provide a means of connecting two or more shafts together,
At the present time, a limited number of vehicles
are equipped with fiber composite-reinforced fiberglass,
graphite, and aluminum-drive shafts. The advantages of
using these materials are weight reduction, torsional
strength, fatigue resistance, easier and better balancing,
and reduced interference from shock loading and torsional
problems. Some drive shafts are fitted with a
torsional damper to reduce torsional vibrations.
The drive shaft, like any other rigid tube, has a natural
vibration frequency. If one end were held tightly it would
vibrate at its own frequency when deflected and released.
It reaches its natural frequency at its critical speed. Critical
drive shaft speed depends on the diameter of the tube
and its length. Diameters are as large as possible and shafts
as short as possible to keep the critical speed frequency
above the driving speed range. It should be remembered
that since the drive shaft generally tums three to four times
faster than the tires, proper drive shaft balance is required
for vibration-free operation.