Large castle nut torque hassle , 3000 pound feet really needed?

[davejo]

Trying to decide how far to go in securing a castle nut which holds the piston in place inside a hydraulic cylinder.

Whilst replacing leaking seals, the nut was too tight for me to loosen so I took it to a hydraulic shop, just to break the nut loose. Its a 55mm castle nut secured with a 8mm cotter pin. The pin was jammed so I ended up drilling most of it out. Apparently I didn't get things clean enough and when the shop took the nut off, the threads got smeared.

Nobody sells a m55x3.0 castle nut so I agreed to them welding and rethreading the nut. The new threads are not clocked the same as the old threads so now the castle portion of the nut is not in the same orientation to the hole in the rod as it was originally. Finger tight gets a turret lined up with the hole. 1500 pound feet torque ends up with the hole about 1/2 way between turrets. The assembly has to compress .375mm more to get the next turret lined up, If i understand geometry etc. Seems impossible...

I'm tempted to use a shim to get the slot lined up at a reasonable torque value. If the nut is retained by a cotter pin, is the torque spec that crucial?

Other idea is to crank it as tight as I can and tack weld the nut or drill another hole for the cotter pin in the rod or make a new turret, etc.

 

[cvairwerks]

Sure it's an M55? Standard charts shows M52 or M56. If it's really a 55, probably going to have to go OEM for a new one.

As to torque value, it may be required to get the correct compression on the piston/seal stack to handle the required hydraulic operating pressures.

 

[Muckin_Slusher]

I don't think it's about keeping the nut from coming undone, it's about metal fatigue. The tight nut preloads the threads so they don't even know they're being loaded/unloaded.

That being said, it'll probably work, but might not

Watch this video for explanation, should start at 16:53

 

[davejo]

OEM doesn't sell them any more

 

[Tim in Indiana]

Machine the appropriate amount off the base of the nut to get it to align with a hole at your desired torque.

 

[davejo]

I don't think it's about keeping the nut from coming undone, it's about metal fatigue. The tight nut preloads the threads so they don't even know they're being loaded/unloaded.

That being said, it'll probably work, but might not

Watch this video for explanation, should start at 16:53

Interesting video. I looked into Hooke's law and did some calculations for fun. My bolt should stretch .0016 inches under hydraulic operation

Bolt Stretching and Tensile Stress

Tensile stress and Hooke's Law.

www.engineeringtoolbox.com

 

[Monza Harry]

I thought about suggesting to trim the nut, but with a repaired nut (concerned about compromising strength further on an already [compromised +/-] "previously LOVED" nut) I'd do the shim to get it aligned. Issue there is getting it in 1 shot my track record for "anticipating" (fancy name for wild @$$ guess) aligned build ups is usually 3 estimates for ~success(ish) outcome. LOL! I'd guess rotational alignment will only be half the issue, trim or shim, axial alignment may also raise its ugly head! Harry

 

[davejo]

I ended up using a shim. Turns out that a differential carrier shim pack for a ford 8.8 inch differential comes with a handful of different thickness shims that happen to fit over a 55mm bolt. I chose one that got me within a half turret when hand tight and I cranked on it with a long cheater to get the turret lined up with the hole. Nowhere near 3000+ foot pounds of torque, though.

Its a bucket curl cylinder on a big old excavator and most of the abuse will come when the bolt is not in tension. I need to work on a few more cylinders, what is a reasonable way to get large nuts torqued properly? 20 foot cheater pipes don't seem feasible. The torque multipliers I see for sale are good for around 1000 ft#

 

[RichieP_MechE]

I need to work on a few more cylinders, what is a reasonable way to get large nuts torqued properly?

Hydraulic or pneumatic torque wrench. I rented a pneumatic one from Herc a few years ago (thought I can't seem to find it searching their site) and a hydraulic one from a local hydraulic supply shop more recently.

