Track Adjuster Grease Fitting - Torque?

[MrEvilPirate]

Komatsu mini PC50-UU, but looking for general info... what is reasonable torque range for tightening up the track adjuster grease fitting?

I have one side that leaks a bit, I cranked down on it pretty good, maybe 90 ft lbs. In retrospect might have been too tight. I don't want to strip anything.

 

[Allan M]

Hey MrEvilPirate: see this link (https://www.huyett.com/blog/install-grease-fittings).
My general thought here is that don't torque a grease fitting down to 90 ft lbs. Grease fittings generally have a tapered pipe type thread...and should seat with easy tightening (using a 6" or 8" box or open-end wrench) and then maybe another quarter turn. If the fitting is leaking through the ball-stop end then replace the zerk. If it is leaking around the threads you may have damaged threads on the housing or zerk. Try teflon pipe-thread tape on the zerk and reinsert (careful not to overlap the tape on the inside orifice of the zerk) or replace the fitting. If the threads are damaged on the housing then you need to go to plan B which is to retap the housing for an oversized zerk or use a special self-tapping zerk that will reseat in the housing opening. I'm sure some guys on this site are much more knowledgable than me on this topic. I've only dealt with it a few times on a tractor and auto. Best, Allan

 

[MrEvilPirate]

Allan - Thanks for the reply. I'm not talking about just the zerk, but the entire fitting... see the pic in the ebay listing here. You put a 19 or 20mm socket around it and tighten it down.

https://www.ebay.com/itm/2658095976...044&customid=83db7a87f99916da3d411990228a95fe

 

[MrEvilPirate]

And to be clear... the actual zerk needs to be replaced... at the end of pumping grease a lot leaks out. But it doesn't hold and the track loosens up a bit after 8 hours or so to the point where it is very easy to pop it off the idler (rubber track). I'm in sandy and or top soil conditions on a hill in the forest so not ideal. Not sure if it is leaking from the zerk or someplace else, I figured replacing this would be an easy place to start.

I took it off yesterday and cleaned it up real good, threads looked fine, just curious how much you need to tighten this thing down. Like after you open it up to let grease out to get the track back on.

Here is a pic from the ebay listing if someone comes across this thread in the future:

 

[John C.]

First place to look at on those fittings is the cone on the end opposite of the grease fitting. If there is a line worn into it, the fitting is usually junk. Second item is there is usually a check valve inside the main body so the grease fitting shouldn't be losing grease when you remove the grease gun from the fitting. The usual failure of the grease fitting nipple is wear on the latching part in the fitting or in the grease gun fitting. It isn't common for the grease fittings to be screwed into the body of the valve. Most valve bodies have the fitting as a part of the body.

It usually only takes a few pounds of torque to make the whole fitting seal the grease in.

 

[MrEvilPirate]

It isn't common for the grease fittings to be screwed into the body of the valve. Most valve bodies have the fitting as a part of the body.

It usually only takes a few pounds of torque to make the whole fitting seal the grease in.

Thanks John C. Yes I believe what I have on the machine is this where the zerk and fitting are one piece:

Really just a couple foot pounds to seat that entire thing? I am way too tight then.

 

[Allan M]

MrEvilPirate: Per your exchange with John C. it is clear that the main fitting for the zerk whether one piece or not is not pipe type threading (tapered)...meaning it tightens the further your screw it in. So, I re-track my "Teflon Tape" suggestion. Teflon Tape is really more of a lubricant to help fitting go together and tightened properly.

If you have already ordered a new fitting (or try with the old fittine) don't tighten the fitting body more than 10 to 15 ft. lbs. If it still leaks around the thread body (not referring to the zerk nipple and ball valve) then I would use a good quality industrial thread sealant, either a Pipe Dope or Anaerobic Resin Compound. Pipe Dope is solvent based and the resin compound works differently with a catalyst. Both would certainly stop any thread leakage (likely from a damaged or worn housing body if the new fitting also leaks) and the fitting would still be removable with a little effort. I would only put the sealant on the set of threads closest to the zerk. Not on both sets of threads. That way you won't run the risk of a sealant build-up between the threaded portions of the fitting. Best, Allan

 

[John C.]

