Torque wrenches are used regularly in Prosthetics and Orthotics to tighten screws to specific manufacturer recommendations. They may be employed when tightening orthotic knee joints, or prosthetic pylons and adapters.

The manufacturer suggested torque specifications can be found in each the components' user manual. Different fasteners and locations of screws can have different torque settings.

 

Tube Adapter

 

Pyramid Adapter

 

Cap Screw (Also from the tube adapter)

 

Ankle Bolt

 

torque

Torque is a twisting force that causes rotation. A torque wrench is used to measure the torque generated when tightening a bolt, only allowing a set torque to avoid stripping the bolt head and ensures all bolts are tightened evenly.

The torque is measured in foot pound (ft.lb) or Newton Metres (Nm) which describes the torque resulting from a force applied perpendicularly to a moment arm length.

Conversion between the two: 1 foot-pound = 1.3558 Nm

Types of Torque Wrenches

The Click Wrench

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Looks similar to a socket wrench, can have a clutch mechanism where the grip can be pulled downwards and twisted to change the tension or can have clutch adjustment at the head of the wrench.

The Beam Wrench

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This is an older style, and much simpler. The lever arm of the wrench has some flexibility. The harder the user tightens a nut, the more it flexes. The wrench has a scale that shows how much tension is being created, the harder they pull, the more the arrow moves up the scale. When you reach the tension you want, you stop pulling. The downside with this system is there is no tactile signal that the desired torque setting has been reached.

The Electronic Torque Wrench

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These wrenches have a small computer inside of it that works as a strain gauge which measures the torque being applied by the user. The desired torque is set using buttons on the wrench. As the bolt is tightened, the current torque being generated is displayed on an LED screen. These torque wrenches can save torque settings for future reference.