how much loader drop is acceptable?

[California]

30 year old loader... Does anyone know of a direct replacement for this valve?

Baileys seems to have some bargain valves lately. Check this one out.....
....Surplus Center....
I like the off-the-shelf hoses with npt fittings with adapters going to the valves as needed.

California, If you would like joystick operation, then look at this valve....Surplus Center....

Thanks Brad and J_J ! This advice of specific valves is greatly appreciated. :thumbsup:

 

[J_J]

MF1652,

The relief valve is on your FEL valve, and 3pt valve, and dumps the fluid when the cyl meet a certain resistance. In order to keep something from breaking, a relief valve is used to relieve the hyd pressure, and this is set at the factory, but can be adjusted.

The sound it makes relieving is like a screech or whine. It is not hard to hear it, like when you fully extend or retract the cyl. When you hear that sound, that will let you know that the hyd system pressure is at least operating up to the set pressure. The relief valve will go off until you remove the resistance to the pressure.

No matter how hard you push the levers after the valve is relieving, you will not do any more work other than what you are currently doing. However, some of those relief valves are adjustable and some of the guys squeeze out a little more power. More pressure equals more force.

 

[oldnslo]

Roy,

What I was getting to was that if the valve is leaking, with the loader raised, and you removed the PB, and return lose, you should be able to see and collect the fluid from the cyl leaking out the ports.

Yes this would work if the PB line is accessible and there are no other functions that could feed oil into this circuit, like the curl.

Roy

 

[slowzuki]

Based on the info provided, 99% sure its the seals in the spool valve. The curl function on my Kubota does the same since new, boom doesn't move. Drops faster when warm because the oil is thinner. Neighbours NH curl is fine but the boom leaks down really fast, like a foot per minute with a load on it.

Replacement of o-rings in the spool can solve but is a pain. If the cylinder piston seals are shot, you will tend to get blown hoses when lifting full buckets of stuff as once you pick it up, it will leak around so all the weight is carried by the area of the rod. So you had maybe 10 square inches going up then only 4 holding it. Also, piston leak won't let it drop to the ground empty like stated before as both work ports are closed.

 

[oldnslo]

Based on the info provided, 99% sure its the seals in the spool valve. The curl function on my Kubota does the same since new, boom doesn't move. Drops faster when warm because the oil is thinner. Neighbours NH curl is fine but the boom leaks down really fast, like a foot per minute with a load on it.

Replacement of o-rings in the spool can solve but is a pain.

What O-rings. On all the Ag type spool valves I have seen the only O-rings in them where to prevent the tank line from leaking externally onto the ground. The load holding function is a combination of spool to bore clearance, spool to casting land overlap, consistency of the casting land edges, roundness of the spool and bore.

Probably the two most common causes of leakage are the edges of casting lands being rounded or irregular from the casting process.

Land width on the casting.

Really good spool valves have mated parts with very tight tolerances.

Most Ag tractors are mass produced and for the most part have a more than acceptable leakage rate. Every so often a bad casting gets through just like any other product.

OP states that this happened after some use so I suspect either his spool is no longer centering 1/64 inch can make them fail or possibly a land on the valve casting chipped.

Roy

 

[Mace Canute]

You do know your valves, oldnslo!

 

[oldnslo]

You do know your valves, oldnslo!

thanks Mace

 

[slowzuki]

Never had one apart from an ag app, only air cylinder spools. Dealer told me I could rebuild it if I didn't like the leakage, guess not, maybe he meant try a new spool in the existing body.

 

[MtnViewRanch]

What O-rings. On all the Ag type spool valves I have seen the only O-rings in them where to prevent the tank line from leaking externally onto the ground. The load holding function is a combination of spool to bore clearance, spool to casting land overlap, consistency of the casting land edges, roundness of the spool and bore.
Roy

Roy, the Prince mono block valves have O-rings on each end of the spool held in place with the caps. In my opinion the OEM O-rings are total junk. I replaced mine with double lipped O-rings and have had zero problems since. These do show oil leakage when they are bad though, at least mine did.

 

[J_J]

There are o-rings on my Case BH valve.

 

[Willl]

Troubleshooting hydraulic cylinder drift

 

[J_J]

This has been discussed many times, and even Mr Casey agrees that if a load is pulling or pushing on the cyl rod, that fluid will transfer. That is apparently happening with some loader and curl cyl.

Hydraulic lock is only when fluid can not escape.

You could also have both cyl seals, and valve leakage.

Although valves do leak, and even have a drops per minute rate for determining replacement, but it is up to you to say when.

