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Torque Multipliers vs Torque guns

Nige

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Ken, we have had exactly the same situation occasionally with 789C/D hoist cylinders and I have no idea why. 95%+ of the cylinders it's no problem at all, the head cracks and screws right off by hand. Just occasionally one comes along to give you grief - and they all came off the same fleet of trucks doing exactly the same work, there appears to be no rhyme or reason to it. The gland/head either moves about 2 turns with difficulty and then stops and will not go either in or out, or does not want to move at all right from the get-go.

If a head moves the 2 turns with difficulty we know from experience that the internal thread in the hollow rod is goofed, so now if a head does not go easy within half a turn of it cracking it is stop time. In either case (non-moving or 1/2 turn) in order to salvage the more expensive rod #24 in your diagram with its internal thread undamaged we send the whole assembly out to a local machine shop, have them put it in a lathe and machine the head/gland until it's so thin it literally falls out. It's the only solution I have been able to come up with so far. We actually had to send one to the machine shop yesterday for exactly that issue. After removing the head they also clean up the internal thread in the rod using a new head as a go/no-go gauge until the head will screw on and off by hand right until it bottoms. So far we have had no "repeat offenders" after doing this refurb process so maybe the root cause is quality issues in the internal thread in the rod..?
 
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overworked

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We need to get your people to make a tool for us! Have a hoist cylinder off a little 769D that needs a seal replaced. Local Cat dealer can not remove the head from the end of one section to replace the seal and back-up ring!

View attachment 127982

The oring and back-up ring are 25 and 26 inside of tube #24

Only thing that saved us is someone at a different quarry in the company drove another 769D off the face and totaled that one. So we were able to salvage a cylinder off that truck. Otherwise we were looking at about $5,000.00 plus the seal kit and assembling of the cylinder:eek:

Instead of the $250 for a seal kit. I think I will try to talk the boss into letting me send this one to a Mennonite owned machine shop we deal with at times. Let them know the part is scrap now so if they destroy it it's no big deal. I have a couple ideas but don't have access to a cylinder bench to hold the tube or turn the head. Right now head has two 1/2 (I think) spanner wrench holes in the top.

Maybe its the pictures, that rod looks to be a little bent?
 

Cmark

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Another handy way to anchor a rod for repair is to put the end in the clevis on the back of a loader or something and drop the towing pin through the eye. Support the other end on a baulk of timber with a V cut in the end and it's then at a nice convenient height for working on.
 

kshansen

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If a head moves the 2 turns with difficulty we know from experience that the internal thread in the hollow rod is goofed, so now if a head does not go easy within half a turn of it cracking it is stop time. In either case (non-moving or 1/2 turn) in order to salvage the more expensive rod #24 in your diagram with its internal thread undamaged we send the whole assembly out to a local machine shop, have them put it in a lathe and machine the head/gland until it's so thin it literally falls out. It's the only solution I have been able to come up with so far. We actually had to send one to the machine shop yesterday for exactly that issue. After removing the head they also clean up the internal thread in the rod using a new head as a go/no-go gauge until the head will screw on and off by hand right until it bottoms. So far we have had no "repeat offenders" after doing this refurb process so maybe the root cause is quality issues in the internal thread in the rod..?

That might be the way to go on this one. I believe the head in rod #24 is available for about $500. That's one tenth the cost of the rod assembly so even with a few dollars for machine shop work still worth the effort. Now to just convince the powers that be.......
 

still learn'n

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Wwwwwwweeeeeeellllllllllllllllllllll Nige your wrench would look a lot better on the end of my service truck crane then a Rigid pipe wrench with a shackle thru the handle and crane hooked to shackle and having no idea how tight it is getting but as has been mentioned when I have talked to dealer about it it sounds like one of the keys to the problem is retorquing after 4-5 hr of use! And yes the new 4 ft pipe wrench broke but the 3 ft has so far stood up to the abuse!
 

