HYD crash course HELP?!?!?!?

69.5CUDA

69.5CUDA

Blah Blah Blah
ok guys..this one is just out side of my current brain power as ive never dabbled into it...so..i need some pointers and do's and donts

got a 72 oliver with a late 70's mighty hoe on the back....the hoe runs off the pto

the hoe is doing some WEIRDNESS....swing right is slugish swing left is normal..right leg will lift the tractor left leg struggles or fails....pulling and lifting is pretty much stopped it wont do it....pushing out with the bucket is also pretty useless while pulling will actualy drag the tractor

this all came on all of a sudden..but i know my boss ran it pretty empty..we put in close to 8galons to fill it back up...im starting to wonder if some damage has been done to the pto by running it too low?..or is there air in the ssystem that needs bled out or something?...as the sluggesh bits move you can feel them surge and drag on the engine rythmicly

the more i worked the legs the better it got..so i went out to dig on the burn pit and everything got bad..real bad ..so bad i wasnt sure id get the hoe all retracted up .....when i parked it and shut it off ...i pulled the leg levers and 1 droped as one would expect the other just kinda crept a lil and stopped
 
I'm not that familiar with hydraulics, but it sounds to me like you've got some cylinders leaking or control-valve damage.
 
Doc could be on the right track with damage to the control valve. But the first thing I would check is to make sure all the air is out of the system. After filling you should always run each ram thru it's full extension and retraction 2-3 times slowly. Never under load. If you use it hard after being low it will cause the fluid to foam. If that happens, park it overnight. Then, extend & retract everything slowly.

If 1 or more of the functions work correctly, but not all, then my money is on control valve problems.

By the way, my only experience with hydraulic systems comes from 34 years of driving fork lifts. :huh:
 
It sounds like air in the system to me. 8 gallons of fluid is a LOT to replace at one time on a hoe attachment.
 
Not working them so much as repeated unloaded motions. It's just like bleeding a power-steering system--you saw the wheel back and forth repeatedly to run the hydraulics through their travel.

However, with the directional problems you describe, I still lean towards a damaged control valve. I'm certainly no authority on hydraulics or tractor shit, though.
 
I agree with the others, could be a combination of air, or damaged control valves. How old is the fluid that was in the system? If there is water mixed in with the hyd. fluid it can cause a lot of the same symptoms as low fluid or air. But I tend to lean more to a control valve since the hyd rams in question seem to work fine in one direction, but not back in the other. Trace the lines on the cylinders in question and see if they all converge on a central control valve assembly.
 
ALL of the lines both the working and not run into a central controler..but each one has its own control valve...its like a distribution block with 1 in and 6 out..bucket, leg, leg, swing, arm arm........push or pull each lever to run each unit on its own in either direction ...so if its a valve..its all 6 but that makes no sense why its all 1 way......but i know little on the subject

i was hopeing there was someone here who spent enuf time working on this crap on the farm or something lol

i sooo wish there wasnt a filter basket on the filler of the storage tank so i could have a look inside


anyone think it might be a good idea to crack open a line fitting at the cyl's and see what comes out?
 
Right...the central control valve is a delicate piece of equipment, and from what I gather there's damage. I'm not sure of the layout, but it sounds like the left-side circuit's the problem (right swing should be a left-side ram, no?).

Here's my reasoning, and as I've said I'm no expert on hydraulics: If it were air, you'd likely have it in both sides of the system, so swing/lift/pull would be equally affected. This would be the same situation with contaminated fluid, as hydraulic fluid constantly circulates. Also, the control valve is mounted fairly high so running the thing 8 gallons low means you had air at the control valve at some point, probably damaging seals since those seals require not only hydraulic fluid as lubrication, but hydraulic pressure to seal correctly (they're shaped so that the pressure expands them in their bores). I'm guessing about the layout of the rams, but your left/right swing rams should be relatively low--almost certainly below the level of the control valve. Were it air in the system, it would have worked its way to the highest point in the system. If that point was the control valve, you'd have trouble in every direction or operation. That's not the case, so I point to the control valve(s).

My hydraulic experience is limited to golf-course equipment and of course snow plows, so at best this is a somewhat-educated guess that makes sense to me if no one else.

Run the beast again, doing no work but putting it through all the standard motions. If it's air pockets, contaminated or incorrect fluid, the problems will work themselves through the system and eventually performance should decrease across the board. If not, I say rebuild or replace the control-valve body.
 
well when i added fluid to it..you could hear the pump gurgling in the bottom of the tank...and its atleast a 10-15 gal tank...as for the valve set..ima have to see if i cant find some kind of manual or something for the "white mighty hoe"..cause as best i can tell..everything but the tank is 100% stock stuff
 
001NHC-36187.jpg
69.5CUDA said:
ok guys..this one is just out side of my current brain power as ive never dabbled into it...so..i need some pointers and do's and donts

got a 72 oliver with a late 70's mighty hoe on the back....the hoe runs off the pto

the hoe is doing some WEIRDNESS....swing right is slugish swing left is normal..right leg will lift the tractor left leg struggles or fails....pulling and lifting is pretty much stopped it wont do it....pushing out with the bucket is also pretty useless while pulling will actualy drag the tractor

this all came on all of a sudden..but i know my boss ran it pretty empty..we put in close to 8galons to fill it back up...im starting to wonder if some damage has been done to the pto by running it too low?..or is there air in the ssystem that needs bled out or something?...as the sluggesh bits move you can feel them surge and drag on the engine rythmicly

the more i worked the legs the better it got..so i went out to dig on the burn pit and everything got bad..real bad ..so bad i wasnt sure id get the hoe all retracted up .....when i parked it and shut it off ...i pulled the leg levers and 1 droped as one would expect the other just kinda crept a lil and stopped
Click to expand...

Ok sounds like each action (swing, leg, etc) is a separate segment on the valve. One leg ok, one not means the bad legs segment is damaged. Each segment has a spool with wipers and o-rings (usually) and it sounds like all the segments are double acting (pressure up, pressure down). I'd bet getting a rebuild kit in the valve would fix your problems. Running it low on fluid plus crap in the tank plus a filter that's waaaay overdue for a change damaged some of the spools, so you can't develop pressure in some directions(internal bypass)

attached is a gif for an old nh backhoe valve, I'd bet yours is similar.
 

Attachments

  • 001NHC-10427.jpg
    001NHC-10427.jpg
    84.3 KB · Views: 18
Last edited:
damn now THATS some insight and yes there all "double action" valves...that first expanded view is EXACTLY what it looks like
 
74DartSport to the rescue! :dance: I knew it was just a matter of time until someone with some hydro knowledge stumbled across this.

Industrial/agricultural stuff is an arena where my knowledge is limited. It makes me crazy at work when someone calls for that stuff because I want to find what they need, but at the same time the sign doesn't say "Tractor Value". :D The counterman that just quit was really good with that stuff, as well as ATV/UTV parts (we do carry some).

Hey, at least I was on the right track! :)
 
Doc I worked in a parts store in various functions for 20 years. 10 years ago I started as the parts manager of a forklift/construction/ ag dealer, and now we merged another branch in here so I'm doing scissor lifts/stick booms/rough terrain forklifts now too. My knowledge of hydraulics is ok.
 
My hydraulic knowledge consists of brakes, power steering, automatic transmissions, and a tiny bit involving snow plows. You will notice two things: A) I don't have a snowplow, and B) I remove the power steering and automatic transmissions from my cars. I may leave the power steering in the Imperial, though.
 
well i should get a chance to have a better look at it tommarow and ill see what i can pull for info off of it
 
You must log in or register to reply here.

SiteLock

SiteLock
Back
Top