How to Use a Torque Multiplier: From Beginners to Pros

Ever heard the old maxim, “Work smart, not hard”?

In my experience, this saying is definitely true when it comes to tightening and loosening heavy-duty bolts and other fasteners. Under normal circumstances, it can be grueling work, requiring various amounts of elbow grease. You have to tighten the bolt sufficiently to keep parts from moving and remove fasteners after they have been in prolonged contact with various environmental conditions. This is where torque multipliers come in handy, as they provide extra power to turn bolts, nuts or screws. The gear train gives the operator an advantage because it increases the gear ratio of the tool to which it’s attached.

Whether you are a beginning Do-It-Yourself enthusiast or a seasoned professional, a torque multiplier is an invaluable addition to your toolkit because it provides the operator with extra power. In order to use a torque multiplier safely and efficiently, however, it is critical that you select the right type of multiplier for your work and follow the proper steps for use.

Types of Torque Multipliers: Manual, Electric, and Pneumatic

There are three main types of torque multipliers: manual, electric, and pneumatic. To determine which type you should use, consider the demands of the job. For example, if compressed air and electrical power are not readily available, then a manual hand multiplier would be the most appropriate choice. It all hinges on your specific needs, so here’s a rundown of the three types:

• A manual torque multiplier is engineered for precision tightening and loosening of heavy-duty fastening applications such as tightening large industrial bolts for a gearbox assembly. The desired torque is reached when the multiplier stops delivering torque. As its name suggests, a manual torque multiplier is hand-operated. Therefore, this kind of tool is typically lightweight, portable, and well-suited to job sites where there is no electricity.
• An electric torque multiplier is controlled with a microprocessor so its torque corresponds to a built-in controller. It’s best suited for continuous tightening and loosening of heavy-duty bolts and fastening applications. Generally, an electric torque multiplier should be inspected by a service professional once a year or after approximately 1,000 hours of use.
• A pneumatic torque multiplier is a more powerful variation of the electric multiplier. It uses compressed air for power and provides precise tightening and loosening of heavy-duty fastening connections. This type of multiplier operates with a smooth, continuous rotation and is quite easy to use.  

Once you’ve selected the appropriate torque multiplier for the job, it’s time to get to work. But remember, to get the most out of your multiplier, you need to know how to operate it properly—and safely.

How to Use a Torque Multiplier

All three types of multipliers are designed to make fastening and loosening easier. If used correctly, that is what they will do, but improper use can lead to errors and danger. Regardless of which tool you choose, always read the manufacturer’s guidelines or instructions before use. Doing so will save you time, trouble and very possibly, injury.

To use a manual torque multiplier, follow these steps:

1. Review the torque multiplication factor for the individual model of torque multiplier, then set the wrench based on these specifications. For example, if the desired torque output is 400 lbf.ft and the multiplication factor for the multiplier is 4:1, then you would set the wrench to a torque input of 100 lbf.ft.  Make sure you don’t exceed the maximum input torque.
2. Assemble the socket, “O” ring, and retaining pin.
3. Do not use an extra long extension or socket.
4. Place the multiplier on the fastener.
5. Make sure the multiplier rotates in the required direction.
6. Check to ensure the wrench also rotates in the correct direction, then place it on the multiplier.
7. Choose a suitable reaction point.
8. Tighten the multiplier until you hear a “click.” This indicates the multiplier is now locked on and ready for use.
9. Don’t strike the anti-wind-up ratchet.
10. To release the wind-up, follow this sequence:
    • Replace the wrench.
    • Load the torque wrench.
    • Reverse the direction of the anti-wind-up ratchet.
    • Be sure to release the wind-up in a safe and controlled manner.

To use an electric torque multiplier:

1. Place the multiplier on a flat surface.
2. Insert the reaction device into the spline.
3. Place the standard socket onto the square drive.
4. Slide the rubber safety ring over the pin.
5. Switch the tool on and off to test the connection to the power source.
6. Secure a standard socket or connector fully onto the screw or nut.
7. Check that the multiplier is in the correct position. It should be vertical while it’s being fastened to avoid damage, and the support arm should be placed on the same level as the socket or connector.
8. When the preset torque is attained, the motor will stop.

To use a pneumatic torque multiplier:

1. Connect the multiplier to the air supply.
2. While the tool is running, check the airflow.
3. Assemble the socket, “O” ring, and retaining pin.
4. Don’t use an extra-long extension or socket, and also avoid using universal joints.
5. Check the manual or specs to get the required setting for the nut size and necessary torque setting.
6. The tool should be running free as you adjust the air pressure to the correct setting.
7. Hold the tool steady and keep your hands away from the reaction point.
8. Tighten the connection until the tool comes to a complete stop. As you do so, be sure you do not exceed the maximum air pressure noted in the manufacturer’s guidelines.
9. Release the air pressure until the air is depleted.
10. Remove the air hose.

Torque multipliers are designed for ease of use, but it’s always smart to be careful when using any tool. Before beginning work, review these steps and any instructions that come with the tool.

The Benefits of Using a Torque Multiplier

While it does take hard work to succeed, I also make it a habit to work smart, to get the most done without wasting time and energy. To that end, when I approach a job, I always first determine what tools best suit the tasks I will need to perform that day.

If installing bolts, screws and other fasteners are common in your work, I recommend making sure you have the right torque multiplier on hand to help you boost productivity. No matter what type of fastening you’re going to install, a torque multiplier will make the job less strenuous—and that’s something we can all benefit from.