Rebuilding Ark 550 loader cylinders

[JackC 616]

I acquired an ARK 550 loader for my D-200. After I got it installed and tried to use it, the bucket cylinders would not hold the bucket in position with weight in the bucket.  It appears that the cylinders need to be be rebuilt. I can move the cylinders and bucket up or down by pushing one way or the other. I assume the control valve is OK but don't know.

 

I checked with a shop that does hydraulic repairs and it sounds like it would be about $100 per cylinder to rebuild them and two weeks because the shop is very busy.

 

Does anyone have experience rebuilding these cylinders, have a link to a repair manual and know the parts and tool needed?

 

Thanks,

Jack.

 

 

Edited November 8, 2016 by JackC

[82Caddy 851]

Take your cylinders apart and go get some o-rings.  That's all they are.  If they cylinders aren't scored at all, it shouldn't be a problem to replace the o-rings.  It is pretty messy though.

 

Here's what I used (sourced from FleetPride)

 

 

 

Mine had snap rings in the ends.

[JackC 616]

82Caddy, Great thanks.

[82Caddy 851]

It was like 2$ worth of o-rings, so you're not out much more then time if it doesn't work out.

[JackC 616]

Do all 4 cylinders take the same O rings?

[82Caddy 851]

Mine used all the same o-rings.  I took the old o-rings and cylinder parts in with me and had them measure everything to get the right ones.

 

I have one good lift cylinder if one of yours is bad.

[rmaynard 14,893]

I rebuilt all four of my cylinders on my ARC-500. If I remember correctly there are 3 large and 1 small o-ring per cylinder. They were easy to take apart and reassemble, but it is a messy job. I know the small rings are 1" ID x 1/8". The large ones I'm not sure what they were. I'm out of town now or I'd go measure my extras.

[JackC 616]

82caddy and rmaynard, thanks for heads up on being a messy job. I will prepare for that. Good to hear they are not hard to take apart.

[maxiblue 352]

The cylinders only have "O" rings no so called packing, they come part easy do it your self. I paid $16 for all the "O" rings to do all 4 cylinders, and yes it was a piece of cake to do. I went to see about to have them rebuilt and they told me the same $110 each but the guy told me the same do it yourself and I did. been there and done that. 

[953 nut 51,650]

   Take the time to pressure wash everything prior to opening the system, then drive it onto a throw away tarp, block the tires up on some pieces of 2 X 8 and raise the edges of the tarp with some 2 X 4s. This way the lost fluid is contained. Do likewise on the bench when rebuilding the cylinders. This is one job that requires cleanliness. 

[JackC 616]

953nut, I wondered what would happen when I open the lines. Thanks for the suggestion.

 

 

Starting with a clean loader / tractor and based on the inputs so far, my plan is the following:

Part 1 - Cylinder Removal

1. Drive tractor onto a throwaway tarp.

2. Block up edges of tarp to contain the escaped fluid.

3. Close cylinders as far as possible to minimize fluid in each with loader arms down, bucket tilted up.

4. Loosen fill plug at top to minimize pressure in the system.

5. Disconnect pump at quick connect fittings.

6. Loosen top most fittings first.

7. Remove cylinders.

 

Part - 2 Cylinder Repair 

1. Prepare bench / work area for leaking hydraulic fluid when cylinders are disassembled.

2. Locate snap ring pliers.

3. Disassemble first cylinder to get O rings to be matched.

4. Measure diameter and thickness of O rings.

5. Pending:  Acquire O rings for hydraulic cylinders (Nitrile rubber, also known as Buna-N) : Stop at FleetPride Parts and Service in Albany, NY to purchase 3 large and one small O ring per cylinder.  I called FleetPride and they said they would have to order them. They suggested stopping at Mooradian Hydraulics in Castelton, NY to see if they have them in stock. Part numbers may be 6342 (their vendor) 568-222 (large O ring @$.40 each) and 568-214 (small O ring @ $.34 each).

 

Further steps to be supplied.

 

If any suggestions, we can update.