It isn't the threads that hold anything in. It's the cone at the bottom of the fitting.

 

[Swetz]

kinda like a brake bleeder

 

[Allan M]

I would suggest that yes the cone is designed to seat in a receiver housing to direct grease from the grease gun through the relief valve and into the tensioner assembly. It also provides a seal. The primary seal, though, (to prevent back flow of grease and excessive pressure on the zerk fitting) is from a check ball relief valve inside the body of the fitting. I believe a zerk fitting can handle somewhere between 3k to 6k psi. That said, an excavator bouncing around on the tracks and tensioner assembly likely create even greater peak pressures. This would literally blow the zerk out of its housing if a relief valve or check ball valve inside the fitting didn't stop it. All of that said, worn or damaged housing threads (cone likely won't seat properly), damaged fitting threads, worn out zerk, and worn or improperly fitting cone end of the fitting into the housing are all potential leakage points. I believe the design purpose for fittings with two rows of threads with a channel in between or one row of threads with channels on both sides is so that removal isn't dangerous and prevents pressurized grease from blowing in the direction of the operator. I haven't seen this on an excavator but on servicing harvesting and cannery machinery. The two rows of threads act as a pressure safety release. If the threads didn't hold anything then this wouldn’t be in the design. So, a faulty track adjuster valve (I believe this one has a spring ball valve inserted inside the body of the fitting) can fail on several levels: the coned end doesn't seat properly, the ball valve near the cone inside the fitting has debris, is worn, or fails, and the back-up zerk ball valve/spring can't handle the pressure or is worn, the fitting itself wasn't properly tightened and is loose, worn or housing/fitting threads are damaged. Yes, I believe grease can leak around the threads in certain conditions. Best, Allan

 

[John C.]

The threads on the outside do nothing except allow application of pressure on the cone at the end of the fitting.

 

[Nige]

FWIW I found a spec for tightening a similar style of fitting on a Cat excavator - 25 +/- 5 ft lb.

As I see it there are two obvious ways for one of these fittings to leak.
1. If the ball check valve (red arrow) located inside the top of the assembly is defective, grease will leak out of the zerk.
2. If there is a sealing issue between the conical part (white arrow) at the bottom of the fitting and the body of the track adjuster grease will leak up the slot in the side of the fitting, a location where it's supposed to exit from when the fitting is unscrewed a turn or so to release grease pressure and de-tension the tracks.

 

[kshansen]

FWIW I found a spec for tightening a similar style of fitting on a Cat excavator - 25 +/- 5 ft lb.

Well, if the recommended torque is 25 +/- 5 and it was cranked down to near 90 I would be worried that the part it seats on might be damaged!

 

[MrEvilPirate]

Guys thanks for all the help. I picked up a new fitting will give it a shot this weekend and not tighten it to 90 ftlbs. Luckily the piece it screws into is available for 260 bucks... so worst case scenario I can still buy my way out of this if I created a problem for myself.

 

[MrEvilPirate]

Guys thanks for all the help. I picked up a new fitting will give it a shot this weekend and not tighten it to 90 ftlbs. Luckily the piece it screws into is available for 260 bucks... so worst case scenario I can still buy my way out of this if I created a problem for myself.

 

[MrEvilPirate]

Just closing the loop. New fitting worked great, nothing was damaged, track holds tension just fine and I'm no longer throwing a track every day. Thanks everyone.

 

[skyking1]

cool! it is a bummer that you can't change just the zerk like on a bigger machine. I have never had a seat leak, always just a worn out zerk at the shoulders that prevents getting enough pressure going.
Thrown tracks are bad all around. People get hurt getting them back on, I consider them a primary safety concern on all tracked equipment.