Missed Part 1? [Catch up here： https://www.brake-cylinder.com/info/gb-21670-2008-technical-requirements-testing-103032841.html ] – We decoded core terminology and ABS fundamentals. Now, let's dissect critical structural mandates and real-world compliance hooks.
🔧 4. Structural & Functional Requirements
4.1 Braking Equipment
4.1.1 Non-Negotiables
- Corrosion/aging resistance under all operating conditions
- Zero asbestos in friction materials (global compliance essential!)
- EMC Immunity: Performance unaffected by electromagnetic interference (per GB/T 17619)
- Max static brake force achievable on roller/dynamometer testers
System |
Key Requirement |
Real-World Implication |
| Service Brake | Controllable deceleration hands-on-wheel; works on inclines/declines | Driver-centric safety |
| Emergency Brake | Stops vehicle after single failure in service system | Redundancy = lifesaver |
| Parking Brake | Holds vehicle on ≥8% gradients post-ignition off | Prevents rollaways |
💡 For complex e-control systems (e.g., auto-braking): Appendix D safety protocols apply.
4.2 Critical Subsystem Specs
🛑 Shared Components?
- Independent controls for service vs. parking brakes
- No degradation of service brake linkage efficiency over time
- Parking brake must function even while moving (via service brake backup)
⚡ Energy Storage Systems (Hydraulic/Pneumatic)
- Post-failure energy reserve: Deliver 5 full-stroke stops after 20 simulated cycles
- Pressure alerts: Red warning at >1.55 MPa circuit pressure differential
- Reservoir visibility: Fluid level check without opening reservoir
🔋 Electric Regenerative Braking (RBS)
| Type | Activation Method | Critical Constraints |
| A | Accelerator pedal/neutral only | Never part of service brake system |
| B | Integrated with service brake | Single control device; immune to gear shifts |
⚠️ RBS Type B failures trigger yellow dash alerts per 4.2.21.1.2
🚨 Alarm Systems – The Vehicle's "Check Engine" for Brakes
1. RED signals (immediate action):
- Fluid leaks • Circuit failures • Traction battery < OEM voltage threshold
- Rule: Must illuminate before brake application during failure
2.YELLOW signals (inspection needed):
- Pad wear • ABS sensor faults • RBS degradation
3.Audible alerts mandatory if red light alone insufficient
🔧 Wear & Maintenance Safeguards
- Auto-adjustment for service brake wear (post high-temp testing)
- Visual/audio wear indicators for friction materials
- Tool-free inspection via access ports (wheel removal allowed)
⚙️ Hydraulic System Commandments
- Reservoir volume = Fluid needed from new pads → fully worn
- Labeling: Brake fluid grade (GB 12981) + symbols (GB/T 14168) within 100mm of cap
- Failure response: Pressure loss activates red alert until ignition off
🔌 Electronically Controlled Brakes – Make-or-Break Details
- 40ms tolerance: Transient errors must NOT impact performance
- Low-voltage scenarios: Red alert if battery can't sustain emergency braking
- Parking brake defaults: Mechanical fallback if electronics fail (≥8% grade hold)
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