Backhoe 511 backhoe seems weak

[jrchafin]

Hey all,
Have a new 7520 with 511 backhoe. As I'm sure is standard, the backhoe hooks into one set of rear remote valves.

I only have experience with a much smaller tractor/backhoe which was much smaller/weaker, but I must say I expected this one to be stronger. Of course, I was attacking stumps as my first job, so maybe that's the problem. I was digging around the sides of some old half-rotten stumps with an 18" bucket. Of course I don't expect it to tear right through a 4" root, but it just didn't seem to have the downward ripping force that I was expecting. And the curl/dump on the bucket was quite slow, much slower than the boom and dipper cycling. This normal?

I would hook the bucket teeth under a root and curl the bucket while pushing the boom into the ground, trying to pry the edge of the root up. Instead, the bucket would just slip out from under the root. Just didn't seem like the 6000 pounds of ground ripping force that I was expecting. Does this sound normal? Anybody have any tricks to test these?

Thanks,
Jon

 

[LAWALLSTRACTOR]

First, do a hydraulic pressure test at the tractor rear remotes. I believe it should be arround 2650 psi, if my memory is correct. I will double check that spec a little later. As far as speed is concerned time the speed at which your loader goes from ground level to full height. When the tractor is warm your tractor should raise in about 6 seconds.
How old is your tractor and how many hours on it?

 

[BobG_in_VA]

Just a note, and probably not worth mentioning since you already have used backhoes, but there is a knob on the controls of the 511 that increases/decreases speeds (ie. increase/decrease fluid flow). Have you tried adjusting it?? As an aside, I've not had that problem with my 511 as I run it off a PTO pump. BobG in VA

 

[jrchafin]

The tractor is new, the loader works fine.
There is a knob on the backhoe to adjust swing speed, which I haven't adjusted. I don't see any other knob for adjustment. Would this affect the speed of the bucket? I won't be able to test this again for a few days.

 

[MessickFarmEqu]

Bradco backheos are no joke, its almost certianly low hydraulic pressure. Its not typical to plumb the backhoe to he remotes, the couplers will get burning hot from that amount of constant flow, and you'll have to bungee the lever open. It really should be plumbed off the power beyond ports.

 

[LAWALLSTRACTOR]

I checked and the hydraulic pressure at the remotes should be 2690 psi.

 

[jrchafin]

Bradco backheos are no joke, its almost certianly low hydraulic pressure. Its not typical to plumb the backhoe to he remotes, the couplers will get burning hot from that amount of constant flow, and you'll have to bungee the lever open. It really should be plumbed off the power beyond ports.

I assume power beyond ports are an option, correct? I don't see any other ports available. Anybody else have a 7520 with a backhoe? How are your hydraulics hooked in?

By the way, it came from the dealer with a small metal lever that holds the lever in the open position. I wonder if the problem isn't just inadequate flow through this remote valve.

 

[Blu 82]

I have a 7520 w/backhoe and yes it hooks into the remotes on the back of the tractor. I don't have experience w/any other tractor or backhoe, but I know that my backhoe will pull my whole tractor so it seems plenty strong for me. I have used it to pull my tractor out of a mud hole I got stuck in when clearing my property. The wheels were fairly deep in the mud and the frame was bottoming out. It will pull the tractor quite easily even with the "legs" down and the bucket firmly on the ground. I have not measured the pressure coming from the remotes but they seem to work fine. I have also dug plenty of stumps out. If the root is large and is well into the dirt, then it takes a little work to dig it out. Sometimes you have to go out several feet away from the stump to dig it out. I have dug some fairly large stumps and deep pine stumps and have always been able to dig it out but it may take a little time, maybe 20-40minutes or longer depending on how big the stump is.

Make sure the lever that routes hyd to the backhoe stays fully engaged. I did have some problems with it "popping out" when the backhoe was under a lot of stress but fixed the metal "clip" to hold it better in place.

Yes, some of the functions work quicker than others. You can dial up the swing such that it moves very quick, almost too quick for me. As for the other functions, I don't know of a control to change the speed of that particular operation.

I have 313 hrs on the tractor with a good amount of time on the backhoe. This is one extremely versatile machine!

