Hey got a cat 303.5e mini excavator when using a function such as boom bucket or stick it stops and I have to release the joystick then pull back and it starts again, the functions also slow down when this happens, this same problem also occurs while tracking and you have to release the lever then push again for it to work, it only happens when the engine speed selector switch is on 5 or above when below that it works normal. Can you all please help?
Start by checking pilot pressure
I'm getting 2800psi on main relief and 460psi on pilot. How do you suggest I proceed? When functions stop working pilot stays the same, if you keep the function activated it slowing starts moving sometimes
Tee into pilot line on spool depending on where your testing pilot you might have flow restriction if pilot checks out if assume pump regulation issue
Since its occurring on more than one function which one do you suggest I tee into? Remember the problem only happens if the machine is running at engine speed over 5 it works fine when ran under that
Any one that acts up just so you have a definite path to follow
Ok have to get some fittings to make the tee would update you as soon as I do. Is the main relief pressure to low tho?
Too many 303.5E options to take a guess which one you have. Need a S/N.
S/N rky02808
Main Relief Setting 3590+/-35psi Pilot Relief Setting 493+/-30psi Has anyone thought to check the precharge pressure in the pilot system accumulator.?
Yes that was actually my first thought, I checked that by shutting off the machine and turning key to on and dropping the boom and it worked so I'm guessing that's ok. Well my main relief is low according to your specs, I tried adjusting it but it neither goes up nor down, I know some Mechanics were fiddling around the machine trying to fix it and they adjusted most of the reliefs to no avail.
Although the pilot is in spec it’s only just.... Don’t you think it’s weird that you can’t reduce the pressure at the main relief.? Surely if you wound the adjustment right out the pressure ought to fall.?
Yes I think it is weird was thinking about taking apart the relief and see if anything's wrong, I'm going to tee into the pilot line at the spool and see what my pressures are when I lose functions
So I tee into pilot line for spool boom raise when it stops moving I'm still getting pilot pressure there so I guess that checks out, if I use the boom up and down alone it works but if I used another function with boom raise it stops, where do I check from here? How do I go about checking pump regulation?
Check suction strainer and return filter if they look good need to tap into load cense pressure at pump regulator
Is the return filter in tank? What am I looking for at load sense?
Is there a load sense?! Never messed with E generation, isn’t E pump is the same as previous or it is an LS pump?! Or the load sense is the line from gear section to a piston sections compensator. You need to identify which functions you having problems with! Because if the E have the same pump as previous - you basically have three hydraulic circuits in one package. There’s piston section which basically two pumps in one, there’s gear section. You Main Control Valve is also divided in to three sections ( although it looks like one) with two of those doing some flow combining. If my memory do not fail me - the gear section serves dozer and swing or slew. Look at both auxiliary pedals, weather they are not packed with mud or rusted in activated position - that will throw you off for the loop!!! Check the auxiliary switch if it is not somewhere in between positions, check weather pattern changer is in correct position - I’ve seen the stop roll pin on those bent many times. it would help to know the history of the machine. Did you just buy it with the problem or was it working fine then problem showed up It kinda sounds like someone was messing with pressure compensator spring inside the pump, but that shouldn’t affect the pressure in the functions that powered by gear section. Also, if that machine does not have separate “fourth” pump for the pilot - it means two or all three circuits have branches going to pilot block, there might be problem with check valve(s) in there. I’ve had JCB doing weird things because check valve in that block came out.
If it is only happened at higher engine speeds - kinda sounds like the compensator spring is either broken or miss adjusted. If at slower engine speeds combined operation of right and left joystick does the same - that’s another clue!
Forget what I said about patterns changer and one/two way auxiliary - on E it is totally different from what I used to!
So I'm having problems with boom lift stick and bucket and also tracking, it only happens at engine speeds higher than 5 l, thinking it may be a pump compensator problem but how do I check that?
History of the machine is it was working fine and then the problem started to occur, I think the gear section is just for pilot pressure
Let’s start with the history! Was machine working fine and developed the problem? Or you just obtain the machine or just started working on it?
