A pneumatic torque wrench is a planetary torque multiplier or a gearbox that is mated to a pneumatic air motor. At the end of the gearbox is a reaction device that is used to absorb the torque

Torque

Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....

 and allows the tool operator to use it with very little effort. The torque output is adjusted by controlling the air pressure.

These planetary torque multiplier gearboxes have multiplication ratios up to 4000:1 and are primarily used anywhere accurate torque is required on a nut and bolt, or where a stubborn nut needs to be removed.

The pneumatic torque wrench is sometimes confused with a standard impact wrench

Impact wrench

An impact wrench is a socket wrench power tool designed to deliver high torque output with minimal exertion by the user, by storing energy in a rotating mass, then delivering it suddenly to the output shaft.Compressed air is the most common power source, although electric or hydraulic...

, because it looks similar, but is actually a totally different tool. A pneumatic torque wrench is driven by continuous gearing, and not by the Hammers of an impacting wrench. This is why a pneumatic torque wrench has very little vibration, and excellent repeatability and accuracy.

Torque capabilities of pneumatic torque wrenches range from 118Nm, up to a maximum of 47,600Nm.

Air requirements

A pneumatic motor using compressed air

Pneumatics

Pneumatics is a branch of technology, which deals with the study and application of use of pressurized gas to effect mechanical motion.Pneumatic systems are extensively used in industry, where factories are commonly plumbed with compressed air or compressed inert gases...

 is the most common source of power for pneumatic torque wrenches. CFM requirements are usually 20-25 CFM of air consumption per tool.

See also

• Electric torque wrench
  Electric torque wrench
  An electric torque wrench is a planetary torque multiplier or a "Gearbox". This gearbox is mated to an electric motor. At the end of the "gearbox" is a reaction device that is used to absorb the torque...
  
  
• Socket wrench
  Socket wrench
  A socket wrench is a wrench with interchangeable heads called sockets that attach to a fitting on the wrench, allowing it to turn different sized bolts and other fasteners. The most common form is a hand tool popularly called a ratchet consisting of a handle with a ratcheting mechanism built in,...
  
  
• Torque wrench
  Torque wrench
  A torque wrench is 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. It was invented by Conrad Bahr in 1918 while working for the New York City Water Department...
  
  
• Hydraulic torque wrench
  Hydraulic torque wrench
  A hydraulic torque wrench is a tool designed to exert torque on a fastener to achieve proper tightening or loosening of a connection through the use of hydraulics. A torque wrench is applied to the nut either directly or in conjunction with an impact socket. Hydraulic torque wrenches apply a...