CAT 523-3713 80mm Inner Diameter Bushing

CAT 523-3713 is a wear-resistant steel bushing from Caterpillar’s SEM series, suitable for the hinge joints of booms, sticks, or connecting rods in excavators, loaders, and other equipment. Its core function is to reduce friction and wear between the pin and the pin hole, withstand heavy loads and impact loads, and improve the connection accuracy and service life of the hinge joint. It is a key wear-resistant component of the working device, Cat® Parts. The following is structured technical and application information:

Core Technical Parameters
Item Details
Basic Attributes
Model 523-3713 (SEM Bushing), type is straight cylindrical steel bushing, material is medium carbon alloy steel (4140/4340), quenched and tempered (hardness HRC 50-55), surface coated with molybdenum disulfide solid lubricant coating (thickness 0.02-0.05 mm), single weight approximately 2.5 kg, operating temperature -40℃ to +120℃, load type is radial load + impact load, lubrication method is grease lubrication (recommended Cat 2 lithium-based grease), design life ≥8000 hours (normal operating conditions)

Key Dimensions
Inner diameter 88.9 mm (3.5 inches, tolerance 0/+0.02 mm), outer diameter 101.6 mm (4 inches, tolerance 0/-0.015 mm), total length 127 mm (5 inches, tolerance 0/-0.1 mm) 6.35 mm wall thickness, inner hole surface roughness Ra≤0.8 μm, end face perpendicularity≤0.02 mm, inner and outer circle coaxiality≤0.015 mm
Compatible Models and Accessories: Compatible with Cat 320D2 and 323D2 excavators (boom and boom hinge pin), 950M loader (boom cylinder connecting rod pin), E320D excavator (bucket pin), with matching 523-3714 seal ring, 3B-8489 grease fitting, 1J-6472 retaining ring, 8T-4125 pin
Performance Parameters: Radial rated load 350 kN, allowable linear velocity ≤0.8 m/s, impact load ≥200 kN, coefficient of friction ≤0.1 (grease lubrication), wear resistance ≤0.05 mm/1000 hours
Structural and Performance Advantages: 4140/4340 Made of medium carbon alloy steel, after quenching and tempering, it possesses both high hardness and wear resistance in the outer layer and core toughness, capable of withstanding frequent impacts and heavy loads, reducing the risk of fracture.

The inner bore features a molybdenum disulfide coating, reducing dry friction during startup and providing continuous lubrication during long-term use. It is suitable for reciprocating pin oscillations and low-speed, heavy-load conditions, reducing wear.

The straight-cylinder design facilitates easy installation and provides a stable interference fit with the pin and pin hole, ensuring coaxiality and connection accuracy at the hinged joint and reducing pin wear.

Installation and Maintenance Points: Before installation, clean the bushing and pin hole, checking for cracks, rust, and deformation. Measure the inner diameter of the pin hole (101.6 mm) and the outer diameter of the bushing, ensuring an interference fit of 0.01-0.025 mm.

The bushing is pressed into the pin hole using a cold pressing method (using a hydraulic press and special tooling). Striking the bushing end face is strictly prohibited. After installation, check that the bushing end face is flush with the pin hole plane, and that the pin rotates freely without jamming after insertion.

Maintenance and Replacement: Replenish grease every 1000 hours and check for bushing wear. If the inner hole wear is >0.2 mm, or if cracks or coating peeling appear, replace immediately. It is recommended to replace the bushing at the same time as the sealing ring and pin to ensure sealing and fit accuracy.