Yes, I looked at the parts diagram and it looks like gear is a pilot with the pilot relief valve right on the pump. if my theory is correct and machine developed the problem, then most likely one of two springs inside the compensator is broken. If you not afraid to tinker with that adjustment, then mark the position of the adjustment screw ( so you can put it back) and tighten the adjustment half the turn and see if it is helped anything.
You mentioned earlier if you using boom up only that it is fine, but if you do combined operation then machine stops. if you using the function that on the same circuit ( usually it is bucket) and it does stop - then I am wrong. But if you using something that on the another circuit ( usually it is stick and/or swing), and machine stops or slows down - then most likely I am right. You see, that compensator is just a spring ( actually two, but works as one), so when force applied by piston overcome the spring force at set value - spring starts to collapse, swash plate moves and reduces the pumps flow. When you increase the engine RPM it increases the force applied to the spring at the same pressure as at lower RPM. When you using function from another circuit - you inducing the pressure on second row of the pistons, which increases the effective area twice, and also increase the force applied to the spring.
What am I looking for at load sense?
Tried playing with the compensator adjustment but no improvement, took it apart spring is good inside. Where should I look at next?
Isolate the pump from main control valve and pressure test it. This way you will know what part of system you having problem with. Do not use plug/cap!!! Use needle valve, if using flow control valve ( there’s a difference) make sure arrow points away from the pump.
Did you play with compensator adjustment marked by yellow arrow and checker springs 19 and 20? Or played with pilot relief valve, marked by red arrow and checked the spring there?
My bad I played with valve marked with red arrow, I would play with yellow marked valve and check springs in there and give you an update
So remove outlet hose from pump and replace with needle valve to check pump pressure?
Yes, you can either dump other hose straight in to tank or just install needle valve downstream from where your gauge teed in to, start the engine, go to operating rpm and slowly turn knob in. See what pressure you can get out of pump. Just make sure your gauge is installed between pump and needle valve.
Also consider the pump coupler going bad and friction driving the pump. Although in this case it would be one hell of a friction drive!!! But you know what they say - never say never!!!
Ok as seen in the picture I would remove from where fitting goes into valve bank and install needle valve there and dump outlet of needle valve directly into tank. I would have to source some fittings and a needle valve to do this diagnosis, is there any particular type of needle valve I would require?
Ahaha that's true, I wouldn't mind this being the problem tho
I would go to hydraulic shop to pick up needle valve. It have to withstand greater pressure then your max. Operating pressure, and hose size need to be close ( or bigger) to the line you install it on. They usually stock only NPT ported ones ( ORB usually have to be ordered), so you gonna need couple of adapters from NPT male to ORFS and whatever you gonna run to tank. But I would leave it fir later! I would check the springs, adjustment and coupler, see if you can avoid buying all this stuff.
Good day Have you checked to see if the fluid is foaming? Kind regards Uffex
Fluid is not foaming
I took apart valve and didnt find any springs inside
That’s interesting. I used your serial prefix when was looking for the pump parts diagram. And parts breakdown says 19 and 20 are springs. Well, put new o-rings and re install.
Can you see weather springs are behind this vave? That pump looks like SBS pump, so if it is SBS you can only find it on CAT, Mitsubishi/TMC equipment. That thing that you took apart is the one that line from gear section supposed to come to, when gear section is used to power up the dozer blade and swing. If your machine has only one gear section for pilot - it might not be in use.
I cant see but didnt feel any with my finger just oil pouring out
It looks like that valve buts against the piston, and on the other side of the piston there’s two springs that push against the seat which connected to the pin, and that pin is the one that pushes on swash plate.
Short of buying the manual for this machine, that’s the only information I can get on that pump: https://avspare.com/caterpillar/sebp5957/sebp5957025/#SEBP59570252
Thinking to buy new valve and install. Bypassing this step of the diagnosis for now what do you think I should look at next?
