Hydraulic Cylinder Question

[ScottNC]

My DB885's loader dump cylinder is restricted to about 1/16" in the extend side swivel hose fitting (not the cylinders actual pipe thread fitting. The collapse side swivel fitting is wide open, about 1/4". Is this restrictor factory or an add-on to prevent leverage damage to the cylinder? The dump/rollback cycle is painfully slow on this loader to the point it is not possible to rattle the bucket to shake loose clinging dirt. I suspect this tiny orifice is why.

 

[Jim.ME]

My DB885's loader dump cylinder is restricted to about 1/16" in the extend side swivel hose fitting (not the cylinders actual pipe thread fitting. The collapse side swivel fitting is wide open, about 1/4". Is this restrictor factory or an add-on to prevent leverage damage to the cylinder? The dump/rollback cycle is painfully slow on this loader to the point it is not possible to rattle the bucket to shake loose clinging dirt. I suspect this tiny orifice is why.

To be completely clear, is cylinder extend dumping the bucket and cylinder collapse rolling the bucket back up?

That may have been done to slow the extension of the cylinder when dumping so that it doesn't travel faster than the pump can replace the oil in the other end which could allow the bucket to slam into its travel stops. Look at how fast a trip bucket dumps, gravity has an effect even on hydraulics and will speed up travel when dumping.

To know if it is OEM or not, I think you may need to consult the manuals and parts catalog for your loader model (which you have not mentioned here or posted pictures of). I am guessing it is a DB(?) loader with one dump cylinder on the right side like a couple pictures I found on the web of an 885 with a loader on it. If this is right slowing the cylinder travel may help reduce twisting of the bucket and frame one offset cylinder could cause.

Just my thoughts

 

[Bob Bancroft]

My DB885's loader dump cylinder is restricted to about 1/16" in the extend side swivel hose fitting (not the cylinders actual pipe thread fitting. The collapse side swivel fitting is wide open, about 1/4". Is this restrictor factory or an add-on to prevent leverage damage to the cylinder? The dump/rollback cycle is painfully slow on this loader to the point it is not possible to rattle the bucket to shake loose clinging dirt. I suspect this tiny orifice is why.

Related issues;
I know of one loader where the bucket cylinders were damaged because there were never any bucket dump stops built onto the loader.
I have a rear mounted boom mower on a large, modern tractor. The functions are controlled through the tractor remotes. I can adjust lift speed from the tractor seat. BUT, I have no control over drop speed. Electric over hydraulic controls don't allow for any feathering. So to avoid damaging the mower, I installed adjustable restrictors on one end of each cylinder.
You may have similar challenges with your loader. Some careful study and experimentation may result in an improvement.

 

[Fritz Maurer]

Take the orifice out and see what it does.

Just one cylinder, as in, one in the middle?

I haven't seen everything, so I can think of no reason to restrict the bucket cylinder which is not all that fast to begin with. Conversely, many tractors with farm loaders had a check valve orifice on the lower boom cylinder circuit to control the boom drop, useful especially with a loaded bucket.

In short, if the rod does not come in contact with anything at full extension, and it doesn't slam at the end of the stroke, leave the orifice out and don't worry about it.

 

[bob p mn]

Could be like what happened to me once, bought a handful of those swivels from the Fleet store as I like to use on cylinders to make it easier to replace hoses. One of the swivels had the resrictor in it and ended up on one of the lift cylinders. Took alot of cussing and head scratching to figure that one out as it was a new loader install and I had put those swivels on all the cylinder ports.

 

[m16ty]

A orifice in a line is to slow the cylinder down, it doesn’t restrict the cylinder force.

 

[ScottNC]

The loader is a Dunham-Lehr model 22. It uses a single, centered dump cylinder. The hole is .063" and in the female end of an add-on swivel. The hole looks to be hand drilled due to it being off center and a bit cockeyed. The cylinder collapses to dump and there are physical stops for both directions. The boom cylinders must have a means of controlled lowering, even when heavily loaded the lowering speed is smooth.

I'll substitute an open swivel for the restricted one and give it a go. I thought it might have be added to keep from over pressuring the hydraulics via leverage if grading with the bucket in a dump position.

 

[shaun wallace]

Drill out to 1/8 and see how works.

 

[Jim.ME]

The AGCO parts book for a Farmhand 22 (was Dunham Lehr 22) shows the same swivel part number for both ends of the bucket cylinder 70935781.
Here is a link to the parts book for you.

FarmHand 2 / 22 loader parts book

And here is the replacement for that swivel now, just a male ORB to male JIC elbow. (size not given, you can figure that out from your cylinder port and hose end)

 

[moresmoke]

If the orfice is in the base end of the cylinder, and the cylinder is collapsing to dump, the orfice will hold the oil in the cylinder slowing the dump rate. The orfice will not change pressure, it changes flow. Try it without. If the dump rate is too fast, drill the orfice out one size at a time until you get the speed you want. Keep in mind there will be a difference between cold and warm oil.

 

[BarnyardEngineering]

If it's in the add-on swivel, it's not meant to be there. Get rid of it.

 

[m16ty]

The last experience I’ve had with a orifice was with a loader grapple. I bought it used and and orifice fitting was damaged. I tried it without the orifice, but the grapple moved so fast it would eventually destroy itself, do to the small size of the cylinder.

I my day job I deal with a lot of forklifts. Most of them have an orifice check valve. This allows unrestricted flow going up, but when going down the check closes and the fluid has to pass through the orifice. This allows for the forks to come down in a more controlled manor, if somebody just pushes the lever all the way. Otherwise the forks would just fall pretty fast.

