Auto Repair Q&A

Popular

Engine

Cooling System

Brakes

Suspension

Transmission

Exhaust/Emissions

Electrical

Body

Interior

Understand

Directory

Auto Repair Products

Torque Tools

Torque Wrench Gauge

The term "torque tools" can refer to two types of toolsets: torque wrenches or air- or electrically-driven automatic wrenches. Among mechanics, torque tools refer to wrenches made specifically for setting the amount of torque or pressure is put on a fastener (bolt or nut) as it is tightened. Air-driven automatic wrenches are usually properly referred to as "impact wrenches."

Torque wrenches are used to precisely gauge the pressure (torque) put onto a fastener to prevent over or under tightening. Many items on a vehicle's engine or body will require a specific torque be applied. Head bolts for the engine heads, bolts on the timing belt pulleys, or the oil drain plug on some specialty vehicles are examples of bolts and nuts that require torque be accurate.

For doing this, various types of torque wrenches have been developed.

Beam Type

Beam Type Torque Wrench Scale, courtesy WikimediaThese are the oldest and most common torque wrenches. They are a single shaft wrench onto which a socket fits and which has a second, thinner shaft of spring steel running parallel along its length. This will bend at a given rate for every pound of torque applied to the handle, indicating the torque being applied on a gauge (pictured).

These are common wrenches, but are limited due to space requirements, the strength limits of the operator, and the requirement that you be looking at the gauge to see the torque being applied.

Click or Clutch Type

These wrenches look like fat-handled standard socket wrenches. The handle can be "clicked" to a specified torque setting. When the operator's pressure reaches this setting, the wrench has a clutch mechanism that gives way, indicating the torque has been reached.

These are a common wrench as well and are used by many mechanics because they are easier for one operator to use alone. They also suffer from limitations based on the operator's strength limits and some space requirements.

Electronic Type

Several types of electronic torque wrenches are available, but most work in the same basic way. A setting is entered through the electronic interface. Once the wrench is tightened (torqued) to that setting, an alarm, an automatic clutch, or another indicator of torque being reached is given.

These are expensive, but often used in professional applications because they operate on a more accurate level based on sensors in the steel of the wrench feeling the torque being applied. They are still limited by the operator's strength, however, but can be more compact and maneuverable than the two previous types.

Mechatronic Type

These are a mixture of the mechanical (usually dial-in) and electronic wrenches that can physically show the torque application while electronically recording it. These are often required in garages that certify or insure their work in order to guarantee that the mechanic did proper torque settings during assembly.

Conclusion

Most home mechanics should have some type of torque wrench on hand. The less complex (beam type) are most common because they fail less often and have accurate enough readings for the casual use a home mechanic will put them to.

Related Articles

Spoke Torque Wrench

Open End Torque Wrench

Questionare