# 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!

### Algorithm:

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

Bruce Bowling

bbowling@earthlink.net

Bowling Superior