Torque Wrench history

[scott12180]

Anyone have a feel for when the torque wrench became a common tool for the home mechanic, or small-scale shop?

When did  the concept of tightening bolts to specific pre-determined values become used in factories on assembly lines?

[trimacar]

Invented in 1918, a revised version invented by and used by Chrysler late 20's/early 30's, and in 1938 they became available, apparently, in retail.  So, in answer to your question, I'd say they started being used by home mechanics in the 40's, and by then probably had become standard equipment on assembly lines.

 

from Wikipedia:

"The beam type torque wrench was developed in the late 1920s/early 1930s by Walter Percy Chrysler for the Chrysler Corporation and a company known as Micromatic Hone. Paul Allen Sturtevant—a sales representative for the Cedar Rapids Engineering Company at that time—was licensed by Chrysler to manufacture his invention. Sturtevant patented the torque wrench in 1938 and became the first individual to sell torque wrenches.^"

[Spinneyhill]

Doesn't seem to be mentioned in Dyke's 1937 18th Ed. nor in the 1940 Service Station and Motor Mechanics Manual.

[trimacar]

I don't have any personal knowledge of this topic, just searching web.....but the below shows that torque wrenches were used for some head bolt tightening in 1942, at least in the UK....and if this was known technology, surely it was being used in the good ole USA!

 

Again, from Wikipedia, about the company Norbar in UK:

"Norbar Torque Tools is owned and run by the descendants of the founder, William (Bill) Brodey.

1940s[edit]

In 1942, at the height of World War II, Bill Brodey was engaged in selling various tools and machines including Joseph Sunnen honing machines used for honing cylinder bores of engines. Torque wrenches were being imported and sold alongside of the honing machines because it was known that uneven torque tightening of engine cylinder head bolts would distort the cylinder bore. Bill and his friend Ernest Thornitt applied to the UK Ministry of Supply requesting permission to manufacture torque wrenches in the UK. Torque wrenches were much in demand for the manufacture of Rolls-Royce Merlin aero engines and the UK Government was keen to manufacture in the UK wherever possible to reduce pressure on the Atlantic supply convoys. Consequently, permission was granted to 'The North Bar Tool Company' to start manufacturing torque wrenches in 'North Bar Place', Banbury in the United Kingdom. The address 'North Bar' gave the company its name and this was later contracted to 'Norbar'."

[Spinneyhill]

MoToR's Manual 1947 gives torque values for various fastenings back to the 1935 model year vehicles. We can't know whether those values were available in 1935 or are written retrospectively to reflect current practice. The 1935 Studebaker shop manual doesn't give them.

[ply33]

9 minutes ago, Spinneyhill said:

MoToR's Manual 1947 gives torque values for various fastenings back to the 1935 model year vehicles. We can't know whether those values were available in 1935 or are written retrospectively to reflect current practice. The 1935 Studebaker shop manual doesn't give them.

 

The earliest publication I've seen that gives torque values for Plymouths is a 1944 MoToR manual. Like the equivalent for your Studebaker, the manual gives values back to the 1935 model year.

 

The factory service manual for 1936-42 Plymouths also gives some torque values but it the copy I have was published in 1945. The only factory service manual I have that was actually published in the 1930s is for a 1934 Plymouth and there are no torque values it that at all.

 

I strongly suspect that the use of a torque wrench by the service mechanic started after WW2 and that the values they used for pre-war cars were as you note "written retrospectively".

[trimacar]

So, you have to have respect for the millions of professional and backyard mechanics who, pre-WWII, got everything "just tight enough".....

 

How do the early manual describe tightening head bolts?  Snug?  Then run engine and  snug again?

[Gary_Ash]

Tighten until the bolt head comes off, then back off half a turn...

[ply33]

1 hour ago, trimacar said:

So, you have to have respect for the millions of professional and backyard mechanics who, pre-WWII, got everything "just tight enough".....

 

How do the early manual describe tightening head bolts?  Snug?  Then run engine and  snug again?

