Hydraulic Quick Coupler Problem

[lpakiz]

I thought it might be beneficial for members to hear of an experience I had a couple days ago.
We had a huge snowstorm/blizzard a couple days ago and I was super busy with the 1754 and front mounted snow blower. I cleaned out several neighbors yards on an emergency basis, as I don't care to go into strange yards and possibly damage my equipment.
After finishing about 6 hours of work, I came home and cleaned up my yard.
I was almost finished when suddenly, the blower would not lift. I had plenty of down pressure, easily raising the front wheels off the ground, but it would not lift the blower. I dragged it backwards into my shop.
First, I checked that a coupler didn't get unhooked. Everything was good, and I hooked and unhooked the 2 hoses a couple times.
I determined then that the piston packing may have failed, altho working fine one way (extend) and not working at all when raising seemed to me to be unlikely.
I took the cylinder to a Mennonite hydraulic shop, where they had the exact replacement packing on hand. An hour later, I was on my way home with my rebuilt, tested cylinder. The bill was $33!

Same thing!?!

I noticed one of the male tips on the hoses was leaking a bit of oil. Upon closer examination, I saw that the "poppet" tip was not exerting enough pressure to seal the oil inside the hose. It should take significant pressure from my finger tip to force the poppet back into the tip, and in my case, the poppet was actually loose, wobbling around in the tip, not even attempting to close off the flow of oil on my floor.
I stole the tip off my pressure gauge and lo and behold, problem solved!!

Thinking back, I believe that something in the male tip SUDDENLY failed, like the spring broke or the seat that supports the spring had shifted or broke. When that happened, the faulty male tip couldn't exert enough pressure to force open its COMPANION poppet inside the female half of the coupler, so I had pressure one way and not the other.
I think of those two poppets like a pair of mountain goats, butting heads. Each poppet must force the opposing poppet off its seat to allow oil to flow. If one is sufficiently weaker, it won't push the other poppet off its seat.

Also, for the record, my tips are Pioneer 4010-3P. Parker uses the same number. An aftermarket number is AG3F3-PV.
They are described as 3/8 coupler by 3/8 Female NPT. EBay had a group of 8 for $80, so I grabbed them. Usually they are in the range of $20-$22.
This is the third tip in 10 years to fail by leaking, but the first that actually blocked flow.

 

[Dmacleo]

good post.
keep in mind a ball style male end will fit into a pintle style female end but fluid will not flow.
A pintle style male end will not fit into a ball style female end, she will block you.
I've always replaced both male/female ends each time I (admittingly rare) I work on hydraulic systems.

 

[JWR]

I agree with Dave. Great post, good info for all of us.

I was also amazed at how this sounds exactly like here in So MD when IPpakiz said "I took the cylinder to a Mennonite hydraulic shop, where they had the exact replacement packing on hand. An hour later, I was on my way home with my rebuilt, tested cylinder. The bill was $33! " Yep. We too have a Mennonite metal fabrication and hydraulics shop nearby and I have had the very same experience dealing with them. Such a good resource no matter when you are trying to get things done.

 

[SPYDERLK]

good post.
keep in mind a ball style male end will fit into a pintle style female end but fluid will not flow.
A pintle style male end will not fit into a ball style female end, she will block you.
I've always replaced both male/female ends each time I (admittingly rare) I work on hydraulic systems.

Good observation. I mix and match and they work ok. I have had some puzzling temporary issues sometimes after 1st hooking up, a/or disturbing the connector in use. I think youve pegged it. ... Apparently they are almost compatible, at least in the 1/2" Pioneer size.

 

[Dmacleo]

Good observation. I mix and match and they work ok. I have had some puzzling temporary issues sometimes after 1st hooking up, a/or disturbing the connector in use. I think youve pegged it. ... Apparently they are almost compatible, at least in the 1/2" Pioneer size.

its my own inherent built in ineptitude that drives me to advocate replacing coupler ends in pairs. screwed up too many times in past

 

[lpakiz]

I had a chance to do a post-mortem on my failed coupler tip.
Inside the coupler tip is a small, black, flat-wound snap ring that got pushed back out of its groove, which reduced the pressure of the spring to hold the sealing poppet out.
That spring pressure also assists in pushing the OPPOSING poppet off of its seat.
Since it was "weak" it couldn't push hard enough, so the opposing poppet wouldn't permit flow, except one way, which is when pressure helped push that opposing poppet back. When reversing flow, the volume and flow of the hydraulic fluid actually helped seal that opposing poppet even tighter.
So what happened is that SOMEHOW in the heat of the battle, the snap ring became dislodged.

You will have the same symptoms when a quick coupler is not fully seated. The 2 "billy goats" aren't pushing against each other hard enough to displace both poppets, so you have no flow, or flow one way but not the other.