ABSTRACT: Vehicle brake linings are also called vehicle brake pads. They are composed of steel plates, friction materials, and adhesives. They are installed on the brake calipers. Under the pressure generated by the brake cylinders, they create friction with the brake discs or brake drums. Generate heat to achieve the purpose of vehicle deceleration. Brake linings and brake discs or drums are extremely important parts of the vehicle braking system. According to UN R90 regulation, non-original replacement brake lining assemblies, discs and drums need to be tested and achieve the E-mark type approval as vehicle parts in order to get access to the EU market.
GENERAL TECHNICAL REQUIREMENTS FOR REPLACEMENT PARTS
1. Satisfy the vehicle requirements of UN R13, UN R13-H or UN R78.
2. A replacement part shall display performance characteristics similar to that of the original part it is intended to replace.
3. A replacement part must possess adequate mechanical characteristics.
4. Brake linings shall not contain asbestos.
5. A replacement brake disc/drum shall exhibit sufficient deformation resistance under temperature.
6. The minimum thickness of the brake disc shall not be less than the minimum thickness of the original brake disc as specified by the vehicle manufacturer.
7. The maximum permissible inside diameter of the brake drum shall not be more than the maximum permissible inside diameter of the original brake drum specified by the vehicle manufacturer.
MECHANICAL CHARACTERISTICS OF REPLACEMENT BRAKE LINING ASSEMBLIES
For M1, M2, N1, O1, O2, L vehicles:
1. The minimum acceptable shear strength is 250 N/cm2 for pad assemblies and 100 N/cm2 for shoe assemblies.
2. The compressibility values shall not exceed 2 percent at ambient temperature and 5 percent at 400 °C for pad assemblies and 2 percent at ambient temperature and 4 per cent at 200 °C for shoe assemblies. This requirement does not apply to parking brake lining assemblies.
For M3, N2, N3, O3, O4 vehicles:
1. Shear strength test applies only to disc brake pad assemblies. The minimum acceptable shear strength is 250 N/cm2.
2. The compressibility values shall not exceed 2 percent at ambient temperature and 5 percent at 400 °C for pad assemblies and 2 percent at ambient temperature and 4 percent at 200 °C for shoe assemblies and drum brake linings.
3. Material hardness’s requirement applies to drum brake lining assemblies and drum brake linings. Replacement brake lining assemblies or replacement drum brake linings of the type for which approval is requested shall be tested for hardness according to Standard ISO 2039-2:1987. The hardness figure for the friction material at the rubbing surface shall be the mean value out of five sample linings from different production batches (if available) by taking five measurements at different places of each brake lining.
GENERAL TECHNICAL REQUIREMENTS FOR REPLACEMENT DISCS OR DRUMS
1. Original replacement brake discs/drums: no further requirements.
2. Identical brake discs/drums: no further requirements.
3. Equivalent replacement discs or drums: geometric requirements for discs; material and metallurgical requirements for discs or drums.
4. Interchangeable replacement discs or drums: material and metallurgical requirements for discs or drums.
TEST PROCEDURES OF VEHICLE TEST AND INERTIA DYNAMOMETER TEST FOR REPLACEMENT BRAKE LININGS OF M1 VEHICLES
- Bedding (burnishing) procedure
- Performance check
- Service braking system (Type-0 test with engine disconnected, Type-0 test with engine connected, Type-I test); Secondary braking system (Type-0 test with engine disconnected, vehicle laden); Parking braking system.
- Cold performance equivalence test/Speed sensitivity test
Inertia dynamometer test:
- Burnishing phase 1
- Burnishing phase 2
- Perform 5 brake applications from 80 km/h to 0 km/h
- Cold performance equivalence test
- Speed sensitivity test
THE PROCEDURE OF UN R90 TYPE APPROVAL
1. Application Submission
2. Initial Assessment
3. Technical Documents and Samples Preparation
4. Sample Delivery and Testing
5. Prepare test report and certificate
6. Submit test report and certificate
7. Issuance Certificate
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