 

A 1930s manual for my car says:

Cylinder head nuts should be tightened in the order shown in Fig. 5. First run all the nuts down snug with a speed wrench. Next, tighten them fairly snug with a head nut wrench in the same order and finally go over them a third time drawing them down securely. If the same order of tightening is followed each time the nuts are tightened, danger of wrinkling the gasket or distorting the head will be avoided.

[trimacar]

Nice, so the procedure was snug, fairly snug, and then securely!  Interesting.......thanks!

[edinmass]

Rolls Royce in Springfield Mass had a connecting rod bolt stretch specification in 1922,  the true correct way is to measure the stretch, and the torque wrench is a better option than nothin, but it is a short cut. 

[Restorer32]

The 1916 Pullman manual says to tighten head bolts securely but be sure to stop before the bolt breaks.

[trimacar]

2 minutes ago, Restorer32 said:

The 1916 Pullman manual says to tighten head bolts securely but be sure to stop before the bolt breaks.

 

That sounds like excellent advice!  How many of us have said to ourselves, "Gee, that's snug, but just a little more would be perfect",  right before we heard the snap......and I don't mean the snap of a torque wrench....

[Restorer32]

Now if you want to start an argument just mention that a pointer type torque wrench is more accurate than a more expensive clicker type. Simple rule of physics, the more you complicate a system the more "sloppy" it becomes.

 

 

[JV Puleo]

The Phantom I RR head torque spec was "a strong man with a wrench no longer than 3""

The understood that things should be tightened uniformly, it was just the measuring device that needed to be invented. That said, there is a "feel" that you can develop it for tightening bolts. I think I have it and have very rarely if ever, broken a bolt while tightening it. I had an employee years ago who didn't and broke bolts constantly. The worst was a head bolt in a MKVI Bentley... they are actually studs that go completely through the engine. I had to take the sump off to get to the other end.

Edited December 23, 2017 by JV Puleo (see edit history)

[Spinneyhill]

2 hours ago, Restorer32 said:

Now if you want to start an argument just mention that a pointer type torque wrench is more accurate than a more expensive clicker type. Simple rule of physics, the more you complicate a system the more "sloppy" it becomes.

 

LoL! Yes. They operate on the same principle: bending of the arm! So how good is the metallurgy of the arm and how good is the calibration of each tool?

[Spinneyhill]

The first Studebaker shop manual giving tightening torque for head studs was 1938 (280 on the gauge or 1000 inch.lb., although nowadays torque is correctly specified as lb.ft or Nm or force.distance).

[MikeC5]

I thought it was the original German spec, gutentite......

[Larry Schramm]

On ‎12‎/‎23‎/‎2017 at 10:34 AM, Restorer32 said:

Now if you want to start an argument just mention that a pointer type torque wrench is more accurate than a more expensive clicker type. Simple rule of physics, the more you complicate a system the more "sloppy" it becomes.

 

 

 

I actually have both.

[Ben Bruce aka First Born]

30 minutes ago, Larry Schramm said:

 

I actually have both.

 

 As do I. The beam/pointer I bought when I as about 18. Been awhile.

 

  Ben

[Larry Schramm]

7 minutes ago, Ben Bruce aka First Born said:

 

 As do I. The beam/pointer I bought when I as about 18. Been awhile.

 

  Ben

 

Same for me.  Beam first because it was all that I could afford at the time.

[Bush Mechanic]

I tested my 45 year old 'clicker' type recently, and found it to still be quite accurate. Of course I do release the spring tension each time it goes in the drawer. And I'm reluctant to loan it out!

[JACK M]

8 hours ago, Bush Mechanic said:

I tested my 45 year old 'clicker' type recently, and found it to still be quite accurate. Of course I do release the spring tension each time it goes in the drawer. And I'm reluctant to loan it out!

 

I unload mine as well.

Also leave the valves on my jacks open when not in use.

[Guest]

This sure seems to be a twisted topic.