I wouldn’t buy that valve unless I see damage to it and know for sure that’s a problem. Next is basically your choice, coupler or isolate the pump and pressure test it. As far as I understood from the previous posts that your problem is low pressure. So it is either pump or main control valve. I would test the pump first.
So I've been doing some research and I believe these springs are the ones you mentioned but they are located inside the pump to get to them. So I think I'm gonna pull the pump to check coupler.
Cant say, never messed with that pump. Can you share the link where did you found that picture?! If I am right, and this is an SBS pump, then there should be two socket head bolts on each side of the valve that you posted pictures of. Possibly if you take those bolts off you might get to the springs. Although taking pump off, inspecting the coupler and inspecting the valve plate and pistons might be beneficial also. All depends on your skill set!
There’s also could be phenomena known as “block lift”, which pertains only to piston pumps. Your valve plate have to be pretty much worn out for that! I haven’t dealt with that on these duplex pumps, but I just remember stumbling upon information about the Takeuchi mini excavator that had that, and one side was a lot worse than the other! Which is strange because it is the same piston block and the same valve plate. Maybe it is have something to do with which row ( inside and outside) and geometrical vectors and physics of forces applied. The block lift always accompanied by pump overheating, that’s another clue for you.
Need to monitor load sense pressure at pump. you got a better chance winning powerball than them pumps friction driving and speed related slipping
Usually internal springs neutral pump. Broken springs would give u pump out pit my experience leads me to believe you have issue with load sense pressure or the regulator is not working
Block lift should be pressure related first comes on hard digging sounds like this is acting up no loaf
As I admitted before - I never worked on E series of these machines, but: the only pumps that servo piston springs are return to neutral is the closed loop or hydrostatic pumps! And this is definitely not the case!!! So here is the question: do you for certain know that this is LS pump ( then those springs are bias springs, but still not returning to neutral), or that is what they call a mini excavator duplex pump?!
So an update, I pulled pump coupling is ok
So how do I go about troubleshooting load sense or regulator issue?
Have not took apart pump yet what do you suggest?
I only can say what I would do. I would open up and inspect, but you have to decide on your own.
I would open and inspect and get back to you with what I see
Pump looks fine internally no unusual wear no broken components
Well! It is not duplex pump. There’s some contamination scratches on the piston slippers. If you can, please post the picture of the piston block where the valve plate rides against, and also wipe the valve plate off and take a picture again, please.
No problem I would have to take the pictures when I'm back at the machine but there were no major or deep digs or scratches if that's what your looking for. Saw some wear on swash plate bearing which I dont think would cause the problems I'm having.
These springs are those you mentioned before. Also the spool at the end of this valve sticks if pushed inside to far, dont know if that is normal.
Those springs, do they upstroke the pump ? Is there small 1/4” line going to that spool from MDCV?
I know you didn’t get the answer from the person who come up with idea of the load sense. If there is load sense, then there would be a separate line from MDCV port marked LS, to the pumps regulator. At neutral the pressure on that line would be close to 0, but pumps discharge pressure would be at value what is called “LS gain pressure” usually it is around 300 psi. So LS would register the pressure on the other/work side of the spool ( the side that goes to the cylinder or the motor), and relay that pressure to the pumps regulator. Regulators job is to constantly upstroke the pump to maintain that “LS gain” value. For example if the pressure on your boom cylinder is 1000 psi, then LS will “show” that pressure to regulator, and regulator will upstroke the pump to make it 1000 psi plus LS gain ( let’s say 1300 psi). But because there multiple spools in the MDCV and only one LS gallery, there’s check valves in it. And basically the check valves job is to open channel between spool with highest pressure on it, and shut rest of them from LS gallery. So pump will “see” the only highest pressure at the moment. And those check valves get stuck often. When check valves get stuck then you loose the function or two completely. But that’s not what you described.
I think they are an adjustment for pump flow I believe. There are no lines going to that spool. The lines go to the other spool which is the pump control and has the line signal, pilot out etc.
