Product Name: Weichai WP10 / WP12 / WP13 Air Compressor Assembly (Twin-Cylinder Air Brake Compressor)

Part No.: 1000406884（some channels list it as 100040688）

Product Overview: This air compressor assembly is the original equipment twin-cylinder, reciprocating-piston compressor supplied with Weichai WP10, WP12 and WP13 series diesel engines. It is driven from the engine gear train and supplies compressed air to the vehicle's brake system, clutch booster, air horn and other pneumatic auxiliary devices. As the core air-supply component of the brake circuit, it directly determines how quickly brake pressure builds up and therefore the overall safety of the vehicle.

Application / Compatibility: Suitable for Weichai WP10, WP12, WP13 and WP10H series engines. Typical installations include Shacman Delong, Sinotruk HOWO and FAW Jiefang heavy-duty trucks, tractors, dump trucks and special-purpose vehicles fitted with Weichai 10–13 litre diesel engines. The twin-cylinder design offers a clearly larger air delivery margin than single-cylinder units, which suits heavy-duty operation with frequent braking, continuous downhill running and repeated stop-start cycles.

Design and Key Features: Twin-cylinder reciprocating-piston construction with a cast cylinder block, water-cooled, flange-mounted to the engine and gear-driven. The two cylinders work alternately, giving continuous delivery and minimal pressure pulsation; air pressure recovers quickly under sustained braking, reducing the risk of low-pressure warnings. Supplied as a fully assembled unit including cylinder block, cylinder head, piston and connecting-rod assembly, crankshaft and intake/discharge ports, allowing complete replacement without internal overhaul.Weichai parts WP10 / WP12 / WP13

Interchangeable Part Numbers: Numbers commonly listed as belonging to the same family or as substitutes: 612630030405, 612630030047, 1000769549, 1002048701, 1003185665 and 1003185668. These are successive part numbers of the same twin-cylinder compressor generation, but they are not universally interchangeable — differences lie in flange angle, intake and discharge port positions, whether an unloader valve (pressure regulator) is fitted, and whether water-line unions are included.Original Weichai Engine Parts Before ordering, compare the replacement against the original unit removed from the vehicle, or provide the vehicle VIN for the supplier to verify. Do not rely on the part number alone.

Common Faults and Diagnosis: Slow pressure build-up or insufficient air delivery usually indicates a failed cylinder-head gasket or worn piston rings — check for oil seepage at the head joint. Oil carry-over into the air circuit, or oil-and-water mixture when draining the air receiver, points to worn piston rings or a scored cylinder bore. Pronounced knocking during operation is generally related to worn connecting-rod bearings or excessive crankshaft clearance. If the compressor fails to rotate or slips, inspect the drive gear and coupling. In most of these cases, replacing the complete assembly is more economical and reliable than component-level repair.