CAT 489-0728 BEARING AS

CAT 489-0728 is a double-row tapered roller bearing assembly used by Caterpillar for excavator slewing gearboxes. It is compatible with the slewing motor output of Cat 320D/E and 323D/E models, and is used to withstand radial and bidirectional axial loads. The following is raw data and does not include replacement parts information.

Core Technical Parameters (Raw Data)

Item Details
Basic Attributes
Model 489-0728, Type: Double row tapered roller bearing assembly (including inner ring, outer ring, rollers, cage), Material: Inner/outer ring: Chromium bearing steel (GCr15), Rollers: Carburized bearing steel (G20CrNiMoA), Cage: Phenolic resin, Single weight: 18.6 kg (41.006 lbs), Operating temperature: -40℃ to +120℃, Rated dynamic load: ≥850 kN, Rated static load: ≥1200 kN, Lubrication method: Oil lubrication (compatible with Cat TO-4 transmission oil), Rated life: ≥12000 hours (standard operating conditions)

Key Dimensions (Metric/Imperial)
Inner diameter: 165.10 mm (6.500 in), Outer diameter: 247.65 mm (9.750 in), Width: 76.20 mm (3.000 in), Number of rollers: 2 x 30 units, roller diameter 19.05 mm (0.750 in), roller length 38.10 mm (1.500 in), inner ring large end face diameter 203.20 mm (8.000 in), outer ring flange diameter 247.65 mm (9.750 in), mounting stop diameter 228.60 mm (9.000 in), stop depth 5.0 mm (0.197 in).

Matching and performance parameters: Fitting shaft diameter 165.10 mm (k6 tolerance), fitting housing bore diameter 247.65 mm (H7 tolerance), radial clearance 0.15-0.25 mm, axial clearance 0.08-0.15 mm, contact angle 30°, roller and raceway surface roughness Ra≤0.4 μm, rotational accuracy P5. **Structure and Adaptability**
**Structural Design:** The overall structure features a double-row symmetrical tapered roller design. The inner ring has a flange, and the outer ring has a flange. The rollers are separated by a cage, allowing it to withstand large radial loads and bidirectional axial loads simultaneously. It is suitable for the connection between the output shaft and the housing of a slewing gearbox, ensuring smooth operation of the slewing mechanism.

**Materials and Processes:** The inner and outer rings are hardened and tempered (HRC 60-64). The rollers are carburized and hardened (surface HRC 62-66, core HRC 30-40). The cage is made of phenolic resin, offering excellent strength and wear resistance, suitable for long-term use in harsh working conditions of construction machinery.

**Suitable Applications:** Primarily used in slewing gearboxes for excavators such as Cat 320D, 320E, 323D, and 323E. It plays a crucial load-bearing role in the connection between the slewing motor and the slewing bearing, ensuring stable transmission of the slewing mechanism under heavy loads and impact conditions, and preventing shaft slippage and vibration.

Installation and Maintenance Points (Original Data)

Installation: Clean the bearing assembly, journal, and housing bore surfaces, ensuring they are free of oil, metal shavings, and rust. The inner ring and journal should be heat-fitted (heating temperature 80-100℃), and the outer ring and housing bore should be cold-fitted (cooling temperature -20 to -30℃). After installation, check the bearing clearance; radial clearance should be controlled at 0.15-0.25 mm, and axial clearance at 0.08-0.15 mm.

Use specialized installation tools, avoiding impact to the bearing end face. After installation, tighten the bearing end cap bolts to a torque of 80-100 N·m (Cat 2S-3261 anti-loosening agent is recommended).

Maintenance: Check the bearing’s operating condition every 2000 hours. Monitor the temperature to ≤80℃ and vibration to ≤2.5 mm/s. If abnormal temperature rise, unusual noise, or increased vibration occurs, stop the machine immediately for inspection.

Change the lubricating oil in the rotary gearbox regularly, every 5,000 hours, and clean the oil filter to ensure unobstructed oil flow.