On our 10K D6C, I believe a while back I posted a problem with the steering clutches not releasing completely & we finally got around to checking the pressures today & here is what we found; on the valve body that in the picture is located just below the fill tube for the transmission, (I marked the plug with white), the pressure reads 250 psi & then at the check plug is where the gauge is hooked, that one reads 250 psi as well for the left steering clutch. The plug going to the right steering clutch reads the same. It reads about the same at a fast idle as when it is running at full speed. Any idea what the pressure should read there? Once the machine is really warmed up, the steering clutches drag on just a bit, but when cold it is much worse. Metalman.
D6c Steering clutches not releasing Here's the specs...looks like 275 +/-25 psi. (low idle) Mine did the same thing...pressure was ok, so I pulled the clutches and put in new seals and checked clutch plates & spring pressure. Changed very little....still drags when cold, but is pretty much ok when warmed up. View attachment Scan_Doc0002.pdf View attachment Scan_Doc0003.pdf View attachment Scan_Doc0004.pdf
Ok thanks. Can I get some clarification on a couple of items, as the one pdf was hard to see the details on? In order to get the pressure up to 275 psi, where is the location to set the pressure up, if it can be done? Maybe the one pdf did show it but had trouble reading it. I wonder with the steering clutches dragging a bit if that is not something to worry too much about, seeing that we only put 150 hrs. on the machine annually? When the tractor is warmed up, with both clutches pulled back & just creeps ahead slightly, however when cold it seems as though 40% power is going to both tracks.
Can't seem to find an illustration in the book anywhere. In the first scan (pg. 35) the diagram shows it as #6....Located in the pressure line between the oil filter and the steering clutch valve, but where exactly I'm not sure. Looked at online parts store and the 7s1993 for the relief valve is still a good number but couldn't find a diagram there either. Hopefully someone else knows where to look. If I remember my pressure was in the ok range, but if you tweak yours toward the upper limit and it helps, I might try the same thing.
Your not looking at the right specs. The 7S1993 relief valve is for the earlier D6's with direct drive. Check the hydraulic pump pressure. Should be 310psi +/- 10 psi. Same pressure at the steering clutch test ports. Minimum is 275psi. Relief valve is set for 350psi max and you should not have to fool with that. If your not making pressure either the pump is weak or you have leakage at the steering clutches.
Both steering clutch ports tested out at 250 psi. Exactly where is the pump located? Likely there is a test port on the output side of it?
Pump is located on the RH side forward of the flywheel housing. Test port is either on the pump or at the filter (top).
You mean the trans filter on the left front side of the engine right?
My Bad... You are correct....I was looking at the wrong pages. Here's specs for powershift. View attachment Scan_Doc0005.pdf View attachment Scan_Doc0006.pdf Looks like pump pressure (checked at port on filter housing) is min. 315 psi and max 350 psi....controlled by the sequence relief valve. Steering clutch pistons: (checked at locations H & J) 315 psi min...no max listed...suppose it would be same as max pump pressure. Makes me wonder what spec I was using when I checked my pressures...
Need to correct myself, pump location is on LH side, sorry about that. You can see the test port on top of the filter and there is also one on the pump . Specs vary according to s/n. Pressures are higher with later units. Steering clutch pressure is controlled by the pressure control valve not sequence relief valve
Is the transmission pump located under the hyd pump, forward of the flywheel housing on the same side as the trans filter?
should be on back side of flywheel housing behind hyd. pump.Follow hose back from filter. Bob
Ok, we are getting back on this steering clutch issue again on the D6C 10K 6516, where they are not releasing completely, especially when oil is cold (95% better when warmed up) & here is what we are getting for current readings. On the centre pressure tapp, the one located over the bevel gear compartment (see pic) with the steering clutches pulled back we get approx. 290 lbs at low idle & about 305 lbs. at fast idle. The tapps going to both steering clutches give the same readings, a little low according chart that member D6C 10K posted last summer which suggests a necessary pressure of 315, so not far off the mark. The pressure tapp on the filter housing gave readings of about 310 lbs at low idle & 375 at high idle. I see now on the sheet posted that it says the gear selector is to be place in neutral when checking this pressure on the filter housing....... I forget how we did that test...it may have been in gear with the steering clutches pulled. Will this make much difference? Oil was cold when we took these reading today.
