Driveshaft Velocity Calculation By Bowling

Did you know that driveshafts and axles with single universal joints undergo a RPM change as they are rotated from a fixed RPM source? The following program illustrates this effect. The inputs are driveshaft RPM (revolutions per minute), and relative driveshaft angle, which is the angle between transmission yoke or differential pinion, and the driveshaft tube. The greater the angle, the more pronounced the effect. The results of this program drives home the fact that one should set up the yoke and pinion to be in the same plane - this implies a geometry which is symmetric (i.e. a 5-degree angle between the yoke/driveshaft, and a -5-degree angle between the pinion/driveshaft, for example). Just imagine the incredible torsional forces exhibited to the driveshaft if the angles were say +5 and -10 degrees, and the transmission was turning the yoke at a fixed RPM and the differential was turning the pinion due to the vehicle motion!

Program Inputs:

Driveshaft Angle in Degrees:

Yoke/Pinion RPM :

Press this button to submit a computation:

To reset the form input:


The following equations are used:
w = (6.28314 * rpm)/60.0
tmp1 = TAN(angle)
tmp2 = 1/COS(DriveshaftAngle)
tmp = (1. + tmp22 * tmp12)
dtdt = w/(COS(DriveshaftAngle) * COS(angle)2 * tmp)
f = dtdt / (6.28314/60.0)

Bruce Bowling
Bowling Superior