cylinder detached again I tried moving the selector yoke with a lever to get a feel of it. Reverse one could feel it pushing on the return spring and then contact the plates and go firm. Forward there was slack and then contact and no movement. No sign of the return spring of the sliding of the pressure plate.

Next drained the oil. There was a fair bit of bronze flecks and a few small chunks, sort of what you would expect after maybe 1000 hours, but rather a lot for just 170 hours on the clock. Then I removed the selector shaft and yoke… and low and behold it looked just like Greg's one in 'Total tear down of dozer'. Badly burnt, worn, and misshaped.

So certainly the yoke needs either replacing or possibly making an improved version (which at present I am thinking is the wise way to go as it appears there is a weakness here)… but the question remains as to what other damage there is.

I think I may do a temporary repair of the yoke, and just try it to see is it will free up the pressure plate… else it is out with the engine and pull it all apart. 

Here is a link to Circle-G's dozer parts.

Northern Tool is also a good known source for dozer parts.

Update, got the shuttle out and dismantled. The forward thrust bearing was cooked and seized. Clutches them selves seem in good order. I have been able to source the bearings locally (should turn up Monday), but the return springs (cooked and lost temper. Needs to be a matching pair) are proving more difficult. The selector ring and pressure plate I have tided up on the lathe and I think will be fine.

Oh and the dead bearing looked like this after I pulled it off. Gosh I just had to use that smiley!!! 

do you have in mind what caused this?wrong or lack of lube ,poor assembly?

There is an inherent design flaw with this type of clutch, although it is simple in design. The clutch relies solely on the actuating cylinder to hold it engaged whereas manual types of the same clutch (the “Johnson Bar”) will have internal over-centering devices that “lock” the shifter in forward or reverse and take the load off of the thrust bearings.

You've done a great job so far.

That bearing looks like a typical ball-thrust clutch release bearing, which are designed for intermittent service and typically have a MTBF rate of around 4,000 hrs. You might want to re-address the type of oil you are using in the clutch.

I will also speculate that the hydraulic cylinder has been out of adjustment for quite awhile, and also that forward position gets used the most, particularly under load.

“do you have in mind what caused this?wrong or lack of lube ,poor assembly?”

Well first and foremost the oil had got a bit low (main seal to bell housing is perished, but I am not too offended as it is Chinese and nearly twenty years old. Also I had not realized that the clutch housing has a separate dip stick to the gear box, so hadn't been checking it.). Second I got stuck and gave it some welly getting out (nose up hill in a drain buried in mud), which would have worked her harder than I normally would.

But there are a couple of issues with design. Firstly as Bob points out the thrust bearing is rather little and is really a clutch release bearing, not a clutch engaging bearing! So the life expectancy is a bit limited straight off. Secondly the yoke pushing on the selector slip ring would only need to be a tiny bit off true to put all the load on one side of that bearing.

If she goes again, I would be inclined to try and find some sort of self aligning roller thrust bearing…

But I have my hopes that as long as I keep the oil to the right level that she will serve surprisingly well.

Bob said

“The clutch relies solely on the actuating cylinder to hold it engaged whereas manual types of the same clutch (the “Johnson Bar”) will have internal over-centering devices that “lock” the shifter in forward or reverse and take the load off of the thrust bearings.”

Bob, tell me more! Do you have a diagram for this layout, I would like to see it and get my head around it, and if possible implement the logic somehow.

Yesterday was getting a a bit frustrated as to what to do about the springs. In an earlier photo you will see one is as good as new, but the other is cooked and permanently compressed. I had not managed to find anyone that could supply anything close or suggest who might be able to. I have recently been reading 'Hardening, Tempering, and Heat Treatment' by Tubal Cain, and knew in theory that I should be able to anneal, re shape, harden, and temper the damaged spring… But I have done it before… Well what have I got to lose, the spring is wreaked anyway?!?

So I annealed it (heated to cherry red and let it cool slowly), re shaped it to pretty darn close the the good spring, hardened it (back up to cherry red and instantly dunked in water), and broke it! @#$%&* 

It was as fragile as glass! I then tried tempering (heating very gently to the point the shiny metal goes past purple to light blue) the largest fragment. It seemed perfect, like the good spring. I was furious, if only I had been more careful, it could have been successful.

Well I was both angry and encouraged now… talk of mixed emotions! So I decided to have a go at making a matching pair of springs from scratch. Rooted through the old fence wire, found some #10 that was about the same thickness as the spring, annealed and burnt off the galve, shaped it, hardened it (was blimming careful with it this time), and tempered it. I now have two spring that are pretty close to the original dimensions and spring rate, and well matched to each other, which is the main thing. Pretty satisfying in the end.

