Hydraulic quick connects

[blazemaster83]

I am converting a big press from a single acting cylinder with hand pump to a double acting cylinder with electric pump. I would like to put quick connects on the new cylinder, it is tall and needs to be removed from the press if I ever need to move it to a different building.

Just curious what kind of quick connects people are using. I would like to be able to disconnect under pressure, and needs to be able to flow at least 30gpm.

I have been looking at these, but I can't find anybody mentioning them anywhere. I find lots about the flat faced ones, and people say they are hard to connect under pressure without tools.

https://www.surpluscenter.com/Hydra...-Brass-Wing-Nut-Quick-Coupler-Pair-9-8314.axd

Probably will get disconnected and connected less than 10 times in its life.

 

[Sumboodie]

Just undo at a hose fitting. Use JIC and thread in a cap on each end to it doesn't drip all over and make a mess.

I don't know of any setup that would allow disconnection with pressure in the lines. That would be dangerous.

 

[LopezBart]

I think connecting a press under pressure is a Bad Idea, TM. You'll need the 3/4" size ones. Use a valve w/ load checks between the cylinder and the quick disconnects and there won't be any pressure to work against.

 

[bigfunwmu]

If you want to trap pressure under that style of QD at the cylinder, install a high pressure ball valve between the QD and the cylinder and close it before releasing the pressure at the QD and disconnecting it.

Most QDs are not rated to connect or disconnect under pressure and most of the ones that are are only rated for "residual" pressure or very low pressure trapped in a line. Connect under high pressure couplings good for 30 GPM will be very expensive.

 

[scooby074]

Agree with the suggestion to just use JICs and caps when moving. For so few disconnects its not worth it.

 

[dutchgray]

Just undo at a hose fitting. Use JIC and thread in a cap on each end to it doesn't drip all over and make a mess.

I don't know of any setup that would allow disconnection with pressure in the lines. That would be dangerous.

Merlo Male quick release screw type coupling 025587

Merlo Male quick release screw type coupling. RVW Pugh new and used farm machinery, parts and servicing in Cheshire, Staffordshire, Shropshire and Mid Wales

rvwpugh.co.uk

Screw type couplers, you can make or break under pressure.

 

[Sumboodie]

Merlo Male quick release screw type coupling 025587

Merlo Male quick release screw type coupling. RVW Pugh new and used farm machinery, parts and servicing in Cheshire, Staffordshire, Shropshire and Mid Wales

rvwpugh.co.uk

Screw type couplers, you can make or break under pressure.

Looks like porta power style connections.

Can't unscrew them with pressure, least not in my experience.
Residual pressure, sure, but maybe 100 psi, not 5000.

Not sure why a person would want to unhook under pressure? Maybe im misunderstanding?

In the middle of pressing a bearing and... ope, it's moving time, let's go.

 

[txvwnut]

You can disconnect just about any hydraulic QD under pressure. Reconnecting them under pressure is a different story, as in ain't gonna happen. 30GPM shouldn't be an issue as I believe any QD that is a 1/2" pipe or larger should handle that flow easily.

 

[mreisner]

Poppet ORB ISO 5675 Agriculture Quick Connect | ISO 5675 Agricultural | Hydraulics Direct

Poppet ORB ISO 5675 Agriculture Quick Connect, ISO 5675 Agricultural,Hydraulics Direct

www.hydraulicsdirect.com

 

[LopezBart]

You can disconnect just about any hydraulic QD under pressure. Reconnecting them under pressure is a different story, as in ain't gonna happen. 30GPM shouldn't be an issue as I believe any QD that is a 1/2" pipe or larger should handle that flow easily.

1/2" disconnects are typically rated somewhere between 12 and 24 GPM max; the OP wants 30 (unclear why). 1/2" hydraulic hose is typically rated at 20 GPM max. I assume the OP is going with a two-stage pump (like a log splitter might use); otherwise the power requirements of 30 GPM at 3000 psi are pretty steep - 60+ hp.

My guess is the OP has a calculation error somewhere; the fact that this press was originally manually operated suggests that it will take far less flow than he estimates. A press should operate slowly for safety's sake. I would guess that a 2 stage pump of just a few GPM would be completely satisfactory, offering quicker movement for raising and lowering the ram while slowing down as the pressure rises above a few hundred PSI.

If the existing cylinder's working pressure is much lower than 3000 psi, I'd consider another cylinder.

 

[dutchgray]

Looks like porta power style connections.

Can't unscrew them with pressure, least not in my experience.
Residual pressure, sure, but maybe 100 psi, not 5000.

Not sure why a person would want to unhook under pressure? Maybe im misunderstanding?

In the middle of pressing a bearing and... ope, it's moving time, let's go.