 

[Monza Harry]

I took a quick search and found this one: https://placide.com/en/bessey-jm-12...plier-3-4-dr-f-x-1-1-2-dr-m-bessey-besjm-1200 this tool and budget aren't going to be used in the same paragraph. You will also need 1 1/2" drive socket set, that is "I've never even seen a catalog listing for those" expensive! Torque Multipliers aren't exactly easy to use. On a mould its, weight helps the Torque reaction of the multiplier and the actual Torque bring applies a cylinder rod is beyond my thought process. Clamping the rod in a vise isn't a real option, a collet apparatus (?) would need to be fashioned and then an anchor of suitable heft would be needed as well. Please share your outcomes both successful or not. Harry

 

[GoToGuy_Ron]

Does the repair process allow you to use shims? What is the material, is it appropriate for what your doing? That size nut is torqued with hydraulic torque machine. So on reassembly the original hole doesn't line up, move over 90 degrees approximately give or take, drill new cotter pin hole, acceptable repair.

 

[Milton Shaw]

Lightly sand the bottom of the nut on fine grit on glass sheet. Just a ten thousant or two will make it line up.

 

[Honch]

OEM doesn't sell them any more

The picture from the manual you posted answers your question.

"Select the proper thickness of shim to align the cotter pin group in the castle nut with the pin hole in the piston rod.

 

[larry_g]

https://www.youtube.com/@CuttingEdgeEngineering

The above guy rebuilds a lot of large cylinders. In one recent video he talks of taking one rod assembly to a friends shop who has the correct tools to reach the high torque values needed. You might check your local hydraulics shop and see if they can torque this for you. I realize that you have this done but for future reference and jobs.

In my post here; https://www.garagejournal.com/forum/threads/tapping-threads-object-orientation.500907/#post-9677394 , I go into a bit of the basic math for figuring out the thickness of selecting a shim for orienting the the fastener or fitting.

lg
no neat sig line

 

[davejo]

What happened is that I took the rod to a shop just to have the nut loosened. I knew the seals would be around $200 regardless who sourced them. I thought it would be a couple hundred bucks for a shop to loosen the nut for me. Things snowballed on me when the threads got destroyed and I got the rod, piston and sealhead back for $900. Resealed, but not assembled.


Maybe they knew that retorqueing it would be another $500? I guess I should have asked, in hindsight...

But then I wouldnt have learned all the cool stuff from this thread

 

[Muckin_Slusher]

Replace nut with tension nut? Then you can use your smaller torque wrench.

Obviously it's probably not a viable solution for cylinders due to clearances (and cost!).

Just thought I'd add it for anyone who's never seen them.

Tension Nuts according to ISO 898-2 - HEICO Fastening Systems - HEICO-LOCK Wedge Lock Washers, HEICO-TEC Tension Nuts, HEICO-FORM Cold Forged Parts, HEICO-NAILS Upholstery Nails

www.heico-group.com

 

[Zewnten]

Repair manual literally says use a shim of correct thickness to get everything properly lined up. No one in this thread can read.
Edit: one person can read.

 

[Honch]

Repair manual literally says use a shim of correct thickness to get everything properly lined up. No one in this thread can read.

The picture from the manual you posted answers your question.

"Select the proper thickness of shim to align the cotter pin group in the castle nut with the pin hole in the piston rod.

Who can't read?

 

[Zewnten]

Who can't read?

Sorry my internet is slow and skips as I scroll. Re-reading it you're still the only one to point it out.

 

[Honch]

Sorry my internet is slow and skips as I scroll. Re-reading it you're still the only one to point it out.

No reason to be sorry, I'm not an internet tough guy

 

[Zewnten]

Haha no worries I try not to be one that skips to the end of thread without reading it and offers an opinion especially if someone already answered it.

 

[Monza Harry]

Sorry my internet is slow and skips as I scroll. Re-reading it you're still the only one to point it out.

Reread post 7 please. Harry

 

[Zewnten]

Reread post 7 please. Harry

With the run on of thoughts in that post even knowing it was there, it was hard to separate that from the jumble of everything else. Not trying to be rude, I do it myself. Separating out your individual thoughts goes a long way in writing.