Ec35 driving issues

[Asa Joel Spicer]

Hey guys, I bought this 2005 volvo ec35 about a year ago

Everything functions flawlessly... boom/bucket/swivel/plow all work great... until you go to turn.

Driving straight, high and low speeds both work. As soon as I let go of one of the levers even a bit, i lose all momentum.

If I try to turn with one stick forward and one stick back, usually only one track turns and it's very slow. Seemed to be the right track was the worst for this but now seems the left is getting slower also.

If I live the machine with the boom and swing with only one track it usually turns very quickly.

If I'm traveling I can use any boom or blade controls fine, doesnt seem that I've lost any power in those.

Motor does not seem to bog either. Maintains rpm during the steering maneuvers.

Once oil is warm, I can only turn in low gear. If it's in rabbit and I try to turn, both tracks quit. If I switch to low they start moving

Any help or pointers would be great!

I'm wondering if the valve body that the levers go into may be bad? Other than the pump isnt that the only thing both tracks share?

 

[John C.]

It's possible the swivel is leaking internally or that the pumps are de-stroking at a low pressure.

What you are describing is pretty common on a lot of mini excavators. They generally aren't designed to be able to turn in high speed mode. Sometime things like this can be aggravating to an operator but very expensive to find the issue and fix it for the owner of the machine. And one may have to consider that it is an operating characteristic of the machine and not a problem at all. Others should be along and comment if they have the same machine and same issues or not.

 

[Asa Joel Spicer]

Well I looked at a YouTube video of another ec35 and that's what made me post this, turning was very fast and effortless

 

[David Boreham]

Hi, I have a similar machine (ECR38) that has the opposite problem: it turns great but won't drive in a straight line in one direction. I haven't yet got the bottom of what's causing this (see other thread) but one technique I found useful in investigating which I don't think you mentioned trying is: use the bucket/boom and blade (on opposite end from bucket) to lift the machine clear off the ground. You can now try running the tracks in all combinations of directions/speeds and easily see the speed the track moves at (and also hear the sound they make). I found this much easier to get an idea what's going on vs actually driving.

 

[John C.]

That won't tell you what the travel is like under load. Mr. Spicer's problem is travel under load. Variable flow pumps are reactive under pressure and flow.

 

[Asa Joel Spicer]

Yeah but I never thought to just life the whole machine. Lol. But yes... doesnt solve my problem found out I have two bad lower rollers on one side so I'll be down for a bit (on the left side, right side has the most turning problems)

 

[Asa Joel Spicer]

John, how does the center swivel leaking relate to weak tracks? Are they in the same system somehow

 

[Asa Joel Spicer]

By the way guys, one day a few weeks ago I was running the machine pretty hard (like normal but this was the first time since winter) and after a while I noticed the tracks had alot more life in them... I thought, great! But then the next time I used it, back to weak again

 

[Ronsii]

The swivel joint provides *ALL* power to the tracks so any leakage in that joint will affect the tracks.

 

[Asa Joel Spicer]

Oh! Nevermind I thought you were talking about the swivel "motor" I understand now. It's definitely oily under the machine body. Not dripping but definitely "moist"

 

[Ronsii]

For general pressure troubleshooting on these things I'd recommend you get at least a cheap set of gauges the import stuff starts at around 40-50 bucks... then all you *might* need extra are some different adapters. Track stall tests are fairly simple but it does help to have a service manual for your specific machine to eliminate a lot of guessing.. Without the gauges you could still pull case drain lines and do some pressure side swapping to diagnose issues and figure out where the problem is....

 

[Asa Joel Spicer]

How much for max pressure do I look for on a gauge set?

 

[Ronsii]

According to ritchie's that machines main bypass is @3335psi So I'd guess a set with 5k max would work.... most of the cheepie test kits out there go with 3.5,5 and 9k gauges; but this is the guessing I was talking about without a service manual instead of having hard numbers from a book you would have to compare sides or find out pressures from someone else that knows the machine... I haven't really worked on volvos so don't know the specifics... the track motors may only get 2k or 2500psi???

 

[John C.]

The swivel is a rotary manifold the channels oil from the implement valve in the house down into the carbody and then to the motors. It is just a barrel with a spool running down the center. The spool has passages and what look like plates machined into it. On the edges of the plates are hydraulic packing seals which seal each passage off from the others. Piping is hooked up in the carbody to route the oil to each motor. Each motor will have in your case four hoses to it from the swivel. A and B flow, two speed travel and case drain. The swivel will have four large hose connections that run the motors and two small connections that are teed to the case drain and the two speed function.
The leakage can occur in the swivel because when you are moving both tracks you have a high pressure on one passage and a low pressure return possibly on a passage next to it. A leaking seal might allow high pressure oil to bypass into the low pressure passage which means you don't get as much oil to that motor and it doesn't have the same speed or power.
Sometimes you can check the swivel by traveling one way and observing the slow track, and then reversing direction and see if the other track is now slow and weak. You can waste a lot of time troubleshooting a swivel so for the most part if there is a question a lot of times it's just easier on many machines to just remove and reseal it. There are other possible issues it could be that involve a pretty fair amount of knowledge and experience with some risk of spending copious amounts of money for dubious results. I would highly recommend finding someone local to help walk you through troubleshooting what may or may not be a problem worth fixing at this point in the machine's life.

 

[David Boreham]

How much for max pressure do I look for on a gauge set?

I have the ECR38 Service Manual (note: different but related machine). It says operating pressure 240 bar, secondary pressure 300 bar. fwiw the manual was not too costly to buy on a popular auction site.