M936 Hydraulics - or - How Fast Can An Old Fat Man Move!?

[Mullaney]

In the continuing adventure, today as I was retracting the Jib - nice and easy - I had a line break. The one that controls "IN" on the Jib Cylinder. It is amazing how fine the spray can be and how far it goes! What was really amazing was how quickly I got up out of the gondola, took three steps across the bed, two more steps down and one big leap up into the cab of the truck. Hit the power switches, grabbed the transmission shifter and the power divider at almost the same instant. The second the power divider came forward - the geyser stopped!!

Strange how it works. I had been eyeballing hoses. Been thinking there were a few that needed to be replaced - or at least checked for soft spots. Not any more. The one I was a little concerned about - yep, it's definitely a problem.

I guess the good news is that some of my truck looks like it was freshly painted. Better part is that I managed to stay dry. Couple of pictures below for the entertainment value only. Rocks are about 20 feet from the truck. Too bad I didn't have an audience that was recording me...

 

[simp5782]

Most of us with wreckers it has happened to before.

I never sit In the seat when I am operating it. Usually I stand behind the seat box. I have had my lap covered in hydraulic fluid one too many times

 

[Mullaney]

I was just getting comfortable with it. Had stood beside or behind every time - until today. Move a little, look a little, move a little more and look again... Really amazing how quickly I managed to go from leaning back and relaxed to bolt upright and moving .

I am guessing the soft spot in the hose could have been caused by the spades being dropped on it. Or maybe the couple of heavy steel plates laying in the bed. Or maybe just old age.

Several hoses on the truck don't have the crimp on fittings. The one that fails is that way. About half of the hoses appear to be the kind with reusable fittings where new hose can be make on-site.

 

[WildernessJeep]

I have a small seam leak on the hydraulic tank itself. Anyone have an extra sitting around? Opinions on repair or replacement?

 

[simp5782]

I have a small seam leak on the hydraulic tank itself. Anyone have an extra sitting around? Opinions on repair or replacement?

@Csm Davis has one I am sure.

Drain it. Clean the tank exterior and weld over it.

 

[Csm Davis]

@Csm Davis has one I am sure.

Yeah one or two.

 

[Mullaney]

May 18, 2020: Removed the "access cover" to gain better access to the hydraulic hose that failed. According to my best interpretation of TM9-2320-272-24P-2, the rubber line that failed is P/N 12256658-2. Sad part is - if the other access cover had been in place ## years ago when something got dropped on it - then I wouldn't be replacing the hose.

Pictures are attached. Looks like I found something else that needs a little paint too. Can't see that much surface rust and not treat it now.



Maybe the glove that is soaked in hydraulic fluid is from the last person who worked on this truck?



It seems that I incorrectly reported that the Jib Cylinder hose failed in an earlier post. As best I can tell, the failed hose (Figure 505, Item #38 connects to the metal tube labeled "12256637" (Figure 505, Item #24). Picture above has orange tape on the metal line attached to the failed hose.

Strangely the TM shows that line connecting to the Winch Motor. My failed hose dives down under the truck. Guessing (because it is raining) it goes to the Pump...

 

[simp5782]

those hoses have reusable fittings on it as designed from the military so you don't have to have ends crimped on. Just simply replace the hose

 

[Mullaney]

those hoses have reusable fittings on it as designed from the military so you don't have to have ends crimped on. Just simply replace the hose

That would be fantastic! Any idea where to get the hose? I found a local hydraulic shop over on Graham Street here in town... My plan had been to pull the hose off and carry it with me.

 

[simp5782]

I buy it off ebay.

I use hydraulic supply company on Westinghouse Blvd when around Charlotte and I need somethint.

 

[71DeuceAK]

Welcome to the fun of what an oily, greasy mess the 936 wreckers can be. Most weren't the best maintained to begin with and many military guys reported they leaked even when brand new. I feel your pain, though- every one of these I've ever climbed around on was an oily, greasy mess. That access cover is heavy. I've had the pleasure of pulling one of those drag winch control valve assemblies off...in ND winter temps at that.

