Brake pad wear sensor: operating principle, replacement, installation
The braking system is one of the most importantmaking up any car. The main elements of it are the disc and pads. Braking is based on frictional force. The pads are in contact with the disc, resulting in resistance to the torque. The car starts to slow down. However, over time, the friction material wears out, and the shoe requires replacement.
It is important not only to properly install thesedetails, but also in time to diagnose wear and tear. This helps the motorist wear the brake pads. The principle of operation, the device, the types - is in our article.
Based on the name, it becomes clear thatThe main function of this element is to determine the degree of wear of the friction material. A special lamp is displayed on the instrument panel. When the thickness of the shoe closes to a minimum, the contacts close. The driver sees the corresponding signal on the instrument panel.
At the moment there are several types of sensors:
They can be installed on either one or several axles of the car. To find out their essence of work, we will consider each type separately.
Mechanical wear sensors shoe
This is fairly simple, yet effectivetool for tracking wear of the friction lining. Such a brake pad wear gauge has a simple device and consists of a plate of a certain shape. It is mounted on the base of the shoe. How does this element work? The principle of operation is as follows. The sensor plate is installed in such a way that its ends protrude beyond the shoe. When the friction material is erased to the minimum value, this protruding end will begin to contact the disc. As a result, a characteristic creak appears. On it and determine the wear.On modern cars, the installation of a sensorwear of brake pads of mechanical type is not produced, because they have a number of drawbacks. The first negative is the possibility of losing the plate. The second drawback is the frequent false triggering of the mechanism. The element is located in such a way that dirt and other sediments adhere to it. Therefore, even new pads are squeaking. Also, the mechanical wear sensor of the brake pads can not be installed on the drum mechanisms, due to their structural features.
This is more modern and technologicalinstruments. They interact with the lamp on the instrument panel. The driver no longer has to listen to his car. All the necessary information is on the panel.
In turn, the electronic brake pad wear gauge is divided into two more subspecies:
- External devices.
The first type is installed on the metal partpads. There is a special notch on the side. The main advantage is that you do not need to change the sensor when replacing the shoes. It can be rearranged to a new brake element. Integrated devices are located inside the friction lining. It is not possible to extract them. They are changing with new brake pads. It should be noted that these elements are more simple to replace.
Features of work
The electronic sensor consists of a metalThe core, which is placed in a plastic case. To eliminate the risk of damage to the brake disc (since the core will contact it when you pressthe relevantpedal), the rod is made of soft steel grades.Brake pad wear sensor functionis based on the closing of contacts. So, when the thickness of the pads is minimal, the electrical circuit will close. A corresponding light bulb will appear on the instrument panel. Recently, manufacturers often install a two-signal brake pad wear gauge. Thus, the lamp can change its color depending on the degree of wear of the friction material.
Symptoms of malfunctions
This element can fail on severalreasons. The most common is the damage or breakage of the power wires. In this case, the lamp does not light up even when the wear of the pad is 99 percent. The second reason is the oxidation of contacts. This often occurs at the connection point of the sensor and the plug, near the caliper. During operation, water and dirt can enter the sensor. All this affects the resistance of the circuit. As a result, the red lamp can catch fire even with new brake pads.Also note that the eclectic sensor willto maintain its function even in the case of malfunctions with wiring. The fact is that inside the element there is a steel core. When touched with a disc, it will cause a characteristic sound. That is, the element will continue to operate, but only as a mechanical sensor.
How to replace?
Replacement of the brake pad wear sensor canbe produced independently. To do this, you need to subdivide the necessary part of the car and unscrew the wheel. The external sensor will be near the hub (we will not change the integrated one separately). The element is fixed on a spring or with clamps. Carefully remove the fastening mechanism and take out the wear sensor of the brake pads. Next, carefully clean the seat of dirt and deposits. The sensor contacts themselves are also processed. In place of the old install a new element and attach the wheel back. We lower the car from the jack. We check the operability of the new element. If the pads are worn out, the lamp should light. In some cases, in order to restore the sensor working correctly, it is enough to clean the contacts.
Padding exchange regulations
Many are wondering about theperiod of time to change pads. The exact answer to it will not be given even by the manufacturer, since it all depends on the style of riding. Practice shows that with moderate use, the front pads "go" up to 40 thousand kilometers.The rear serve twice as long, sincethe main force is placed on the front. With an active riding style resource of friction materials will be up to 15 thousand kilometers. Experts do not recommend a long ride with a lighted indicator lamp. The steel tip quickly wears off, so, apart from the pads, you will have to change it.
So, we figured out how the wear sensor worksbrake shoes. As you can see, this is a very useful device that automatically signals the need to replace friction pads. Such an element can often be seen on cars "Mercedes" and "BMW." If desired, this device is installed on other cars. The easiest way to put a mechanical device. The electric sensor can not be set, because there is no corresponding indicator lamp on the instrument panel.