CAT 177-6738 Radial Needle Roller and Cage Assembly

CAT 177-6738 is a Caterpillar original single-row radial needle roller and cage assembly, compatible with the swing mechanism or gearbox gear shaft of Cat 320D/323D excavators and 950H loaders, for radial heavy-duty support in space-constrained conditions. The following is pure original data and does not include replacement parts information.

Core Technical Parameters (Raw Data)

Item Details
Basic Attributes Model 177-6738, Type Single-row radial needle rollers + stamped steel cage (no inner/outer ring, with shaft and housing as raceways), Material Needle rollers: GCr15 bearing steel, Cage: SPCC + galvanized, Single weight 0.42 kg, Operating temperature -40℃ to +120℃, Rated dynamic load 85 kN, Rated static load 78 kN, Limiting speed 4200 rpm, Coefficient of friction ≤0.002 (oil lubrication), Corrosion resistance IP65, Service life ≥6000 hours, Suitable for pure radial load ≤85 kN, No axial load capacity

Key Dimensions Needle roller center circle diameter (Fw) 65 mm, Needle roller outer diameter (Ew) 75 mm, Assembly width 28 mm, Needle roller diameter 5 mm, Number of needle rollers 24, Cage inner diameter 65 mm (tolerance H7) +0.030/0 mm), cage outer diameter 75 mm (tolerance g6 0/-0.030 mm), needle roller length 26 mm, chamfer 1×45°, cylindricity ≤0.012 mm, radial runout ≤0.02 mm, installation interference 0.015-0.035 mm (cold state), total needle roller clearance 0.018-0.040 mm

Performance Parameters: Needle roller hardness HRC 62-64, hardened layer depth 0.8-1.2 mm, cage tensile strength ≥345 MPa, elastic modulus 207 GPa, linear expansion coefficient 12×10⁻⁶/℃, forced oil lubrication, oil film thickness ≥0.015 mm, fatigue life ≥8×10⁵ cycles, wear rate ≤0.0015 mm/1000 hours

Structural and Performance Advantages: Ringless design: eliminates the need for inner / The outer ring uses the mounting shaft and housing bore as the raceway, significantly saving radial space and making it suitable for compact installation scenarios such as gear shafts and pins.

Stamped cage: SPCC galvanized material, separating the needle rollers to prevent friction, improving speed stability, and the galvanized layer enhances corrosion resistance, suitable for harsh working conditions in engineering machinery.

Dense needle roller layout: 24 small-diameter needle rollers achieve uniform line contact and load bearing, providing high radial stiffness in a small cross-section, suitable for impact loads in rotating mechanisms.

Installation and maintenance points (raw data)

Installation: Clean the shaft and housing bore (Ra≤0.2 μm, hardness HRC 58-64), cold press installation (pressure≤45 kN), ensure shaft and housing coaxiality ≤0.02 mm, and maintain a needle roller end face and flange clearance of 0.1-0.2 mm. Do not heat installation (>80℃ will damage the cage). Maintenance: Check lubrication pressure ≥180 kPa every 800 hours, check oil cleanliness (NAS class 10 or below) every 1200 hours, and measure radial clearance every 1500 hours (replace if >0.1 mm). Avoid overload (≤110% of rated load). Use Cat-specific anti-wear hydraulic oil/gear oil.

Troubleshooting: Abnormal noise is often caused by worn needle rollers or deformed cages, requiring component replacement; excessive temperature is often caused by insufficient lubrication, check for oil passage blockage; abnormal vibration is often caused by coaxiality misalignment, recalibrate and reinstall.