This confuses me. The point of a differential is to make it so the wheels don't slip when one needs to be turning faster than the other, such as during turns.
So if the rear wheels are directly connected by a solid axle, doesn't that force them to turn together? How is turning handled?
FWD cars dont have a rear axle, the wheels are mounted independently, there may be some situations where there is a tube there, but it will not have an axle shaft.
The wheels just ride independently on bearings, they aren't connected by an axle like in a RWD vehicle.
I think you misunderstand the true purpose of a differential. A ring and pinion is necessary to take the rotation of the driveshaft and change it's rotational axis. That is, the driveshaft is spinning about an axis from front to back of the vehicle and something needs to convert this rotational force perpendicularly to turn wheels.
True that differentials (non-spools) allow one wheel to "slip" but that is a design to handle that scenario rather than the true intent of the differential.
I hope this makes sense.
It seems to me there's some confusion about terms here.
An axle is just a bit of ironmongery holding the wheels in place. The wheels can rotate independently of the axle: there's a bearing between wheel and axle.
Here's a Ford model T front axle:
The two wheels are connected, and suspension is provided by leaf springs between the axle and the chassis. This has some drawbacks:
To solve these issues, modern cars usually have independent suspension: there is no physical connection between the wheels. Both wheels are attached to the car body instead. The term 'axle' is still used to indicate the two wheels that are in line across the car.
When the wheels are driven, there is a physical connection: the drive shafts. Then you'll also see a differential in the middle, to allow the wheels to run at different speeds when you take a turn.
Here's a Ford model T rear axle:
In this case, the axle is a tube. The drive shafts run inside the tube.
In independent suspension, there's normally no tube so the drive shafts are exposed.
(images borrowed from this site)
On FWD cars the rear wheels do not transmit the power, they are free to rotate freely
The purpose of the differential is to allow two axles to turn at different speeds while delivering power to them.
If wheels are not used to deliver power to the road then they can just be allowed to spin independently. No differential is needed.
So a front wheel drive vehicle has a differential at the front. A rear wheel drive vehicle has one at the rear. A four whel drive vehicle has differentials at both the front band back and often a center diff too.