If it's like my 10K you'll get significantly lower pressures with warm oil, especially back at the steering clutches. I couldn't make much sense of the readings I was getting on mine until I was able to get it inside a heated shop and run it until pretty well warmed up (25-30 minutes) and hook gauges to all test ports. I've been fighting the same problem with mine, working on it on/off most of the winter. Been checking pressures at all the test ports (I think there are 10-12 check ports) My biggest problem was leakage at the steering clutch seals. If I blocked off the tubes back on the bevel gear case I got decent pressure (still a little below spec.), but with the tubes open to the clutches I was losing nearly 100 psi when the clutches were released. I pulled it all down and replaced not only the seals, but the bearing cages and hubs to be sure I had everything good. Before I put it all back together I test ran it with the covers off the bevel gear case to see what the pressures did......gained maybe 25 psi and was still gushing oil through the clutch seals. The problem with mine came down to the seals (genuine Cat).....They are a split ring seal and they leave about an 1/8" end gap on the ring which allows a lot of oil to leak through. That might be ok for a new tractor, but for a 40 year old machine with wear everywhere in the hydraulic system, it just couldn't maintain pressure. I thought about it for quite a while and finally decided to make my own seals. I bought a sheet of Teflon (PTFE) material and turned out seal rings on my lathe and milled them to thickness to match the Cat seals. I left the seals full circle, which makes them a little tougher to assemble, but I was going for no leakage. I probably could have split them and just fitted them with a close end gap and it would have been just fine. I rented the hydraulic puller for a 2nd time ($125 each time) and installed the homemade seals. This time when I checked it there was no visible leakage and my clutch pressure will come up to the same reading I'm getting at the steering clutch valve. At least now any low pressure reading I'm getting aren't related to the clutches and just today I've pretty well got it all back together. As I said, my pressure at the steering clutch valve is still a little below spec, especially at low idle, but I can chase that problem without having a major tear-down. My trans pump is in good condition and I have good pressure at the sequence valve. I've got two things that still may be losing pressure......The steering clutch by pass for lubing the bevel gear bearings seem to flow an excessive amount. (If you remove the rear cover plate you can see the amount it's flowing) The 2nd possibility it the transmission relief valve.....it's bypassing quite a bit oil when the engine is warm. Talked to the Tech at Cat and a couple of the mechanics but couldn't get a definite answer about what's normal. Her's what my clutch leakage looked like: https://www.youtube.com/watch?v=ArhkfCFQlGU Here's the bypass at the trans relief valve: https://www.youtube.com/watch?v=1ScFPuHgh4U Here's the view through the back cover: https://www.youtube.com/watch?v=j475kwoWYQM The stream that's up by the trans pto shaft is the lube bypass The stream nearer the camera is the port that dumps oil from the clutches back to the sump. (notice it flows some all the time) Anyway, I don't know if any of this helps but at least you might compare what I'm seeing with what you see on your tractor. I'd be especially curious to know how your trans relief valve and steering clutch valve compare to what my videos show. Hope you have an easier time getting your's figured out......mine has turned into a "quest" to get it sorted, but I think I've got it to the point where it's "ok" for now at least.
We removed the rear cover plate on our D6 today & the oil bypassing & running down under the steering clutch valve appears to be somewhat less than your video was showing. Some did flow all the time however, but a smaller stream than yours. More would pour out momentarily, when the levers were returned in. Also the constant stream to the pto shaft seemed to be less volume then yours too. Did you have any trouble getting parts from Cat? Not sure if this means much, but we travelled the machine back & forth with the back cover off & did not observe any shifting or slop in the bevel gear & shaft....all looked tight. Pried on it various ways & seemed real tight that way to. We will be working on ours outside, so will wait for the temps to moderated a bit before tearing things apart. Thanks for the information.
