The drive shaft and differentials
On the other side of the transmission is the drive shaft. This is a shaft with a hinged connection on either side. Now, the actual construction of a drive shaft can vary dramatically between cars because it’s surprisingly difficult to transmit power from the engine across a distance to wheels within the context of driving in the real world.
Think about trying to use a broom from a distance, you’re holding the handle end with one hand and trying to sweep something two meters away. You may be able to do an ok job of it inside, but if you’re trying to do this while moving – or if there are any other external factors like wind – then it becomes a significantly harder job.
The drive shaft faces a similarly difficult problem. While driving on a road, your car is subjected to a whole host of different forces as it accounts for bumps and unevenness in the road – as well as other factors. The drive shaft needs to be rigid in order to effectively transmit the torque from the engine to the wheels, but if it’s a single rod then it can’t account for any flexing.
That’s where the hinges come in. They allow the front and end of the drive shaft to move up and down, as well as change angle, within certain parameters while still rotating.
Here’s a great video on how a drive shaft works:
The end of the drive shaft is attached to a component known as a differential. This is like a big cog set at a right angle to the drive shaft – so the rotation of the drive shaft is turned into rotation along the axis of the axles, and then the wheels.
An added task of the differential is to be able to account for differences in wheel speed between the left and right side such as when driving through corners.
Now, you may be wondering how this works for both front and back axles. But this is exactly what rear or front wheel drive means! Unless you have a four wheel drive. Only one set of wheels is actually driving the car.
Hopefully, that’s everything you need to know for a general awareness of the drive train system in a car. There are a whole set of different systems and parts here that could take books to explain. But this should have given you a good overall knowledge.
If you’re concerned about an aspect of your car’s drive train, don’t hesitate to get in touch with your local Kwik Fit Centre.