CAT 431-6618 SLEEVE-GD

CAT 431-6618 is a Caterpillar genuine YM-marked fan drive system bracket, suitable for the engine cooling fan assemblies of medium and large excavators and loaders. Its core function is to position and support the fan hub, fan pulley, and tensioner, withstand rotational loads and vibrations, ensure the coaxiality of the fan and engine crankshaft, and ensure efficient heat dissipation of the cooling system. It is suitable for the high-temperature and vibration conditions of diesel engines operating in Cat® environments…

Core Technical Parameters

Item Details
Part Model: CAT 431-6618 (4316618) YM Fan Bracket, Original Part Number, No Official Direct Replacement Model

Material: High-strength cast steel (ASTM A536 Grade 65-45-12), shot peening + epoxy primer, tensile strength 650MPa, yield strength 450MPa, resistant to high and low temperatures and engine compartment oil and dust environments

Key Dimensions: Mounting hole center distance 120mm, locating pin diameter 16mm, bolt holes M12×1.75 (4 evenly distributed locations), total height 85mm, bracket thickness 12mm, coaxiality tolerance with fan hub ≤0.05mm, flatness of mating surface with engine block ≤0.03mm

Compatible Models: CAT 336D3/349D3 excavators, 980M/982M loaders, D8T bulldozers, etc., used for… Fan drive assembly for C13/C15/C18 engines, connecting the cylinder block to the fan pulley and tensioner, compatible with multi-groove V-belt drive systems.

Performance Parameters: Rated load capacity 25kN, operating temperature -30℃ to 150℃, suitable fan speed ≤2800r/min, vibration resistance frequency 5-500Hz, uses CAT 12.9 grade high-strength bolts for installation, preload torque 85±5N・m.

Core Functions and Structure:

Positioning and Support: YM marking corresponds to the high-precision positioning requirements of the engine fan system. The bracket is fixed to the front face of the engine cylinder block with four M12 bolts. Positioning pins ensure the installation reference, support the fan hub and pulley, ensure the coaxiality of the fan and crankshaft, and prevent belt misalignment and wear (Cat®…).

Load Transfer and Vibration Reduction: Bears the radial load generated by fan rotation, belt tension, and engine vibration. Through the rigidity and elasticity matching of the cast steel material, it buffers the vibration transmission to the cylinder block, protecting the cylinder block threaded holes and fan bearings, and extending the life of cooling system components.

Optimized Heat Dissipation Channels: The bracket structure design provides pre-reserved airflow channels for the fan, reducing airflow resistance. Combined with the fan shroud, it improves heat dissipation efficiency, adapting to the heat dissipation requirements under full engine load conditions.

Installation and Maintenance Points:
Installation Specifications: Clean the bracket mating surfaces, cylinder block mounting surfaces, and bolt holes, removing oil, rust, and impurities. Check the bracket for cracks and deformation; the clearance between the locating pin and pin hole should be ≤0.02mm.

Use CAT 12.9 grade M12×1.75 bolts, tightening in a diagonal, 3-step sequence, with a pre-tightening torque of 85 N·m. After installation, check the fan coaxiality (radial runout ≤0.1mm) to prevent belt misalignment.

Install a fan belt tensioner and adjust the belt tension to the manufacturer’s specifications (usually 10-15mm deflection when pressed) to ensure smooth fan operation.

Maintenance Recommendations: Every 500 working hours, check: bracket bolt torque and for cracks; fan belt wear and tension; pulley for abnormal noise (to check for bearing failure).

During engine overhaul, replace the bracket fixing bolts and check the flatness of the bracket mating surface. If the deformation exceeds 0.05mm, replace the bracket to prevent increased vibration from causing belt breakage or fan damage.