Torque spanner

What is a torque spanner and when is it necessary?

A torque spanner is both a tightening and measuring tool. The precision tool is used when the prescribed tightening torque must be precisely adhered to. You use it to fit nuts and bolts using nuts and bits in a controlled manner with precise tightening for an even and gentle hold. The tightening torque ensures the best and greatest possible clamping force between the components, even under maximum mechanical load. The torque spanner is used for tasks such as fitting wheel rims on cars, tightening steering bearings on bicycles or milling or cutting heads on machine tools. The precision tool is handy and very easy to use. For this reason, the torque spanner is not only a popular tool for professionals, but also for DIY enthusiasts.

How does a torque spanner work?

A torque spanner is similar in function to a ring spanner, open-end spanner or ratchet. They are used to loosen and tighten threaded bolts and nuts. Just like a ratchet, the torque spanner is equipped with a ratchet mechanism. This means that, unlike a ring spanner or open-end spanner, you can leave the spanner on the nut or bolt.

Nevertheless, a torque spanner is different from a ratchet. You can always exert force with a ratchet, but with a torque spanner this can only be done up to a certain set torque (Nm). The leverage of the ratchet works thanks to the solid handle. The leverage of the torque spanner lies in the spring. If the spring tension increases, the torque spanner can exert more force. The more tension, the more force.

The torque is set on the handle of the spanner using a scale or digital display in Newton metres (Nm). The locking mechanism is then unlocked to prevent unintentional adjustment during work. The force preselection takes place within the working range specified in the product description in which the tool can be adjusted. Many models in the SFS eShop have a two-stage setting: The coarse setting scale is used to set the next lowest scale value to the desired Nm value. The fine scale is then used to add the missing Nm value to the target tightening torque.

For a reversible model with clockwise and anti-clockwise rotation, determine the direction of rotation. Finally, attach the required socket and you're ready to go! The torque spanner is placed on the screw or nut. The fastener is tightened by turning it clockwise. The tool stops automatically when the set torque is reached. The fastener is now tightened to the specified tightening torque.

The following tips may be helpful when using a torque spanner:

• Pre-tightening: Take your time when setting the target value on the handle scale or the electronic display. The more precisely you select the torque, the more precisely the tightening force will be maintained.
• Observe the limit: Do not turn the tool beyond the measuring range after triggering.
• Relax: Reset the torque spanner to the lowest torque (lowest scale value) after work. This allows the mechanism to relax and accuracy is maintained for a long time.
• No lever extension: Do not work with handle extensions.
• Cleaning: Do not immerse the spanner in water, oil, grease, solvents or paint. Occasional wiping with a dry cloth is sufficient for cleaning.
• Lubrication: If the torque spanner is not to be used for a long period of time, loosen it several times with the scale set low to ensure correct lubrication.
• Checking: The torque spanner should be checked once a year. Various calibrated tools are suitable for this purpose. As soon as the release torque is outside ±1 Nm, you should consult a specialist.

What types of torque spanner are there?

In the field of torque spanners, a distinction is made between releasing and indicating spanners. Releasing spanners include bend spanners, click spanners and slip spanners. Indicating spanners include mechanical and electronic indicators.

Discover more information about the individual torque spanners and how they work here.

Releasing torque wrench

1. The bend spanner is a tool that bends or breaks off when the maximum torque is reached. This stops the force being exerted.
2. In contrast to the bend spanner, the click spanner is one of the best known and most common torque spanners. As the name suggests, reaching the torque is signalled by a click. At this point, the user must stop applying force. The click spanner is handy and easy to use.
3. The slipper works in a similar way to the click spanner. It slips as soon as the maximum torque is reached. This stops the power transmission. This spanner is also very simple and convenient. It is particularly suitable for inexperienced or less experienced users.

Indicating torque wrench

1. The mechanical spanner has a dial gauge or mechanical scale that displays the torque value. This is attached to the tool. As soon as the desired torque is displayed, the user stops applying the force.
2. The electronic spanner works in a similar way to the mechanical spanner. The biggest difference is that the torque is shown on your digital display. However, even with this model, the user has to pay attention to when the torque is reached and adjust the force accordingly.

Are there also accessories for the torque spanner?

You can find various spare parts and accessories for the different spanner variants in our e-shop.

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