Interesting to hear that your oil flow is less.....but if you're outside the oil is likely colder too. Also your lube line arrangement is a little different than mine. No problem getting parts from Cat but I bought aftermarket bearing cages and hubs....MUCH less expensive. Cat's prices are about 5 times higher.....more than I could afford. I didn't end up using the new hubs once I found out I just had a seal problem so I'll have them available if you should find yours are bad. (have the genuine CAT hub seals too that I didn't use) Before you tear it apart I'd block off the clutch tubes at the bevel gear case. (I made some blocks out of 16 ga. sheet metal) Run it long enough to get it good and warm and check pressures to the clutches. Then remove your blocks and check pressures again to see what the difference is.
]134762[/attach] The weather finally has warmed up here so we got started on pulling the steering clutch/brake assemblies apart today on the D6C, removing the RH side first. The seal on the clutch piston was still intact & it looks like there would be about 1/8 to 3/16 end gap when installed. One thing I noticed was there is about 1/16" play up & down on the hub shown in the one picture where the clutch assembly bolts up on the outside, which heads out to the final drives...... I wonder if this means trouble? Oil does migrate out to the finals from here & they always run over full. Nothing else looks real bad but we will pull the clutch pack apart tomorrow & see what we find there. The main hub with the inner spline (see picture) has some noticeable wear where the clutch splines slide, being a bit wavy......not sure how much is ok?
Yair . . . Metalman 55 If the machine is a keeper I believe you would ignore this at your peril. The hub is either loose on the top pinion or the pinion bearings are on the way out. Either way it needs looking into or it could get very expensive . . . if its bearings and you catch it now the gear may still be okay. You also need to check the cross shaft bearings. Sadly, (in my experience) lifting the lid on the back end of a tractor very often results in a can of worms. All the best with it. Cheers.
We got a little deeper into it today, have the left side apart now as well. Note the notches in the inner spline of the outer hub that the clutch discs slide in, not real deep (maybe a little over 1/64") but sort of jagged. Also the inner part of the other hub that the inside of the clutch discs slide against is grooved as well. Clutch discs seem intact, no loose pieces coming off, maybe about 1/64" left to the bottom of the grooves on the clutch fibre. Maybe all clutch discs should be replaced if there is only that much left? Is there any point in trying to smooth up the inside of the spline of the outer hub, thinking that by doing so it may allow better travel of the clutch fingers without "hanging up" on the lumps n bumps. The outer part of the hubs where the brakes make contact looks real good. We plan to look into the pinion shaft slop next, going out to the final drives next. It may spell trouble, with both sides moving up & down about 1/16". Maybe this will be the "can of worms"?
Yair . . . Metalman55 Nothing I see there looks too extreme, it can never hurt to smooth rough edges. I don't know if I'm thinking Cat or Allis but the clutch is sometimes judged by the stack height of the assembled plates. There will be minimum value thickness for individual frictions . . . in other words if the individual discs are within spec. you can adjust the stack height with an extra disk. Don't let me lead you astray here, there are folks on here a lot more knowledgeable than I and it has been along time since I had anything apart. Cheers.
Is it just the camera angle in the first picture or is that disc warped up a bit in the center? I would say if there are any burs in the splines that would cause the discs to hang up a little it would be a good idea to smooth them off. Someone else with more experience with these clutches might know the wear limits on them, but just looking at the pictures they don't look bad but I sure get the spec's and measure each and every one. Update: Checked SIS and found this: 4. Check the discs and disc assemblies for wear. If the parts are worn, use new parts for replacement. The thickness of a new set of steering clutch discs and disc assemblies is 2.012 in. (50.10 mm) to 2.222 in. (56.44 mm). The minimum thickness for a used steering clutch unit is 1.800 in. (45.7 mm). mm). So they don't give wear limits for individual plates and disks but give the total "stack height" which is just as good or better. But I would use a straight edge to check each one for warping as this could trow off the measurement of the stack.
Thickness of one new 5M1199 disc assembly is 0.176 to 0.192 in. Thickness of one new 3S1691 disc is 0.084 to 0.098 in. Clutch pack is 8 new disc assemblies and 7 new discs. What I see so far looks pretty good to me.
No visible warping that I am aware of.....they did look very flat. We will check the stack height to see how it compares to the specs provided.
