Brake wear indicator: Difference between revisions
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[[File:BrakePadWearIndicators.svg|300x300px|none|Olika varianter av slitagevarnare.]] |
[[File:BrakePadWearIndicators.svg|300x300px|none|Olika varianter av slitagevarnare.]] |
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Pads '''B''' are mounted on carriers '''G'''. These are pushed against the rotor '''A''' by the piston '''D''' which is pushed by the brake fluid '''E'''. This induces wear on the pads. The rotor '''A''' also experiences some wear, but to a lesser extent than the brake pads. The modules '''C''' are joined to the cylinder that houses the piston '''D''' and acts as counter-force to the piston '''D'''. |
Pads '''B''' are mounted on carriers '''G'''. These are pushed against the rotor '''A''' by the piston '''D''' which is pushed by the brake fluid '''E'''. This induces wear on the pads. The rotor '''A''' also experiences some wear, but to a lesser extent than the brake pads. The modules '''C''' are joined to the cylinder that houses the piston '''D''' and acts as counter-force to the piston '''D'''. |
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Wear sufficient enough to validate a change of brake pad has been worn down to a level where: |
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# The gap '''1''' no longer is visible or close to be unavailable. |
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# The embedded sensor in the pad '''2''' gets in contact with the rotor and creates a connection to ground of the sensor. |
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# The metal plate '''3''' gets in contact and creates a noise. |
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# The distance between the cylinder for piston '''D''' and the carrier '''G''' becomes too large causing the sensor '''F''' to send a signal on the sensor wire '''4''' which is outside the permitted range, or ground the sensor wire '''4''' if '''F''' is a contact. |
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Notice that '''F''' can either be an analog sensor or an on/off contact. |
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Under normal conditions only one of the alternatives 2 to 4 are used. Many cars are only equipped with wear indicators on the front wheels. |
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== Electric wear indicator == |
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[[File:B10 Critically worn brake linings.svg|100x100px|thumb|Symbol for worn brake pads]] |
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Electric wear indicator is the alternatives '''2''' and '''4''' as displayed above. |
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== References == |
== References == |
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Revision as of 08:24, 5 October 2013
A Brake wear indicator is used to warn the user and/or owner of a vehicle that the brake pad is in need of replacement. The main area of use for this is on vehicles. However brake wear indicators are also useful in industrial applications[1][2].
This article refers to disc brakes as an example, but the principle is the same for other types of friction brakes.
Types of indicators
There are different types of wear indicators for brake pads:
- Ocular inspection: A cut is made in the pad material to the depth where it shall be replaced. Requires manual inspection of the pads.
- Mechanical[3][4]: A metal plate is designed to scratch the brake disk causing a noise when the pad has worn down to the desired level.
- Electrical[5]: A metal body is embedded in the pad material that comes in contact with the rotor when the desired wear level is reached. This will light an indicator in the instrument cluster.
- Position sensor[6]: A sensor that measures the position of the brake mechanics and indicates to the driver when the desired position has been achieved.
Of the alternatives above the first three are simple and cheap since their lifetime coincides with the lifetime of the brake pad. The last one is more expensive since the sensors needs to be designed to survive the design lifetime of the vehicle. This means that the last alternative is usually only seen on heavy duty vehicles.
The idea is that in all cases alert the driver and/or owner of the vehicle that it is time to replace the brake pads to ensure that the traffic safety is preserved for the vehicle.
Detailed description
Pads B are mounted on carriers G. These are pushed against the rotor A by the piston D which is pushed by the brake fluid E. This induces wear on the pads. The rotor A also experiences some wear, but to a lesser extent than the brake pads. The modules C are joined to the cylinder that houses the piston D and acts as counter-force to the piston D.
Wear sufficient enough to validate a change of brake pad has been worn down to a level where:
- The gap 1 no longer is visible or close to be unavailable.
- The embedded sensor in the pad 2 gets in contact with the rotor and creates a connection to ground of the sensor.
- The metal plate 3 gets in contact and creates a noise.
- The distance between the cylinder for piston D and the carrier G becomes too large causing the sensor F to send a signal on the sensor wire 4 which is outside the permitted range, or ground the sensor wire 4 if F is a contact.
Notice that F can either be an analog sensor or an on/off contact.
Under normal conditions only one of the alternatives 2 to 4 are used. Many cars are only equipped with wear indicators on the front wheels.
Electric wear indicator
Electric wear indicator is the alternatives 2 and 4 as displayed above.
References
- ^ http://www.icpltd.co.uk/contents/en-uk/d26_industrial-brake-pads.html.
{{cite web}}: Missing or empty|title=(help); Unknown parameter|titel=ignored (|title=suggested) (help) - ^ "Crane Brakes".
- ^ "How Stuff Works: How Disc Brakes Work".
- ^ "Installing Subaru 4-Pot Brakes".
- ^ "Professional Motor Mechanic; Brake Pads - Questions and Answers".
- ^ "Gill Sensors; Through-Hole Position Sensor".