merziac

Not that you'll agree, let alone understand but here is one.

https://thetorquehub.com/torque-wrench-guide/#tab-con-2

How Does A Torque Wrench Work?

A torque wrench is a calibrated tool that is going to apply a certain amount of load to a nut or a bolt. The amount of torque that is applied depends on the mount of force that you apply to the tool’s handle and the length of the wrench. To figure out the torque, the torque formula is: force x length = torque.

So, let’s say your torque wrench is a foot long, and you apply 30 pounds of force to the handle. That means you are applying 30 ft/lbs of torque to the bolt or nut that you are tightening. If your wrench is twice as long (2 feet) and you’re applying the same amount of force to the handle (30 pounds), you are going to be applying 60 ft/lbs of torque to the bolt or nut.

The torque wrench tells you how much force you’re applying to the fastener because it uses a deflection beam or a spring mechanism that’s been calibrated. The tool usually features a scale or a display screen and it shows you the load that’s been applied.

These can be calibrated to read foot-pounds (ft/lbs), inch-pounds (in/lbs) or Newton-Meters (Nm). Usually when you’re working a car, the you will be using a foot pound torque wrench is going to read either 200 ft/lbs or 250 ft/lbs. It could also read 150 or 200 Nm.

The torque values for a fastener that has a 1/2inch (or larger) wrench size head will be specified in ft/lbs (English) or Newton Meters (metric). Torque values for fasteners with less than 1/2inch wrench head size is going to be specified in/lbs instead.

merziac

Seems pretty simple to me,

Force X Length = Torque

I've been a professional, ASE and FoMoCo Certified Sr. Master technician most of my life so what do I know, I only made my living doing it and used my knowledge to keep things together on 1000's of runs on mc's going over a 100 mph at the dragstrip.

Kontact

That is not an explanation how a solid shaft running from the click pivot all the way to the adjuster is affected by where your hand is placed. Clearly you think that it should be done per instructions, and that is a perfectly sound conclusion. But you also don't seem to understand the basic objection I've made or why manufacturers like Park say things like "this is hard to explain". Not only are you not explaining it, you don't seem to even realize that it is a complicated question.

This gent at least alludes to the mystery, but also isn't able to explain it, aside from repeating a theory that a thick steel shaft is flexible,


At about 4:20 he gives the flex theory (which he derides), then wades into another one that shows how the wrench works, but again fails to address how holding a handle one place or another could effect an internal mechanism. Which is a lot like saying a nail can tell where you held the handle of a hammer.


BTW, implying that I'm not intelligent merely implies a lot about yours. So cut it out.

gearbasher

Try this video. I think he gives a good explanation.

merziac

I'm not implying anything, your obstinance here says it all.

Homebrew01

Good thing I don't need a torque wrench for my bike. Jeeesh.

Kontact

For those interested, here's a GIF of the actual click mechanism in action:



Click on link to see it animated:
https://www.google.com/search?q=how+does+a+click+torque+wrench+work+gif&sca_esv=114751fe4ad266cf&sca_upv=1&rlz=1C1CHBF_enUS 972US972&udm=2&biw=1366&bih=641&sxsrf=ACQVn0-nO66FLVjbRJq3VPlTlwPK0JRY4g%3A1714347455269&ei=v90uZpj_D-7P0PEP37-LwA8&ved=0ahUKEwjY2t74ieaFAxXuJzQIHd_fAvgQ4dUDCBA&uact=5&oq=how+does+a+click+torque+wrench+work+gif& gs_lp=Egxnd3Mtd2l6LXNlcnAiJ2hvdyBkb2VzIGEgY2xpY2sgdG9ycXVlIHdyZW5jaCB3b3JrIGdpZkj5DFCGBFjWCHABeACQAQ CYAVSgAZ8CqgEBNLgBA8gBAPgBAZgCAqACecICBBAAGB7CAgYQABgIGB7CAgsQABiABBiGAxiKBcICBhAAGBYYHsICCBAAGBYYCh gemAMAiAYBkgcBMqAHrAY&sclient=gws-wiz-serp

Kontact

You've posted more often than I have about this. Congratulations on your obstinance.

Care to explain how hand placement effects the mechanism I provided a diagram of?

steelbikeguy

he had me at "free body diagram".

In fact, I'm pretty sure this is the one that I've seen before that explained it well (with the caveat that I'm an engineer)

Steve in Peoria

Kontact

Looking at the GIF cutaway, what you're looking at is essentially five moving parts:
1. The ratchet head with a pivot that runs though the handle tube.
2. A 45 degree link.
3. The head of the spring tension mechanism.
4. The roller on the top of the spring tension mechanism.

The link has a enough mechanical advantage to keep the ratchet head from pivoting. When enough force is applied to the pivot, the link overcomes the spring force from the tensioner, forcing it to compress the spring. Since the like is off center, the roller converts that off center force into movement concentric with the spring.

This shows that the workings of the wrench are contained completely within the handle.

merziac

No need and there never was, the video like the manufacturers instructions clearly state why practical, hands on common sense is the correct way on this.

Not some esoteric, theoretical, phycho babble BS that is fundamentally wrong just like you are.

I came to add context, you came to argue and deride as usual, like I said your track record speaks for itself.

panzerwagon 

This video quite clearly shows the maths behind it. The difference arises from the fact that the shaft pivots at a different point than the fastener location. The video above uses an example of 1” apart.

As a result, manufacturers need to build a “fudge factor” into their calibration, proportional to the ratio of the handle-to-shaft-pivot distance, to the handle-to-fastener (socket) distance. If a different hand-hold is used, this fudge factor will no longer hold, and the applied torque might be very different from the torque value the wrench is set to.

I especially appreciate the closing statement in the video— “if you feel the need to convince others, do it nicely and embrace the academic debate”.

Kontact

Thank you! It is definitely a little spooky, but I see now how the fact that you are simultaneously putting torque on two offset pivots leads to the problem.

Probably the easiest way to picture what is happening is to imagine putting force on the shaft at the click pivot - doing so would produce fastener torque with zero corresponding click.

Too bad the "do it nicely" part couldn't have been part of the conversation with Merziac.

IdahoBrett 

I just use the white knuckle method. One through four. Fifteen or so inch pounds per knuckle. Then if it needs more than that I add in the grunt method. Small to large. On the rare occasion I will break out the xtra large grunt.

Steel Charlie

Kontact - give up. The difference between a beam torque wrench and a spring loaded sear is obviously too difficult to explain or understand. You have my sympathy but you are fighting a confusion that will never yield.

​​​

Kontact

You should read both of my posts prior to yours.

It isn't confusing once a cogent explanation is offered.

Steel Charlie

Dude, I'm on your side. Belief systems will never succumb to facts. Take a breath, relax, walk away.

Kontact

It isn't a belief system. It is clearly important to hold the handle in the right place, and I was wrong for suggesting otherwise. The problem was that I couldn't find any explanation for why.

Pompiere

That is probably more accurate than the "ugga dugga" method my son told me about. He learned it from the older guys while working on farm machinery. Ugga dugga is the sound the impact wrench makes when it starts to labor, so 50 ft-lbs is one ugga dugga, 100 is two ugga duggas, 150 is three, etc.

merziac

"Because, physics".

Kontact

"Because, manual."

merziac

Yep, that too.

Kontact

Not really an explanation that involves the science you mentioned, is it?

curbtender

Either way works, just you lose the mechanical advantage holding it further down. Over the years you learn monkey tight isn't always the best.