Hydraulic Problem With Pilot Controls

[OCR]

Hydraulic Problem With Pilot Controls:

Here's a quick test you might try, if you can see your hoses, while you engage a function.

If boom up is causing a relief to squeal, try booming up and watch the boom hoses. If they both swell up or jerk a little, that would indicate a block in the return, at or in the return port.

Try this on any circuit that seem to open a relief and watch the hoses.

Can you trace all main hoses to the the correct valve port?

Do you have any quick couplers on the affected circuits?

I sure would like to see the schematics on these machines.

Affirmative.


OCR

 

[bremery]

Here is a link to a copy of the hydraulic circuit from the service manual. http://www.bremery.com/530/530_Hydraulic_Circuit.PDF

 

[willie59]

Here is a link to a copy of the hydraulic circuit from the service manual. http://www.bremery.com/530/530_Hydraulic_Circuit.PDF

Wow, I haven't seen an excavator circuit like this one before. Pretty interesting.
Hey I see your problem already, the schematic shows you have two "left track motors"!
Seriously, I'm studying it. Thanks for the link.

 

[Iron Horse]

Have you checked the auger/hammer solenoid is not open ? If it is stuck or turned on , the machine will behave as you describe .

 

[willie59]

I'm not sure Iron Horse, what I'm seeing on the schematic is the aux valve is the dump line for pumps 2 and 3. The schematic is showing three positive displacement pumps, all of equal displacement. The circuits are open center valves, pump 2 and 3 circuit is dumped to tank via aux valve, pump 1 circuit is dumped to tank via solenoid valve. I'm trying to figure out what operates that solenoid that goes to tank on the P1 circuit, I'm thinking maybe high drive, but I've never seen it like this, because it appears it would give you high speed boom, bucket, and crowd as well. Haven't seen this before. Does the machine have high drive bremery?

 

[willie59]

After looking at the hydraulic circuit I have discovered that there is a high power circuit that is engergized by a solenoid. When engergized redirects return flow from from circuit 1 (Which is the dozer blade, swing, and slew) to the other two circuits. This is currently how the machine is running in high power mode. When power is shut off to this circuit flow from circuit 1 goes back to the tank. With the solenoid off the machine barely moves except for the functions on circuit one. They still work all the time.

Went back to review the thread, found this at post #9. This is exactly what I'm staring at on the schematic. Your problem could be the one way check valves at port P4 and Z (or 7, can't tell), seems crazy, though, because it would require failure of all 3 check valves. But I've seen crazy things before, and it would definitely cause your problem.

 

[bremery]

I didn't have much time today to work on the machine, but I did make some progress. I changed the hydraulic filter and it did not help. I did exercise the hammer circuit at the spool and it did not help. However, while holding the hammer circuit open I can get the non working functions working individually. Meaning I do not need to cheat and open another valve on another circuit, nor do I need to operate in "high power mode". I guess this is good news.

I need to pull these two check valves out of the valve block. They appear to be in the valve block pretty tight, and little access to get a socket on them.

It also appears that I have a stuck drive track. The lower rollers do not move. Will a little heat and penetrating oil work?

Thanks for everyone's help so far.

 

[willie59]

I did exercise the hammer circuit at the spool and it did not help. However, while holding the hammer circuit open I can get the non working functions working individually.

I'm not sure what your describing. When you refer to the hammer circuit, are you referring to the aux circuit? And I'm unsure of "exercise hammer circuit" and "holding circuit open". Help me get on the same page with you. Also, what operates the high power mode?

 

[OCR]

Hydraulic Problem With Pilot Controls:

bremery, or ATCO,
A quick question:

Is this Aux. valve circuit considered a "power beyond" circuit?


OCR

 

[willie59]

bremery, or ATCO,
A quick question:

Is this Aux. valve circuit considered a "power beyond" circuit?


OCR

Technically, I think you could consider it power beyond, because it get's it oil after the oil has gone through other valve banks. But it's unique to the other functions because the aux uses oil from both P2 and P3 combined. Boom, bucket, and left track uses oil only from P3, except in high power mode, where P1 oil is supplied as well. Right track, and crowd use oil from P2, except in high power mode. Boom, bucket, drives, and crowd never combine P2 and P3, the aux circuit does.

