1. Applicable Standard & Certification Scope

This product is the extreme heavy-duty certified grade Notation #3 of UIC LL low-friction brake blocks, manufactured in accordance with UIC Leaflet 541-4 (6th edition, 2020), technical resolution B126 RP N11 and Usage Guidelines for LL Composite Brake Blocks (10th Edition). It is the load capacity expanded upgraded version of Notation #1 and #2 basic grades, fully certified under EU TSI railway interoperability specifications and authorized for cross-border heavy-haul operation across all European railway networks. Exclusive restricted application limits of Notation #3 certification:

· Brake mounting structure: Fully compatible with both 2×Bg single-side single block and 2×Bgu double-side dual block brake systems, covering light, medium and ultra-heavy freight bogies;

· Maximum allowable axle load: 27.5 tons (higher than 22.5t limit of #1 and 25t limit of #2, top-level load capacity in LL series);

· Maximum vehicle operating speed: ≤120km/h;

· Matching wheel diameters: Standard steel tread wheels 730mm / 760mm / 840mm;

· Applicable lines: UIC railway network with maximum 40‰ extreme gradient heavy haul freight lines, dedicated for mine, steel plant and ore heavy-duty wagons, adapting to long-distance cross-border continuous downhill braking conditions. Unified core product logic: Replicate friction output curve of P10 cast iron brake blocks for drop-in retrofit without brake system modification, different from K high-friction blocks which require full brake rigging replacement.

2. Structural & Heavy-Duty Material Composition

(1) Heavy-Duty Friction Contact Surface

Ultra-high temperature resistant heavy-duty asbestos-free modified phenolic resin composite matrix, reinforced with high-filling aramid & basalt hybrid fibers, mixed with high-purity flake graphite long-acting solid lubricant and multi-component sulfide friction modifiers. Free of asbestos, lead, cadmium and other hazardous heavy metals, no carbonization, toxic fume precipitation or massive peeling under long-term continuous high-temperature braking. Dynamic friction coefficient stably ranges 0.13~0.17, friction fluctuation strictly controlled within ±15% under dry, wet, extreme temperature and full-load drag conditions. Curved contact surface precisely fits wheel tread radian to achieve full uniform contact under double-side heavy-duty braking, drastically reducing wheel tread spalling, local thermal scuffing and thermal crack risks under ultra-high braking pressure. High-density internal buffer micropores absorb massive braking impact load and eliminate high-frequency squeal noise during low-speed station approaching, rainy operation and long downhill continuous braking. All edges are thickened and passivated to prevent chipping, cracking and corner peeling during heavy transport and long-term extreme service.

(2) Reinforced Thickened Steel Back Base

Stamped integrally from 6~7mm extra thick high-strength Q235 cold-rolled low-carbon steel plate, thicker than Notation #1 and #2 grades for drastically improved anti-bending, anti-impact and anti-fatigue bearing capacity. Deepened and widened multiple trapezoidal anchor grooves are pressed on the inner side; friction compound deeply embeds into grooves during hot molding to reach bonding strength far exceeding UIC standard limits, preventing delamination, chipping and interface peeling failure under long-term cold & hot cyclic and full-load drag braking. Universal dual-spec integrated buckle at the bottom fits both 2×Bg and 2×Bgu standard brake shoe holders for unified maintenance replacement. The steel back is equipped with thickened wear warning boss: continuous sharp abnormal metal friction noise occurs when friction layer wears down to safety limit of 12mm to remind mandatory full block replacement, eliminating safety hazard of steel back grinding wheel tread.

3. Mandatory UIC Special Heavy-Duty Performance Requirements

1. Friction Stability: Friction coefficient fluctuation ≤±15% under normal temperature, rain immersion, 40‰ long downhill full-load drag and -40℃ extreme cold environment, without obvious cold or thermal fading; mandatory passing UIC 60-minute full-load drag extreme durability special test;

2. Extreme Thermal Resistance: Max continuous operating temperature 350℃ (320℃ for #1, 330℃ for #2), instantaneous peak temperature 450℃ under wheel lock emergency braking, no bubbling, carbonization, delamination or cracking failure;

3. Long-Term Wheel Protection: Wheel tread wear reduced by over 50% compared with traditional P10 cast iron blocks; wheel-rail equivalent conicity precisely controlled under ultra-heavy load. First wheel profile inspection at 120,000 km for newly reprofiled wheels, routine inspection every 60,000 km during normal operation to avoid vehicle hunting and running instability risks;

4. Full Track Circuit Compatibility: Low-conductivity non-metallic composite formula generates no hard metal debris to interfere with railway signal transmission, passing full strict UIC track circuit compatibility inspection;

5. Noise Reduction & Eco-Friendliness: Braking noise decreased by 10~18dB(A) versus cast iron blocks, fully complying with European heavy-duty freight wagon noise control regulations; biodegradable braking dust with no pollution in underground tunnels and ultra-long downhill heavy haul lines;

6. Mechanical Safety Limit: Impact strength ≥2.0 kJ/m², normal temperature compressive strength ≥30 MPa, no large-area chipping or fragmentation under emergency wheel lock, wheel-rail slipping and heavy impact conditions.

4. Application Scope, Maintenance & Storage Rules

1. Applicable Rolling Stock: European standard ore open wagons, metallurgical heavy-haul wagons, cross-border container heavy vehicles and mine special freight wagons, covering all 2×Bg single-side and 2×Bgu double-side heavy-duty brake bogies;

2. Mandatory Replacement Standard: Full brake block replacement required when residual friction thickness ≤12mm; grinding, splicing and secondary reuse are strictly prohibited;

3. Running-in Operation Rule: Stable low-speed operation within the first 500km after installation, avoid frequent emergency braking to realize uniform fitting of friction surface; full-load long downhill continuous braking forbidden during running-in period;

4. Storage Condition: Store in dry & ventilated warehouse, avoid sunlight exposure and rain soaking, stacking height ≤10 layers, shelf life 18 months;

5. Mandatory Inspection Cycle: First wheel equivalent conicity inspection at 120,000 km for newly reprofiled wheels, simultaneously check friction layer cracking, partial uneven wear and chipping defects every 60,000 km during routine operation.

5. Core Differences Between UIC #3 Grade & UIC #1 / #2 Grade LL Brake Blocks

1. Applicable Brake Structure: #1 only for 2×Bg single-side brake; #2 compatible with 2×Bg & 2×Bgu; #3 fully dual-structure compatible and dedicated for ultra-heavy bogies;

2. Max Allowable Axle Load: #1 22.5t, #2 25t, #3 27.5t with top load capacity in LL series;

3. Structural Strength Configuration: #3 steel back thickened to 6~7mm, friction body adopts basalt & aramid hybrid heavy-duty formula with comprehensively upgraded high temperature resistance, impact resistance and fatigue resistance;

4. Certification Test Scope: #1 only completes basic dynamometer tests for 2×Bg configuration; #2 adds special double-side heavy-load tests for 2×Bgu; #3 additionally passes special certification including 40‰ extreme gradient, 60-minute full-load drag and long-distance continuous downhill durability test;

5. Market Application Positioning: #1 basic retrofit model for light ordinary freight wagons; #2 universal upgraded model for medium-heavy haul; #3 high-end dedicated grade for mine, metallurgy and cross-border ultra-heavy special freight wagons.

Low-friction synthetic brake block–UIC Standard3