Forklift Crankshaft

Forklift Crankshaft: Forged Steel Crankshafts for Xinchai 4D27 & 495 Diesel Engines

The crankshaft is the central rotating component of the engine — a precision-forged steel shaft that converts the reciprocating (up-and-down) motion of the pistons and connecting rods into rotational torque delivered to the flywheel and ultimately to the transmission and drive wheels. Each cylinder’s connecting rod attaches to a crankpin (rod journal) that is offset from the crankshaft centerline — as the piston is pushed down by combustion pressure, the connecting rod pushes on the offset crankpin, rotating the crankshaft. The crankshaft rotates inside precision-machined main bearing journals supported by the engine block’s main bearing saddles, separated by a hydrodynamic oil film approximately 0.001-0.003 inches thick that prevents metal-to-metal contact. A cracked, bent, or severely worn crankshaft is the most catastrophic engine failure possible — a broken crankshaft destroys the engine block, connecting rods, pistons, and sometimes the cylinder head in a chain reaction that turns the entire engine into scrap metal. Crankshaft journal wear beyond the undersize grinding limit (typically 0.25-0.50mm undersize for forklift diesel engines) makes the crankshaft unserviceable and requires replacement.

Kingstream supplies replacement forged steel crankshafts for Xinchai 4D27 (fits 4D27G31 engines in HELI CPCD30 and 3-ton forklifts) and Xinchai 495 (fits 495 diesel engines across HELI, Hangcha, and agricultural equipment). Every crankshaft is inspected for journal diameter, surface finish, straightness, and crack detection before shipment.

Types:
• Xinchai 4D27 Crankshaft (4D27-CRANKSHAFT) — Forged steel crankshaft for Xinchai 4D27 and 4D27G31 2.7L diesel engines. Fits HELI CPCD30, Hangcha, and Baoli 3-ton forklifts. Direct factory sale, high quality. Designed for the 4-cylinder engine configuration with 5 main bearing journals and 4 connecting rod journals. The 4D27 crankshaft is gear-driven (no timing belt): a crankshaft timing gear drives the camshaft gear and injection pump gear simultaneously, requiring precise gear alignment during engine reassembly
• Xinchai 495 Crankshaft (495-CRANKSHAFT) — Forged steel crankshaft for Xinchai 495 diesel engine (the larger-displacement variant of the 490/495 engine family). Fits 495-powered forklifts and agricultural equipment. Wholesale factory direct pricing. 4-cylinder configuration with 5 main bearings for crankshaft stability under sustained full-load operation. The 495 crankshaft shares the same main bearing journal diameter as the 490 but with a longer stroke for increased displacement — verify your engine model before ordering as the 490 and 495 crankshafts are not interchangeable

When to Replace Crankshafts:
• Loud knocking noise from the bottom of the engine that increases with RPM and does not change when individual injectors are disabled → Spun connecting rod bearing. The bearing has welded itself to the crankshaft journal and spun in the rod bore. The crankshaft journal is scored. Replace crankshaft and all bearings
• Metal particles (steel-colored, magnetic) in the oil filter or on the magnetic drain plug → Crankshaft journal or bearing material. The journal surface is being machined away by metal-to-metal contact. Replace crankshaft before catastrophic failure
• Crankshaft broken into two or more pieces — typically at a main bearing journal or crankpin fillet → Complete engine destruction. This is caused by fatigue cracking from repeated torsional vibration stress. Replace crankshaft and inspect block for collateral damage
• Main or rod bearing journals measured below the minimum undersize specification after regrinding → The crankshaft has been machined past its service limit. Undersize bearings are not available beyond 0.50mm. Replace crankshaft
• Visible cracks in any crankpin or main journal — detected by magnetic particle inspection (Magnaflux) → Fatigue crack that will propagate to complete fracture. Replace crankshaft immediately

OEM Cross-Reference:

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Compatible: Xinchai 4D27/4D27G31, Xinchai 495. Browse our engine parts catalog.