What is the MDCV? And where would these check valves be located?
MDCV is your Main Directional Control Valve.
Pilot should be isolated circuit on this set up.
For TVA's benefit, here is the Hydrayulic Schematic.
How many discharge lines go out from piston section of the pump?
Thanks Nige!!!
And here's the pilot system. Had to shrink it down a bit to get the schematic to fit on the page.
I’m going to have to spend time with it. But it is NOT classic LS flow control, not NFC either.
Although I was wrong! Looks like it is classic LS flow control, the PPS line threw me off ( usually they just get that one from pumps discharge line), but also looks like this got hydraulic toque limiter build in to the regulator, which even considers pilot pump load. It is understandable with the small engine. Pretty sophisticated MDCV, with in flow ( pre compensation) controller for each spool!!! Just like “Big Boys”! Must have save a lot of fuel and provide good proportional control! Nige?! Can I be impudent enough to ask for explanation of function of this pump Controller?!?! Please?!?! I am a little fuzzy ( gross understatement) on hydraulic torque limiters?!?! Too young! Only dealt with electronic EPPRV/power shift stuff!
Here you go. Sorry I had to get a bit funky with the formatting in order not to chop off bits of schematics.
Missed a couple .........
Aaron! Your pump doesn’t look too bad, need to replace the swash plate bearing inserts and polish the journals. Still check the port end on the piston block and pistons themselves. And of course some lapping. But nothing catastrophic ( at least from what I did see). I am still going to have to learn this stuff what Nige graciously provided. But I suspect that the problem is in the spool that on the pilot pump ( not on top of the piston pump), that looks like torque limiter that kicking on too early, and for some reason not coming back right away. You can take that apart and check for wear and scoring, while I am still “in school”!!! Or find someone smarter then me, and knows what the hell he is talking about!
Sir!!! You’re very gracious and generous!!! Thank you!!! Thank you very much!!!
The spool that is on the pilot pump? Do you mean the same one I sent a picture of? I saw no scourges on the spool but for some reason the spool sticks when pushed in all the way.
What I wanted to say was - don’t know for sure, but think that the problem is in the regulator that have three lines going to it, not the one with the springs.
Torque limiters are there to not let the engine bog down with hydraulic load. But it is sounds like yours was kicking in too early and was not coming back as soon as it should.
Also could be unloader ( or unloading valve), that valve on schematics everywhere, but no designation for it on the MDCV Drawings. It is item #13, it is in the inlet section. Usually it is a spool with round holes through the side, with tiny, looking like carburetor jet hole on the top and spring on the bottom. Last one that gave me head ache was on HAWE valve bank, it had travel limiting stop which wore out, and let unloader spool travel too far, to the part in the bore that was not ground and polished, so the spool would be showed in there by the pressure and would not come back. Not sure what is the function of it in this particular application, but usually it is used for converting valve bank from LS configuration to Fixed Display Pump configuration.
Spool does not seem to be damaged or anything. Such a weird problem it's frustrating with no obvious cause
So it's in the inlet section of the MDCV?
Look for hex plug, probably on the top or the bottom of the inlet section, it should be under there. I usually just shove it down with fat Allen key and see if it will jump back or get sticky.
Yes. Kinda looks it is on the bottom of inlet section, the cover with three ( or two) socket head screws.
OK, Aaron. While you have pump apart: there should be an office between pilot (gear) pump discharge line, and that long and skinny piston in the regulator that have three lines going to it. Check if that orifice is there, not loose or unscrewed and free of damage. Also Check the old o-rings between the pumps body and that regulators body. This system has variable “LS gain” Or more correctly LS margin, and gear pump flow is used as sort of “tachometer” to determine what margin supposed to be at what RPM. Unloader valve also controls LS margin. And somewhere along the way. At RPMs position 5 and under pressure, something leaking out margin pressure. At least that’s one of the going theories at this time. Just noticed that one of the holes on that regulator body doesn’t show the stain from the o-ring.