 

[jrchafin]

Blu,
Does your bucket curl/dump go quite a bit slower than your boom/dipper?

 

[bindian]

Hey all,
Have a new 7520 with 511 backhoe. As I'm sure is standard, the backhoe hooks into one set of rear remote valves.

I only have experience with a much smaller tractor/backhoe which was much smaller/weaker, but I must say I expected this one to be stronger. Of course, I was attacking stumps as my first job, so maybe that's the problem. I was digging around the sides of some old half-rotten stumps with an 18" bucket. Of course I don't expect it to tear right through a 4" root, but it just didn't seem to have the downward ripping force that I was expecting. And the curl/dump on the bucket was quite slow, much slower than the boom and dipper cycling. This normal?

I would hook the bucket teeth under a root and curl the bucket while pushing the boom into the ground, trying to pry the edge of the root up. Instead, the bucket would just slip out from under the root. Just didn't seem like the 6000 pounds of ground ripping force that I was expecting. Does this sound normal? Anybody have any tricks to test these?

Thanks,
Jon

Jon,
What RPM are you using? My 6520 has to run at full RPM to get max use out of my 511. Your 17 gpm pump vs. my 11 gpm pump should give you a lower rpm to give your 511 it's muscle. As to trying to hook a root while pushing down on the boom, try moving boom and bucket in short alternating movements. I do know backhoes are not designed to push and you won't get full rated specs in trying to push anything. I have found getting closer to the root gives more mechanical advantage. Also, bringing my rear tires off the ground gives me a better advantage. My bucket curls and dumps slow compared to the boom and dipper stick.
hugs, Brandi

 

[Blu 82]

Yes, the curl/dump of bucket is slower. I generally run about 1500 rpm and as I said, it will pull the whole tractor. I have never tried it at full power--probably overkill. On pine trees, I have had to dig down as far as the BH will go to get the stump out. On some of the roots, I have to work at them to either break them or pull them out. Eventually, the BH wins though.

 

[bindian]

Yes, the curl/dump of bucket is slower. I generally run about 1500 rpm and as I said, it will pull the whole tractor. I have never tried it at full power--probably overkill. On pine trees, I have had to dig down as far as the BH will go to get the stump out. On some of the roots, I have to work at them to either break them or pull them out. Eventually, the BH wins though.

Try cranking your RPM up to around 1800 or 2000. I am not a fluid dymanics engineer (where is Dougster when you need him ), but I am guessing your hyd. pump's power curve kicks in rather high on the RPM side to hit the GPM you need to make your 511 feel powerful. My 6520 has to go full throttle to get that feeling. Also, get your rear tires off the ground. The 511's stablizer pads, I feel, are way to small for the 6520/7520 tractor. Mine slide a lot, until I put air between the ground and my rear rubber. I have been meaning to buy some 3/8 inch plate to make my pads larger.
hugs, Brandi

 

[SPYDERLK]

Blu,
Does your bucket curl/dump go quite a bit slower than your boom/dipper?

Check to make sure the lever can be moved to its full extent in the dump/curl directions. Mine was pinching the boot between the joystick and the plastic cover and preventing full motion.

Relating to strength, there are 2 relief valves on the tractor and at least one on the bh. The 1st is on the loader valve, and is probably set at 2500 or less. This will limit the pressure to the loader and also the power beyond port to 2500. The PB port goes from the loader valve to feed all other hydraulic functions. So you are probably limited to 2500 at the remotes even tho the relief in the remote valve body is set at around 2700. If the relief valve in the BH is set at 2500 or more thats what youll have at the BH. If less than 2500 youll have whatever the lower setting is.
larry

 

[Tim_in_IA]

check the RPM. It makes a huge difference. I run the 511 on a 6500 with a PTO pump. You should be fine with 17gpm on yours. It is either low RPM or a pressure issue. There are a couple relief vales in the loader and main tractor and one of those may be malfunctioning.

Also is the tractor warm when you are doing this? I doubt you are overheating but I don't know what the fluid capacity is on your tractor. Don't try to bite off everything at once. Take slivers out. Use the curl to rip out little bits at a time.