This dozer is surprising me…

I was half dreading the first time I would have to do mechanical work on it because I feared what I might find regarding quality and design, and thought I may lose respect for it rapidly. But I have been very pleasantly surprised, it is simple, surprisingly clever, and pleasant to work on. Some bits are rough, but they are bits that don't matter, and the bits that do matter are pretty well made and finished.

Interesting… I never expected my respect for it to grow… but it is! lol

Typically, coil spring steels are simple carbon steels of the 1050 to 1095 variety.  If the steelis at the high end of that range, say above 60 or 65 points carbon, then the quenching medium should be oil heated to 140F.  Quenching in water is too harsh and will crack them. 

Likely, your fence wire is much lower carbon steel, (probably no more than 20 points of carbon), so it will harden in water just fine, but it won't have the durability or tensile strength of a higher carbon steel.  If it were my machine, I'd get some spring wire, also called music wire, which is usually 1095 carbon steel, and make new ones hardening in the heated oil.  Draw the temper to a blue or even straw and you should have a good, durable spring. 

Greg Here, So it looks like we need to improve this design before we put our dozers back together.   First we need a more slippery material between the thrust bearing and thrust plate.  Maybe some nickle plating of parts.  Or better bearing with a teflon coating.  I am Aerospace Engineer, but not a metals expert, but I do have co-worker that are.  I will get with them see what they say.  Also there is porbably a better synthentic oil out there we could us. 

If I had some lumps of bronze, I would make some little shoes to go on the slip ring… but other than that i don't think she is too bad design wise… Well actually it is a but daft having the thrust bearings constantly loaded, but I haven't thought of a way to modify that yet!

I am on the whole alot more impressed with this little machine than i expected to be.

As for the springs… Well I'll see how well the ones I have made last. If they get through the summer I will be happy, I can redo them next winter if need be. I agree though Rich, that it would be better to use proper wire, but yet again it is the issue of tracking it down and the two hour drive to the city.

It is turning out to be a busy few weeks, so not managed to finish fixing the dozer yet, but nearly there. I managed to track down a couple of release bearings that were close enough, and a replacement main shaft seal (140x110x12). The selector yoke I built up with weld and re ground. The slip ring I polished. The pressure plate I ground….

The problem with being in NZ is it often takes to long to get parts from other parts of the world, so I tend to end up modifying or making… If it is something I can't make do, then I will pursue more seriously getting it from USA or China.

Greg, when I get a spare hour or two I'll scan in that parts manual and email it to you. Thanks for all info. How many hours has your 252 done? Mine seemed to have no wear other than the damage from the seized thrust bearing. But frankly that is my fault, it had no oil in there!!!!

I got the engine back in yesterday and tried the drive, all seemed ok shunting in the work shop, so just need to put all the panels and guards back on… Next week maybe. I'm working out in the bush this week on the IHI is35GX excavator…

Once I get the dozer fully back together the mission is with the dozer and excavator to cut the new track through a small canyon in the bush into 80 acres of farm that we have never been able to access with machines… Should be alot of fun.

Hi, I finally figured out how to repair the older dozer shuttle clutch.

I found various design flaws with this clutch.  The front hydraulic fluid

distribution block of the main shuttle clutch shaft with clutch packs, was supposed to have four holes instead of 2, with attached guide screws and springs.  I fixed this by adding two more holes to keep the distribution block, with internal bronze bearings from skewing.

Another problem was the internal splines of the final drive cylinder were too small, not correctly cut, thus stripping out along with the external splines of the #1 transmission drive shaft.  To fix this I obtained from tractor supply co. PTO adapter parts.  Using the internal splined part cut from the adapter, I placed it inside the final drive cylinder, making new, bigger splines of better material.  The #1 transmission shaft that goes inside this female piece, was built up using hard facing rod at about 150 amps with a conventional 220 volt supplied welder.  The new wider splines were fitted to the female piece, making a much stronger connection.

I also found a problem with the forward shuttle clutch shaft external splines.  There were burrs on it that caused the forward clutch shaft to jam.  Sanding them off to fit did the trick. I use air pressure to check the operation of the finally assembled clutch packs on the main shuttle clutch shaft.  I have perfection.

Another related problem was the internal splines of the plate that attaches to the engine.  Replaced defective smaller splining with PTO

internal splining.

Al Lamore

nanapljr3@sbcglobal.net

Hi Al,

My guess is that clutch is in a Guilin dozer. I think Yuchai made some big improvements when they took them over. No doubt they read some of your older posts and took them to heart.

Well a few years have past since I was last on here, but just to update, my shuttle clutch repairs on the old Gulin worked well while I was using and maintaining it. However I was away from the farm for a couple of years, and the guy the used it in my absence ran it out of oil again and totally cooked it. So a month or so ago I rebuilt it again much as I had done before, though I machined it up some what different so I could fit larger release (throwout) bearings. Also made new springs again! All going good again now, so i am working her hard for a few weeks while I am back at the farm.