Wrecker: Unseizing Boom Jacks

[zebedee]

I am sure this is a common issue with a lot of wreckers - M62, M543, M246, M816, M819, M936 etc.
They lay on their sides for years without being used - the lower one can often be semi submerged depending on the angle of the bed, debris daming rain water.. The close tolerance of the two tubes promoting capillary action of water and the unpainted inside of the inner tube is prime for surface rust to build up.

I have had my boom jacks stored inside for a few years, one had been painted to the point that you cannot introduce penetrating oil into the joint. The other has been occasionally 'oiled' at the pin holes and end of the outer tube.

I have tried using the big winch on my M916A1 and a 2:1 snatch block with the boom jack shackled to the far end of a lowboy trailer - but no go.

I considered flexing the tubes - which may break the rust adhesion, but am concerned that any distortion will add to the resistance. Equally, I was not going to hammer on the outer tube for the same reason.

I had spoken to member "5ton", a retired Hotel 8 instructor, who tried using two D9 dozers to pull them apart...... to no avail.



So... I have decided to make a hyd jack press jig - to try and push the two tubes apart..

split colletcollet seatedouter collar welded to colletchannel extensions for jack sizebasic design premisejig in place

Using various scraps, I sized some collars and a split collet to go over the eye - it's a bigger diameter than the inner tube - humpf > to get a pretty close fit on the end of the outer tube. Included a very slight taper on the collet face which MAY slightly flare the end of the outer tube to enable oil penetration..

The channel from the collar allows room for the jacks which sit a on heavy angle base. I have two 20 ton (M916A1 Bii) jacks, and if needed, two 30 ton (M816 Bii) jacks...

Trying to visualise failure points, I beefed up weak points - hopefully. I can always add more scraps...

Next step is fabrication of the inner tube eye anchor - this needs to be close to the eye so that I do not just bend the pin that will go through it.....
(I am aware that I could tear the eye apart - however since the boom jack only works in compression, the eye isn't really a structural member and I can rebuild - in any event - the boom jacks aren't really any good to me unless they telescope! - Worst case scenario, I'll cut off the 4 ends and re-man new legs. Sourcing telescoping tube may be an issue. Could just split the outer tub length wise and cut it off with a torch and remake the outer.....)


If this works - I'd be prepared to make it available (w/o jacks) for other wrecker owners in the same situation. Possible a deposit to ensure safe return or transport to next member......

 

[timntrucks]

i hope that works vs hooking to a tree and pulling them apart

 

[CMPPhil]

Hi

What have you tried as a penenatrating solution? The old home brew acetone and AT seems to work on stuck engines given time to soak in so might work in this situation. Add low heat might help.

What ever you find works let us know.

Cheers Phil

 

[NDT]

Good luck. I tried to pull those apart by hooking one end to a 22B Bucyrus crane and the other end to a D-7 dozer with a cable. Broke the eye off.

 

[zebedee]

Yup - this will be hung inside my shop - through trap door to loft, so that the jacks work vertically. I'll caulk the collet/collar so that I can pool penetrating oil whist the setup is left under pressure.

Haven't ever tried the acetone/TQF but I'd like to.

.............. Watch this space!

 

[73m819]

Howard, you going to WAY to much work, you ARE over thinking the issue.

1 -- dead mam one end to a UNMOVABLE dead man.
2 -- Attach a HEAVY chain to other end.
3 -- Attach the other end of chain to anther UNMOVABLE dead man, this could be a bunch of trucks sideways, or whatever.
4 -- Use TWO HEAVY chain binders, fit to the chain, pull the first one as tight as you can get it using a decent cheater pipe, then fit the second one again pull pull TIGHT.
5 -- Take two 5 lb hammers walking back and forth along the support hit the tube with both hammers at the same time, 180 deg. apart, keep doing this for a bit.
8 -- Fire up the rose bud, heat the tube to hot, NOT RED but VERY HOT .
9 -- Once hot, check to make sure the binders ARE TIGHT, then do the hammer beating again,
10 - REPEAT this process till there is movement, let cool down then reheat, this WILL allow the cooling/heating of the tubes to move at a different rate.
11 - keep the pin holes FULL OF PENETRATING FLUID, this will seep in between the inner tubes and help to lube the od/id of the offending support.

I do not believe that bending the tubes to break the rust will work, because you will be bending in reality 5/8" thick 3" steel tube. nor just hanging under pressure, right now the tubes are the same a welded by the rust EXPANDING on the inside tube as well on the outside tube, about the ONLY way to BREAK this rust weld is to EXPAND the outer tube, this is the reason for the rose bud, the hammering causes fractures in the rust weld, the hitting with hammers 180 deg. apart to to keep the shock IN the tube assembly.

