CAT 7Y-0251 Radial Needle Roller and Cage Assembly

CAT 7Y-0251 is a Caterpillar radial needle roller and cage assembly, which is compatible with the final drive, hydraulic pump drive shaft and other parts of Cat 320D2, 336D2 and other excavators. It uses the journal and housing bore as the raceway and is suitable for working conditions with limited radial space and the need to withstand medium and high loads, helping the transmission system to operate efficiently. The following is structured technical and application information:

Core Technical Parameters

Item Details
Basic Attributes
Model 7Y-0251, Type: Radial Needle Roller Cage Assembly without Inner Ring, Material: Needle rollers are high-carbon chromium bearing steel (chromium content 1.5%), cage is stamped steel plate, needle rollers are hardened (hardness HRC60-64), single weight approximately 0.32 kg, applicable temperature -40℃ to +120℃, lubrication method: grease lubrication, limiting speed: grease lubrication 2800 rpm

Key Dimensions
Needle roller diameter 4.0 mm, number of needle rollers 22, assembly inner diameter 35.0 mm (compatible with journal tolerance g6), assembly outer diameter 42.0 mm (compatible with housing bore tolerance G6), assembly width 25.0 mm (tolerance ±0.10 mm), needle roller length 24.5 mm, cage thickness 1.2 mm, needle roller surface roughness Ra≤0.04 μm

Compatible Models and Applications
Compatible Cat 320D2, 323D2, and 336D2 crawler excavators use this bearing for final drive planetary gear shafts, hydraulic pump drive shafts, and swing motor output shafts. Supporting parts include 567-7154 seals and 7T-4214 retainers. It withstands pure radial loads and is suitable for space-constrained transmission components, transmitting torque and reducing friction.

Performance Parameters: Rated dynamic load 58 kN, rated static load 105 kN, contact fatigue life ≥12000 hours, coefficient of friction ≤0.0015, permissible skew angle ≤1°, suitable for impact loads ≤1.1 times the rated dynamic load.

Structural and Performance Advantages:
Lightweight and Compact Design: The inner ring-less structure with slender needle rollers results in a small radial cross-section, suitable for space-constrained applications. It offers higher load-bearing capacity than ball bearings of the same size within the same installation space, meeting heavy-duty requirements.

High-Precision Cage: The stamped steel plate cage precisely positions the needle rollers, preventing them from contacting and rubbing against each other, reducing operating noise and wear, and improving component stability and service life.

High-wear-resistant needle rollers: The needle rollers undergo quenching treatment, resulting in excellent surface hardness and wear resistance. The modified needle rollers reduce end stress, making them suitable for medium-to-high-speed operation and reducing the risk of early failure.

Convenient installation and maintenance: The modular component design facilitates installation and disassembly without complex tools. They directly serve as raceways for journals and housing bores, reducing the number of parts and lowering maintenance costs.

Installation and maintenance points: Before installation, clean the components, journals, and housing bores. The journal surface hardness should reach HRC58-64, the hardened layer depth ≥0.8 mm, and the surface roughness Ra≤0.32 μm. Use a special tool to install the component into the housing bore, ensuring coaxiality ≤0.05 mm. Do not strike the needle rollers to avoid deformation.

After installation, add Cat Moly-Dee grease and run for 20 minutes to confirm there is no jamming or abnormal noise. The bearing temperature should be ≤75℃, and the radial clearance should be controlled between 0.02-0.05 mm. Maintenance: Check the condition of the components every 800 hours. Replace immediately if pitting of the needle rollers, cage deformation, or radial clearance >0.1 mm. Use original parts first to ensure compatibility and performance, and avoid damage to transmission components due to incompatible parts.