Wheel hub - what is it and why is it needed in a car (device and photo)

- a part designed to install a car wheel on an axle called an axle.
Hub bearings, in such a connection, are a key element not only of the hub, but also of the entire chassis as a whole, since they are responsible for the controllability of the car and largely ensure the safety of the driver. photo gallery:
The purpose of the hub is to connect the shaft and the wheel rim to transmit torque. On one side, the car hub is mounted on the shaft, and on the other, it has a special seat for mating with the wheel rim. The hub transmits rotational motion from the crankshaft axis to the wheel. A brake disc is also attached to it, so it also participates in braking. The wheel rotates thanks to the hub bearings.

Standard Features and Dimensions

Bearing parts for fastening wheels are made in different sizes. We are talking about the diameter of the hub. The dimensional characteristics of the spare part will always depend on the make of the car and the size of the rims. Manufacturers adhere to the rule: the cylinder of a metal product must always match the size of the car wheel. A special system, DLA, is responsible for determining these parameters. The fact is that large wheels on hubs of small diameter will dangle. Sometimes, for large-diameter wheels that a standard hub does not fit, an additional adapter ring is installed.

Final assembly

To assemble, follow these steps:

• Install the hub onto the axle.
• Place the washer and tighten the nut by hand.
• Install the brake drum and tighten the studs.
• Place the wheel and lower the car.
• Tighten all threaded connections.
• Place the nut on the hub.

Reassembling the entire assembly occurs in the reverse order. The hub nut must be tightened to a torque of about 200 N*m.

If, while operating a vehicle, problems with the chassis are identified, this is a reason to take urgent measures to eliminate the problem. A suspension failure can lead to unpredictable consequences, including an accident.

In this sense, the front hub is a very important component in a car that requires special attention.

Wheel bearings

This part is a rolling bearing consisting of inner/outer rings and a cage. What types are distinguished:

1. • persistent;
2. • radial;
3. • thrust-radial;
4. • radial contact.

» Vehicle systems » Steering » Front wheel hub - design and first signs of failure
When driving my personal car, I do not forget about its technical condition. But trouble comes unexpectedly, and even my constant monitoring of the situation did not help me avoid breaking such an element as the front wheel hub.

For the sake of safety and comfortable operation, I want to share some points regarding this mechanism, starting with the general structure and ending with repairing faults.

Part device

The front wheel hub, which has various functions, is called a component of the vehicle's chassis system. When a part is taken out of working order, the vehicle cannot be moved. To fully understand the purpose and functions, you do not need to have special knowledge.

It is only enough for me to know that it transmits torque to the wheel in order to make forward motion. At the same time, the fastening to the axle shaft should be as reliable as possible, because a disk with internal rotating bearings is connected to it. There is no point in specifying all possible functions; the basic ones will suffice:

1. The basis of the basics is to qualitatively connect the disk that is located on the steering knuckle.
2. Due to the location of the brake disc on the hub, it ensures good braking and the general condition of the braking system.
3. The presence of a hole with splines and the end of the axle shaft allows the vehicle to safely drive on sections of the highway (for front-wheel drive vehicles).

All modern cars are equipped with information sensors that collect data from the hub. A sophisticated electronic system will protect the driver on the road.

Drawing

The drawing of any hub is quite simple to understand. The wheel axle tube (4) and the shaft (5) are connected by welding. A pair of roller bearings (2) is well and reliably protected from sand and dust from the side of the axle (4) using a protective washer (3), and from the side of the nut (7) by means of a special cap (8), which is inserted into the housing with interference.

To remove the cap, use a bolt (9). The bearing play (2) is adjusted using a pressure washer (6) and a castle nut (7). The nut (7) is fixed with a cotter pin through the shaft hole (5). The housing (1) is well attached to the wooden wheel (10) using several screws (11). The space inside the hub is filled with a special lubricant.

How to check the front wheel hub

To check it yourself, you should study the device in more detail:

• frame;
• bearings;
• hairpins;
• sensors

The hub body consists of a cast part that is processed with turning tools. Together with studs and bearings, this is a single complex that comes from the manufacturer in a single design.

Such a monolithic assembly has a longer wear period for the part, as well as increased strength and safety.

You can carry out repair work yourself only with certain skills, knowledge and tools.

But checking is much easier. It will require the following tools:

• jack;
• screwdriver;
• wrenches for bolts and nuts;
• chisel;
• hammer.

