CAT 6E-4381 BUSHING

CAT 6E-4381 (6E4381) is a Caterpillar steel-backed bronze/PTFE composite bushing, also commonly known as a “self-lubricating bushing.” It is primarily used in the hinged/sliding parts of engine valve rocker arms, pushrods, throttle linkages, or hydraulic control levers. It is compatible with engines such as the 3306, 3406, and C15, as well as connecting rods, rocker arms, and steering tie rods in loaders/excavators. It provides low-friction sliding, wear protection, and positioning, is suitable for reciprocating/oscillating operations, and extends the life of pins and bearings (Cat®…). The following is the core information:

Core Technical Parameters
Item Details
Part Model: CAT 6E-4381 (6E4381) Composite Bushing, Self-lubricating, available in two structures: without oil groove / with oil reservoir

Material: Steel back (Q235/40Cr) + Bronze intermediate layer + PTFE / Graphite solid lubrication surface layer, coefficient of friction ≤0.05, suitable for dry friction / boundary lubrication conditions

Key Dimensions: Inner diameter 19.05 mm (3/4 in), outer diameter 25.4 mm (1 in), length 22.23 mm (7/8 in), wall thickness 3.175 mm, unit weight approx. 0.03 kg, suitable for mounting positions with a shaft diameter of 19.05 mm and a mounting hole of 25.4 mm

Compatible Models: CAT 3306/3406/C15 engine, 980G/988H loader, 345C/349D Suitable for excavators, D8T/D9R bulldozers, etc., and compatible with valve rocker arm shafts, pushrod supports, throttle control linkages, hydraulic cylinder lugs, steering tie rod hinge points, etc.

Performance Parameters: Load capacity ≥50 MPa, operating temperature -40℃ to 200℃, oil-free operating life ≥5000 oscillation cycles, suitable for reciprocating/oscillating frequencies ≤10 Hz.

Core Functions and Structural Features:

Self-lubricating and low-friction: The PTFE/graphite surface layer requires no additional oil supply, resulting in a low coefficient of friction under dry friction, suitable for hard-to-lubricate hinge parts, reducing wear on pins and seat holes.

Steel backing – bronze – lubricating layer composite structure: The steel backing ensures structural rigidity and compressive strength, the bronze layer buffers impact, and the lubricating layer reduces friction, suitable for vibration, impact, and heavy-load conditions, and is not easily deformed/detached.

Wear-resistant and anti-jamming: The wear-resistant surface is suitable for harsh environments such as dust and oil contamination, preventing jamming at hinged joints and ensuring precise operation/transmission.

Suitable for various working conditions: Can be used in dry friction, thin oil lubrication, or grease lubrication scenarios. Installation does not require a complex lubrication system, simplifying maintenance.

Installation and Maintenance Points
Installation Specifications
Clean the seat hole and pin, removing burrs/metal filings. The seat hole diameter tolerance is H7 (25.4 mm + 0.021 mm), and the roundness is ≤0.01 mm.

Use cold pressing/hot fitting (heat the seat hole to 80–100℃) to press the bushing into the seat hole, ensuring the end faces are flush and not tilted. The inner diameter shrinkage after pressing should be ≤0.05 mm.

After assembly, check the pin’s sliding flexibility. There should be no jamming/abnormal noise. The clearance should be controlled within 0.03–0.08 mm to avoid interference that could cause seizing.

Maintenance Recommendations:

Inspect the bushing every 500–1000 working hours: Replace immediately if the bushing is loose, the surface layer is peeling off, or the inner diameter wear is >0.1 mm.

For oil-lubricated parts, regularly check the oil quality/level to prevent oil and impurities from entering the bushing-pin clearance and accelerating wear.

When replacing, prioritize using original equipment manufacturer (OEM) or equivalent quality composite bushings; avoid replacing with ordinary steel bushings as this can lead to premature failure.