torque wrench

Pneumatic torque wrench

Torque wrench – a tool used to precisely apply a specific torque to a fastener such as a nut or bolt. It is usually in the form of a socket wrench with special internal mechanisms. A torque wrench is used where the tightness of screws and bolts is crucial. It allows the operator to measure the torque applied to the fastener so it can be matched to the specifications for a particular application. This permits proper tension and loading of all parts.

  • It was invented by Conrad Bahr in 1918 while working for the New York City Water Department. It was designed to prevent over-tightening bolts on water main and steam pipe repairs underground.
  • How to use a torque wrench (video 2:33) – Torque is a measurement of torsion, a twisting force. A “torque wrench” has a spring-loaded indicator that gives a numerical readout of the amount of torque being applied through it.

What’s the problem?

  • Ask – Sometimes it really matters how tightly a nut, bolt or screw is tightened. Too tight and something will be damaged. Not tight enough and the joint will leak. How can you tell how much a fastener has been tightened?
  • Imagine – In most cases, it isn’t possible to directly measure the pressure on the fastener. Can the amount of force needed to tighten the fastener be measured? Does this provide enough information to determine the right amount of tightening?
  • Design, Build? – How does the wrench measure the tightening force? Can it be calibrated to ensure that its measurement is the same as some standard?
  • Improve? – Torque wrenches have been fitted with electronic sensors and digital readouts to improve accuracy and usability.

That’s engineering

  • Touch – The sense of touch is spread through the whole body. Nerve endings in the skin and in other parts of the body send information to the brain. There are four kinds of touch sensations that can be identified: cold, heat, contact, and pain.
  • Torque – the tendency of a force to turn or twist. If a force is used to begin to spin an object, or to stop an object from spinning, a torque is made. The force applied to a lever, multiplied by the distance from the lever’s fulcrum, multiplied again by the sine of the angle created, is described as torque.
  • torsion – a twisting force

Engineering ideas

  • torque, fastener, tighten, loading, torsion, Newton-metre, calibration, standards, measurement, accuracy, usability

Do It
Challenges for you to work on…

  • find other references to torquend mechanisms that measure or use torque