 

[ScottNC]

No check valve used here, so the effect of the reducer should be the same no matter on which end the small orifice is used? I ask because as I put the cylinder back on the tractor I noticed the hydraulic shop put the reducer on the opposite end from where I found it at disassembly. I'll look for an unrestricted fitting tomorrow and give it a go, if the action is too rowdy I'll make small adjustments on the original. I already know the way it was the dump cycle was snail slow and was a PITA, especially when working a burn pile.

 

[Jim.ME]

No check valve used here, so the effect of the reducer should be the same no matter on which end the small orifice is used? I ask because as I put the cylinder back on the tractor I noticed the hydraulic shop put the reducer on the opposite end from where I found it at disassembly. I'll look for an unrestricted fitting tomorrow and give it a go, if the action is too rowdy I'll make small adjustments on the original. I already know the way it was the dump cycle was snail slow and was a PITA, especially when working a burn pile.

The parts book calls it an elbow, is it actually a swivel or a fitting like the ACGO picture I posted? The info in the parts book showed that part number elbow I posted for you, was used at both ends of the cylinder and other places for a total of 6. That being the case they should all be the same. You posted the orifice in the one in question is drilled off center and a bit cockeyed, which to me indicates it is not OEM. Given the info in the parts book, I would just get and install the new fitting.

 

[moresmoke]

No check valve used here, so the effect of the reducer should be the same no matter on which end the small orifice is used? I ask because as I put the cylinder back on the tractor I noticed the hydraulic shop put the reducer on the opposite end from where I found it at disassembly. I'll look for an unrestricted fitting tomorrow and give it a go, if the action is too rowdy I'll make small adjustments on the original. I already know the way it was the dump cycle was snail slow and was a PITA, especially when working a burn pile.

To be effective, the orfice needs to hold the oil in the cylinder when it is dumping. If it is on the opposite end, the weight of the load will push the oil out at full speed, and pull a vacuum on the opposite end.

 

[ScottNC]

To be effective, the orfice needs to hold the oil in the cylinder when it is dumping. If it is on the opposite end, the weight of the load will push the oil out at full speed, and pull a vacuum on the opposite end.

Makes sense. Then it needs to put back on the end it came off of.

Jim.ME - I struck out on that fitting. The 70935781 came up as a New Holland number so I called my dealer. He said by dropping the last digit it came up a valid but he could no longer get it. Same story with Messick's. I'm gonna go up 25% of area (not diameter) and try that. .063" = .00311 sq.in. so + 25% = .0039 or .070".

 

[Jim.ME]

Makes sense. Then it needs to put back on the end it came off of.

Jim.ME - I struck out on that fitting. The 70935781 came up as a New Holland number so I called my dealer. He said by dropping the last digit it came up a valid but he could no longer get it. Same story with Messick's. I'm gonna go up 25% of area (not diameter) and try that. .063" = .00311 sq.in. so + 25% = .0039 or .070".

I can't say if the New Holland part is correct or not. I'm not surprized you didn't get much luck with your NH dealer or Messicks. Your Durham Lehr Loader falls under AGCO's FARMHAND brand, as I posted, not New Holland. Did you talk to an AGCO dealer? An AGCO dealer should have seen the original part number of 70935781 has been subbed to SN4454. That is the info from the parts catalog and a check for price and availability for the 70935781. That is in the picture I posted for you.

That picture shows a common male ORB to male JIC 90-degree elbow fitting. If you can figure out the thread sizes of the male O-ring Boss end in the cylinder and the male JIC end for the hose a local shop or parts store should have a matching elbow. OR just take the old one in hand so they can match the fitting ends. It may be a 3/4-16 thread both sides, if your loader has 1/2" hoses. That would use a 7/8 wrench on the hose fitting and likely the nut you tighten on the ORB side.

 

[PJH]

My DB885's loader dump cylinder is restricted to about 1/16" in the extend side swivel hose fitting (not the cylinders actual pipe thread fitting. The collapse side swivel fitting is wide open, about 1/4". Is this restrictor factory or an add-on to prevent leverage damage to the cylinder? The dump/rollback cycle is painfully slow on this loader to the point it is not possible to rattle the bucket to shake loose clinging dirt. I suspect this tiny orifice is why.

I'm certainly not a hydraulics expert, but here are pictures of the flow restrictor for the rear gate on my New Holland 848 round baler. The baler gate opens fast, but the restrictor makes it close slowly, even to the point of causing the tractor relief valve to squeal. I replaced the hydraulic hoses late one evening and the restrictor fell out in the dirt in the dark corner of the barn where I was working. Next time that I used the baler the gate would slam shut with alarming speed and impact. I stopped baling, went to the barn and searched around with a flashlight and found the restrictor in the dirt. When I put the restrictor back in its proper place the baler gate worked like it was designed. Installed properly, the gate opens fast and closes slowly. Installed incorrectly, the gate opens slowly and closes with an alarming bang.

 

[ScottNC]

Good to know. I'm impressed how much volume moves through such small orifices. I'm waiting on a water pump for the tractor so haven't had an opportunity to try the loader with the slightly larger dump restrictor.

 

[ScottNC]

In case anyone might be interested - After having used the loader enough to form an opinion after altering the dump cylinder restriction, it is my observation that increasing the area of the restriction by 50% (area, NOT the diameter) has noticeably increased the dump/rollback cycle. A seat of the pants measure of the time to preform an up/dump - lower/rollback cycle has both moving so close to the same speed as to be indistinguishable. Before the change the rollback after dumping took twice as long as the time required to lower the bucket.