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LM503349 – Timken Tapered Roller Bearing Cone
Part Number: LM503349
Manufacturer: The Timken Company
Series: LM503300 (Light Medium Series)
Common Synonyms: Wheel Bearing Cone, Inner Race & Roller Assembly
Overview Section
The LM503349 is a high-precision tapered roller bearing cone (inner ring assembly) manufactured by Timken, the global leader in friction management. This component consists of the inner race, a set of precision-ground tapered rollers, and a high-strength cage that maintains roller spacing.
Designed to handle simultaneous radial and axial (thrust) loads, the LM503349 is typically paired with the LM503310 cup (outer race) to form a complete bearing set. In aerospace applications, this bearing is frequently found in landing gear wheel assemblies for light-to-medium aircraft, where it provides the low-friction rotation required for smooth taxiing, takeoffs, and high-impact landings.
Enhanced Technical Data
| Technical Metric | Specification Data |
| Bore Diameter (d) | 1.8125 in (46.038 mm) |
| Cone Width (B) | 0.8268 in (21.001 mm) |
| Dynamic Load Rating (C90) | 4,190 lbf (18,600 N) |
| Static Load Rating (C0) | 16,600 lbf (73,800 N) |
| Maximum Operating Speed | 6,300 RPM (Grease) / 8,500 RPM (Oil) |
| Material Base | Case-Hardened High-Alloy Steel |
| Weight | 0.37 lbs (0.17 kg) |
| Series | LM503300 |
Advanced Engineering & Structural Application
The LM503349 is engineered using Timken’s Case-Hardened Steel technology. This process creates a hard, wear-resistant outer "case" while maintaining a tough, ductile inner "core." This is critical for aircraft landing gear, as it allows the bearing to absorb the sudden shock loads of touchdown without fracturing.
Engineering Insight: Controlled Contact Geometry
Timken utilizes a specialized "crowned" profile on the rollers and raceways. This ensures that under heavy loads, the stress is distributed evenly across the roller length rather than concentrating at the edges (a phenomenon known as "end loading"). This geometry significantly extends the fatigue life of the bearing in high-stress aviation environments.
Aircraft Compatibility
The LM503349 is a standard component in several general aviation and regional aircraft wheel assemblies:
Cessna 300 & 400 Series: Frequently utilized in main wheel assemblies for twin-engine models.
Beechcraft King Air / Duke: Found in specialized nose or main wheel hubs.
Piper PA-31 Navajo: Standard equipment for high-load wheel configurations.
Cleveland / Parker Hannifin Wheels: The primary bearing cone for several 6-inch and 8-inch wheel assemblies.
The Timken LM503349 is the benchmark for reliability in aviation wheel bearing applications. When safety is determined by the transition from flight to ground, the precision and metallurgical superiorities of a Timken bearing are indispensable. This cone assembly offers the thermal stability required to withstand the heat generated during heavy braking and the structural toughness to endure thousands of landing cycles. By choosing the LM503349, maintenance technicians ensure their airframe is equipped with a component that meets or exceeds original equipment specifications for load capacity and service life.
Installation & Maintenance Addendum
Proper Greasing: Use only aviation-approved wheel bearing grease (e.g., Aeroshell Grease 22 or Mobil Grease 28). Ensure the grease is "packed" into the cavity between the rollers and the cage until it extrudes from the opposite side.
Inspection: During every 100-hour or Annual inspection, clean the LM503349 thoroughly and inspect for pitting, spalling, or "brinelling" (indentations in the race). If any surface irregularities are found, the bearing must be replaced.
Preload Setting: When reinstalling the wheel, follow the Aircraft Maintenance Manual (AMM) torque procedures exactly. Over-tightening the axle nut creates excessive preload, which leads to rapid overheating and bearing failure.
