WHAT IS A TORQUE WRENCH?

WHAT IS A TORQUE WRENCH AND WHAT IS IT USED FOR?

A torque wrench is a tool that technicians use to tighten nuts and bolts with a predetermined twisting force, tightness or tension commonly referred to as torque.

The torque wrench allows the technician to tighten nuts, bolts and other fasteners to the optimum tightness (torque) without the fastener being too loose or too tight or damaging the fastener.

The correct torque allows the equipment to have the maximum lifespan to get the best value out of it.

The torque wrench allows the technician to measure the pressure applied to nuts, bolts and screws, to ensure it matches the recommended specifications for the task.

In the automotive industry where vehicles are subjected to many years of vibration and movement, it is important that parts of a vehicle are properly fastened to ensure they function effectively and last as long as required.

Overtightening fasteners can cause parts to lock up, fail, be out of alignment, get damaged or have a shorter life.

How does a torque wrench work?

Parts of a vehicle such as spark plugs and wheel nuts require a specific torque.

The required torque is determined by the manufacturer who knows what the optimal torque should be and usually reflects it on the part of the packaging.

The torque wrench is used much the same as a wrench or spanner but with a measuring function indicating the force applied.

The wrench is set to the required torque and the fastener is turned until the torque wrench indicates that the required torque has been reached. How the torque wrench indicates the correct torque depends on the type of torque wrench.

Types of torque wrenches

• A digital or electronic torque wrench indicates the torque with a digital display.
• A beam torque wrench has a handle or lever on which force is applied. A scale or meter releases or stops when it reaches the right torque. It usually keeps the reading until it is released.
• A click torque wrench makes clicking or ratchet sound when the set torque is reached.
• Hydraulic torque wrenches are used in industrial environments and work hydraulically.
• Micrometer torque wrenches have forward and reverse capabilities. They are mostly used in industrial settings, plumbing and metalworking.
• Dial torque wrenches indicate torque with a dial mechanism and are widely used in the automotive industry.
• Slipper Torque Wrenches slip or release when the required torque is reached which makes it impossible to overtighten.
• Split Beam Torque Wrenches are more accurate than standard beam torque wrenches. It releases when the required torque is reached, so overtightening is impossible.
• No-Hub Torque Wrenches are mostly used in the plumbing industry to tighten pipe connectors without the risk of over or under-tightening.

How do I know which torque wrench I need?

The type of torque wrench you will need depends on the work you do and is dictated by the maximum tightness (torque) required by the fasteners you will torque.

The 12,5 – 25mm Snapon torque wrench is quite adequate for an average auto shop or tyre workshop.

Calibrate your torque wrench

Torque wrenches need to be calibrated at regular intervals as they are often dropped or bumped against equipment in a workshop setting.

The moment the technician realises that the torque wrench is not correctly calibrated, he will manually compensate by under or over-tightening. That results in manual tightening and a guessing game which renders the torque wrench ineffective and increases the risk of costly mistakes and potential damage.

A maximum of a 5% error margin is acceptable for a torque wrench.

Get a torque wrench

A responsible employer or workshop manager will make sure that his auto repair or tyre shop always has properly calibrated torque wrenches for his technicians.

A professional technician will always use a torque wrench so he can be sure that the work he did for a client is up to standard.