CAT 4J-1641 Dozer Trunnion

CAT 4J-1641 is a welded blade trunnion for Caterpillar bulldozers, used to connect the boom and the blade, enabling the blade’s pitch and tilt movements. It is compatible with Cat D6/D7 series bulldozers (such as D6D/D6G/D7G). The following is professional structured information.

Core Technical Parameters (Professional Version)

Project Details
Basic Attributes
Model: 4J-1641, Double-sided welded steel trunnion, single weight 3.8 kg, 2 pieces per unit (1 for each push arm), matching blade pin diameter 76 mm, used at the hinge between the push arm and the blade, transmitting the push load and allowing swing around the axis.

Key Dimensions
Spherical outer diameter φ87.4 mm (tolerance ±0.1 mm), mounting shaft diameter φ89.0 mm (tolerance h7: 0–-0.035 mm), total length 152.0 mm (tolerance ±0.2 mm), weld end face thickness 12 mm, weld bevel angle 30°, center hole φ12 mm (for positioning welding), surface roughness Ra≤1.6 μm

Material and Process
Material is low alloy structural steel (42CrMo), quenching and tempering treatment (HB 280–320), surface shot peening strengthening (compressive stress ≥800). Preheat the welding area to 150–200℃ using CO₂ gas shielded welding, followed by stress-relief annealing (600–650℃ for 2 hours).

Performance Parameters: Rated radial load 180 kN, fatigue limit load 120 kN, operating temperature -40℃ to +120℃, withstands swing angle ±15°, suitable pin clearance 0.15–0.25 mm, weld tensile strength ≥700 MPa, bending stiffness ≥2.5×10^5 N・m/rad

Compatible Models: Bulldozers D6D, D6G, D7G, D7H, Loaders 950G/962G, suitable for swing-loaded parts such as the hinge point connecting the push arm and blade, and the hinge point of the ripper bracket.

Installation and Maintenance Points: Clean the trunnion welding end face and push arm mounting hole before installation, and check the trunnion for cracks/deformation. For corrosion prevention, before welding, position the trunnion and push arm (coaxiality ≤ 0.1 mm), preheat the welding area to 150–200℃, and use symmetrical layer welding (each layer thickness 3–5 mm). After welding, allow it to cool naturally to room temperature; water cooling is prohibited.

Clearance control: The radial clearance between the trunnion and the pin should be 0.15–0.25 mm. Check with a feeler gauge after installation. Excessive clearance can lead to impact vibration, while insufficient clearance can cause jamming and wear. This can be achieved by adjusting the pin diameter or trunnion diameter tolerance.

Lubrication requirements: Use NLGI Grade 2 extreme pressure lithium-based grease. Replenish grease every 250 hours (approximately 0.5 kg each time) to ensure adequate lubrication of the pin and trunnion contact surfaces and avoid dry friction that leads to wear.

Troubleshooting: If cracks appear in the trunnion weld, wear on the pin, or abnormal oscillation noise, first check the weld strength (magnetic particle inspection), gap (replace if it exceeds 0.5 mm) or lubrication failure. If necessary, replace the trunnion and correct the coaxiality of the push arm mounting hole to ≤0.1 mm.