Torque Wrench End Fittings

Torque wrench end fittings allow the operator to adapt a torque wrench, so that it can apply torque to different types of fasteners. They’re essential for jobs that require specific fastener engagement, like working with hex bolts, Torx screws or specialised fasteners, and can be used to tighten fasteners instead of a socket.

No, not all end fittings are universally compatible with torque wrenches. Always check the torque wrench’s specifications and ensure the fitting’s size and attachment method match your tool.

Some torque wrenches have rectangular mount sizes, with popular sizes being - 

• 9mm x 12mm
• 14mm x 18mm
• 22mm x 28mm
• 24.5mm x 28mm

The general rule of thumb is the bigger the mount size, the bigger the fastener size the torque wrench end fitting will tighten.

In addition, rather than a mount, some torque wrench end fittings have different fitment types, such as a spigot or tang, which are secured to the torque wrench with a locking pin.

If the end fitting is a standard square/rectangle mount for the tool, typically it will slide into the drive of a torque wrench, until the locking pin engages with the end fitting. The operator will know it has been engaged, because there will be a resistance if the end fitting is gently pulled from the torque wrench. 

For torque wrenches that use an end fitting with a spigot or tang, ensure all the holes are aligned correctly and install the safety pin.

Interchangeable end fittings make a torque wrench more versatile, by allowing it to work with a range of fasteners. This eliminates the need for the operator to need multiple tools and ensures precision across various tasks.

For example, one torque wrench could use a ring end fitting, an open end fitting and a Torx end fitting, which all tighten different fastener types and improves the efficiency and cost-effectiveness of the torque wrench.

Machine assembly, automotive repairs, the renewable energy sector, rail, oil and gas, and the aerospace sectors often use specific fittings that need precise and repeatable torque applying to them, and it is also common for these sectors to need to adhere to strict safety standards, require traceability, as well as sometimes having access limitations.

Yes, there are end fittings designed specifically for tight or awkward spaces, such as crow-foot fittings, open-end fittings and ratchet torque wrench ends, which are all useful where fasteners are close to walls, pipes, or where clearance is limited.

• Crowfoot fittings are useful when the operator needs to reach over an obstruction to access a fastener that needs torque applying to it.
• Open-end fittings are useful because they can grip the sides of a fastener, and then be easily taken off and reapplied to a different side of the fastener, until the required level of torque has been applied.
• Ratchet fittings have a built-in mechanism that enables the operator to turn the tool in one direction, whilst rotating freely in the other direction, which is useful when tightening a fastener in an awkward space with a socket attached to a torque wrench.

Keep end fittings clean and organised in a protective case, which will help to prevent corrosion, contamination and potential damage that could happen if the tool was dropped or knocked.

When the fitting has been used, clean it with a cloth and apply a thin coat of oil to help prevent corrosion. When it is stored, clearly label each torque wrench end by size, type and torque rating, to reduce the risk of selecting an incorrect or underrated fitting, which is especially important in safety-critical environments.

Leaving a torque wrench end in a torque wrench increases unnecessary stress on the wrench mechanism, so always ensure it is removed and stored safely after each use.

Ultimately, this depends on the manufacturers guidelines because some manufacturers pre-lubricate ratchet heads during assembly, by using controlled amounts of approved lubricant.

Lubricant may help increase the life and smooth running of the ratchet mechanism, however adding additional lubricant outside of the manufacturers guidelines, can attract dust and dirt to the ratchet mechanism, which will interfere with internal components and potentially affect torque accuracy.

Changing the effective length of the torque wrench, if the torque wrench end is longer than what is specified for use by the manufacturer, could change the effective length of the torque wrench, which in turn, alters the leverage applied and this will either  increase or decrease the actual torque output value set on the torque wrench.

A torque wrench would need calibrating if the torque wrench end does not match the manufacturers guidelines, on what can be used on the wrench.

Torque wrench end fittings are typically made from stainless steel, chrome vanadium or chrome-molybdenum for strength and durability. All of these materials resist wear and deformation, which ensures reliable performance under repeated use.

Most torque wrench ends are also plated with chrome or black oxide, which improves corrosion resistance to lengthen the life of the tool.

Yes it is possible to use adapters, extensions and reducers with torque wrench ends, however they must be used carefully because they can affect torque accuracy and safety. Each of these tools require different precautions -

Adapters and reducers will change the drive size of the tool being added to them, which in turn will introduce additional flex, so adapters and reducers should always be torque-rated for the applied load. In addition, it is not recommended for the operator to use a reducer to drive larger sockets for high-torque applications, because the torque will overstress the adaptor and reduce accuracy.

Extensions that are placed in line with the drive generally have little effect on torque accuracy, as long as they are rigid and properly rated. Do not use wobble extension bars or flexible extension bars, as they will affect the torque applied to the fastener.

Yes, interchangeable torque wrench ends can be just as accurate as fixed square-drive ends, which are built into some torque wenches, as long as they are manufacturer-approved, designed, used and calibrated correctly.

Only use torque wrench ends for the manufacturer approved wrench model, and avoid mixing manufacturers between torque wrench end and torque wrench.