CAT 3Q-0570 TRUNNION

The CAT 3Q-0570 is a genuine Caterpillar trunnion, designed for use on the working device hinges of mini excavators and loaders. It connects the boom, stick, or bucket, bearing radial loads and oscillations. The following are key specifications (no alternative parts available):

Key Technical Parameters
Item Details
Part Model: CAT 3Q-0570 (3Q0570) Trunnion (for mini excavator working device hinges, connecting boom/stick/bucket, bearing radial loads + oscillation)

Core Material: 42CrMo alloy steel (heat treated, hardness HRC 32–36, tensile strength 1080 MPa, yield strength 930 MPa), hard chrome plated (thickness 0.05–0.08 mm, hardness HV 800–1000)

Key Dimensions: Diameter 40 mm, Length 120 mm, Mounting journal diameter 40 mm, Shoulder diameter 50 mm, Shoulder thickness 15 mm, Thread Specification M16×1.5 (length 20 mm), coaxiality tolerance ≤0.01 mm
Single weight: Approx. 0.98 kg (2.16 lb)
Compatible models: CAT 305.5E2/306E2 mini excavators (boom and boom hinge), 906M/907M loaders (bucket and rocker arm hinge), compatible bushing model 3Q-0571, matching nut 3Q-0572 (grade 10.9)
Working compatibility: Rated radial load 65 kN, ultimate bending moment 8.5 kN・m, operating temperature -40℃ to +120℃, suitable for low-speed oscillating conditions (≤50 rpm)
Core functions and structural features: High strength and fatigue resistance: 42CrMo quenched and tempered, matching the alternating load of mini excavator working devices, strong impact resistance, and service life of over 4000 hours.

Wear-resistant and corrosion-resistant: Hard chrome plating reduces the coefficient of friction, minimizes wear with the bushing, and enhances corrosion resistance, making it suitable for dusty and humid environments.

Precise positioning: The shoulder and mounting hole clearance is 0.01–0.02 mm, and the thread and nut fit precisely, ensuring no looseness and flexible movement after assembly.

Easy installation: Positioning grooves on both ends of the shaft journal facilitate quick alignment during installation. The threaded end is compatible with 10.9 grade nuts, eliminating the need for additional welding after installation.

Installation and maintenance points:
Installation specifications: Clean the mounting hole and trunnion surface, ensuring it is free of rust, oil, and burrs. The mounting hole tolerance is +0.01–+0.02 mm. Use cold pressing, with a pressing force of 6–8 kN. Do not strike the shaft end.

After installation, check the coaxiality to ensure it is ≤0.01 mm. The clearance with the 3Q-0571 bushing is 0.02–0.03 mm.

Tighten with the 3Q-0572 nut to a torque of 85–90 N·m, and lock after tightening (with a cotter pin or anti-loosening rubber).

Maintenance Recommendations: Inspect the trunnion every 500 working hours for scratches, wear, or rust. Replace when the hard chrome plating wears more than 0.03 mm.

Lubricate with Caterpillar-specific lithium-based grease (NLGI 2), applying 15–20 g each time, ensuring adequate lubrication between the bushing and trunnion.

Replace the 3Q-0571 bushing and 3Q-0572 nut simultaneously to ensure compatibility and connection strength.