Rick;
Thanks for the info, sounds like an interesting class you teach, all
this math business is to much for me though. (thus my previous post) I
wasn't the one interested in torquing my valves just provided the
correct setting. Like was said THE LIST is a learning curve isn't it.
I'll keep the info for further reference!!! My rockers sound OK but ya
never know...........
Best Wishes & Safety Fast
Andy 77B
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From: REwald9535@aol.com
To: Proudfoot, Andrew; mgs@autox.team.net
Subject: Re: torque settings with a crowsfoot
Date: Saturday, April 10, 1999 12:32AM
Andy,
Nice thought but it won't work.
When you tighten a bolt or nut it requires a certain force to turn it.
When
you stop turning it and then go to start turning it again you have to
overcome the friction of the bolt at rest. It takes more force to start
a
bolt turning than it does to keep it turning. Recall Mr. Newton "an
object
in motion wants to stay in motion, and object at rest wants to stay at
rest"
When I teach a rear axle class, I give the students a demonstration of
this.
The pinion nut on the axles we are working on has a torque of 180-200
Nm. I
have a student tighten the pinion to 160 Nm. Then stop and go to
retighten
to 200Mn. The wrench will click off without moving at all.
Also before anyone asks, no you can't tighten with one torque wrench and
loosen with another to check the accuracy of the wrench in question.
The
force require to loosen a bolt and tighten are different.
This is probably why torque testers cost serious big bucks.
You can calculate the difference in torque via math (covered in other
posts
on this subject) and think of it this way a 15 to 1 ratio is a 6.67%
difference. This is probably more accurate that your torque wrench.
(I'm
guessing that your torque wrench is plus or minus 10%)
The question was asked what about if the crowfoot is not straight out
from
the end of the wrench. Well, if the crowfoot was straight out off the
end of
the wrench the correction factor applies (+). Because the wrench is
longer.
If the crowfoot is under the wrench and inline with the axis of the
wrench
the correction factor applies (-). The wrench is now shorter (why
anyone
would do this is beyond me) If the open end of the crowfoot is 90
degrees to
the axis of the wrench there would be no correction as the wrench is the
same
length.
i hope this helps
Rick Ewald
In a message dated 4/9/99 8:33:33 PM Pacific Daylight Time,
proudfa@NAVCANADA.CA writes:
> If you used a crowfoot wrench on the torque wrench could you not bench
> test it?
> ie- tighten a nut & bolt in your vise both with and without the
> crowsfoot and compare the difference? 22lbs without would equate
> to.......?
> Just another thought.
>
> Safety Faster
> Andy Proudfoot 77B
> Gander, Nfld.
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