Hydraulic plumbing advice

[MoCo]

I am installing auxiliary flat-faced hydraulic plug-in lines to the front of my KX033-4 excavator to hook up a brush cutter. The fittings screw into the switchable double port near the bucket end, (also used for the hydraulic thumb.) My questions:
1. Is it good or bad practice to use Teflon pipe tape on these high-pressure fittings?
2. Is there a proper procedure to determine where to use the female and male fittings or which is supply and which is return? Is there some universal rule as to which fitting on a skid steer or excavator should be supply or return and how can I determine which line does what? On the thumb cylinder, one hose goes to the top and one to the bottom. Am I correct that the top hose (where the piston retracts) is supply?
Thanks.

 

[North Idaho Wolfman]

I am installing auxiliary flat-faced hydraulic plug-in lines to the front of my KX033-4 excavator to hook up a brush cutter. The fittings screw into the switchable double port near the bucket end, (also used for the hydraulic thumb.) My questions:
1. Is it good or bad practice to use Teflon pipe tape on these high-pressure fittings?
2. Is there a proper procedure to determine where to use the female and male fittings or which is supply and which is return? Is there some universal rule as to which fitting on a skid steer or excavator should be supply or return and how can I determine which line does what? On the thumb cylinder, one hose goes to the top and one to the bottom. Am I correct that the top hose (where the piston retracts) is supply?
Thanks.

I personally avoid PTFE tape, I use PTFE dope.
There is no standard, as they are both supply, it just matters which way the valve makes it at the time.

 

[Runs With Scissors]

The answer to your question #1 is almost as controversial as the "Best oil" question.

I have been using "teflon tape" since Jesus was a Corporal, and I have never had a problem.

Either one is fine when applied properly IMHO.

I have about 237 rolls of it somewhere, because I can never find it when I need it, so I buy another one, then "magically" find the other 236 rolls as soon as I get home.

 

[biketopia]

Like NIW mentioned, they are both "supply" depending on how the flow of fluid is directed. Put one male and one female on the implement side and vise versa on the tractor side. That way it always operates the same when you hook it up.

Also only use PTFE tape or paste ( I prefer paste) on fittings that require it.

 

[Alfred_2345]

From what I have read here on OTT, the general advice is tho leave the end thread bare so the tape/dope does not get into the hydraulic fluid. The main concern with tape seems to be getting tape material into the fluid where I am assuming it could cause problems. Never really explained....

Not really experienced in hydraulics so take this for what it is, some random dude posting on the internet

 

[MoCo]

Thanks for the replies. I used Teflon pipe thread sealant in a tube, which seemed safer and provided a good seal.

 

[mikester]

I am now preferring the thick teflon tape because it doesn't make a mess on disassembly.

The thin stuff shreds if you have to disassemble. I find the liquid/paste pipe dope crumbles when it dries out and when you pull apart fittings it makes the job messy.

 

[rh74]

I use this Permatex product. If I'm in a bind, I'll use tape then make the proper repair ASAP.

Permatex® Pneumatic/Hydraulic Sealant, 36 ML - Permatex

www.permatex.com

Another option is Hercules paste. I use this on LP gas lines and Compressed Air lines. It works great, however it's not easy to take the connection apart. Also wear gloves when using it, it sticks well to everything and doesn't wash off easily.

Hercules® Brush-on Block™ | Oatey

Hercules® Brush-on Block™ is an all-purpose, high-performance pipe joint and gasket sealing compound. Recomended for use on metals including aluminum, black iron, brass, copper, stainless steel, galvanized steel and plastics, including PVC and CPVC. Behold the power of Hercules®, products built...

www.oatey.com