Ark front end loader questions

[Matt Polk 27]

I’ve got a ark 508-qm front end loader that I’ve put on my 520h. I bought the loader with already the wrong pump on it. Does anyone know the proper pump number or gpm for the hydraulic pump? The pump that’s on it runs 5.8 to 11gpm at 4000rpm.. the pump is using a 5 inch pulley. The tractor will only pick up 100 pounds, won’t try to lift anymore, or if even lift the front tires off the ground. Any help would be amazing because I would love to use this tractor! 

[wallfish 16,988]

The original Cessna pumps are NLA. That pump you mention is a little high on the output GPM but that only speeds up the movement. Is there a PSI rating on the pump? It should run about 4-5 GPM. More will just run it faster. Volume of the fluid doesn't necessarily affect the power. PSI does.

I'm guessing the issue is in the valve.

Like the pressure relief is set too low and fluid is bypassing

Maybe seals are worn and allowing fluid to bypass

The connections are in the wrong ports could be possible too. Looks like the return is coming from the power beyond port but I'm not completely familiar with that model loader or what the exact valve is. I'd assume it's the same as mine but IDK. How about some closer up pics of that valve set up?

Also possible, the seals on the cylinders could be worn and allowing fluid to bypass

All the air has to be worked out of the system if you had it a part. Be sure to keep filling the reservoir as use it and remove the air.

Just use the bigger one in the back!

 

Here's a good replacement if you do need one. The input RPM can be controlled with different pulley sizes and therefore control the GPM volume.

https://www.northerntool.com/shop/tools/product_200329712_200329712

Edited August 21, 2022 by wallfish

[squonk 41,040]

Volume will effect the speed and a lot depends on cylinder size. When that piston moves in a cylinder you need to fill the space vacated by said piston. 5 GPM is pretty much correct. My loader is home built. I have a .5 cu.in. pump on my Power King loader.

 

 

I do not have the exact specs but a same sized and branded pump on e bay  is rated at 2610 psi and 4.43 GPM @ 2000 RPM. The stock pump for my tractor was a 6.15 GPM 1250 PSI @ 3300 RPM. My pulleys are a 3" on the 14HP Kohler engine and 4" on the pump. the loader frame is 3/16" box tubing so it's quite heavy. I can pick up the empty bucket at idle. And this boulder was no problem.

 

 

 

 

[Matt Polk 27]

Here are some photos of the setup I have. Does anyone know where the pressure relief valve is for this loader? So it sounds like I need to find a different pump with lower psi and gpm.. I haven’t had anything apart I just purchased the loader and started having issues with it when I went to use it.  The pump that is on it is a cb2a-f11sa I believe the psi is 3000 but I’m not sure. Thank you for all the help so far. 

[squonk 41,040]

Just curious. Is your PTO clutch disc in good shape and not slipping under load? 

[Matt Polk 27]

I don’t think it is… 

[Pullstart 62,812]

I believe that big flat head slot on the left of your hand controls is your relief valve..

[Matt Polk 27]

When I took it out briefly, a bunch of fluid came out and spring… so I just put it back in. Is it behind the spring? 

[wallfish 16,988]

Yes, that flat slot is the pressure relief. The tension on that spring is what holds the fluid pressure back to where it's set. Tighten to increase the pressure but now you should get a gauge to measure the pressure.  Excessive pressure can be a big problem! Fluid under pressure can be very dangerous when it's released.

Also. The ports are clearly marked on the valve body.

IN should come from the pump. ( But that unidentified port may also be IN) OUT should be the return.

Are you using any other circuits that would require the use of the power beyond port? BYD

BYD port is for additional circuits but requires a special port insert to do it.

It may work the way it is plumbed but IDK for sure

 

[Matt Polk 27]

That’s what I was wondering if the ports were messed up, but the loader works great with not weight.. except for when I try to push the loader back down it seems like it wants to go up before it goes down like it’s fighting itself. That relief valve screw is tighten all the way to the right.. when I loosen it it comes out with a spring and fluid comes with it..? 

[Heatingman 971]

39 minutes ago, Matt Polk said:

That’s what I was wondering if the ports were messed up, but the loader works great with not weight.. except for when I try to push the loader back down it seems like it wants to go up before it goes down like it’s fighting itself. That relief valve screw is tighten all the way to the right.. when I loosen it it comes out with a spring and fluid comes with it..? 

The flat head screw is the adjustment. All the way in would be as high of a setting as the relief will allow. 
 

The set point of the adjustment should be set using a pressure gauge. 

 

 

[wallfish 16,988]

I'm guessing you may be missing something inside that relief valve. Remove that flat head screw and take a look in there. It's possible that screw may be a cover and there's an adjustment in there. Is that spring a very stiff spring capable of ho;ding high PSI?  Fluid would come out of that hole that has passed the relief valve.

Basics of a relief valve

 

[wallfish 16,988]

Is the reservoir full?

 

[Matt Polk 27]

Yes the reservoir is full, I’ll take that screw out and spring and see what behind it let y’all know. Thank you everybody for trying to help out! The problem I have with the pump is that it seems all the pumps that run around 4 to 5 gpm at a lower psi are on back order.. 

[squonk 41,040]

Since your pump has been replaced It was probably done so to correct the problem you're having. Another one most likely won't fix it  Sounds like an issue with the control valve to me. Something is stuck letting enough fluid to slowly raise it and not releasing ( changing direction) to lower it.

[Matt Polk 27]

The guy that replaced the pump told me just bought the wrong pump and thinks that’s part of the reason that’s it’s messed up.. to much pressure maybe? I’ll check behind that flathead screw this afternoon and see what I find. 

[oliver2-44 9,713]

With to much pressure the loader would move fast and would pick up lots of weight…maybe even more than designed for. 

[Matt Polk 27]

Alright so I doubled checked it’s full of fluid, I unscrewed the flathead plug and found a spring and a metal dowel looking thing inside( picture attached) some fluid did come out when I took it out. I messed with it some as far as turning it less or turning the cap all the way and it didn’t seem to do much to the lifting capacity. I also noticed when I tried to roll the bucket to try and left the front of the tractor, the lift cylinder still moved. Everybody’s help is great, just itching to find the culprit. 

[wallfish 16,988]

yup, that spring is the tension for the relief valve like pictured above for that basic relief valve video.

Maybe some information on the pump? Make model etc etc. Is it capable of making pressure turning counter clockwise? Some pumps are directional. Some pumps are bi directional but the in and out ports switch to accommodate that.

Maybe remove that BYD port hose and connect it to the OUT port. Put the cap on the BYD port

Verify all the hoses are plumbed correctly

Could be a bad pump. I know how I would verify it but high pressure fluid is dangerous. Too easy to blow a hose or seals or whatever. Search hydraulic fluid accident images and it will give you real respect for the forces involved

I'm out of ideas so maybe taking it to a hydraulic expert is the best and probably cost effective

[Handy Don 12,177]

4 minutes ago, wallfish said:

high pressure fluid is dangerous

 

4 minutes ago, wallfish said:

hydraulic expert is the best and probably cost effective

 

@Matt Polk unless you've got really trustworthy info on that setup and trust your own level of self-education on hydraulics, I agree heartily with @wallfish--get an expert. They'll have the right test equipment and will tell you very quickly if anything is incorrectly plumbed. A good one will gladly answer your questions and may give you a useful lesson in maintaining your new toy!

Edited August 22, 2022 by Handy Don

[Matt Polk 27]

THANK YOU for everyone's help ill try to get it figured out!!