The Clutch Discs and Brake Drum look very good to me, measure the Clutch pack thickness for total stack size also checking the spring hight, then swap the clutch and drums to the opposite sides, on the pinion flange lift even with new bearings you will have a small amount of lift on D6 and up tractors, you might find it easier to use the D6D long nose adaptor to pop off the flange from the pinion, I remove the pinion nut then screw on the D6D press up adaptor with a 1/8th or so gap from the flange then press the flange Off as the flange is very dished, there is 2 adaptors for the D6 tractors the short 1 is for the C's the longer 1 is for the D's, I tend to always use the D6D long item as it works a lot better, the flange has to come off on D6 tractors to remove the top pinion. tctractors
Ok......some more measurements to report on here.........Left Side Pinion travel up & down is .024, Left Side Pinion end play is .029. Right Side Pinion travel up & down is .020 & the end play is .050. Those measurements for the up n down movement were taken on the od of the flange hub which would be about 2" or so in from the bearing, which means a bit less slop at the bearing itself. Does that much play sound acceptable? We have seals leaking oil, presumable from the pinion seals getting into the final drives, overfilling them, so plan on replacing them & see what else we find.
OK, probably just the camera lens and angle.
I couldn't find any specs but that amount of movement in roller bearings is excessive and would give the seals a real work out to keep up.
Have you checked the bevel gear bearings? Later Bob
If you are referring to the inner hub/shaft on the opp side of the clutch assemblies, yes we did & they seemed tight, no movement. There is however some play in the rotation of bevel gear shaft. How do we measure what is acceptable there?
We will pull the worst side apart & see what we find. Can everything be taken apart from inside the clutch compartment when disassembling, as far as the pinion shaft, bearings & seals are concerned?
the right side stacked height is 2.011" disc assembly .174" .178" .175" steel disc .091" .087" .084" the left side stacked height is 2.087" disc assembly .174" .172" .172" steel discs .087" .091" .085" Measurements for the stacked & random individual measurement's on disc assemblies & steel discs as well.
The end float on the top pinions is not a problem it is a good thing allowing the bearings an amount of running comfort, the lift that you measure is going to be checked when you pop out the top pinion's to replace the seals so its not worth worrying about but even with new bearings fitted slight lift is often to be found, when the new seals are fitted it will make the lateral movement hard to measure, by the look of your clutch plate tips things are running fairly well, the cross shaft bearings will be hard to check for lift with any lateral movement that is easier to spot not a good thing, even with no movement on the cross shaft I have found the bearings starting to fail, the cross shaft needs a good amount of care to set up correctly so if this is a new thing for you to tackle understand the method and technical issues needed within this area, read the service book making a script of all the torque loadings, Lash setting and ton pressing data, I can knock them out easy often with only 2 shim adjustments to get the correct lash but the bearing pre-load can be a game with 4 or 5 shim changes to get things good. tctractors
If you keep the shims as they were 1 to 2 is about all you need to move I have found. Bearings are built to very close tolerances. A good rule of thumb is to have the bearings set so it takes only a good grip of the tapered spline of the bevel gear shaft with your hand to turn it, that will be 60"lb. Then install the gear and check the backlash. Remember the pinion is floating and must be pushed towards the trans and locked with a bolt to check backlash, check in 4 spots. Later Bob
Check the bearing behind the bevel gear, it caries the heavy load. Later Bob
You can remove the inner bearing and cage, seals (duo-cone) and pinion from the steering clutch side but the outer bearing and race is only accessible with the final drive case/cover removed.
