How do you torque hydraulic lines?

[BloomingtonMike]

I installed my 3rd SVC loader arm hydraulic oil lines tonight on my JD 3320. They are the metal oil lines (hard lines). In the instruction manual it said to torque them? How do you torque those metal lines? You need a line wrench to tighten them to eachother. My torque wrench is just a socket wrench type.

 

[_RaT_]

Perhaps a crows foot type attachment for your torque wrench. Its an open end wrench basically with a 1/2" or 3/8" socket opening. I used them for adjusting and torqueing the valves on my old Datsun.

 

[Mike_Lipke]

If they don't give values, then the word "Torque" is interchangeable with the wore "tighten".
You are torquing a fastener everytime you tighten it, whether you are measuring the torque or not.

 

[SCB]

General rule of thumb for us at one of the largest aircraft mfg. is if accessability prohibits use of a torque wrench on hydraulics, you tighten until the fitting bottoms out. Then you will turn it two more flats(1/3).

 

[JoeL4330]

Our old rule of thumb was "finger tight plus a half turn ...30 ft.lbs, as I recall"

 

[turnkey4099]

Yeah, they don't need to be really "reefed" on. The internal design takes care of the sealing with reasonable tightening.

Harry K

 

[dent8]

Tighten 'til it strips then back off 1/4 turn. /forums/images/graemlins/crazy.gif
Dennis

 

[CT_Tree_Guy]

<font color="blue"> Tighten 'til it strips then back off 1/4 turn </font> /forums/images/graemlins/crazy.gif

Dennis, that is a GOOD one! Welcome to TBN, you're going to fit right in, I can tell. /forums/images/graemlins/laugh.gif

I've never measured the torque on any hydraulic line or coupler, just make it good and snug - well, halfway between snug and tight as he$$. I used to be "torque wrench happy" until I realized that MOST torque specs that you find in any manual are just based on a universal torque chart that relates torque to the diameter of the bolt/size of the nut. Once you have a "feel" for what those torque values are, you can work much faster. For example, I used to use a torque wrench on spark plugs, which are usually around 15 ft/lbs. Now is just go by feel - make sure the little metal gasket gets fully crushed, then add a hair more. Without a gasket, just make them good and snug.

Of course there are MANY fasteners that should (MUST?) be torqued with a torque wrench. Head bolts, crank pulleys, intake manifold bolts, main bearing caps, piston rod caps, stuff like that.

 

[EddieWalker]

I'm in agreement with everyone else. Just tighten them until they won't go any further. They self seal when tight. If they leak,then you need to get them tighter. /forums/images/graemlins/grin.gif

Eddie

 

[slowzuki]

I think most plug torque specs now have to do with protecting aluminum heads eh? I have a few torque wrenches but rarely use em, I've broken enough bolts now I have a good feel for where I should be! At least they've all been rusted bolts I'm trying to unscrew.

</font><font color="blue" class="small">( <font color="blue"> Tighten 'til it strips then back off 1/4 turn </font> /forums/images/graemlins/crazy.gif

Dennis, that is a GOOD one! Welcome to TBN, you're going to fit right in, I can tell. /forums/images/graemlins/laugh.gif

I've never measured the torque on any hydraulic line or coupler, just make it good and snug - well, halfway between snug and tight as he$$. I used to be "torque wrench happy" until I realized that MOST torque specs that you find in any manual are just based on a universal torque chart that relates torque to the diameter of the bolt/size of the nut. Once you have a "feel" for what those torque values are, you can work much faster. For example, I used to use a torque wrench on spark plugs, which are usually around 15 ft/lbs. Now is just go by feel - make sure the little metal gasket gets fully crushed, then add a hair more. Without a gasket, just make them good and snug.

Of course there are MANY fasteners that should (MUST?) be torqued with a torque wrench. Head bolts, crank pulleys, intake manifold bolts, main bearing caps, piston rod caps, stuff like that.

)</font>

 

[QRTRHRS]

Watch the strong arm style on fittings with an o-ring. You can squash the ring and cause a leak.

 

[Green4Me]

You are so right. I just installed the third valve kit on my CX. When the o-ring bottoms, they are good. These connections seem to work well.

 

[CT_Tree_Guy]

<font color="blue"> Watch the strong arm style on fittings with an o-ring. You can squash the ring and cause a leak. </font>

This raises a good point, in line with what I was trying to say in my previous post about developing a "feel" for torques. There are so many other factors that one needs to develop a "feel" for, and understanding of. It's ALL about physics and "uncommon" sense.

For instance: what material is the fastener made of? Grade 2? Grade 5? Grade 8? Brass? Stainless? What's it being threaded into? Cast iron? Aluminum? Mild steel? Cast steel? Is it fine pitch or coarse pitch? How many threads are going to be doing the holding? 10? 30? Is it a JIC hydraulic fitting, where the seal is just metal to metal? Or is it a fitting with tapered threads that requires teflon joint sealant and maybe it needs a little more, or less torque to get it pointing the right way? Does it use O-rings that don't want as much torque? Or a compression fitting, or does it involve ferrules, or is it a banjo fitting with copper washers?

Lots of things to consider, for sure, but it's not all that tough if you just apply a healthy amount of that uncommon sense. Don't be like my friend who tightened his auto tranny drain plug so tight that he stripped out his heavy cast aluminum pan and it's been leaking ever since. I'm like, dude, how tight did you think that needed to be?

Anyway, for hydraulic lines, I still like Eddie's advice - if it's leaking, tighten it a little more. Now THAT is uncommon sense! /forums/images/graemlins/smile.gif

 

[3RRL]

</font><font color="blue" class="small">( There are so many other factors that one needs to develop a "feel" for, and understanding of. It's ALL about physics and "uncommon" sense.)</font>

You are so right...
What's the old saying..."common sense isn't very common"? There's no diploma like the one from the "School of Hard Knocks"

 

[BloomingtonMike]

I did use line wrenches - a fist for me. Very nice. I will own a set now.

As for the 212ft/lb torque rating on the loader arm mount on the JD - **** that is torqued!!

 

[mark4Jesus]

If you are going to actually torque the fitting, then RaT is correct that you need a crows foot on your torque wrench. The important thing is that the crows foot opening has to be at a 90 degree angle from the wrench. If the opening is in line with the wrench you will end up with a higher torque value than what the wrench is set at. With the opening at 90 deg. the actual torque will be the same as what is set, or where you stop looking at the pointer, depending on the type of torque wrench you are using.
A standard rule of thumb for tightening tube fittings is hand tight, then 1/4 turn. Any more than that and the sealing service, whether flared or a ferrule, will be damaged.