Why not check valves in FEL?

[brokenot]

Well that's where I differ from you.....I see it all the time.....new tractor cylinders are not engineered the same as these pics you show of manlifts, cranes, and quality construction equipment......not the same internally.......

Just open up a Bobcat cyl and look at the piston seal.....it's .125 wide....They are a great machine but there cyls have always been chinsy....

You misunderstood my post. I said that the cylinders on the machines I used as examples are far better than your typical run-of-the-mill cylinders. I realize that it may have gotten confusing when I mentioned that the manlifts aren't required to have rapid cycle times like the telehandlers, but all of the cylinders used for any load lifting/positioning/holding applications on both types of machinery are high-dollar units with holding valves/load checks built into the cylinders.

How "high dollar" are they? Well, as an example, the fork tilt cylinder circled in blue in this photo of the telehandler costs us about $1600....and that's dealer cost. We've had them damaged before and the customer gets upset when they get a bill because they "can buy a cylinder that size for $200 over at Fleet Farm or TSC...."

(and they "know that" because that's what the FEL bucket curl cylinder for their tractor at the farm cost them...)

:laughing:

 

[picker77]

How about this situation....In a twin cyl application......a DPOCV or counterbalance valve doesn't open exactly at the same pressure and you are trying to feather the control......If someone goofs around with any adjustments on these valves you end up with one severely bent rod (whether under load or not)........:thumbdown:

Good point. Even with my kindergarten level knowledge of hydraulics, I can see why simultaneously operated cylinders might end up fighting each other if they had slightly different pilot valve cracking pressures. That would not be good. I wonder how the mfr's get around that in twin-cylinder applications such as the main boom hoist cylinders on the telehandler you pictured? I assume they just use a single big external DPOCV and feed both cylinders with it?

 

[wdchyd]

You misunderstood my post. I said that the cylinders on the machines I used as examples are far better than your typical run-of-the-mill cylinders. I realize that it may have gotten confusing when I mentioned that the manlifts aren't required to have rapid cycle times like the telehandlers, but all of the cylinders used for any load lifting/positioning/holding applications on both types of machinery are high-dollar units with holding valves/load checks built into the cylinders.

How "high dollar" are they? Well, as an example, the fork tilt cylinder circled in blue in this photo of the telehandler costs us about $1600....and that's dealer cost. We've had them damaged before and the customer gets upset when they get a bill because they "can buy a cylinder that size for $200 over at Fleet Farm or TSC...."

(and they "know that" because that's what the FEL bucket curl cylinder for their tractor at the farm cost them...)

:laughing:

I hear ya Brokenot......no comparison to the Aggy Style Cyls.....I just get frustrated with all the shortcuts cyl mfg's use to make some of the newer cyls....ie: lock wire retainers, no wear bands or bushings in glands ect....

Yes, you were correct that newer materials are far better than old stuff but I guess I still like the ole "V Packing" for it's forgiving nature to damaged rods and worn parts.....

The newer cyls just need tighter tolerances to be effective and to last.....

 

[wdchyd]

Good point. Even with my kindergarten level knowledge of hydraulics, I can see why simultaneously operated cylinders might end up fighting each other if they had slightly different pilot valve cracking pressures. That would not be good. I wonder how the mfr's get around that in twin-cylinder applications such as the main boom hoist cylinders on the telehandler you pictured? I assume they just use a single big external DPOCV and feed both cylinders with it?

I'm sure a few do use one valve for twin setups but the norm is to use two....that way integrity is not compromised during hose/tubing failure....

Twin-Cyls need to be adjusted and tuned properly....

This brings up an old war story few years back......A customer brings in 1 cyl of two for OVH.....Bent Rod, egged-out gland, scored barrel, piston junk.....basically the nut on the rod was the only good part....

A previous repair was done by competitor, over and over again......they decided to up the dia of the rod from 1.75 to 2.00"....That bent too...

