# torque wrench and universal joints

I have found this equation that applies to torque as applied thru an angle.
T * cos A = TA; where TA is the applied torque (to a bolt), T is the torque applied from the wrench, and A is the angle between the plane of the wrench and bolt.
For example, at 40 degrees (the angle between the two extension bars joined by the joint, stright up and down is 0), only 75% of the wrench torque is applied to the bolt. (This equation may be wrong.)
But to the main question about the swivel that is used to implement this angle. This "U" joint is a common flexible coupling you find in many tool socket sets.
Does this common joint apply torque evenly throughout its rotation? My feeling is that it doesn't. And if it doesn't, is there a "constant force" joint that will? (constant velocity joint?)
Thank you.
Torque is being applied slowly and constantly.
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On Sun, 13 Apr 2014 09:49:47 -0700 (PDT), snipped-for-privacy@yahoo.com wrote:

No.

Just put two universal joints in series, There are two ways to do this. Look at a car with a front engine and rear-wheel drive to see which is the right way. Or try each way and decide which is correct.
The reason front-wheel drive cars have constant velocity joints is that one universal joint with constant velocity input will not have a constant velocity output. I don't think it will have constant torque either. By putting two joints in a row, it evens out the output velocity, and the torque.
Rear wheel drive cars, with a long drive shaft also have a constant velocity joint, made up of two universal joints. One is at the front of the drive shaft and the other is at the rear, but that makes no difference as far as the differential and rear wheels are concerned. They still see the output of two universals in a row, a constant velocity output. (The drive shaft itself speeds up and slows down, probably twice in each rotation, but that doesn't matter.)
A universal joint has, if I recall the names of the parts correctly, two forks with two tines each, and a spider in between them (an X shaped metal thing attached both to the front fork and the rear fork.
Two of the forks are built into the drive shaft. I think one of them is 90 degrees rotated from the other. If so, that's what you should do. It's possible I'm wrong and both forks are in the same plane. If so, that's what you should do.
You might also consider a wobble extension. Short ones are no longer than a socket wrench universal. Shorter and easier to handle than 2 universals in a row. In any case, the female end is undercut so that one can apply the wrench at an angle. I'm sure this is not constant torque either, but the wobble extension works better than a univeral some times. For one thing, two universals in a row may wrap themselves into a knot, almost.
I bought my wobbles, in 3 lengths, at JCWhitney.com

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On 4/13/2014 11:33 AM, micky wrote:

The speed is not constant. Not sure about torque.

Forks (yokes) are in the same plane. And the engine drive shaft and differential shaft are parallel.
In a CV joint the forks in the center are also in the same plane, and the total angle between input and output shafts has to be split between the u-joints.

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On 4/13/2014 11:49 AM, snipped-for-privacy@yahoo.com wrote:

It depends the angle -- if keep the angle constant as rotate, then to a reasonably good approximation it applies same torque. The only place else for it to go that isn't transferred to the bolt is into deformation of the the u-joint and that's pretty minimal given a decent device, anyway.
With a ratchet on the driving end, one can hold a reasonably consistent angle most of the time over a restricted range for the drive handle. Going 'round 'n 'round, generally there's something in the way and one varies the direction rather significantly quite often.
--

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