With the pinion removed only the outer bearing that is fitted into the cover of the final drive cannot be changed, both races on the pinion can be swapped out along with the duo-cone seals, if I have oil transfer from the main case to the F/Drive I check for other ways this might be happening, so with the top pinion removed and the back end oil drained, I pour central heating oil through the pinion hole into the F/Drive flooding the case up to the lower bolt holes of the pinion housing, any cracks are easy to spot plus leaks from the intermediate gear housing that is often the cause of oil migrating, after testing the 1 side I pump the leak test fluid from the 1 side to the other side to see what might be leaking, on the cross-shaft work I try to use a new shim kit as often the old shims are damaged, the bearing pre load is best set with the correct torque gauge the spec' is in the Book as Bob said its Inch Lbs,I have a torque wrench with a clock face to read off this detail, you need to keep the bevel gear turning min 3 rotations to set the rollers in the correct running position before these checks. tctractors
Ok.....more to report on here..... First the back lash on the bevel gear is at .022 with the pinion gear fixed tight, no end play on the bevel gear shaft. I noticed it was recommended to check in 4 spots though & we only did one...... Left side pinion (the worst one) is out & bearings seem good, however looks like some past damage has marked up some of the teeth on the pinion. I took two pictures of the worst teeth. Some of the teeth have no marks on them. The gear on the dead shaft has some bits n pieces out of it from past damage too. Prying on the dead shaft gear gives a bit of movement, but not excessive. Ducone seals will be changed out on both pinion shafts. With this visible damage to the pinion & the intermediate gears, is this something we should be overly concerned about, based on the fact that we only intend to use this machine about 4oo hours or so in the next 6 years?
Went ahead & checked the backlash on the bevel gear in 3 more places & it ranges from .022-.023. If there is no end play & with the backlash is in that range, how necessary is the preload check? BTW everything looks clean in the bottom of the 3 compartments...no chunks or pieces anywhere to be found. Pulled the RH pinion out & bearings & the gear look good, much better than the LH side with no marks on any of the teeth. Only seals to change out here.
There should be no end movement of the bevel gear shaft. From zero movement there should be 0.005" preload applied to the bearings. The bevel gear back lash spec is 0.015" +/- 0.004" so your a little beyond recommended. Rest of it looks good.
The checking of the Bevel gear lash in 4 spots around the hub is to check for a bent cross shaft as this is a common drama, don't be scared to pour heating oil in through those big holes the pinion lives in, as this might show you how the oil transfer is happening, blame is often placed on the top pinion seals??? I often find this to not be the cause. tctractors
Someone with more experience overhauling finals might comment, but I'd be a little concerned with the pinion gear flaking out as much as it is.
pull the right hand brg cap off on the bevel gear; side that takes the thrust and visually check the brg. Your in this deep and its only 6 bolts. That is the brg that gives all the trouble in there. It was actually updated to a larger brg on D6Ds from the previous C models. There is a cat service magazine article about regrinding the shaft to fit the improved brg if an owner wanted to do it. As TC and Bob said its a slow and careful job setting up bevel gears and brgs so take your time. Also make sure you rotate the shaft at least 20 revolutions to force the rollers up on the brg ramps to make sure they are properly seated before checking preload; which is 30-40 inch pounds on a D6C
I wonder if these marks on the teeth are from some sins from the past where something broke & got wedged in the gears, chipping them? To me it does not look like anything recent, but not having much experience with such things, cannot say for sure. Can anyone else weigh in on the marks on the gear teeth?? BTW D6C10K, with your problem with the steering clutch's not releasing, did you change all the disc assemblies & metal discs on yours? Were the inside splines on your hubs rough like mine are (see pics)? We have decided to buy all new disc assemblies & metal discs & just clean up the rough on the inner splines.
Yair . . . Metalman55 . I believe what you see is wear and tear, possibly made worse by a worn bearing in the past. In my experience on larger tractors the gears hold up fairly well until a worn bearing allows some misalignment and they don't start popping teeth off wholesale until there is a complete bearing failure. When we got severe spalling it was standard practice to swap gears to the other side to present a better face on the load side. Cheers.
I didn't replace any of the discs as the stack height was good and none were warped. Your drum looks to be grooved on the top of the spline teeth from the edges of the steel discs but not so much down in the splines. I had the same kind of wear but perhaps not quite as much. If there isn't much wear down in the splines I think taking a disc sander to the tops of the splines would be fine......I think I did the same thing to mine the first time I had it apart. I did have a small amount of wear down in the splines from the disc teeth but the local shop didn't think it was a concern. I did stone/file the splines some just to be sure. During this last go around I was just about frustrated enough to replace everything in sight but that gets pretty expensive. Mostly I was fighting with a low oil pressure to the clutches. Trying to get that fixed is was led me to make my own full-circle clutch seals.
