# Is prevailing torque the same as running torque?

## Is prevailing torque the same as running torque?

Running Torque vs Prevailing Torque Also, it is to overcome unintentional interferences which include weld spatter, contamination, and cross-threading. Because of these varying conditions, the application of prevailing torque is a lot more complex in comparison with running torque.

## What is a prevailing torque?

Prevailing torque is defined as the driving torque required to overcome friction in a threaded fastening application, which produces no clamp load, or bolt stretch.

What is a running torque?

Running torque is the determination of how much torque is required to keep the part rotating at a constant angular velocity once it starts rotating.

What is free running torque?

Free running, prevailing, or friction drag torque is the amount of torque it takes to turn the nut on the threads. This value will be very small for a plain nut and somewhat higher for a self-locking nut. Regardless of the number, this torque value must be added to the desired torque to achieve final torque.

### How is running torque calculated?

To calculate load torque, multiply the force (F) by the distance away from the rotational axis, which is the radius of the pulley (r). If the mass of the load (blue box) is 20 Newtons, and the radius of the pulley is 5 cm away, then the required torque for the application is 20 N x 0.05 m = 1 Nm.

### Can you reuse a prevailing torque nut?

Prevailing torque lock nuts are reusable a limited number of times because the prevailing torque declines each time the nut is used. Always follow the manufacturer’s recommendations regarding nut reuse, thread lubricants and torque values.

How do you use running torque?

The proper procedure is to run the nut or bolt down to maybe half a turn to contact (washer still loose). Measure the torque required just to move the nut the last bit before the nut makes contact, and add that to the total.

How much torque does a 14mm bolt need?

Metric Recommended Bolt Torque

Bolt Diameter (mm) Recommended Torque (Nm)
Class 8.8 Class 10.9
12 100 135
14 160 215
16 245 335

#### Is breakaway torque the same as tightening torque?

Breakaway torque is the rotating force required to “break” the head loose, going in the same direction as applied – tightening. This will usually give a value HIGHER than the original tightening torque because dynamic (when the bolt was tightened) is lower than static (when you try to break loose the bolt head).

#### How to calculate prevailing torque?

normal dry: K = 0.2.

• nonplated black finish: K = 0.3.
• zinc-plated: K = 0.2.
• slightly lubricated: K = 0.18.