Ok so on the inlet there is only one Allen head plug took it off and there is nothing inside just a hole. The o rings on the pump body have no cuts but they do look a little flat would see if I get a part number and get them from cat and change them out.
What is underneath of the cover with two socket head bolts and the hex on the middle? The main relief is In the outlet section - on the opposite side of the valve bank. Did you find orifice in the pump? Although it might be just calibrated hole in the housing. Anyway, try to look for a carburetor jet looking thing, or set screw looking one with little hole in the middle, or at least the place where it should screw on to. Never mind! Just found two orifices in the pictures, set screw looking ones. Just make sure that they are clean and tight.
OK, I missed something that you said yesterday ( it was late and I was tired) about spool with springs being sticky when pushed further! We might be on to something here. Let me look at the docs. some more and I will get back to you.
You never showed the shorter piston inside this valve, the one that the skinny plunger at the end pushes on. That one have to have O-ring and back up ring on it.
Also you need to check all the channels inside the pump for obstructions.
The eroded, worn out and started to delaminate cradle bearings ( or swash plate bearings) are not helping things go smooth either!
Here it is, there is only an o ring on it tho no backup ring.
The one with the two socket head bolts and hex in the middle is some sort of relief valve I didnt take apart that one tho. Yes I found 2 orifices both were clean and tight.
That "spool" (or at least the outside end of it) doesn't move. IMO and without consulting the Parts Book it looks for all the world like it should have a backup ring installed.
I think that was my mistake, the figure showed it in red, as an pump delivery pressure, and I took it for a back up ring. And looks like it only can be moving with adjustment.
I can see it now! Everything looking good there? Everything mowing free and no sticking, o-ring nice round and sticking out little bit from the groove? No scratches or scuffs anywhere? Especially on the skinny one?
I’ve been asking about this one:
Where this one go, on that picture?
The only valve shown inside the inlet section is the unloader valve.
I had never seen insides of that pump before - but for some reason I don’t think inner spring supposed to be shorter the outer. There is no spring guide going through, and no way to insure that inner spring will go correctly around the “snout” of that seat. Can you look closely to the picture of the manual you found before, and see if the springs supposed to be the same lengths? From what o see - the inner spring is broken on the bottom, and broken piece wound inside of the remaining part. Or that’s just oil looking like that. Or the outer spring supposed to be pre compressed to the length of the inner spring when installed.
That one goes inside the hole which you see on the one that has the o ring and yes that one looks fine o ring is fine
It's just the oil that has it looking like that, it's not broken. From the picture I had found it's not clear to see the length of both springs.
I would take apart the one with the 2 socket heads and hex in the middle and inspect.
Can you circle it on this picture?
Just see if outer spring gets pre compressed when installed in to pumps body. If that inner spring is weaker then supposed to - it is a reason the torque control kicks in earlier then supposed to.
It looks to be in this area
Yes the spring gets some compression when installing front cover plate of pump.
Can you check weather it gets compressed to the point where inner spring touches both seats?
Everything in red color indicates hollow cavities filled with pump supply pressure oil. But these schematics are wrong all the time - so no big deal! Looks like that little one is the one that actually do the pushing on that bigger one. Because that gland with o ring is stationary.
Did you ever had main relief valve off and inspected? I know you were going to, and tried to adjust it with no results.
No specifications for those two springs, unfortunately. So even measuring free length wouldn't tell you anything. In case of any doubt that the springs could possibly be the root cause of the problem, or even a contributing factor, I'd vote to fit new ones just in case.
Thanks Nige! I don’t think you can buy those separate from the pump. Lots of these rebuilding companies use aftermarket or manufacture their own parts for rebuilding. But those are wear parts like valve plates, pistons and slippers and piston blocks. I don’t think anyone have these for sale, unless they have very high failure rates! If no damage will be found anywhere, beside already discovered, Aaron going to have to find someone with differential pressure gauges to find out weather the problem caused by drop of LS margin pressure or Torque limiter maul functions. Just to get an idea in which direction we would have to “dig”!
