CAT 5J-4817 TRUNNION

The CAT 5J-4817 is a Caterpillar original heavy-duty trunnion, compatible with the boom and stick connection pins of the Cat 320D2/323D2 excavator, and the hinge joint of the slewing platform. It is used to bear combined loads and allow for component oscillation. The following is pure raw data and does not include replacement parts information.

Core Technical Parameters (Raw Data)

Item Details
Basic Attributes
Model: 5J-4817; Type: Integral solid trunnion (with double support journals, positioning steps, and mounting threaded holes); Material: 42CrMo alloy steel (tempered and quenched, hardness HRC 32-36); Surface treatment: carburizing and quenching (carburized layer depth 0.8-1.2 mm, surface hardness HRC 58-62); Single weight: 12.5 kg; Applicable pin diameter: φ90 mm; Rated radial load: ≥450 kN; Rated axial load: ≥200 kN; Working temperature: -40℃ to +120℃; Connection method: bolt fastening (M20×1.5, 8.8 grade high-strength bolts); Protection level: IP67; Assembly clearance: 0.020-0.040 mm

Key Dimensions
Overall length: 320 mm (tolerance ±0.20 mm); Support journal diameter: φ90 mm (2 locations, tolerance +…) 0.03/+0.02 mm), journal length 80 mm (tolerance ±0.15 mm), positioning step diameter φ110 mm (tolerance 0/-0.02 mm), step thickness 15 mm (tolerance ±0.10 mm), mounting end face to journal center distance 140 mm (tolerance ±0.15 mm), thread hole depth 30 mm (tolerance ±1.0 mm), fillet radius R5 mm, roundness ≤0.01 mm, cylindricity ≤0.015 mm

Performance Parameters: Yield strength ≥900 MPa, tensile strength ≥1100 MPa, impact toughness ≥60 J/cm² (-20℃), fatigue life ≥15000 hours (rated load cycles), surface roughness Ra≤0.8 μm, wear resistance ≥500 HV (surface hardness), corrosion resistance: neutral salt spray test ≥48 hours without rust

Structural and Performance Advantages:

42CrMo alloy steel material: quenched and tempered + Carburizing and quenching treatment ensures both high strength and surface wear resistance, making it suitable for heavy-load and impact conditions at the boom hinge.

Integral solid structure: No weak weld points, high load-bearing capacity, avoiding the risk of fracture due to localized stress concentration.

Double-support journal design: Works with bearings/bushings to ensure oscillation accuracy, reduce radial runout, and suit high-frequency oscillation conditions.

Positioning step + threaded hole: Quick positioning and installation, reliable bolt tightening, prevents axial movement of the trunnion, and improves assembly efficiency.

Installation and maintenance points (raw data)

Installation: Clean the mounting surface and journal (free from oil/rust/impurities). Position the trunnion with the locating pin, tighten the M20×1.5 bolts (preload torque 350-400 N・m). After installation, check that the radial runout of the journal is ≤0.02 mm and the gap between the positioning step and the trunnion is ≤0.05 mm. Do not weld the trunnion body, and do not heat to temperatures exceeding 100℃.

Maintenance: Check bolt tightening torque every 1000 hours (retighten if attenuation ≤10%), check journal wear every 2000 hours (replace if wear >0.10 mm), and check for surface cracks every 3000 hours (magnetic particle testing; replace immediately if cracks are found). Avoid prolonged uneven loading (uneven load ≤20% of rated load). Clean journals regularly and apply rust-preventive oil.

Troubleshooting: Excessive journal wear is often due to insufficient lubrication or foreign object ingress; replace the trunnion and bushing accordingly. Loose bolts are often caused by vibration; retighten and apply thread-locking adhesive. Surface cracks are often due to overload or material fatigue; replace the trunnion immediately and investigate the cause of abnormal load.