D610K,did you have a chance to try out your full circle clutch seals and could you share the results please.
Just my thoughts, but those plates, drum and hub look very good to me, the marks on the top of the splines are nothing that would get me spending coins, just swap the clutch over to the other sides would be the only thing I would do, the top pinion spins very fast and is often found knackered like the thing you have, a CAT Classic Part is the best way to go on this item, don't forget the bearing is pinned also don't use a cutting torch to Nip things through as you will damage the shape of the housing/s. tctractors
So far the seals seem to be working fine. I ran the machine with the bevel gear case open and they were sealing up good. The original seals spray oil out at the end gaps on the seal....the full circle seals hardly leak a drop. You can't see the clutch plates in assembly, but I could tell the clutch was releasing because of the oil movement out of the clutch drum when the clutch was released/engaged. The pressures came up quite a bit with the new seals...still just a little below spec. but I think that's probably caused from something else. Two likely suspects: trans relief valve bypasses more oil than seems normal and the clutch control valve bypass that lubes the bevel gear bearings seems excessive too. With pressure close to spec. I decided not to replace more parts. All said, I still get a little clutch drag when cold....don't think it's ever going to release like a dry clutch. With the double reduction of the final drives it doesn't take much to move the tractor.
Thanks for the info. Seems you have done about all that is practical. Some drag when cold is expected.
I had a final rebuilt in my 6D a year and a half ago, used a cat pinion, but replaced the outer gears with cat classic. they ran 116 hours till the intermediate pinion shelled out taking the other outer gears with it. my advise is never ever use cat classic anything. There is NO cat warranty on any of that "classic" junk. I was lucky, no tooth got caught between gears and destroyed the case. this was 10G that I didn't need to spend.
I use plenty of "classic" junk gears but I do think the C.G.R. stuff is O.K. the Classic junk has the same Warranty I think as pucker CAT? anyhow there is often other variable points that cause trouble within a gear train that might be the reason of early failing, so I am not put off using lower cost gear sets, some of my customers will only have the genuine parts fitted to their tractors, I don't try to sway anyone to buy anything usualy just giving the customer the parts list of items I need letting them sort out the requirements, the "classic" junk range is better than lots of junk that is being sold at this time, I probably do more F/Drives than anyone else in the U.K. at this moment so my comment is a fair outlook on things. tctractors
I might have been better off buying the c.g.r. parts here, but cat didn't sell them and was pushing their "classic" aftermarket parts. I have used c.g.r. parts several times before and they have all been fine. I just thought my experience might help somebody else avoid this kind of a disaster. wish I could have had you come over and help me with it. I did use all new bearings/seals all the way and replaced them all over again after all the metal went through them.
Better to get good used cat parts than Classic or any aftermarket. I saw a Chineese bull gear destroy the steering clutch and bevel gear case of a mint condition 13X 955. Some $avings. Later Bob
We pulled the hub off on the "abuse" side of the bevel gear to expose the bearing & race in the hub & all looks good we think. We do not plan to remove the bearing from the shaft at this point. We plan to tighten up the backlash a bit more by moving one shim to the opp side then check the preload. The thinnest shim appears to be about .007", so thought we would try that first. Can anyone weigh in on this while it is still apart?
One thing leads to another....the ring gear needs to be removed to get an accurate pre-load torque on the shaft once your shims are set. As mentioned torque should be 30 - 40 in-lbs although up to 60 in-lbs is probably ok. Might be able to reduce some of that back lash in the process.
Ok, thanks for the additional information. We were glad to find the bearing to be in good shape.
The actual spec for this test is 275 psi +- 25 psi, at idle, at operating temp with the clutches disengaged
We were able to locate a used "Genuine Cat" LH top pinion from our local cat dealer to replace the one with the wear for reasonable cost. All other parts & seals appear to be readily available too, so hope to start putting things back together in a few days. For the reinstall of the hubs that go back on the bevel gear shaft & the top pinions, someone with extensive experience mentioned that you do not use the retaining nuts to pull the hubs on, rather they need to be pressed on. Our manual is not clear on the reinstall of those components. Can I get any information or diagrams on what kind of hardware in required in order to press the hubs back in place?
