Do you know the difference between a semi-float axle and a full-float rear axle? Knowing how they work and which one is right for a particular application is important to make sure you are using the best product. We are here to help explain the differences.
Any drive axle must be capable of performing two functions: support the weight of the vehicle safely and transmit power to the wheels for propulsion. By design rear drive axles may be semi-floating or full-floating.
Axles permit to the wheels to rotate so that the driver can operate the vehicle properly. The vehicle’s weight is also supported by these axles too, regardless of which type of axle you have in your vehicle.
Most manufacturers design their light-vehicles with semi-floating axles while others use heavy duty full-floating axles. The type of vehicle you have has a lot to do with which type of axle you end up with.
You will learn more about the difference between these two axle types.
You might wonder, why not just use a full floating axle always? Well, semi-floating axles are lighter and more simply too. This means it's easier to install them in a vehicle and cheaper for purchasing department.
Now, how is the full floating axle able to support so much more weight? The axle rod and wheel hub are connected to each other. The wheel is mounted right onto the axle housing instead of the axle rod. The benefit is that the axle rod receives the torque effect, but it does not bend. This torque is the differential power which goes to the wheels.
This design employs one wheel support bearing mounted on the outer end of the axle shaft and inside the axle tube. All the wheel forces including vehicle weight, wheel side skid, wheel traction, and torsional drive, are supported by the axle shaft. The outer end of the axle shaft is supported in the axle tube and support vehicle weight.
Wheels are supported by bearing that mount on the outer end of the axle tubes. Wheel forces due to vehicle weight, vehicle tractive effort, and side skid load are reacted by the axle tubes. The outer end of the axle shaft is unsupported or “floats” in the axle tube and transmits torsional drive forces only. This design is used for heavy duty applications.
The choice between a semi-floating axle and full floating axle will depend on two things: your budget and your vehicle. If you vehicle is working into certain stress limits and you don’t use it for any heavy duty purposes, then a semi-floating axle is just fine. You would not gain much benefit for the cost to convert to a full-float axle.
On the other hand, if you regularly haul a lot of weight in the back of (or behind) your vehicle or are involved in off-roading, then you’ll want a full floating axle. It may cost more money, but it’s more durable and supports more weight.
A benefit of a full-floating axle, finnally, is that even if an axle shaft breaks, the wheel will not come off, preventing serious accidents.
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