 

Updated based on suggestion by 82Caddy to take one apart to be sure to get the right O rings.

 

There were a few variations to the Ark 550 loader through the years so best to verify before ordering O rings.

 

Thanks for all the inputs so far.

Edited November 8, 2016 by JackC
Updated based on suggestion by 82Caddy to be sure toi get the right O rings.

[82Caddy 851]

Take one cylinder apart first and take it with you to ensure you get the correct o-rings.  

 

I have no idea on the history of mine so they may have been turned or not be the exact same sizes as yours.

 

I'd locate the snap ring pliers first...so you can stop and get another set if you can't find them

 

[JackC 616]

I will keep updating the procedure as it evolves. Last update was based on an input from 82Caddy.

[brandonozz 168]

JackC,

I had the same questions when I found my cylinders leaking on my new Ark loader.  Here is a thread to my rebuild and it worked well.  The only difference is I have retaining rings that need to be "peeled" out of mine but other members have reported theirs are different.  Take a look and see if the thread helps.

Brandon

[JackC 616]

Taking the cylinders off the loader was very easy.  The tarp was a big help in dealing with the fluid leaking from the cylinders and the lines. I used a small ice tray to collect the leaking fluid. Less than a quart leaked out in total. The system holds about 6 to 7 quarts. A drift help to keep the cylinders from rolling all over the place while I was trying to drain them.  Only a few basic tools are needed. After I got the cylinders off I found that one was so bad I could push it in and out with very little effort. I was not sure how bad the other one was so I decide to just rebuild the two bucket cylinders. I decided I would leave the loader cylinders alone for now. I got the cylinders cleaned up and put them in the back of my station wagon. On the way home I stopped at Mooradian's Hydraulics in Castelton, NY since I was told they would have the O rings. When I walked into their shop it looked like hydraulics heaven with all kinds of tubing and machinery all over the place.  I asked if they had the O rings and they asked if I wanted to rebuild them myself. I said not particularly. They said they would take a look at them and to call the next morning, so I left the cylinders. I called the next morning around 10 AM and they said they were all done and the charge was $135 plus tax. I figured that was well worth not dealing with the mess and having them ready for work this coming weekend. Another shop told me 2 weeks and about $100 per cylinder which is why I was considering rebuilding them myself.

 

Here are some pics. After I installed the loader I discovered that the bucket would not hold weight so the bucket cylinders needed to be rebuilt.  My plan was to do them myself but I found a shop with very quick service and reasonable prices. I store some of my tractors in those snowmobile trailers.

 

 

 

Edited November 10, 2016 by JackC

[JackC 616]

Installed the rebuilt bucket cylinders and the bucket no longer drops from its own weight. The system works fine when cold. After about 15 minutes the system cannot lift the bucket. I took the spool valve to the shop that repacked the bucket cylinders. They said those seldom fail and tested it with compressed air. The spool valve appears to be good. The next suspect is the pump.

 

I assume it may be a gear pump that is worn. If so, it may be better to replace the pump rather than rebuild it with new bearings, chamber and gears if the parts are even available. Has anyone rebuilt or replaced the hydraulic pump on an ARK 550 loader?   I do have an extra pump from a Quick Way loader. Not sure if it will work.

 

I do see gear pumps on eBay for around $100 if I can find a compatible pump.

[JERSEYHAWG / Glenn 4,487]

Jack, nice machine and loader. Your so organized you scare me  

 

Job well done with good documentation.

 

Glenn

[wallfish 15,919]

52 minutes ago, JackC said:

I do have an extra pump from a Quick Way loader.

Use this pump to verify since you have it but it sure sounds like the first pump is suspect.

[JackC 616]

Glenn, I bought the loader for my D-200 without being able to test it. They are hard to find and it was not that far away so I bought it anyway. I paid $1,500 for it. They are not that complicated.  The only problem I am running into besides the issues with the loader itself is the lack of four wheel drive traction. When the bucket is full, and even with a ballast box on the back, sometimes the rear wheel will spin if I am on sand (beach) or an incline.  The loader makes a great stump puller for the land I am clearing and the smaller stumps around 1 inch diameter. I bought a device that grabs the stump and I tie it to the loader with a rope. Raise the loader arms and up comes the stump.

