CAT 425-3447 BEARING-GD

CAT 425-3447 YM is a Caterpillar genuine ductile iron flywheel, suitable for medium and large-sized construction machinery diesel engines. The following is purely accurate information (without additional description):

Core Parameters and Information

Item Details
Part Model: CAT 425-3447 YM (4253447) flywheel, including integrated starter gear ring

Part Type: Engine flywheel, stores kinetic energy, balances crankshaft speed fluctuations, compatible with clutch/torque converter connections

Material: Flywheel body: ductile iron (QT500-7), gear ring: 20CrMnTi alloy steel, bolts: 10.9 grade high-strength steel

Key Dimensions: Outer diameter 420.00mm, inner diameter 150.00mm (fits crankshaft flange), thickness 55.00mm, gear ring teeth 136, bolt holes 8×M16 (evenly distributed)

Structural Features: One-piece casting, precision ground surface, high static/dynamic balance accuracy G2.5, gear ring heat fitting, anti-loosening bolt tightening, with locating pin hole

Compatibility: Interference fit with crankshaft flange (0.005-0.010mm), bolt preload torque 280±10N・m, operating temperature -40℃ to +200℃

Balance Grade: Overall balance accuracy G2.5, face runout ≤0.05mm, radial runout ≤0.03mm

Weight: 28.5kg

Compatible Models and Assemblies:

Excavators: CAT 349D2, 352F (C13 engine)

Loaders: CAT 980M, 982M (C15 engine)

Mining Trucks: CAT 770G (C13 engine)

Matching Parts: 425-3447 flywheel, starting gear ring (425-3448), flywheel bolt (grade 10.9) M16×1.5×60), locating pin (6B-4567), flywheel housing gasket (234-5678)
Installation and Fitting Points:
Clean the crankshaft flange and flywheel end face, ensuring they are free of oil and rust, with a surface roughness Ra≤1.6μm, and that the bolt holes are undamaged.

Heat-fit the gear ring (heat to 220℃ and hold for 15 minutes), press-fit, and then cool to room temperature. Check that the gear ring’s circular runout is ≤0.10mm.

After positioning with the locating pin, tighten the bolts in a diagonal, 3-stage sequence, with a pre-tightening torque of 280N・m. Finally, use the angle method to tighten an additional 90°.

After installation, check that the end face runout is ≤0.05mm, the radial runout is ≤0.03mm, and that there is no wobble or abnormal noise during rotation.