Car wheels are essential components because they provide stability, traction and control to the vehicle. In the wheel, the hubs play a vital role. However, the driven wheel hubs are different from the undriven ones. The car wheel hubs for driving have a different construction and assembly.
Since these driven hubs help drive and steer the vehicle, these have different structures. Let’s go through the complete details about the driven wheel hubs and learn about their assembly and working.
What Are Driven Wheel Hubs?
Driven wheel hubs have a similar resemblance to those of undriven wheels. However, they have distinctive designs due to the necessity of accommodating drive shafts.
For instance, a two-wheel drive vehicle has hubs that serve two purposes: driving the wheels and enabling steering. Moreover, it rotates within or beside a big hub carrier structure. This carrier connects to the suspension using ball joints, which allow it to couple and move up and down.
For cars equipped with MacPherson struts suspension system type, the hub carrier features a ball joint at the bottom bolted onto or integrated with the strut at the top. The strut’s top mount creates the upper pivot, connecting it to the inner wing. Besides, the amount of rotation is controlled by the steering gear and arm.
How Do Driven Wheel Hubs Work?
Power from the final drive is transmitted to the hub through a drive shaft. This shaft incorporates a flexible joint, typically a constant velocity joint, at each end to accommodate steering and suspension motion. Inside the hub carrier, the drive shaft connects with the rotating part of the hub. As the drive shaft rotates, it in turn rotates the hub.
Parts of a Driven Wheel Hub
Similar to wheel hub assembly, the driven one has its own set of components. This includes the following:
Drive shaft splines
The main method of transferring power from the drive shaft to the hub involves using splines – grooves cut along the end of the shaft that fit into corresponding grooves inside the hub. This type of joint is efficient for transmitting significant power.
It is because even though the splines are shallow, they create contact across a wide surface area. This ensures a strong and effective connection between the shaft and the hub, allowing efficient power transfer while maintaining a compact design.
Bearing type
In driven hubs, ball bearings instead of taper roller bearings are used. These bearings are often individually fitted into the hub carrier, either pressed in or secured by a threaded retaining ring. To prevent excessive side loads on the wheel axle bearings when the central hub nut is tightened, a spacer or tube is placed between the two inner races.
Additionally, oil seals are always included to prevent dirt and debris from entering the bearings, ensuring smooth and reliable operation. This setup ensures that the bearings can effectively support the rotational forces generated by the drive shaft while maintaining durability and longevity. However, a bad drive shaft won’t provide the right rotational forces to the wheel bearings.
Bearing Location
A driven wheel hub needs a pair of bearings – inside and outside – to keep the hub steady and allow it to turn smoothly. But for driven wheels, these bearings usually fit inside the hub carrier and around the hub. The drive shaft goes through the middle of the hub.
Some older car models, like certain BL models, have a different setup where the hub doesn’t go into the hub carrier. Instead, the drive shaft goes tightly through the bearings inside the hub carrier. The hub then bolts straight onto the end of the drive shaft, which sticks out through the hub carrier. In this setup, the shaft carries both the weight of the wheel and the power to drive it.
In both setups, a nut at the end of the drive shaft keeps the hub attached to the car. The hub slides onto the outside of the hub carrier, while the drive shaft goes from the inside through the middle of the hub. A part on the drive shaft stops it from pulling through the bearings. The nut is always tightened securely and is usually held in place by either staking it or using a split pin.
How Do Rear-Wheel Drive Hubs Work?
In rear-wheel-drive cars with independent suspension, the rear hubs are often similar to those found on the front of front-wheel-drive cars. However, since the rear hubs don’t need to steer, they may lack certain components related to steering.
How Do Self-Steering Car Drive Hubs Work?
Some cars have rear hubs that can slightly turn themselves during fast cornering to help with stability. This small movement, called oversteer or understeer is usually just a few degrees. However, it is meant to counteract a tendency, where the car’s rear slides out during sharp turns.
For example, Mazda uses special rubber bushes between the rear suspension and hubs in their RX-7 model. These bushes are flexible in specific directions, allowing the hubs to adjust the angle of the rear wheels slightly. This adjustment, called toe-in, helps the car stay steady during braking and tight turns.
Similarly, Porsche employs steering links in their 928 model. These links connect the rear hubs to the body of the car. When the car leans in a turn, the suspension geometry causes the rear wheels to slightly tilt inward, reducing the chance of oversteer and improving handling.
FAQs
What are the different types of wheel hubs?
The main types of wheel hubs are the following:
- Standard
- Tapered roller bearing
- Sealed
- Unitised
- Heavy-duty
What is the difference between driven and non-driven hubs?
Driven hubs are actively involved in propelling the vehicle, whereas non-driven hubs rotate freely and are not connected to the vehicle’s power source.
What is a four-wheel drive hub?
A four-wheel drive hub is a component of a vehicle’s drivetrain system that engages or disengages the front wheels to enable or disable four-wheel drive mode, providing additional traction and control in off-road or low-traction conditions.
These were all the details about the driven wheel hubs. You can find these in all the new and used cars for sale in the UAE. However, you must understand the failures of wheel hubs to avoid major issues.
Stay tuned to the dubizzle cars blog for more details on auto parts and their working.
Related Posts
