Torque Wrenches

Different Types and How to Use

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

Work clothing - such as coveralls and steel-capped footwear

Eye protection - such as safety glasses and face masks

Ear protection - such as earmuffs and earplugs

Hand protection - such as rubber gloves and barrier cream

Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

Refer to the manufacturer's specifications when tightening fasteners.

If replacing a fastener, make sure it has the correct tensile value for the task it has to perform.

Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.

What is a Torque wrench?


The torque wrench is used to apply a specified amount of torque to a fastener.

There are various methods used by torque wrenches to indicate that the correct torque has been reached. Some will give an audible signal such as a click or a beep, while others will give a visual signal such as a light or a pin moving or clicking out.

Make sure the threads are clean before tightening the fastener to a specified torque. Any friction will give an inaccurate reading and will affect the compressive force the fastener will apply to the component.

Always handle a torque wrench carefully. It is a precision instrument that will lose its calibration if mistreated.

Deflecting Beam Type

Torque angle gauge

The torque angle gauge is used to make sure there is equal tightness of fasteners on a component. It is calibrated in degrees.

Tightening by angle rather than torque removes the error that is produced by friction in the threads.

Dial Type

Dial Indicating Torque Wrench

Dial type torque wrenches are very similar in operation to the deflecting beam type. The dial is simply used to register the torque required for a job. There is a memory needle which records the highest torque achieved while using.

Micrometer Setting Type

Micrometer style torque wrench

To use the micrometer setting type, unlock the grip and adjust the handle to the desired setting on the micrometer-type scale, then relock the grip. Install the required socket or adapter to the square drive of the handle. Place the wrench assembly on the nut or bolt and pull in a clockwise direction with a smooth, steady motion. (A fast or jerky motion will result in an improperly torqued unit.) When the torque applied reaches the torque value, which is indicated on the handle setting, a signal mechanism will automatically issue an audible click, and the handle will release or"break," and move freely for a short distance. The release and free travel is easily felt, so there is no doubt about when the torquing process is complete.

Electronic torque wrenches are very similar in operation to the micrometer type. The main differences are that the required torque value is set on a digital display and instead of a 'click' when the setting is reached there is usually a visual indicator such as an LED and and audible 'beep'.

WARNING!

Rules

Torque wrenches are delicate and expensive tools. The following precautions should be observed when using them:

1. When using the micrometer setting type, do not move the setting handle below the lowest torque setting. However, it should be placed at its lowest setting before it is returned to storage.

2. Do not use the torque wrench to apply greater amounts of torque than its rated capacity.

3. Do not use the torque wrench to loosen bolts that have been previously tightened.

4. Do not drop the wrench. If a torque wrench is dropped, its accuracy will be affected.

5. Do not apply a torque wrench to a nut that has been tightened. Back off the nut one turn with an on torque wrench and re-tighten to the correct torque with the indicating torque wrench.

6. Calibration intervals should have been established for all torque tools. When a tool is calibrated by a qualified person, a label showing the next calibration due date is attached to the handle. This date should be checked before a torque tool is used to ensure that it is not overdue for calibration.

Never use in high voltage areas.

A final bit of fun.....

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