If you hung a hyd cyl from a tree limb, filled the rod side with fluid and plugged that port, leave the base end port open and hung a 200 lbs weight on the rod, do you think that if the cyl has a leak that the fluid will transfer, and the cyl rod will extend.

Some might say you would have hyd lock, but if that were true, how come the loader arms descend and a lot of cyl seals replaced and when the seals are removed, you see the reason from torn o-rings, flatten o-rings, extruded o-rings, etc.

Both cyl and valves can be tested, with observation, physical evidence, and just common logic.

If you raise the loader arms, and shut off the engine, and remove the PB, and return hose, if the valve is leaking, the lift arms will descend, and the fluid from the cyl base end will flow out these ports.
If you collect the amount of fluid in the cyl, then you have your answer.

However if the loader arms descend and there is no or little fluid collected from these ports, then the cyl is bypassing, and the seals are bad.

Both you have the hyd shop have the ability to check out a lot of things.

Even a hand hyd pump will test cyl and valves for leakage. You can easily see the results. Even after rebuilding, you should check to see if replacing only the seals fixed the leak. The cyl wall might be worn down, or have a slight bulge.

 

[oldnslo]

This has been discussed many times, and even Mr Casey agrees that if a load is pulling or pushing on the cyl rod, that fluid will transfer. That is apparently happening with some loader and curl cyl.

Hydraulic lock is only when fluid can not escape.

You could also have both cyl seals, and valve leakage.

True statement

Although valves do leak, and even have a drops per minute rate for determining replacement.

Most spool type DCV manufactures don't even publish leakage rates. For reference, Company I used to work for that made D03 size DCV used 5 cubic inches/minute as there criteria for in-house pass/fail @ rated 3000 PSI. I do NOT know if this is any form on industry standard.

If you hung a hyd cyl from a tree limb, filled the rod side with fluid and plugged that port, leave the base end port open and hung a 200 lbs weight on the rod, do you think that if the cyl has a leak that the fluid will transfer, and the cyl rod will extend.

Yes it will extend since you have greater area in the cap end and it is also vented to atmosphere.

Some might say you would have hyd lock, but if that were true, how come the loader arms descend and a lot of cyl seals replaced and when the seals are removed, you see the reason from torn o-rings, flatten o-rings, extruded o-rings, etc.

This is true on curl cylinder where the load is trying to extend the cylinder. Not a true statement when the load is trying to retract the cylinder.

If you raise the loader arms, and shut off the engine, and remove the PB, and return hose, if the valve is leaking, the lift arms will descend, and the fluid from the cyl base end will flow out these ports.
If you collect the amount of fluid in the cyl, then you have your answer.

How do you know if the oil is leaking from the rod end of the cylinder through the seals or out the cap end?. You haven't isolated the two leak points.

if the loader arms descend and there is no or little fluid collected from these ports, then the cyl is bypassing, and the seals are bad.

If the valve isn't leaking the cylinder won't fall. This was pointed out in a previous post.

you have the hyd shop have the ability to check out a lot of things.

Even a hand hyd pump will test cyl and valves for leakage. You can easily see the results. Even after rebuilding, you should check to see if replacing only the seals fixed the leak. The cyl wall might be worn down, or have a slight bulge.

Agree, a good hydraulic shop can check cylinders, valves, etc..

 

[Brad_Blazer]

If a valve has a "load check" on each spool does that not prevent bypass due to spool tolerances?

"Features cast iron construction. Anti-drop load check on each spool. Adjustable relief up to 3625 PSI. Complete handle assembly. Power beyond or closed center available."

Directional Control Valves 220-957 Detailed Information

 

[SSdoxie]

If a valve has a "load check" on each spool does that not prevent bypass due to spool tolerances?

"Features cast iron construction. Anti-drop load check on each spool. Adjustable relief up to 3625 PSI. Complete handle assembly. Power beyond or closed center available."

Directional Control Valves 220-957 Detailed Information

Anti-drop load check is located between the spool and the incoming oil form pump. When you fisrt start to move the spool the spool opens the cylinder circuit (with load on it) to the incoming oil, which at this time has very low pressure through the open center. Present load from the cylinder will push the load check closed until the incoming oil builds equal or greater pressure to open and allow oil into the work circuit. It has no affect on holding load in stationary position when the spool is neutral position.

 

[Brad_Blazer]

Thanks!
Incidentally, I found this nice glossary at Baum:
http://www.baumhydraulics.com/files/infobuild/terms_hydraulic_control_valve.pdf