I'm working on a CAT 320l that's low on track power, you have to use the boom/bucket to pull it on a trailer or up on a dirt pile. It slows down to nothing when you try to turn it. Im not real familiar with CATs, but I've read a little about the pressure reducing valve, could this have anything to do with my problem, and/or what else do I need to look into? Thanks for any help, jonathan.
How many hours on the machine..? Low on track power the first place I'd be looking would be the seals in the centre swivel. Your symptoms are typical of failed seals. If you do a search on the excavators forum for "swivel" it should throw up a number of threads on the subject.
Nige, the unit has 6408 hours on it, thanks for the reply.
I agree 100%
Yes i to agree, i would look for evidence in return filter, but if it were changed they will be gone. I would pull and reseal rotary manifold ( swivel ). do you have service manual ? Not a bad job at all to do.
No I don't have a service manual, I'm a Case tech and only have access to those. From what I've been told none of the filters have been changed since this became a problem. Where's the return filter located at? Thanks for any and all help! Jonathan
Make 1 more post and you can send PMs. PM me your Serial Number plus your e-mail address and I'll send you all the info about where the filters are located along with Part Numbers plus the required parts and reseal procedure for the swivel.
Is low on power on both tracks or just one? Are there any other functions that have reduced power?
if you can post a serial number we can help more. I have service manual for 320n . And Nige is always very helpful,
And welcome to the forum, its always nice to have a case tech in the group.
Dad, you can operate the machine in a straightline wide open and it feels normal, try to turn either way, load on a trailer, or climb any kind of incline and it falls on its face. All boom functions are normal.
Thanks Overworked, I'll post the serial number in the am.
A perfect description of the symptoms caused by failed swivel seals.
Sounds like swivel to me, filter by hyd tank. Later Bob
hyd filters Both return and suction are in top of hyd tank. I'll try to add pic
I've got the machine S/N and his e-mail address. He should have all the info regarding filters and the swivel by tomorrow.
One of the things on here that fascinates me is the screen names people pick. I just had to ask, where did "anorexicvega" come from?
Lol @ Mitch, It comes from my love of 71-73 Vegas, I'm in the process of building a '73 model right now, all aluminum v8, turbo-charged manual trans car, the anorexic part comes from the cars being light, and i'm taking extreme measures to make it even lighter. I use this name on all forums across the net.
I pulled the return filter, I see no evidence of chunks or seal debri in the filter. Is there a troubleshooting procedure to test the swivel seals? Test psi at certain ports or anything?
Not really, if it's strong on the digging parts but not tracking worth a damn it's usually the swivel. No rocketscience involved.
And my guess was a skinny vegetarian,
I'm with Nige on this one.
Replacing the swivel seals is not difficult and would have needed doing at some point anyway. Also I've keyed in on a different Part Number of seal to the one metioned in the Parts Manual that works better at what Cat (laughingly) refer to as "high operating temperatures" but to most of us would be normal. The high temp ones are what I would put in if it was mine. I don't think you really need to go as far as the 2-piece forestry application seals, that would be taking things a bit too far.
Lmao, now that's funny right there....I'm a 6'1 275 country boy, and I love me some meat and taters.
Ok, thanks, I figured Chevy Vegas somehow, but the anorexic part threw me. For what it's worth, I'd go to the swivel first, and I'd trust Nige. He seems to have it all in one sock where Cats are concerned.
In my experience with swivel seals I haven't seen any that came apart, just got hard and wouldn't seal like they should.
Dad5, i have done many swivels, not uncommon to find complete seals missing, mostly in the " cool " running cats. I would follow Nige and put the high temp seals in. Overworked
Right on.
Ok, so I got the seals in and the swivel installed back in the machine. They definitely made a big difference, the unit somewhat turns now, but it doesn't seem like it has full turning power. Any suggestions? any ports that i need to do pressure checks at? Thanks, jonathan
Just sent you the complete Testing & Adjusting manual for the hydraulic system. I suggest do all the basic system cycle time tests to establish a baseline (you may find something else on the machine that is slow), then concentrate on the travel circuit. If you find more than just the travel circuit with cycle time issues go right back to setting up all the relief valves in the system one by one, starting with adjusting up the main relief valve so that you can set all the line & travel crossover relief valves one by one. Then you can go back to setting the main relief valve where it should be. I'm assuming your tracks are not too tight..?
Their a tad on the loose side Nigel.
Just checking ..............