[scott12180]

Don’t get torqued about it 

[D Yaros]

On 12/23/2017 at 9:34 AM, Restorer32 said:

Now if you want to start an argument just mention that a pointer type torque wrench is more accurate than a more expensive clicker type. Simple rule of physics, the more you complicate a system the more "sloppy" it becomes.

 

 

While I have both types, I am more than old enough to recall when the clickers came onto the market.  Their accuracy/reliability was questioned.  I suspect it still is.  I myself tend to put more trust in my beam-er. 

[Spinneyhill]

On 1/01/2018 at 10:31 PM, Bush Mechanic said:

I tested my 45 year old 'clicker' type recently,

How did you do that?

[Bush Mechanic]

 

3 hours ago, Spinneyhill said:

How did you do that?

 

Spinney, I clamped an extension bar in a vice with the tension wrench attached in a horizontal plane, free to move. Measured out one foot from the axis of the wrench, accurately marked. Hung a bucket on it at that point, and poured sand into the bucket until the wrench 'clicked'. Then weighed the bucket/sand to check it against the setting of the wrench. Probably not the official way to test them, but it seemed logical to me, working in ft/lbs. And only as accurate as the scales. Now if I can just devise a way to test the scales.....

 

My newer inch/lbs wrench came with a test certificate. I did wonder how they were officially tested.

[Guest]

I saw a mechanic clamp his click wrench in a vise and with a 1/2" socket pull with his beam-er.  If the click matched to reading on his beam-er everything was okay.  Well I guess it meant they both read the same so they had to both be right or wrong the same amount.

[Spinneyhill]

52 minutes ago, Bush Mechanic said:

Now if I can just devise a way to test the scales.....

I would have done something similar, but using water because I don't have sand. Actually, before I bought my torque wrench (beam and pointer), I used this method to torque the barrel bolts on my motorbike. (It wasn't successful the first two times, I broke the bolts. Then s.k.s. told this idiot that I should make sure the cap nuts were not bottoming on the bolt end before they reached torque. Added washers and third time lucky!)

 

Water's density is easy to look up so the check would be to measure its volume. But now we have a volume measurement to calibrate. Hmmm. Hopefully they agree.

[Bush Mechanic]

5 minutes ago, Spinneyhill said:

I would have done something similar, but using water because I don't have sand. Actually, before I bought my torque wrench (beam and pointer), I used this method to torque the barrel bolts on my motorbike. (It wasn't successful the first two times, I broke the bolts. Then s.k.s. told this idiot that I should make sure the cap nuts were not bottoming on the bolt end before they reached torque. Added washers and third time lucky!)

 

Water's density is easy to look up so the check would be to measure its volume. But now we have a volume measurement to calibrate. Hmmm. Hopefully they agree.

 

We live and learn. I snapped a lot of bolts in my youth, rather than go cap-in-hand to an 'old' bloke asking for a loan of his tension wrench. 

 

I like the water idea for testing scales. Growing up with imperial measurements, I forget that one litre weighs one kg. Having a known benchmark is no burden.

[poci1957]

On ‎1‎/‎3‎/‎2018 at 5:31 PM, Tinindian said:

I saw a mechanic clamp his click wrench in a vise and with a 1/2" socket pull with his beam-er.  If the click matched to reading on his beam-er everything was okay.  Well I guess it meant they both read the same so they had to both be right or wrong the same amount.

 

That is how I check mine from time to time.  

[Spinneyhill]

50 minutes ago, poci1957 said:

That is how I check mine from time to time.  

I have never bothered. Tightening torque is such a variable thing that it is very difficult to get all bolts, e.g. on a head, near the same axial tension. Any slight differences in the thread on nut or bolt, including burrs, roughness, dirt, oil, plating material and quality, the surface the nut is turning onto (roughness, washer?, plating material and quality, oil, dirt, paint etc.) or whatever, plus slight very local variations in bolt and nut strength as well as tightening speed mean that setting bolt tension using tightening torque is an approximate method at best. The axial tension in most of our bolts might be within +/- 35%  with general torque wrench tightening and +/- 15% if we are really particular and use special procedures and equipment.