The algorithm of actions is as follows:

1. I lift the car with a jack, having previously installed the securing bars against accidents.
2. I put stands under the rear wheels.
3. I engage first gear on the gearbox (manual) and put on the handbrake.
4. I use a wrench to remove the bearing bolts and nuts from the hub. Sometimes it happens that the nut cannot be removed with a wrench due to tight tightening. Drilling through the stuck side of the nut will help here.
5. Next, I hold the chisel in my hands and unscrew it to the end point.
6. I remove the wheel, remove the protection cap with a screwdriver, and remove the caliper, which is on the brake disc.
7. Ball joints and ends to the side, turn the drum in its direction, remove the fasteners. If you have a rust remover mixture on hand, minor work on nuts will go faster.
8. I pull out the brake disc, but before that I remove the two bolts and nut in the hub to pull out the brake disc.
9. Next, if there are no nuts on the stand, you can take out the hub and inspect it for damage.

Possible defects, reasons for their occurrence

The failure of the hub assembly does not occur instantly. Usually defects appear gradually. They are accompanied by an increase in the clearance in the bearing, which leads to play and runout of the wheel. Main types of hub malfunction:

1. Destruction of the cage or rolling elements. This usually occurs due to poor quality materials or a violation of the bearing assembly technology. In addition, destruction is possible due to improper installation of the unit.
2. Development of contact surfaces. Bearing parts inevitably wear out, however, the intensity of the process depends on the hardness of the material from which they are made.
3. Loosening of fastenings. The design of the mechanism includes locking rings and nuts. If they become loose, the bearing assembly may become loose.
4. Dry or lack of lubrication. Without a lubricant, the wear rate will increase several times, which will lead to premature failure of the elements.
5. Ingress of dirt or abrasive materials. If the seal is broken, foreign substances contribute to the rapid destruction of parts.

It is difficult to predict what exactly will break. It all depends on the car model, the design features of the hub unit, and the components used. You should not operate the car if there is a suspicion that the chassis components are damaged. Increased clearances in the wheel support lead to increased dynamic loads on suspension components (balls, ends, struts, shock absorbers and other less significant parts). In addition, hub failure while driving can cause loss of control and an accident.

Signs of breakdown

What is the first characteristic sign of damage that comes to my mind:

• tire treads wear off unevenly;
• leakage from shock absorbers;
• transport often deviates when going straight;
• increased vibration;
• the body wobbles from side to side when I turn or brake;
• other extraneous sounds when I move in a car.

I can’t immediately understand the reason, so I put it on a jack and spin the wheels, looking at the appearance at the same time.

A bad type of rubber indicates a malfunction associated with vibration being transmitted to the steering wheel due to improper rotation of the bearing. At the same time, the brake disc heats up, which can be felt after ten kilometers of driving. Of course, there is no thermometer at hand, but temperatures above 70 degrees will be felt.

And if the hub bearing rotates poorly, then there is no need to stop. Steering wheel to the right - hum to the left, and vice versa.

I would like to highlight the main and frequently encountered factors:

• wheel alignment is incorrectly adjusted;
• heavy load on the front wheels;
• elements of the system have worn out over time;
• shock absorbers are not attached as required.

Each damage has a fairly noticeable effect on the speed limit or during braking.

Hub repair is mandatory, although the complexity of the work plays a role, influencing the choice of action scenario:

1. A puller is used; the steering knuckle is not removed.
2. Dismantling with subsequent repairs on a workbench.
3. The entire strut is removed and the bearing is replaced using a vice.

Everywhere there are advantages and disadvantages, more on that. In the first method, the adjustment bolt is not exposed to dismantling, which affects the wheel alignment system. But you will have to be in conditions where there is a hole and a lift in order to knock out the hub and press in the bearing.

If I were going to change the silent block, ball joint or steering wheel end at the same time, I would choose the second method. I make notes about the location of the adjusting bolt. This makes it easier to adjust the regulation during reverse installation.

The third method is for hardcore fans, since the upper support is completely unscrewed and the steering tip is unpressed. Please pay attention to the careful removal of the hub itself and its parts.

A pressing machine will help with this so that the corkscrew ring remains intact. Nobody knows whether it will be included with the new hub. During dismantling, the bearing will most likely be damaged, so you should pay attention to this.

Kinds

• For all driven wheels. For driven ones: the system is mounted on the front discs for rear-wheel drive vehicles. For non-drivers: the element is mounted on the rear wheels of the vehicle, but with front-wheel drive.
• For all driving wheels. For non-drivers: part of the car is mounted on the drive axles of rear-wheel drive vehicles. For those driven: an important unit is mounted on the front axle of cars with front-wheel drive and all-wheel drive.