 

The Wheel Horse tractors with loaders are good for the lighter duty work but four wheel drive traction is the way to go for the heavier duty work where more traction is needed.  Too bad Wheel Horse did not provide a differential lock of some kind to give us at least two wheel drive.

 

[wallfish 15,919]

If the pump supplies enough pressure to pull stumps out of the ground, it seems like it has enough pressure.

Maybe try switching the circuits on the valves? Just re-position the hoses. Then the issue may switch to having a problem with the boom lift and the bucket works fine. That would kind of isolate the issue you have to the one spool valve.

[JackC 616]

"If the pump supplies enough pressure to pull stumps out of the ground, it seems like it has enough pressure. "

 

Actually, I was referring to the use of my Quick Way Loader for pulling stumps. I have not gotten to that point yet with the ARK loader. Everything works fine with the ARK loader when I first start up the tractor.  After about 15 minutes of run time it wimps out and will not lift the bucket or even tilt the bucket properly. I know the bucket cylinders are good since they were just repacked. If I let it sit for several hours it will lift the bucket. Maybe after the fluid heats up and the fluid thins out a little the wear in the pump becomes evident. I also used hydraulic fluid that comes with anti freeze in it which may thin out the fluid a little.  The ARK  may work OK with a thicker hydraulic fluid to overcome the wear in the pump?

 

Here is an article I found on repairing or replacing gear pumps:

 

inspections-for-possible-problems-with-gear-pumps.pdf

Edited November 22, 2016 by JackC
Add article on gear pumps

[JackC 616]

Found this from dgoyette Senior Member while poking around:  This tells me I need to check that my PTO clutch is working properly to drive the pump before I replace or repair the pump. I have a unit that measures RPM by sticking a piece of reflective tape on the device to be measured. I also ordered some Permatex 54540 hydraulic fitting sealant to put the spool valve back on. Some recommend not using Teflon tape because pieces of the tape can get into the system.

 

Posted September 16, 2009 · Report post

Just an update to complete the thread.

 

I noticed the pump sounded louder when I was dumping and lowering the loader bucket. So I tightened the belt off the PTO - no big change. I then noted that when lifting the bucket with gravel in it the pump was turning very slowly but full speed lowering. Well turns out the PTO clutch was slipping so I tightened the the clutch linkage by adjusting the turnbuckle.

 

Seems to work great now. Not sure if it is just coincidence that this happened at the time I changed the fluid. But I suspect maybe it was like that before but the thinner fluid in the hydraulic system was not heavy enough to cause the clutch to slip. The new heavier weight fluid just showed that the clutch needed adjustment. So I now have full lift power back.

 

Darren

[JERSEYHAWG / Glenn 4,487]

Jack, I know what you mean re the 4 wheel drive. This might be a sacralidge here, (we know thats spelled wrong   ). But anyway thats why once in a while I look at other brands with 4 wheel drive.

 

ok  let the stoning begin.

 

Glenn

[roadapples 6,981]

Not sure it makes any difference, but my Ark loader calls for 10w30 or 10w40 motor oil...

[JackC 616]

9 hours ago, roadapples said:

Not sure it makes any difference, but my Ark loader calls for 10w30 or 10w40 motor oil...

Some ARK manuals specify 10W30 or 10W40 heavy duty motor oil and some, including the manual with my loader, specify hydraulic fluid.

I did contact the company that acquired the ARK business to inquire about the pumps they used and they said there is no one left who can provide any helpful information.

 

I did see a reference to using Cessna pumps in the Wheel Horse literature on their loaders.

It appears that Cessna pumps are still available.

 

I am hoping my problem is the mechanical PTO adjustment on my D-200 since I never checked it since getting the tractor.

My D-160 has an electric PTO that does not need adjustment.

 

I will be reinstalling the spool valve and will check the PTO adjustment this weekend.