I guess if nothing else Aaron is going to try to play with this torque control to find the happy medium between bogging engine down on combined operations and having decent power and speed. If instructions would not be found or impossible to follow. But there’s still unloader valve left to Inspect, and I still didn’t see the port side of the piston block.
Aaron, inspect also smaller servo piston and bore, that the one that next to these springs, not the fatter one on the bottom.
Anyway 280-4448 and 280-4449 is the part numbers. Don’t go buy an airbag though! Unless you want to lift your pick up!
Same numbers I came up with. About $150 the pair.
Airbags?!
Yes I did have it off and everything inside seems fine no broken springs or anything
Is this the one that is on top of these springs which contacts with the swash plate and pushes against these springs?
Are these the part numbers for the springs?
Yes and no, there’s two pistons that connected to the swash plate, one on top ( small one), and one on bottom ( bigger one). The small one is up stroke, the bigger one is de stroke. The small on is parallel to the pin that pushes on the springs.
Yes, those part CAT numbers for the springs. But it also come up as partial part number for Continental “air springs” which are air bags for air ride suspension.
The behavior is seems to be LS or torque limiter problem, but we shouldn’t exclude main relief also, but main relief should not be rpm dependent.
Ok so the other piston is at the opposite side of the swash plate? Yes there was a piston there but I was unable to pull it with my hand or a magnet dont know if I need to send air pressure through one of the ports at the pump regulator to get it out.
Do you have a cat part number for the swash plate bearing inserts?
Number 4 is the upstroke piston, and number 6 is the de stroke piston. at this point I am more interested in the condition of the up stroke piston. Although to inspect both would be very nice. Don’t forget to shine the light inside the piston bore also.
Small piston
No, the source that I have access to doesn’t give me that. Maybe Nige can help.
Does the swash plate have the hole or a groove in its face that connects to these lubrication holes? Rexroth A10VO series 51 has orifice in the swash plate that like to get loose.
Here's the parts breakdown for the pump. Not the best illustration in the world but it's the best the system can throw up. It looks like the swashplate bearings are not sold separately.
I cant get that piston there out.
Yes there is a hole on the bearings
Not sold separately oh wow
Not the end of the world. The complete 280-4458 "Swashplate Kit" sells for $255.
Try using compressed air.
Did you mean swash plate face, and channels going to both bearings?
Yep, and kit listed in multiple places. Hey Nige, about those springs, I didn’t see them for sale anywhere ( real once ), are they available through CAT dealers? And do you have the break down of that kit, that actually shows what’s in it? Just a make sure that inserts are there, and not just a swash plate it self, stopper and possibly orifice.?
Aaron, if the orifice on the face of the swash plate is connected to the lubrication holes in the journals, that’s one point of leak - through bad bearing inserts. Need to check if the stopper bolt also has access to that channel and weather it leaks or not. And question about orifice being in that circuit, weather it should be there, if it is still there and weather it is loose or not. Servo piston needs to be removed, piston and its bore needs to be inspected.
The springs I got the price from the Cat Parts website, so dealers sell them. I couldn’t find a breakdown for the kit, so I have no idea if the bearings come in it or not. Are the bearings normally part of the swashplate or are they part of the case.?
Imo when you get it back together tee in a line to load sense line and watch as you run it. I'm assuming no load pressure should stay low as you dig it should rise. When working correctly. My understanding super simplified is Low load sense psi = upstroked High load sense psi = destroked I'm by no means a 305 expert but even if I'm backwards it should give you direction.
I am not 305.5 E expert either ( only worked on some C/CRs), but I know a thing or two in hydraulics. LS will be lower then actuator pressure for the margin value! The thing is this machine has variable margin set by flow of gear pump. Yes, when you see drop in LS pressure under load - there’s something seriously wrong!!! The question is what exactly seriously wrong?! The LS is reflection of the system/supply/discharge pressure lower for a margin value. So bucket cylinder bypassing and can only built 500 psi dead headed you will see 500 psi of LS pressure ( dead headed you will have next to no margin because there’s not much flow through the MDCV spool) - it will not mean that the flow compensator is bad! That’s why when you try to diagnose LS controlled system the differential pressure gauge is a very valuable tool! But for some reason I think it would be not easy to find that in Trinidad. So for now inspecting components for damage is the best thing IMO.