Here's the manual pages: View attachment Cat0001.pdf View attachment Cat0002.pdf I'll get the inside hub pages shortly....
Here's the inner hub page:
Thanks D6C10K.
So not sure what kind of answers you have received, but give me some back ground on your issue in detail. I can tell you that most of the non releasing concerns with clutches and brakes are rarely related to the brake or clutch. Usually a failure in these systems will result with non operative brakes or steering response concerns - worn bands, disks or plates. That type of failure will be indicated in bad oil samples, powertrain screens that contain metal and/or friction material. The typical operation on these clutches are spring applied and pressure released. Keeping that in mind, when you demand a turn - left or right you provide pressurized oil to the appropriate clutch, when released the pressure is dumped back to sump which re-applies that clutch. The very first place you should start is checking the linkage to the valve and verify that it is set to the correct dimension in the manual, you also want to be sure that the apply pressure is correct and that when it releases you drop to 0 psi. If any pressure is seen except for 0 psi, the linkage is not set correctly or the internals on the steering valve(s) are hanging up and not allowing the pressure to return to sump. I would also verify that the passage back to sump is not obstructed with anything. Let me know what the out come of your findings are.
Hi mate any time I have had trouble with steering clutches on the likes of a d6c I have found the right hand bearing in the bevel gear shaft collapsed or on its way out, this causes the White nylon seals on the steering clutch Pistons to cut out, they also cut groves into the bearing cages that house the steering clutch Pistons, what happens is when u pull the steering clutch lever the oil being sent from your steering valve down to the clutch piston bypasses the piston seals instead of putting pressure on the piston to release clutches, this can accur on both sides but in normally worse on one side than the other
We checked the bearing & it seems to be in good shape & adjusted the preload. Have all new seals, disc assemblies etc. & plan to start putting things back together tomorrow morning......
Success so far..........we finished getting things back together this morning, followed Nige's advice & did a flush with #10 wt , followed by 1/2 hr. of light running, drained all compartments again, replaced the trans filter & refilled with #30 wt oil. All seems good so far & the clutches release about 95% better than before we started the project. Just a tiny bit of drag when the oil is cold, but nothing to speak of. It takes al lot less pressure on the brake pedals to turn now, especially when cold. We drained the finals & replaced with #50 wt.. See attached pics of the final drain plugs, with what looks like a minor amount of metal bits . The more close up pic is the LH side & it is a mixture of sludge & metal shards, mostly sludge. Does this amount of deposit seem acceptable? We will keep an eye on them & drain again by fall & see what is back on the plugs after cleaning them off today. So far so good I think....... ATTACH]136166[/ATTACH]
If you don't know when those plugs were last cleaned I wouldn't be having a heart attack just yet. Clean the plugs and put them back. Run the machine for a few days. Get hold of a spare plug so that you can pull one plug out and insert your spare plug without losing any oil. Take a photo of the plug you remove and then reverse the procedure to reinstall the plug without cleaning any accumulated metal particles from it . Do this when the machine is cold. Repeat the process with the plug for the other side. Keep taking photos (try to take them from the same angle and from the same distance away) every time you remove the plug for inspection. The photos will show you the rate of accumulation of metal particles on the plug. When you get to the point that you are ready for an oil change drain the oil and clean the plug. Make a point of ensuring the oil in any compartment is at normal operating temperature before you pull the plug before draining.
Agree with Nige, that amount is nothing to be worried about at this time. Actually I'd say after using the dozer I'd repeat the check of plugs when cold the next day and keep a record of what they look like, post here if you like. Checking these plugs once with no clear record of the hours since they were last removed is like pulling an oil sample with no record of hours on machine or history of previous samples. Now if you were finding things like the head of a bolt or half a tooth then I'd start worrying!
Agreed, there is no way of telling how long it has been since the plugs have last been removed & cleaned. We have only owned the machine for 2½ years & this is the first we have drained the finals. Will try to pull them at intervals & inspect.