Torque Wrenches

[Robert Mangas]

  That's not always true.  IMO what's been missing is specifying which type 
of torque measurement mechanism is being employed by a given wrench.  What 
you said is true about the beam type wrenches, where the measurement is 
actually indicated by deflection in the torque arm.  It's not true about the 
clicker types- those have little elves living in the end that don't care 
what the length of the arm is.  You could apply 90 lbf halfway down the 
lever arm of a 24" clicker wrench set at 90lb ft and still get a reassuring 
click.  Contrawise, you could apply 30 lbf onto a 12" extension (handle 
extension, not reach extension) and still achieve that same reassuring 90lb 
ft click while actually applying 90 lb ft of torque to the fastener.

  $0.01,
Robert

>From: "Al Powell" <apowell at gocougs.wsu.edu>
>Reply-To: apowell at gocougs.wsu.edu
>To: "Q-List" <quattro at audifans.com>
>Subject: Torque Wrenches
>Date: Tue, 2 Dec 2003 08:28:56 -0700
>
>I think a detail that some of are missing (although it has actually been
>stated in other terms) is that a torque wrench is calibrated for the length
>of the wrench as manufactured.  Whether you have an 18" wrench or a 24"
>wrench, they both read correctly for THAT specific wrench.  If you add a
>pipe on the end of a torque wrench, you defeat its calibration and render
>its scale useless because it is no longer applying force from a point at 
>the
>designed distance.  (Aside from that, you'll probably damage the wrench if
>you apply excessive force to it by extending the handle.)
>
>Each wrench is designed to read correctly as manufactured, regardless of 
>its
>length - that's just part of the manufacturing process and assumptions.  So
>adding extensions to a torque wrench is self-defeating because it
>automatically makes it inaccurate.
>
>************************************
>Al Powell
>apowell at gocougs.wsu.edu
>1958 Fiat 1200 Transformabile Spyder
>1983 Datsun 280ZX Turbo
>1993 Audi 90Q
>1997 Chebby Blazer
>1999 Chebby Blazer
>************************************
>
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