# Determining the Size of Universal Joints with Friction Bearings

## DIN 808-FB

The graph shows the transmitted outputs "N" or torques "M" of universal joints as defined in DIN 808-FB (single, friction bearing), depending on the speed "n."   This information is applicable for uniform speed, uniform load and a maximum working angle of 10°. It is not applicable for stainless steel universal joints.

Where the working angles "ß" are larger, an assumed reference output "N" or an assumed torque "M," increased by correction factor "k" must be used (see example below).

Conversion formulas:

Torque M [Nm] = 9550 N [kW] / n [rpm]
Output N [kW]= M [Nm] x n [rpm]
1 kW = 1.36 hp     1 hp = 0.736 kW

Example 1:

Transmitted output N = 0.65 kW
Speed n= 230 rpm Working angle ß= 10°
Correction factor k= 1

Reference output "N" = Rated Output N Intersection "P" is derived from 0.65 kW and 230 rpm (corresponding to a torque of 27 Nm).

The next larger joint corres-ponding to Point P is d1 = 25

Example 2:

Transmitted torque M = 27
Nm Speed n= 230 rpm
Working angle ß= 30°
Correction factor k= 2.25
Reference torque M = 2.25 x 27 Nm = 61
Nm Intersection "P1" is derived from 61 Nm and 230 rpm (corresponding to a reference output "N" = 1.44 kW).
The next larger joint corres-ponding to Point P1 is d1 = 32