After a rerod, rebarrel, new gland,piston and new counterbalance cartridge valve customer was advised to bring in other cyl......of course they said "There's nothing wrong with it"....We just wanted to test and balance the other....

Well the other cyl rod was bent....so a new rod and repack was in order for that one too.....

One valve was preset @ 700 psi and the other was preset @ 1800 psi....The unbalanced valves caused many hundreds of $ before he even stepped foot in our shop.....

When he left with his equipment he said he was "Giddy"...."This thing never worked so good"......That was about 3 yrs ago and this whole problem started with a bad (or misadjusted) counterbalance valve......

This not an isolated problem, it happens in twin cyl applications....

Put these on my Kubota Cyls?.....NO WAY .....

 

[brokenot]

A short description of the lift/lower circuit from the manual. It's written so as to perhaps appear that the individual cylinders don't each have their own set of "safeties" but they do. They say "counterbalance valve", but it should really say "counterbalance valves". Same goes for the "pilot check valve", it should be "pilot check valves".

And here's an exploded view of the lift/lower cylinder. The counterbalance and pilot check valves, (items 4 and 5), are installed in both cylinders....which is why it's important to not try and repair/adjust them.

 

[wdchyd]

Good illustration to show the seals internally.....especially the 4 piece capped piston seal and wear bands on the piston head.....you'd never see this style on a tractor cyl.....the technology is here but mfg's wont spend the money for the cost of these seals......that's what it takes to make a quality cyl....

As an owner, one of the problems of all this hydraulic equipment is you hope that your tractor has the best in it but reality sets in when you have low hours and it's time to repack cyls......without mentioning any names some small tractor mfgr's will use only orings and backup rings for piston seals....that's great for the hyd repair business but bad for "Joe Homeowner"

 

[MtnViewRanch]

While the machines that most of us have do not have the top quality hydraulics, is there any of us that would prefer to pay for the top quality stuff? :confused3: I think few if any of us would really like paying for them. :shocked:

 

[wdchyd]

Absolutly.....100%.....:thumbsup:.....True.....

 

[picker77]

While the machines that most of us have do not have the top quality hydraulics, is there any of us that would prefer to pay for the top quality stuff? :confused3: I think few if any of us would really like paying for them. :shocked:

You're right. My loader arms will leak down about 2" per hour with an empty bucket attached and the arms at 90 degrees. I was ticked about this and thought they should not move at all, but I was told by a JD mechanic that's about right for a standard consumer grade loader. Would I pay another $1500 or even more to have zero-leak FEL cylinders? Probably not, since CUT loaders aren't made to sit for hours in one position, so spending a lot of money to make them do that would seem to be kind of dumb. If this was a man-lift and it was my personal butt up there at 60 or 80 feet trying to work, lift cylinder leakdown would be a major issue!

 

[MtnViewRanch]

You're right. My loader arms will leak down about 2" per hour with an empty bucket attached and the arms at 90 degrees. I was ticked about this and thought they should not move at all, but I was told by a JD mechanic that's about right for a standard consumer grade loader. Would I pay another $1500 or even more to have zero-leak FEL cylinders? Probably not, since CUT loaders aren't made to sit for hours in one position, so spending a lot of money to make them do that would seem to be kind of dumb. If this was a man-lift and it was my personal butt up there at 60 or 80 feet trying to work, lift cylinder leakdown would be a major issue!

When it comes right down to it, does it really matter that our hydraulics leak some? Not really in my opinion, when working our tractors we are constantly using-adjusting our loaders, 3pt hitches, top links and side links. So what if they leak down some every few minutes, I know that I am adjusting them continually. And is it that big of a deal to pull on the loader control for a couple of seconds every 10-15 minutes while working with a rear implement? I guess that is one of the reasons that I am not a proponent of the DPOCV's. If your working a box blade, your constantly making adjustments. I do anyway, makes no difference if my hydraulic bleeds off some because I am changing the adjustment anyway.

Just my experience with my conditions with what I do, others will vary.