Math Question?

[Daren Todd]

So, we were discussing torque specs on a bolt today. This bolt needs to be torqued to 335 ft/lbs. We have to use an impact gun to install due to a couple different factors. The main being that there isn't a way to efficiently lock the motor to tighten by hand with out a bunch of labor. Talked to the tool man, and they don't make a torque stick that big. Largest goes to 140 ft/lbs.

Now my impact does 1100 ft/lbs breaking torque, and 850 ft/lbs tightening, thats at 90 psi. Realistically it gets between 120 and 150 psi depending on wether the air compressors running or not.

Any one have any ideas how to achieve between 330 and 350 ft/lbs torque out of that gun?

 

[North Idaho Wolfman]

You have several options, none of which involve your impact you can not regulate the torque with one of those, dropping the input PSI pressure will not = dropping the output.

120 to 600 lbs
http://www.zoro.com/i/G0514762/?utm_source=Bing&utm_medium=cpc&utm_campaign=PLA

200 to 600 lbs
http://www.amazon.com/Precision-Ins...ref=sr_1_3?s=hi&ie=UTF8&qid=1422478275&sr=1-3

100 to 700 lbs
http://www.northerntool.com/shop/to...t&utm_source=AskAndAnswer&utm_content=Default

Now the cheaper option

Torque multiplier
Use a standard torque wrench to drive it

Cheap model
http://www.amazon.com/Ratchet-Helpe...8904&sr=8-4&keywords=torque+multiplier+wrench

Better model
http://www.amazon.com/Neiko-Pro-Tor..._sbs_hi_7?ie=UTF8&refRID=1PNZ0MMM8FYZTR2QNN1W

Have a Snap On guy, tell him you want to test this model:
http://buy1.snapon.com/catalog/item...roup_ID=675227&store=snapon-store&dir=catalog

 

[Tooljunkie]

335, its a lot to pull by hand, my impact will do 450 max. It has a built in regulator from 85 foot lbs and up to the full rating. There are calculations for use of offset wrenches and loss through extensions. I cant remember where i read it. There are torque guages, but wont withstand the pounding of an impact. Find a smaller impact or torque it by hand, the only two options.

 

[Daren Todd]

Thanks wolfman, I have the torque wrench. Got three of them in fact I know as far as regulating air pressure, won't change the out put. The problem is, I have to use an Impact on this bolt!!

It's the main impellor bolt on a 6" water pump. Takes a 3/4" bolt for it. On the back side of the pump end is a rubber drive coupler. If you pull the starter and lock the fly wheel on the motor, you still take a chance of stripping out the rubber coupler. Which is around 300$ and 3 hours to replace. And there isn't a way to lock the pump end with out removing the whole thing off the skid, which is really labor intensive. Or putting a pry bar into the impellor and taking a chance on damaging it which is around 2k. Not to mention, will drop your flow drastically if it has a gouge in it.

Now depending on the size and type of extension used, it will change the torque on an impact. What I'm wondering is how to determine what size/type impact extension to use, to get the 330 ft/lbs or little more. There is some wiggle room on the upper side

 

[North Idaho Wolfman]

I get what your saying, but if you can't lock down the motor and you can't lock down the pump, it really doesn't matter what you do, you'll never be able to get it to torque down to any accuracy.
Even if your gun will do 850 your going to have loss from movement of the parts, I would say off the top of my head, you easily at 1/2 loss, so hit it with the gun and call it a day.

 

[Diydave]

So, we were discussing torque specs on a bolt today. This bolt needs to be torqued to 335 ft/lbs. We have to use an impact gun to install due to a couple different factors. The main being that there isn't a way to efficiently lock the motor to tighten by hand with out a bunch of labor. Talked to the tool man, and they don't make a torque stick that big. Largest goes to 140 ft/lbs.

Now my impact does 1100 ft/lbs breaking torque, and 850 ft/lbs tightening, thats at 90 psi. Realistically it gets between 120 and 150 psi depending on wether the air compressors running or not.

Any one have any ideas how to achieve between 330 and 350 ft/lbs torque out of that gun?

Not the gun, but here is how I would achieve it sans my 3/4" snap on torque wrench: A 335lb ass, sitting on a one foot long wrench, by definition would do it. Not wanting to gain that much weight, a 187.5 lb ass, on a 2 foot wrench would do it, too.

Whoops didn't read the entire post. Any way to get a big pipe wrench, on the shaft, behind the lovejoy coupling???

 

[Daren Todd]

Not the gun, but here is how I would achieve it sans my 3/4" snap on torque wrench: A 335lb ass, sitting on a one foot long wrench, by definition would do it. Not wanting to gain that much weight, a 187.5 lb ass, on a 2 foot wrench would do it, too.

Whoops didn't read the entire post. Any way to get a big pipe wrench, on the shaft, behind the lovejoy coupling???

No way to get a pipe wrench on the shaft. Got a three footer, and if that didn't work, theres always the shops four footer. I do have a coworker thats around 325 Theres about an inch of shaft exposed inside the bell housing with a drive couple in the way. With out pulling it from the bell housing and removing the coupler, there isn't any way to get to it And is a three person job plus crane to get it lined back up and mated with the fly wheel if the pump end is assembled to the impellor. I just need to figure out how to bleed aboit 200 ft/lbs off the impact. The old one I had was an 800/500 ft/lb and was perfect. No issue with fractured bolts. Problem was it was rebuilt at three years and completely shot by the fourth. Stepped up from a matco composite to the snap on with oil on the anvil instead of grease. 2 years so far and still has all it's butt

 

[OldeEnglish]

You know it's a bad day when you have to break out the 4 foot big Bertha!

We used to opt for the 3' steel wrench with a 10' piece of 4" SCH 20 with two 225 pounders hanging off the other end. Not fun, but works like a charm!

 

[Tooljunkie]

You are saying your nap-on has no adjuster on it? I figured they all did nowadays.

 

[Russell King]

First let me say "I apologize, I just can't help myself"

Torque is in pounds feet (lb-ft).

Torque is not expressed in feet pounds (ft-lb) either, that is units of work.

Pounds/feet is a different thing altogether that has to do with linear density (it is read pounds per foot) like 10 pounds per foot =10 lb/ft.

I know you all know that but it just gets to me to see it used wrong.

Again I apologize and small rant is over!

One idea that may work to hold it -
Can you put something like a rope into the pump and have the impeller blades (or better the impeller back plane) jam the rope against the case and lock it in place? And then get he rope back out?

I have used this on small gas engines (put enough rope through the spark plug hole to lock the engine up) to take off (put on) flywheel nuts.

 

[Daren Todd]

You are saying your nap-on has no adjuster on it? I figured they all did nowadays.

Oops I'll have to look at it a little closer. It's got one of those protective case covers on it. I'll check the case itself when I get into the shop and see if it has any adjustment markings

 

[Daren Todd]

Tooljunkie, your right there is a selector. had to get out the ole magnifying glass to see the thing will give it a try here in a bit