How to Use a Torque Wrench

A torque wrench is an essential tool designed to apply a specific amount of torque to fasteners such as nuts and bolts. Widely used in the automotive, construction, and industrial trades, torque wrenches ensure precision and safety in tightening applications. In this comprehensive Toolstop guide, we’ll explore what a torque wrench is, how it works, its types, and how to use it effectively.

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Torque is a rotational force measured in lb·ft (pound-foot), lb·in (pound-inch), or N·m (newton-meter). Most torque wrenches feature markings for these measurements, with foot-pounds (lb·ft) being the most common.

Setting the Torque

• Find the Torque Value: Refer to the vehicle's manual or online resources to find the required torque value
• Adjust the Handle: Loosen the knob at the bottom of the wrench, turn the handle to set the desired torque, and tighten the lock nut to secure the setting

Click Torque Wrenches

These are the most common type and are known for their simplicity and reliability. They make a clicking sound when the preset torque is reached.

• Usage: Suitable for a variety of applications, especially in hard-to-reach areas
• Feature: Ratcheting mechanism allows for both tightening and loosening

Digital Torque Wrenches

Digital wrenches use electronic sensors to measure torque and display the value on a digital screen. They offer high precision and additional features like memory storage.

• Usage: Ideal for precise applications where exact torque values are critical
• Feature: Beeps or lights up when the desired torque is reached

Beam Torque Wrenches

These are the simplest and most basic form. They have two beams: one for applying torque and one as an indicator.

• Usage: Often used for applications requiring exact tightness, particularly on vehicles
• Feature: Durable and easy to use, with no moving parts

Method 1: Adjusting the Wrench

Step 1: Loosen the Locking Knob

Locate the locking knob at the end of the torque wrench handle. Twist it counterclockwise to loosen it, allowing you to change the wrench's settings. The locking knob is usually a different color, making it easy to find. You only need to loosen the knob until the handle can turn freely; there's no need to remove it completely.

Step 2: Identify the Torque Measurements

Find the torque measurements printed on the wrench's main shaft, just above the handle. These measurements are typically in increments of 10 or 20 pound-force-feet (lb·ft) or newton-meters (N·m). The vertical marks on the top dial of the handle increase by 1 lb·ft or 0.14 N·m increments.

Step 3: Set the Approximate Torque

Hold the wrench body steady with one hand and turn the handle with the other. Turn the handle clockwise to increase the torque or counterclockwise to decrease it. Align the handle's top edge with the hash mark closest to your required torque value.

Example: For a torque of 145 lb·ft, align the handle with the 140 lb·ft mark.

Step 4: Make Precise Adjustments

Once close to your desired torque, use the top dial on the handle for fine-tuning. Rotate the dial clockwise to increase the number or counterclockwise to decrease it. Align the number on the dial with the vertical line on the wrench.

Example: If set to 140 lb·ft, turn the dial to add 5 lb·ft, reaching a total of 145 lb·ft.

Step 5: Confirm the Torque Setting

Combine the numbers from the wrench and the dial to determine the total torque. Ensure the handle's position matches your desired torque value.

Example: 140 lb·ft (handle) + 5 lb·ft (dial) = 145 lb·ft.

Step 6: Secure the Locking Knob

Hold the wrench body steady and turn the locking knob clockwise to lock the setting. This secures your torque setting until you need to adjust it again.

Method 2: Tightening Nuts and Bolts

Step 1: Attach the Socket

Select a socket that matches the size of your nut or bolt. Attach the socket to the head of the torque wrench until it clicks into place. For hard-to-reach areas, use a socket extender.

Step 2: Hand-Tighten the Nut or Bolt

Begin by screwing the nut or bolt by hand to ensure proper alignment. Turn it clockwise until it is snug and can’t be turned further by hand.

Step 3: Position the Wrench

Place the wrench's socket over the nut or bolt. Hold the handle with your nondominant hand and guide the socket with your dominant hand to ensure a secure fit.

Step 4: Tighten with the Wrench

Rotate the wrench handle clockwise to tighten the nut or bolt. Most torque wrenches have an automatic return function, allowing you to move the handle back counterclockwise without repositioning.

Step 5: Listen for the Click

Stop turning the wrench once you hear a click or feel resistance. This indicates that the correct torque has been reached. Avoid over-tightening to prevent damage to the fastener or the wrench.

Tips for Proper Use

• Stop at the Click: Once you hear the click, do not tighten further
• Use a Ratchet First: Do most of the tightening with a ratchet, then switch to the torque wrench for the final adjustment
• Handle with Care: Store the wrench in its case and set it to the lowest setting when not in use to maintain calibration

Regular calibration is crucial for maintaining accuracy. Calibration should be done by a professional, ideally once a year or every 5,000 clicks.

Check out Norbar's top 5 torque wrench tips:

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