Caterpillar Inc 1-1N4333X 1N-4333X Main Bearing

Cat 1N4333X (1N-4333X) is a standard-size Caterpillar main bearing shell used to support the crankshaft mains in select Caterpillar diesel engines. This bearing forms the lower half of the main bearing pair and operates with the engine’s oil-film lubrication to prevent metal-to-metal contact at the crank journals. In Caterpillar catalogs it is listed as Main Bearing STD and is associated with OEM reference 7S8312; an undersize variant of 0.050 inch is documented under 1N4333 (also seen in some alternate catalogs as 1N4333X). The part also appears in cross-reference listings such as M-1N4333 in natural-gas replacement literature, reflecting its role across multiple Cat platforms. Compatibility should be confirmed against your exact engine model and serial number using the official Cat parts catalog or a Cat‑authorized distributor. When replacing, verify the correct size (standard vs undersize) for proper bearing clearance, and ensure you source the correct shell orientation and fitment for your crankcase bore and journal diameters as specified by Caterpillar service procedures.