 

[Katavic918]

In the continuing adventure, today as I was retracting the Jib - nice and easy - I had a line break. The one that controls "IN" on the Jib Cylinder. It is amazing how fine the spray can be and how far it goes! What was really amazing was how quickly I got up out of the gondola, took three steps across the bed, two more steps down and one big leap up into the cab of the truck. Hit the power switches, grabbed the transmission shifter and the power divider at almost the same instant. The second the power divider came forward - the geyser stopped!!

Strange how it works. I had been eyeballing hoses. Been thinking there were a few that needed to be replaced - or at least checked for soft spots. Not any more. The one I was a little concerned about - yep, it's definitely a problem.

I guess the good news is that some of my truck looks like it was freshly painted. Better part is that I managed to stay dry. Couple of pictures below for the entertainment value only. Rocks are about 20 feet from the truck. Too bad I didn't have an audience that was recording me...

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Ugh. I used to hate blown hyd hoses when i was doing equipment work. Always a pita to clean up. Well at least you found a good place to dry your socks.

 

[Mullaney]

Ugh. I used to hate blown hyd hoses when i was doing equipment work. Always a pita to clean up. Well at least you found a good place to dry your socks.

I am "bent" that this thing isn't going to dribble hydraulic oil all the time. I believe I have a leak in the packing on the Jib cylinder. That was what I was planning to investigate when the hose popped. I think most of my pain is from it sitting.

The socks are actually shop rags. Company that does ours for the print shop gives us white ones. The real reason you see them hanging there is to keep me from knocking my head off on the catwalk. That fold-down walk board is exactly head height. Feels wonderful when you inspect it with your forehead!

 

[Mullaney]

Welcome to the fun of what an oily, greasy mess the 936 wreckers can be. Most weren't the best maintained to begin with and many military guys reported they leaked even when brand new. I feel your pain, though- every one of these I've ever climbed around on was an oily, greasy mess. That access cover is heavy. I've had the pleasure of pulling one of those drag winch control valve assemblies off...in ND winter temps at that.

I was amazed at how heavy that access cover was! I recruited help to lift it down to the ground. Seeing how beefy it is, chances are I could have just shoved it off onto the ground - but sure as heck - something would have warped or bent. I have enough troubles without ME creating more!

I saw in the TM that there is a second part of that cover. It protects the hose that was damaged on my truck. I figure I will make my own if I can't talk @Csm Davis out of one...

Yessir, that valve body and the one up in the gondola are no joke. It makes me remember back when I worked inside (freezing cold in the winter, miserable hot in the summer). We had 4 chain falls in every bay. Nothing lifted by hand... Not quite like that in the back yard. Where I have it parked - there aren't even any shade trees. (not whining, just stating fact)

 

[71DeuceAK]

I tried lifting that cover myself and said fugeddaboutit, especially frozen to the ground having been already off! Yeah they are heavy. There are weird Rube Goldberg things on them too like gaskets on top of gaskets. One of my mentors and I (the one in ND) took one apart, in a heated garage with many paper towels- I learned much in the process.

 

[simp5782]

I tried lifting that cover myself and said fugeddaboutit, especially frozen to the ground having been already off! Yeah they are heavy. There are weird Rube Goldberg things on them too like gaskets on top of gaskets. One of my mentors and I (the one in ND) took one apart, in a heated garage with many paper towels- I learned much in the process.

Or just eat some more and you will be a big kid someday to be able to lift it.

 

[71DeuceAK]

LOL! I ate like 6000 calories a day on that trip...working in the cold burns them off quickly! Guy thought it was the funniest thing as I've got the physique of a pencil.

 

[Mullaney]

Or just eat some more and you will be a big kid someday to be able to lift it.

Yeah well... I am still overly cautious. It is bad enough to repair something that is broken. It is REALLY BAD when you (meaning me) broke it for no good reason.