Nige

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As I said what we are doing is easier than what you want to do for the simple reason that we're taking a factory-assembled component, marking the position of the nut, loosening it off, disassembling, fitting new seals then assembling it all back to exactly the same place the nut was at previously using the same rod, piston, & nut. So based on that we should be back to exactly the same torque as was on the nut before we assaulted it in the first place. To a certain extent we're not bothered in knowing exactly what torque we are putting on the nut, we simply want it back to the same spot as it was when we started - because if it was right before it'll be right after we've finished with it.
 

still learn'n

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One more question on torque multipliers somebody advised me to get a 3/4" input drive is that a good idea? I have a 1" drive socket that I need already for output drive and most of the multipliers that I have found have 3/4" input and 1 1/2" output what is best? Also if I get a heavy wall tubing or bushing stock to put on reacter arm is that going to be safe? Also thought of making a bracket to go on disk to hold reacter arm so it cant move around! Thanks for your help Jerry
 

Nige

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In my experience even a 35:1 multiplier will only use a 1/2" input, the same as the more common 18:1. If a multiplier needs a 3/4" input my first suspicion would be that the reduction can't be that high, maybe 10:1 max. Why pull your guts out on a 3/4 bar at a low multiplication when you can do it much easier and with less effort on a 1/2" on a higher reduction multiplier..?
 

mikebramel

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a 3/4" input with a 1" output would be have a single set of planetaries. a 1/2" input with a 1" output would have two sets in compound. Either way you can pull some on a 3ft 3/4" ratchet or 2-3 times the stroke at less weight on a 1/2". the total input power is the same

I don't think any manufacturer would recommend any bar other than what they sell but I have used rod stock cut to length and turned the end to slip fit
 

still learn'n

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ok now looking at the options if I buy a pneumatic torque gun I will still need a reactor arm wont I? I found some used ones for about half the price of new!
 

Nige

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ok now looking at the options if I buy a pneumatic torque gun I will still need a reactor arm wont I? I found some used ones for about half the price of new!
The reaction arm on either a pneumatic or a hydraulic torque wrench generally tend to be of the "foot" type that locks on to the adjacent bolt in the pattern, so they are usually quite short. If something goes pear-shaped they will jump off the anchor. The reaction bar from a torque multiplier can be anchored literally feet away from the bolt in question, and if it flies it can get up a fair head of steam before it finally strikes something, that something often being a human body. Don't get me wrong, both types of tightening tool need to be used with extreme care, but of the two types the torque multipler gets me far more apprehensive when it gets pulled out of the box simply because I know what the consequences can be if it goes wrong.

http://www.mirmgate.com/index.php?coreId=4343
 
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TOM V

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Here is another option for high torque applications, note the reaction arm as these 1 3/4" allen head bolts took about 9000 lbft to crack loose
.IMAG0257.jpg
 

Gavin84w

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The Cat 6V6080 ( I THINK THATS THE NUMBER) 18 to 1 multiplier IS the best general duty multiplier in the industry - period. Unfortunately this multiplier has in some circles been given the worst reputation in some cases. This comes from it,s use and individuals putting themselves in harms way, simple as that. I have used that multiplier successfully for 20 years in the heavy earthmoving game and only ever busted a few shear pins and 1 set of planetaries. Recently i saw an incident report from someone using a hytorc to undo the mount bolts on a carrier roller on a Cat dozer as he got an oil injection, personally i would have though a 3/4 gun could have undone the bolts but you wont get an oil injection from the Cat multiplier and you won,t get hurt when it is used properly, bit like a lot of things really.........
.

Still to this day i say the best purchases of tools i have ever made are the 1 1/2 Cat flogging spanner and then the Snapon 1 5/16, 1 5/8, 1 11/16, 1 3/4 & 1 7/8 sizes, nothing i could not undo with them and a 14 lber on them, Nige i had plenty of home made flogging spanners like your flash one, inch plate just oxy cut to suit, resealed so many rams with those and never had an issue, swinging that hammer to tighten them is a big deal though and you got to have plenty of self confidence!!
 
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Nige

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I agree with Gav about torque multipliers, it's when you read the incident reports about people extending the reaction arms with crowbars, lengths of pipe, etc, that you realize it's not the multiplier itself that's dangerous, it's the fcukwit who was using it. I've never had any issues whatsoever with the 6V-6080 and generally there wasn't much it wouldn't undo or do up apart from 994 axle bolts where it would come up a bit short. In my last job we actually went out and purchased a 35:1 multiplier specifically for that job.

Gav's comments about hydraulic torque wrenches pretty much mirror my experience, that's why we use air-operated RAD torque tooling now instead of hydraulic.

I've cut spanners out of 1" plate before as well Gav, especially out in the bush... however because this one was going to be around for a while I decided to make a job of it and have it plasma cut. They did a very pretty job on it too if I may say so.
 

overworked

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We have many "cut" plate wrenches for cylinder nuts, have the bumpers drilled on the back of the truck to clamp down the rod and use the crane to loose and tighten back up, I thought about getting a scale to put on crane hook to measure the torque, we just do as Nige said go back to starting point. Most problems with torque multiplier are in too much of a hurry and don't plan on needing that much torque so the reaction setup is usually to ( soft ).
 
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