C0

Articles, guides, and products tagged "C0" — a combined view of every catalogue resource on this topic.

User guide

E-scooter functional safety engineering: safety integrity as the sixth cross-cutting infrastructure axis — IEC 61508:2010 (E/E/PE safety-related systems, SIL 1-4) + ISO 26262:2018 (automotive FuSa, ASIL A-D) + ISO 13849-1:2023 (safety-related parts of machinery, PLr a-e, Cat B/1/2/3/4) + IEC 62061:2021 (SIL CL for machinery E/E/PES) + EN 17128:2020 Annex G (PLEV functional safety requirements) + IEC 60812:2018 FMEA + IEC 61025:2006 FTA + IEC 61709:2017 reliability data + MISRA C:2023 software safety subset + ISO/PAS 21448:2022 SOTIF + IEC 61511 process industry + IEC 60730-1:2024 controls + UL 991 + UL 1998 + DO-178C analogy

Engineering deep-dive into e-scooter functional safety as the sixth cross-cutting infrastructure axis — parallel to [fastener/joining](@/guide/fastener-and-bolted-joint-engineering.md), [thermal management/heat-dissipation](@/guide/thermal-management-engineering.md), [EMC/EMI/interference-mitigation](@/guide/emc-emi-engineering.md), [cybersecurity/interconnect-trust](@/guide/cybersecurity-engineering.md), and [NVH/acoustic-vibration-emission](@/guide/nvh-engineering.md). Covers: 10-row standards matrix (IEC 61508, ISO 26262, ISO 13849-1, IEC 62061, EN 17128 Annex G, IEC 60812 FMEA, IEC 61025 FTA, IEC 61709, MISRA C, ISO/PAS 21448 SOTIF); SIL/ASIL/PL/SIL CL cross-mapping; 6-row hazard-by-subsystem matrix (motor controller throttle-stuck, brake actuator loss, throttle position drift, BMS thermal runaway, display HMI critical info, lighting fail-dark); FMEA worked example for BLE throttle injection scenario; FTA worked example for wheel lock at speed; FMEDA with PFD/PFH calculation, Safe Failure Fraction, Hardware Fault Tolerance; risk reduction equation R_residual = R_unmitigated × (1 - RRF); 6-row mitigation matrix; ALARP principle; software safety V-model + MISRA C:2023 + formal methods; SOTIF (ISO/PAS 21448) as extension to IEC 61508; HIL testing + fault injection; 8-row real-incidents timeline (Lime brake recall 2019, Ninebot ES2 throttle creep 2020, Apollo Pro firmware bug, Boosted board fire, Bird scooter rear-wheel hub crack, Tier scooter motor-stuck); 8-step DIY safety check; 6-step DIY remediation; industry shift 2020→2026; 16 numbered sections.

17 min read

User guide

E-scooter rolling-element bearing engineering: ISO 281 L₁₀ rating life, ISO 76 C₀, ABEC/ISO 492 precision, NLGI greases, types, and failure modes

Engineering deep-dive into rolling-element bearings in an e-scooter — parallel to the other engineering-axis articles on [frame](@/guide/frame-and-fork-engineering.md), [motor](@/guide/motor-and-controller-engineering.md), [suspension](@/guide/suspension-engineering.md), [tires](@/guide/tire-engineering-rolling-resistance-grip-standards.md), and [IP protection](@/guide/ingress-protection-engineering-iec-60529.md): anatomy (inner ring, outer ring, rolling elements, cage, seal); types (deep-groove ball — 6000/6200/6300/6800/6900 series; angular contact ball with 15°/25°/40° contact angles; cylindrical/taper/spherical roller; needle; thrust); designation system (first digit — series, last two — bore code: 00 = ⌀10, 01 = ⌀12, 02 = ⌀15, 03 = ⌀17, ≥04 → ×5 mm); ISO 281:2007 dynamic load rating C and L₁₀ = (C/P)^p × 10⁶ revolutions with p = 3 for ball and p = 10/3 for roller (Lundberg-Palmgren 1947 + Ioannides-Harris 2000 modification); ISO 76:2006 static load rating C₀ and true brinelling from static load > C₀/4; ABEC 1/3/5/7/9 ≡ ISO 492 P0/P6/P5/P4/P2 ≡ DIN 620 ≡ JIS B1514 (for ⌀≤18 mm bore: 10/7/4/2.5/1.5 μm runout tolerance), why ABEC 7+ is almost always redundant for low-RPM scooter applications; ISO 286 fits — shaft k5/k6/n6 (interference under rotating inner ring), housing H7/J7/K7 (clearance under rotating outer ring); seal classes — Z/ZZ metal shield contact-free vs RS/2RS rubber contact (NBR/HNBR/FKM compatibility); lubrication — NLGI 0-6 worked penetration ranges 355-385 / 310-340 / 265-295 / 220-250 (ASTM D217 cone-penetration test, 60 strokes, 25 °C, tenths of mm); thickener tribology — Li-12-hydroxystearate vs Li-complex vs polyurea vs Ca-sulfonate-complex temp/water-resistance matrix; base oil ISO VG 32-460 mineral/PAO/ester; EP additives — ZDDP zinc dialkyldithiophosphate phosphate-glass tribofilm formation (Watson et al. 1940s introduction, mixed/boundary regime mechanism), MoS₂ solid lubricant, sulfur-phosphorus packages; Stribeck curve λ-ratio λ = h₀/Rq (oil-film thickness/composite roughness) thresholds λ<1 boundary / 1<λ<3 mixed / λ>3 full-film EHL Hamrock-Dowson formula; failure modes — fatigue spalling (Hertzian contact subsurface origin), true brinelling (static overload P > C₀/4), false brinelling/fretting corrosion (vibration without rotation, hematite Fe₂O₃ third-body abrasion, especially during storage/transit), fluting (electrical erosion, common in VFD motors), fretting corrosion at housing/shaft interface, wear/spalling/seizure from contamination; e-scooter specific — Xiaomi M365 front wheel 6001-2RS (12×28×8 mm) + rear hub motor 6001 + 6201, Ninebot Max G30 6002-2RS (15×32×9 mm), headset semi-integrated angular contact 36°/45° (FSA Orbit / Cane Creek), hub-motor double-row 6900-series, freewheel one-way clutch for geared hub motors; 8 typical failure-diagnostic symptoms and their root causes.

15 min read