Low load sense psi = upstroked High load sense psi = destroked Kinda, but not exactly. All depends on the difference between main/supply/system/discharge pressure and LS pressure signal
By my logic the inserts should be sold separately because usually they wear more often, but how they are sold - you’ll never know! For manufacturers it’s about making money, and not about help you fix your machine as fast and as inexpensive as possible!
Go back and look at the pdf I uploaded for the 374-2025 Pump Gp parts breakdown. Is Item #12 (390-9455, qty 2) the swashplate bushing..? if so they are listed @ $143 ea. In case anyone asks, apparently there is no Reman on the pump and a new one is $2460.
I’ve must have missed it, because I was reading through list of parts by description and not item numbers.
IDK Nige! The parts list simply says “bushing” and arrow points to the housing/front cover mating surface. At that price it should be swash plate bushings! But how do you verify?! Dealers probably will have the same pictures and parts list as you and me.
At this point based on what we know, it seems that problem occurs at more advanced swash plate angles prompted by demand for higher flow and higher LS margin set by higher RPM and consequently higher gear pump flow
So my “fairy tale”: The yellow is “we are leaking some pressure but we don’t really care about it because flow demand and pressure is low” zone! The green is: “we are doing OK with medium flow demand” zone And the red is: “Oh! Crap! We are in high flow demand and leaking pressure off”zone. All this time I wondered: why there’s channel from pumps discharge to front cover?! The problem is I haven’t paying attention to the pictures ( and I haven’t seen all the pictures of this thing)! The swash plate bearing lubrication doesn’t come from the swash plate face, it comes through the channel in the front cover, through slot in one of the swash plate journals, through channel inside the swash plate body and to the journal on the other side! This is either design flaw or assemblers error, the swash plate bushing that on the side where journal do not have slot in it - should not have the lubrication hole in it ( or should e flipped 180*, to the side where the swash plate do not move to in open loop pumps)! I think delamination started from the sharp edge in that hole where oil under high pressure started getting in between the coatings layers!
Still need to inspect both servo pistons! Because there’s contamination scratches on the piston slippers, and both pistons are “dead ends”, and contamination just love to settle down in “dead ends”!!!
Looking at the parts drawing again I am 99.9% convinced those are the swashplate bushings. Reasons.? Location on the pump, price, & quantity. Look at the view below which is "Section B-B". Now that section is cut straight through the centre of the pump and coincidentally right through the centre of the swashplate mounting pins, so all you are going to see is a thin sliver of the bushing (two actually) and one of those two slivers is exactly what the #12 arrows are pointing at.
You are right Nige!!! And screws (13) are there to prove it! And this dark spot must be orifice, which also needs to to be checked, because of its gone or loose - it will bleed off more pressure then the swash plate lubrication supposed to take, might even washed out those bearings we see.
Hey guys so I've been away from the machine as soon as I get back to it I would check that orifice and servo pistons and give you all and update and some more pictures, I would use that part number for the bushings as the bearing inserts and try to source them.
Any updates this one had my curiosity
Im with you rmll WHats the final analysis?
I'm new to the Forum and don't know how to search threads. If someone has time I need help on replacing 303cr pilot lines after mechanic removed main valve and didn't mark lines? No power on front 3 valve functions, boom offset swing, blade and swing. Diagrams and parts book is confusing? Also, can't find accumulator, 2005 Cat 303CR, SN DMA04353. Thanks
The best suggestion is to create a new thread in the Compact Excavators section rather than revive one that's been dead for 2 years and was in regard to a different problem. see here - HeavyEquipmentForums