 

[bremery]

ATCO,
Yes, the hammer circuit is the aux circuit. I exercised the circuit by moving the spool with the lever to make sure it was not stuck open or closed. It moves freely. High power mode is activated by a button on the right joystick. This activates a solenoid to redirect the flow from P1. I hope this clears things up.

 

[willie59]

Technically, I think you could consider it power beyond, because it get's it oil after the oil has gone through other valve banks. But it's unique to the other functions because the aux uses oil from both P2 and P3 combined. Boom, bucket, and left track uses oil only from P3, except in high power mode, where P1 oil is supplied as well. Right track, and crowd use oil from P2, except in high power mode. Boom, bucket, drives, and crowd never combine P2 and P3, the aux circuit does.

Hmm, you got me scratchin' my head OCR, so I did a little research. I was incorrect. Actually, the function valves are power beyond. A power beyond circuit defined at insider secrets to hydraulics describes it this way;

Power beyond - also called high-pressure carry over (HPCO), is a facility on a mobile hydraulic directional control valve that enables the pressure gallery to be isolated from the tank gallery and be carried over to an additional valve - usually another directional control valve.

The boom, bucket, drives, and crowd do this by closing the open center tank port when you engage a valve, then diverts the oil, through check valve, into a galley that supplies oil to other valves as well, allowing operation of multiple functions at one time. Thanks for leading me to correct myself. :notworthy

 

[willie59]

ATCO,
Yes, the hammer circuit is the aux circuit. I exercised the circuit by moving the spool with the lever to make sure it was not stuck open or closed. It moves freely. High power mode is activated by a button on the right joystick. This activates a solenoid to redirect the flow from P1. I hope this clears things up.

Got it, just wanted to make sure that's what you were referring to. I think your problem is very likely a problem with the check valves directly below the P4 port on the scematic. If they are cartidge type valves, it's likely seal failure, but it could be failure of the check valve as well. This is a very simple hyd circuit, and failure of those check valves would cause the exact problem your having. But I am still studying to see if there's another possiblity given the symptoms you've described.

 

[OCR]

Hydraulic Problem With Pilot Controls:

The hyd. system on my 750 dozer is similar. That is, a gear pump that feeds a valve bank. (simplified description)

It also uses control pressure to open a "dump" valve, so oil doesn't have to run through the entire valve bank if no functions are in use... oil goes straight to tank from pump. (return oil)

This is a typical stacked valve arrangement with through bolts connecting the individual valves.

You can put a "power beyond" valve in the system, but it's necessary to plug a port some where in the other valves... as opposed to just stacking another valve on.

Probably way off here, and I'd have to get the books out to do better.


OCR

 

[willie59]

I hear ya OCR, that's what got me disoriented. I was working on the control valve of a Case 1840 once, and Case called the outlet port of the control valve going to the aux valve the power beyond port. Seems we have different uses/application of the same term from the wizards of smart that build these things. Hmmm.

 

[OCR]

Hydraulic Problem With Pilot Controls:

I hear ya OCR

Good!!... I can shut up now...

I think your problem is very likely a problem with the check valves directly below the P4 port on the scematic.

... :thumbsup


OCR

 

[willie59]

Your slippin' OCR, you didn't notice I spelled "schematic" wrong. Gotcha!

 

[OCR]

Hydraulic Problem With Pilot Controls:

Didn't want to embarrass an "Old Hippie"... :lmao

Besides the only reason I caught the words you're reviering to, was when I ran ieSpell for my reply, it checked your PM too... (read carefully)... lol

LOL... when that pop up came up, I though I was in for a rear end chewing or sometning... lol again.

Life's full of surprises though, eh...


OCR...

 

[willie59]

Didn't want to embarrass an "Old Hippie"

Ahh, you can embarass this ole' hippie, I'm good with that. Heck, it wouldn't hurt my feelin's if someone else figured out bremery's problem, it's all about gettin' his problem solved.

 

[bremery]

Pardon my ignorance, but are the check valves you guys are referring to contained inside the valve block? Meaning do I have to pull the all the individual block assemblies apart to get to them?

Also, in normal power mode, when I try to raise the boom or curl the bucket, I do get flow through the hose from P4 to Z which indicates the check valves are not working. I pulled a few hoses off today and did see some black residue that could be the left overs of an o-ring. I also spent some time spraying the stuck rollers with oil to hopefully free them up.

With the help from you guys I am slowly making progress.