How Not To Do Hydraulics !

[danovercash]

Rudi, skip the standard bit, go directly to left hand bit. Bet the bolt comes out before the whole is finished.

[beaconlight]

I go with danovercash on using a left hand first if you decide to drill. The vibration may help loosen the broken bolt. The real problem is that the bolt has bottomed.

[LiL' Red]

If you have a full thread or more why not weld a nut on it and back it out with a wrench?

[Matt Kirsch]

Rudi,

Being the curious type, I'm trying to figure out exactly how you deadheaded the system. The relief valve in your Cessna spool valve should have kicked in before something blew, unless it was set too high, or the oil had nowhere to go. AFAIK, it's adjustable down to 800PSI, but it's set to 2000PSI by default. 2000 is enough to do damage.

Just to be on the safe side, it's probably a good idea to set the relief valve to its minimum setting at first, then increase the setting if normal use causes the relief valve to kick in.

Did you spring for the power beyond plug? If so, there should be three lines between the TC and valve, with the OUT going to your TC fill hole. By the sounds of it, you were missing one of the three lines?

[Rick Prentice]

Matt. I advised Rudi not to worry about the added PBY set-up. It's not needed when the Cub T/C is present. Technically speaking, the Cessna is control valve no1 and the T/C unit is control valve no2. For one thing, the cub pump doesn't produce enough pressure to damage the control valves being sold today. The second reason is the way the T/C system works. It's impossible to continuosly apply pressure with the T/C, as soon as it reaches the desired setting, it kicks out. The only chance of any pressure on Rudi's new Cessna(no1) at the PBY area is when the T/C(no2) is being used. What's the heaviest object being lifted or pushed down when using the T/C? That working pressure inside the T/C is less than what the pump is putting out, for safety reasons.

My opinion,
Rick

[beaconlight]

Rudi I r4ceived a new Harbor Freight catalogue today.
Left hand Drill bit set of 13
$9.99 American
Part # 96146-08FA
Harborfreight.com
800 423-2567
I hope this helps

[George Willer]

If you have a full thread or more why not weld a nut on it and back it out with a wrench?

The reason I didn't recommend welding the nut on is because of the probable damage to the gasket surface. Otherwise it's a good plan that I recommend. It depends a lot on the experience and ability of the welder. Maybe it's the best plan?

[Ken (48 Cub)]

I've had good success using Donny's approach. If there is enough bolt sticking out, cut a straight slot accross it using a Dremel tool and small cutoff wheel. The heat and vibration from the cutting will loosen the bolt. Then just remove it with a screw driver

[kinelbor]

I also like welding a nut to the end of bolts and even stripped out screws. Hasnt failed me yet.

[Matt Kirsch]

Rick,
I agree with you wholeheartedly. You don't really NEED power beyond with the Cub's low-pressure hydraulics and modern valve designs. OTOH, if it was a 3000PSI system... That's another story.

My main purpose here is root cause analysis. WHY did Rudi blow a gasket?

It was a good thing he did, or else he may have stripped the cam gear, snapped off the pump shaft, etc. etc... Expensive, bad things that we really really don't want to see happening.

From what I understand here, Rudi pulled the lever with nothing connected. That should have caused a quick buildup of pressure followed by the relief valve in the Cessna popping open.

Given the fact that the bolts are too long, perhaps there wasn't enough pressure on the gaskets, and they blew out before the pressure built up to the relief valve setting?

[Rudi]

Root cause for blowing the gasket Quite simple. Stoopidity.. and accidentally hitting the lever. If I had known more about hydraulics, then I would have known to put in the jumper.... to be on the safe side. After I did it, I talked to Rick and poof there it was... yup.. stoopid..

See, the main problem is that I, unlike the rest of the fellows, did not hook up my cylinder right away. Big Mistake as that can lead to dead-ending/dead-heading accidentally. One needs to make sure that the circuit is not closed like that. Fluid needs to make a complete journey from point a to point b and then back to point c. I didn't do that. However, I am learning and that is the important part of the exercise. Thank God for my good friends on the forum.

Anyhoosie.. that is neither here nor there now. Problem identified, fix identified, now fix needs to be implemented. The last couple of days I haven't been able to do much, been on the road.. Traveled to Fredericton yesterday, and then had to go to Richibucto today. Tomorrow have appointments till about 3pm. THEN.. maybe I can get some relax time in and play with the Hydraulic problem.

1. I have a jumper installed now.
2. I have left handed drill bits.
3. I have 2-1/4" Grade 8 5/16" bolts.
4. I have gasket material and am going to make myself a few gaskets.
5. I am going to cut a guard for the TC unit before I drill. Don't want no crud in my TC..
6. I am going to cross my fingers and pray that I don't screw it up again.

Wish me luck

[flag]

Take your time, be patient and best of luck Rudi.
Sure was a lot of methods posted on how to remove a broken bolt, I can't afford several of them but all of them sure sound good and proper!

[Matt Kirsch]

See Rudi, that's what I don't get.

I keep harping on the relief valve, because it's supposed to prevent exactly what happened to you. It's supposed to make the system "upstream" of the valve deadhead-proof.

[John *.?-!.* cub owner]

I am not sure how well a homemade gasket will work on that installation, the gaskets on my touch controls appear to be a special material that is harder than normal gasket material.

[Jim Becker]

See Rudi, that's what I don't get.

I keep harping on the relief valve, because it's supposed to prevent exactly what happened to you. It's supposed to make the system "upstream" of the valve deadhead-proof.

I agree with Matt on this point. If the problem is lack of a jumper and that is the only change to fix the problem, you will have the same problem the first time you bump the end of the stroke of your external cylinder. Your root problem is either:
1) Manifold wasn't bolted down tight enough against the gasket.
2) Relief valve in the remote valve set too high or not present.