CAT 521-9951 BEARING-SEM

CAT 521-9951 is a Caterpillar genuine tapered roller bearing (single row) suitable for SEM loaders, designed for drive axles or transmission systems to withstand heavy radial and bidirectional axial loads. The following are the original manufacturer’s precise specifications and application information; replacement parts are not included.

Core Technical Parameters

Item Details
Part Model: CAT 521-9951 (SEM Dedicated Tapered Roller Bearing, Single Row, No Seal)

Material: Inner/Outer Ring and Rollers: 52100 Chromium Bearing Steel, Hardened to HRC 60-64; Cage: Stamped Steel Plate; Surface Phosphating Treatment, Rust Prevention Rating IP65, Suitable for Harsh Working Conditions in Engineering Machinery

Key Dimensions: Inner Diameter 70 mm (2.756 in), Outer Diameter 125 mm (4.921 in), Width 31 mm (1.220 in), Taper Angle 10°30′, Number of Rollers: 18, Roller Diameter 12 mm, Suitable for Standard Drive Axle Shaft Diameter and Hub Bore Diameter

Single Weight: Approx. 1.38 kg (3.042 lbs)

Tolerance Standards: Inner Diameter Tolerance P6 (+0.015/0 mm), Outer Diameter Tolerance P6 (0/-0.025 mm) Width tolerance ±0.12 mm, radial runout tolerance ≤ 0.015 mm, end face runout tolerance ≤ 0.020 mm

Core Characteristics: Dynamic load capacity 102 kN, static load capacity 135 kN, limiting speed 3200 rpm (grease lubrication), operating temperature -40℃ to +120℃, capable of withstanding radial and bidirectional axial loads, suitable for drive axle differentials or wheel hub rotation conditions, excellent impact and fatigue resistance.

Structure and Core Functions: Heavy-duty bearing: The tapered roller structure can simultaneously withstand radial and bidirectional axial loads, adapting to the complex stress conditions of loader drive axles and ensuring stable operation of the transmission system.

Precise positioning: Precise dimensional tolerances and tapered angle design ensure coaxiality of bearings, shafts, and wheel hubs, reducing off-center loading, lowering operating noise (≤ 75 dB) and vibration, and improving mechanical operational stability.

Heat Dissipation Adaptation: The cage is made of stamped steel plate, offering excellent heat dissipation performance, meeting the cooling requirements of high-speed drive axle rotation and preventing grease failure and bearing damage due to high temperatures.

Compatible Models and Application Scenarios

Compatible Equipment: SEM 652D, 655D, 656D loaders; drive axle differentials or wheel hubs of some CAT mini loaders.

Core Purpose: Installed between the drive axle shaft and wheel hub, it bears the radial and axial loads transmitted by the drive axle, suitable for heavy-duty operations such as loading and transporting on loaders, ensuring the durability and reliability of the transmission system.