 

[marchplumber]

Interesting................ amazing what a little water and time can do to lock something up. Good luck and will be watching to see how this turns out. From what others have shared, straight pull isn't the way. Is it possible to rotate the inner leg? soak in penetrating oil/liquids and turn back and forth? There by breaking the bond and allowing for extraction? Just a thought. Good luck!

 

[wcuhillbilly]

as far as a penetrator, I use the purist form of Iodine that I can find from the tack store mixed with a little diesel or Kerosine. Freed up a lot of stuck pistons and manual trans that way, but it takes time letting it sit for a few days while bathing it or allowing it to sit in a bath of it. Kroil is a good penetrating oil too,,, supposedly creeps to a millionth of an inch.-machine/tooling supply.

hanging from the trap door loft,,,,, hope you hung it upside down and reversed your jacks..... in other words, hung the jigged end down toward the ground, and turned your jacks 180 from your picture so that the jack rams face up and the smaller diam tube of the boom jack faced down. this way if it finally breaks free the end popps into the dirt/floor and not eliminating tension 8ft off the ground allowing everything to crash. If configured like I just said, go to the upper end,(which would be the foot of the boom leg) drill a small hole and push your penetrating solution in filling the chamber partially, now allow gravity to work on the penetrating solution while applying pressure over the next couple days. your not on a ladder trying to balance a couple 30 ton jacks in a home made jig, safety first.....

 

[topo]

I tried to separate a set to make gin poles and ended up splitting the outside tube with a torch and replaced it with another tube . The rust was not real heavy but ran the full length .

 

[Jbulach]

Bring them over and turn my kids loose on them with a feather pillow and rubber hammer, they'll have them apart or destroyed in no time...

 

[kc5mzd]

Lots of heat - until they are ready to start to glow at night in a dark room - but not glowing red where you can see them glow in daylight. Then put them under pressure while hammering and keeping them hot enough to just start to glow. It will be the consistent pressure and not extreme pressure that makes them start to move.
Have you thought of drilling, taping and installing a air fitting. Then filling them most of the way with trans fluid and airing them up to around 100-150 psi for a few days of so?

 

[Recovry4x4]

I had a similar situation with stiff leg jacks on my old M756A2. In the end, I ended up putting tension on them with a deuce winch and employing a long chain. With as much tension as the winch could apply, I went to the rosebud torch. Right after heating sections, I would beat on the chain with a spud bar. Between the winch tension, heat and shockloads from the spud bar, the did separate.

 

[rosco]

73M819 nailed it. The hammers & heat will do the job. Not too hot though... not over 500F. You need that tension on them too, to start the movement & hammers.

 

[gimpyrobb]

Since the boom powers up, I wonder if that would be a way to proceed. Actually its power up and down. I'd try using that(up AND down) and some way to affix the tube to the wrecker body.

Steel is easy to weld to and then grind off...

 

[doghead]

Lots of heat - until they are ready to start to glow at night in a dark room - but not glowing red where you can see them glow in daylight. Then put them under pressure while hammering and keeping them hot enough to just start to glow. It will be the consistent pressure and not extreme pressure that makes them start to move.
Have you thought of drilling, taping and installing a air fitting. Then filling them most of the way with trans fluid and airing them up to around 100-150 psi for a few days of so?

That is the equivalent of leaving a bomb activated.

I've seen a 4" air cylinder fly over 1/8 mile with 100 psi when the end uncontrollably came off.

Don't pressurize any cylinder that is stuck.

 

[Jbulach]

Use oil not air. Safer and lubes your stuck part...


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[dmetalmiki]

Use oil not air. Safer and lubes your stuck part...


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Sound advice. Pressure collapses as soon as there is any movement with oil, but the supply must be high pressure and low volume.

 

[Jbulach]

Paint sprayer or porta-power pumps work nice. I would doubt he'll get a good enough rust seal to build any real pressure, but may be worth a shot?

 

[Jbulach]

Maybe pump em full of grease, but who wants to deal with that mess.

 

[73m819]

Since the boom powers up, I wonder if that would be a way to proceed. Actually its power up and down. I'd try using that(up AND down) and some way to affix the tube to the wrecker body.

Steel is easy to weld to and then grind off...

This WILL NOT WORK, I think everybody who has had stuck supports tried this FIRST and had to find another way to get them apart because they are the same as welded.