Is this a straight 320L, B or C or what? On these smaller HEXs, we had a lot of trouble with bad crossover relief valves. To test, block the sprocket and check relief pressure in fwd and rev. Exchange the positions of the crossover reliefs, check again and see if the pressure difference (if any) has changed direction.
its a straight 320l Cmark.
CM, I e-mailed the OP the full hydraulic Test & Adjust manual for his machine (9KK prefix) with a recommendation that he go right through the machine in the same sequence as the manual checking relief valve pressures and resetting and/or diagnosing as necessary. IIRC the travel crossover valve was 3rd or 4th on the list of settings to check. I would do everything in order. Even if he finds nothing out of spec on any particular relief valve at least he knows he checked it.
check case drain for propel motors
I found that on one side, both travel crossover valves have basically zero pressure, and the other side is just a lil bit out of spec.
Ah-ha. The thick plottens ............
I swapped both valves from one side to the other side, and those to the otherside, the side that had no pressure, still has no pressure, and the side that did, still has pressure.
Check the travel operation in hard going with one circuit stalled(bucket closed would be good). That will tell you if it's pump or motor. In equalized travel one pump feeds both travel motors. Counter rotate might work good. Later Bob
Now you're making progress. My next move would be to block off the main pressure lines at the motors (flange fittings, yes? 2 bits of 1/4" flat bar with holes drilled in them, and longer bolts) and if you now have good pressure, you're looking at a fault in the motor. You could, as an alternative, check the case drain flow from the motor but I prefer to block the lines as this will tell you if all the other components upstream are in good order.
flange fittings yes, so if I block them and the pressure returns, the wheel motor is bad?
Correct !.
Double correct!!
I blocked both ports off, still zero pressure, I switched the pilot lines from the opposite side, and that made no difference either. My main relief pressure is within spec, the boom, stick, bucket are all within spec. This equipment is bound and determined to make me old and gray headed...lol
Sounds like one spool is not moving far enough, if at all. Have seen them get jammed with broken parts from old failure that wasn't cleaned out. Later Bob
sorry might have over looked a step, you are changing test port location from one to the outher when checking both tracks, correct. one section of pump for each track, side with zero pressure is guage on correct side? sometimes we overlook things easyer as we get more frustrated. overworked
does track with no pressure move when you lift machine off the ground? if yes then you have some pressure, i think we are missing something simple now. i agree with Bob, if track moves some you should have some pressure, if spool stuck completely then maybe no pressure, if not moving all the way i think you would see slow track movement ie- low flow, but should still have pressure, then again , i say tell the customer the diag is complete when the machine is fixed, alot of straws holding up one pile. overworked
You switched the pilot lines where? If you switched them at the MCV so now left lever is controlling right track, and vice-versa, and you've resealed the swivel then as far as I can tell the problem should be in the MCV. Spool not shifting or something not telling the pump to upstroke. Is it loading the engine down at all? Maybe check the schematic for something in the MCV that can effect the load control circuit or the NFC circuit but is mutually exclusive to each spool?? It's past midnight for me now and I'm going to bed. Someone in a different time-zone will chime in now, I'm sure Edit: Above written while bob and overworked were typing their replies.
what Cmark said, if there is something wrong like that, running both track should get around it to see pressure and pump upstroke
Unless i'm mis-reading the service manual, it says to check the left and right crossover valve at port (3) on the bottom side of the pump, pin the sprocket and check forward and reverse pressure. one side doesn't move the guage in either direction, the other side is within spec.
the track with no pressure according to the guage, pulls when its on the ground, in dirt, rock ect. the machine just don't turn like it should, hard to put in words.
I switched the pilot lines at the top of the control valve, it made the hand levers work backwards when I did this. It's loading the engine when I move the lever to the side that's reading no pressure. it seems to me it has pressure, but something in the circuit is not letting it read.
You need two hoses and gauges, each pump drives one side. I think you are getting pressure, just need to move hose or get one more setup. Later Bob
Yep. Bob's right. You're checking the wrong test point. The machine has two pumps. One drives the left track, one the right track. You need to switch your pressure gauge to the other test point....
your correct bob, I moved the gauge to test port 2 and got pressure within spec, the manual says check both at test port 3. I guess the only thing left is checking case drain at the wheel motors.
Do something less messy first. Raise each side one at a time run at full throttle and time the track revolutions, each side forward and reverse. Then check those Reassures again at low throttle setting and compare. Come on back with what you get. Later Bob