These mechanisms are made dismountable and monolithic, which affects the possibility of their repair.

• Monolithic design. If a roller bearing breaks, you will need to buy the entire part as an assembly, since replacing its individual components will simply be impossible.
• Collapsible design. In this case, it will be possible to remove the roller bearing or other components of the mechanism and then replace them.

What is a hub for?

The function of the hub is to allow the wheel to rotate and to keep the wheel firmly in place. This means that each wheel has its own hub. In addition, the functions of the hub also include transmitting torque from the gearbox to the drive wheel.

Typically, the hub assembly is a single piece that already has an axle shaft. There are also such designs when the hub assembly has a slotted hole for the CV joint axle shaft, which is called a constant velocity joint.

In addition, even in the braking process, the hub is involved, because it holds the brake disc or brake drum, it depends on the car. Many new cars use an electronic motion control system, which means that special sensors or an impulse disk are additionally installed in the hub.

Summarizing all the above information, the wheel hub performs the following functions:

• holds the wheel rim tightly;
• it holds the brake disc or drum;
• thanks to the hub the wheel rotates;
• holds all the necessary components on the axle shaft;
• transmits torque to the wheel from the axle shaft;
• The system elements are attached to the hub.

Tools

The “package” of tools includes:

• hammer, pry bar;
• socket wrenches (for drum pins), spanner wrench;
• passages (for rings).

Note!

You can use an additional wooden block to soften the blow, and it’s good to add a long pipe to the socket wrenches.

Appearance of socket wrenches

What is a hub and how is it designed?

Usually, while driving, the hub takes on a lot of load. In order for it to cope with this load, the hub is made as follows: they take a solid steel blank and grind the hub using turning and milling.

Every experienced car enthusiast knows what a hub looks like, for those who don’t know, you can look at the photo above and below to see what it looks like. The design of the wheel hub is quite simple: it is a round-shaped part with an outer rim in which there are the necessary holes.

Functions of hub parts:

• on the outer rim there are holes for guide bushings and bolts that hold the wheel to be screwed into them; on some models, instead of bolts, studs are used, which are screwed with nuts;
• the inner part of the hub is needed for bearings to be installed in it;
• a hole with slots is necessary in order to install CV joint axle shafts into it;
• in a car with ABS, there is a seat on the hub for an impulse disc or ABS sensor.

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Bearings are used to rotate the wheel; depending on the design, they may differ. Usually there are sealed roller and cone bearings. It is rare to find ball bearings, as they have a small contact area.

There are cases when, after diagnosing the wheel bearings, it was determined that they were worn out, you can immediately change them, but on most modern cars the hub has non-removable bearings and therefore, if they wear out, you will have to change the entire hub assembly, which is not very beneficial for the car owner . It would be easier to just change the bearings for pennies. In general, it all depends on the car; on VAZs, for example, you can change the bearings separately from the hub.

Malfunctions

The breakdown of this element of the car is a fairly serious defect, when further use of the car can lead to wheel jamming and other extremely dangerous situations.

At the first sign of damage, contact the service for professional repair or, if you are well versed in this, carry out the repair.

All the causes of the problems boil down to the following:

• Incorrect installation of subassembly. During installation, tapered bearings can be clamped with a strictly defined torque. If the nut is not tightened enough, the bearing will gradually break while driving on uneven roads. If the nut is pinched, the roller bearing will heat up from constant friction, and this will soon result in rapid wear of the installed bearing.
• Poor quality. Most modern assemblies, even cheap ones, are of normal quality. But you can still stumble upon various fakes, which after some time actually fall apart.
• Frequent driving on broken and uneven surfaces. Dynamic loads from this are the main cause of rapid wear.
• Lack of or contamination of the lubricant used. The assembly unit must be well lubricated. If there is too little lubrication, the working surfaces will very quickly become unusable.

Increased wheel bearing wear

The part is often faulty when a strange hum is heard in the car. Its source can be determined very simply. On a straight, level and empty road section, you need to accelerate to the speed when the hum starts to appear. After this, you need to slightly turn the steering wheel in different directions. If the noise increases when you turn the steering wheel to the right, then the right assembly is broken, and vice versa.

Hub failure

Problems with the assembly unit can be identified by the strong heating of the part. If you have any suspicions, then after the trip you need to carefully touch all the discs with your hand. If in the end you find an element that is really hotter than others, then there are definitely problems with it.

Bearing failure

A breakdown of the front assembly can be determined by greater play in the steering wheel. The latter will tremble when driving at high speed on an uneven road.