CAT 518-8191 BEARING–SEM

CAT 518-8191 is a Caterpillar original SEM (hub/final drive) single-row tapered roller bearing, suitable for final drive hubs of loaders/excavators, etc. The following is purely accurate information (without additional description) Cat®…:

Core Parameters and Information

Item Details
Part Model: CAT 518-8191 (5188191) SEM Single-Row Tapered Roller Bearing

Part Type: Single-row tapered roller bearing, used for final drive hubs/planetary carriers, bearing radial + bidirectional axial loads, suitable for heavy loads, impacts, and low-speed conditions, limiting axial movement of the hub

Material: Inner ring/outer ring: Chromium alloy steel (SAE 52100), integrally quenched + tempered, hardness HRC60-64; Rolling elements: Chromium alloy steel, hardness HRC62-66; Cage: Stamped steel plate, surface manganese phosphate treatment, corrosion resistant

Key Dimensions: Inner diameter 120.00mm (4.7244in), outer diameter 180.00mm (7.0866in), width 42.00mm (1.6535in), cone angle 12°30′, number of rollers 18, roller diameter 14.00mm, pitch circle diameter 150.00mm

Structural Features: Separable structure (inner ring separable), with cage, no seal ring, suitable for oil lubrication, rated dynamic load 220kN, rated static load 320kN, operating temperature -30℃ to 120℃

Compatible Structure: Final drive hub bearing assembly, compatible bearing outer ring CAT 465-8981, inner ring CAT 518-8191, installation torque 120-140N・m

Applicable Working Conditions Final drive hub area, speed ≤1500rpm, radial load ≤180kN, axial load ≤80kN, suitable for gear oil lubrication.
Compatible Models and Assemblies:
Loaders: CAT 938M, 950M, 966M (final drive hub bearing assembly)
Excavators: CAT 320D, 323D, 330D (traverse mechanism final drive bearing assembly)
Compatible Assemblies: 950M final drive hub bearing assembly, 320D travel mechanism final drive bearing assembly
Installation and Fitting Points: The mounting surface should be clean and burr-free. The inner ring should have an interference fit with the shaft (interference 0.015-0.025mm), and the outer ring should have a transition fit with the hub housing (clearance 0.005-0.015mm). Do not directly strike the bearing end face; use a special press tool for installation.

Before installation, check that the coaxiality of the inner and outer rings of the bearing is ≤0.02mm, the rollers rotate freely without jamming, and the raceway is free of scratches and rust.

After assembly, the bearing preload is 0.05-0.10mm. Tighten the bolts twice in a crisscross pattern to the specified torque (120-140 N·m). Use matching anti-loosening washers.

For disassembly, use a special puller to remove the inner ring. Do not pry the bearing edges. When replacing, check the wear on the journal and hub seat. If the wear is >0.05mm, it needs to be repaired or replaced.