What is a Live Axle?
A live axle is a shaft that laterally connects two wheels that are rotated along with the axle. It connects to the driveshaft, a component of a vehicle that transmits energy from the engine to the wheels to turn them. This axle design is simple, easy to implement, and easy to repair, but it has some significant drawbacks. Since the 1980s, the design has become increasingly uncommon, in lieu of others that are more efficient.
There are no constant velocity (CV) joints in a live axle. CV joints allow the wheels to turn at different angles while maintaining their speed. Live axles also don't have differentials, components that are designed to allow wheels to turn at different speeds. The lack of CV joints and a differential poses some substantial problems for vehicles with this type of axle. They are difficult to turn because both wheels turn at the same speed instead of allowing the inside wheel to slow while the outside wheel speeds up, and when these vehicles go over bumps and rough roads, the lack of a CV joint causes the whole axle to displace.
In addition, these axles add to the unsprung weight of a vehicle, the weight that comes into direct contact with the road instead of being lifted by the suspension. This can interfere with handling. Such axles were standard on vehicles until the 20th century, when different types of axle and suspension designs began to be developed to meet the needs of increasingly complex vehicles.
There are some advantages to the live axle design that make it popular for certain applications. Traction tends to be better, and the axle maintains a consistent height, both of which can be very useful traits for off-road vehicles. These vehicles are usually driven more slowly, making handling and cornering less of a concern, and the ability to have more traction can be very valuable. This style of axle is also used on some types of trucks.
Generally, the axle design a vehicle is equipped with is intended to meet the needs of situations the vehicle is most likely to encounter. Information about the axle and other systems in the vehicles can be provided by request for people who want to know more about the components of their vehicles. It is also possible to retrofit vehicles to change axle and suspension designs if people want to retain certain characteristics of a car while changing others.
"Live axles also don't have differentials,"
That is not true. I own a Mahindra Jeep with live axles (Dana 44) at front and back. There are differentials in both the axles.
@emtbasic - I had some experience with Unimogs when I was in he Army in Germany. The German troops used them and you're right, they could go anywhere.
I now work in mining and a lot of our heavy equipment uses some kind of live axle setup. It doesn't go very fast, and the traction is more important than precise high-speed cornering. I think you'll see this kind of setup staying around for a long time in certain applications.
They used to make live axle go karts when I was a kid. Sears used to sell one in that fantastic Christmas catalog we all used to read cover to cover back in the day. I asked for one when I was 10 or 11, and to my surprise it was under the tree come Christmas morning.
It definitely would not have been very good for off road, but the local go kart track was a flat track, and for that the live axle go kart suspension was perfect.
That thing *flew*. No seat belts, no roll cage, nothing. I bet nowadays you'd probably get arrested letting your little kids go racing around on something like that. Best gift ever, though. If I had been riding it in the woods, I would have wanted something with an independent suspension. But for the flat track, the live axle was perfect.
I had an old Mercedes Unimog, which is one of the coolest off-road vehicles ever. It had live axles, and this thing could literally go anywhere. We used to use it to go out to my cabin every hunting season.
The roads out there were hideous, and really were nonexistent in many places. That thing just kept going. With the live axle, the rear suspension (and the front, for that matter) was a little stiff, and you really couldn't go very fast. This was not a freeway road trip kind of a vehicle, but for what it was I've never seen a better truck.
Those things are all over the place in Europe and even Africa, but they are really rare in the states for whatever reason.
Post your comments