CAT 1U-1204 Blade Trunnion ball

The CAT 1U-1204 is a Caterpillar bulldozer blade trunnion used for the articulation connection between the bulldozer boom and the blade. It is compatible with Cat D6D/D6E/D6H models, and its core function is to support the blade and transmit bulldozing loads. It allows the blade to swing within a ±15° range and withstand heavy loads and impacts. It is a key load-bearing component of the bulldozer’s working device. The following is structured technical and application information:

Core Technical Parameters

Item Details
Basic Attributes
Model 1U-1204, Type: Integral Forged Trunnion, Material: 42CrMo Alloy Steel (Quenched and Tempered, Hardness HRC35-40), Single Weight: Approx. 6.8 kg, Applicable Temperature: -40℃ to +120℃, Maximum Radial Load: 120 kN, Fatigue Life: ≥5×10⁵ cycles, Surface Treatment: Nitriding + Shot Peening (Nitriding Layer Depth 0.3-0.5 mm, Surface Hardness HV850-1000)

Key Dimensions
Overall Length: 245 mm (Tolerance ±0.20 mm), Ball Head Diameter: 127 mm (Tolerance 0 to -0.03 mm), Journal Diameter: 80 mm (Tolerance 0 to -0.02 mm), Journal Length: 85 mm, Mounting Hole Diameter: 28 mm (Tolerance +0.02 to +0.04 mm) Ball head curvature radius 63.5 mm, center distance 180 mm (tolerance ±0.15 mm), chamfer 2×45°
Compatible Models and Applications: Compatible with the push arm and blade hinge of Cat D6D/D6E/D6H bulldozers. Matching parts include bushings (328-5240), pins, dust rings, and grease nipples. Used to transmit radial and axial loads during bulldozing, allowing the blade to swing up and down and tilt. Suitable for hydraulic drive of the working device.

Performance Parameters: Ball head surface roughness Ra≤0.8 μm, journal cylindricity≤0.015 mm, bending stiffness≥2.5×10⁵ N・m/rad, torsional stiffness≥1.8×10⁵ N・m/rad, impact load ≥50 kN, post-assembly swing resistance≤50 N・m

Structural and Performance Advantages: High strength load-bearing capacity: 42CrMo alloy steel forging + Heat-treated and nitrided ball joints enhance bending and torsional resistance, making them suitable for heavy-duty bulldozing operations. Their lifespan is approximately four times longer than ordinary carbon steel trunnions.

Wear and Corrosion Resistant: The nitrided layer provides excellent wear resistance, while shot peening eliminates surface stress and prevents fatigue cracks. Suitable for harsh outdoor environments such as damp and dusty conditions, reducing the risk of corrosion and wear.

Precise Hinge: High dimensional accuracy of the ball joint and journal, combined with specialized bushings, ensures flexible blade movement and stable load transmission, preventing component damage caused by jamming or uneven loading.

Easy Installation: The integrated structure allows direct mounting to the push arm mounting base with standard fasteners, facilitating quick on-site replacement and minimizing downtime.

Installation and Maintenance Points
**Before installation, clean the trunnion, bushing, and mounting base. Inspect the ball end and journal for scratches, deformation, and corrosion.** During assembly, use a specialized lifting tool for positioning and evenly tighten the bolts (torque 850 N·m), ensuring the trunnion fits snugly against the mounting base, with a clearance of 0.05-0.10 mm between the ball end and bushing.

Add grease (Cat Moly Grease Plus recommended) every 200 hours of maintenance, using approximately 0.2 L each time. Check the trunnion for looseness and the bushing for wear. Replace immediately if journal wear > 0.15 mm or pitting appears on the ball end.

Prioritize original parts for replacement to ensure material and dimensional accuracy. Aftermarket parts may lack strength due to improper forging or heat treatment, leading to breakage or deformation.