Well you certainly wouldn't want to unhook under pressure if you were in the middle of a press job, The OP must mean the residual pressure from the ram weight hanging.
They technically are only rated to be connected under residual pressure, which on Merlo Telehandlers can be quite a bit, but you can connect that type easily by hand without tools unlike standard couplers which you can fight for ages if there's a bit of pressure.

For a double acting press ram in the vertical position they would be perfect to enable easy disconnects without having to bother with cracking lines or shut off valves and easy to reconnect with the cylinder weight hanging keeping one side under pressure, they also will not pop of accidentally like some types if you catch the locking ring with something.
They are however not cheap and I have no idea if you can get them in the states.

 

[Sumboodie]

Well you certainly wouldn't want to unhook under pressure if you were in the middle of a press job, The OP must mean the residual pressure from the ram weight hanging.
They technically are only rated to be connected under residual pressure, which on Merlo Telehandlers can be quite a bit, but you can connect that type easily by hand without tools unlike standard couplers which you can fight for ages if there's a bit of pressure.

For a double acting press ram in the vertical position they would be perfect to enable easy disconnects without having to bother with cracking lines or shut off valves and easy to reconnect with the cylinder weight hanging keeping one side under pressure, they also will not pop of accidentally like some types if you catch the locking ring with something.
They are however not cheap and I have no idea if you can get them in the states.

I've fought with flat face couplers before. Just a little pressure and it's not hooking up.
To the point I keep a propane torch with the skid steer in the winter as the snow ends up freezing them up.

 

[blazemaster83]

Thanks for the replies.

First off, I meant residual pressure. Not gonna be running the press and actuating valves while I disconnect the cylinder.

Second, the quick connects I linked say can be connected under pressure.

Third, this sytem uses a lot of oil. The cylinder is 12" bore, 60" stroke. I dont want to clean up 10 gallons of oil whenever I disconnect the hoses.

Fourth, I don't know what the GPM flow is for the system(pump tags are worn off), but everything uses 3/4" npt or 3/4" lines. I just picked 30gpm because similar pumps have around that rating. I don't want to size everything, then have the quick connects be the bottleneck.

 

[scooby074]

I think youre vastly overestimating how much oil will be lost over the 10ish disconnects this thing will experience. You should neutralize any residual pressure before disconnection regardless. Id estimate youll lose a quart of fluid at a time assuming you get the caps on in a reasonable timeframe. Quality flat faced connect under pressure couplers will cost you hundreds of dollars vs. a couple caps that cost $10. But you do you.

 

[Sumboodie]

Thanks for the replies.

First off, I meant residual pressure. Not gonna be running the press and actuating valves while I disconnect the cylinder.

Second, the quick connects I linked clearly say can be connected under pressure.

Third, this sytem uses a lot of oil. The cylinder is 12" bore, 60" stroke. I dont want to clean up 10 gallons of oil whenever I disconnect the hoses.

Fourth, I don't know what the GPM flow is for the system(pump tags are worn off), but everything uses 3/4" npt or 3/4" lines. I just picked 30gpm because similar pumps have around that rating. I don't want to size everything, then have the quick connects be the bottleneck.

They can't.. well... not easy.

We use them in dump trailers. If there's a bit of pressure, like it got unhooked not 100 against the stops, it requires a sledhammer, and sometimes it breaks the coupler or messes up the threads. They started putting vall valves on some to help (and as a safety)

That press is way bigger than a normal shop press im used to. I was picturing maybe a 5-6" cylinder, 5000 or 10,000 psi.

Even the 400-500 ton units in the big shops aren't anywhere that size of a cylinder!

 

[blazemaster83]

Spool valve has load checks. it's a big cylinder but will only be getting 1500 psi, a little over 80 tons. It's rated for 5000.

I am probably overestimating fluid loss, quick connects just sound nice.

I did find these but they are spendy

 

[Firebrick43]

If you don't need any thing high pressure and are only running 1500 psi, regular pioneer style tractor quick connects (aka ISO 5675) 3/4" size will flow 30 gpm.

No matter what style of connector you choose, on the cylinder side install a tube and ball valve between ports. Then no matter what you can equalize the pressure and get the quick connects hooked up easily.

 

[Rockable]

These Parker 6100 coupler can be connected and disconnected under pressure and you can select a size that will match your flow rate. Tractor/trailer dump trucks use them, for one example.

https://ph.parker.com/us/en/product-list/connect-under-pressure-high-flow-quick-couplings-6100-series

 

[LopezBart]

Interesting... a 12" bore cylinder will need just under 1/2 gallon of fluid to extend 1". So a 30 gpm pump will extend the cylinder at 1" per second. A multi-stage pump and one of those generative valves ( a position that connects the rod end port to the other one to traverse faster) would make this feasible w/o a huge electric motor; you'll want a method to retract the ram in finite time as well.