The WEICHAI WP12 Crankshaft Group is the core rotating assembly that converts linear piston motion into rotational torque for WP12 series diesel engines. This forged steel crankshaft group includes the crankshaft itself, main bearings, thrust washers, and flywheel mounting flange, all precision-matched to OEM specifications. When you invest in genuine WEICHAI Engine Parts, you receive a fully balanced assembly capable of withstanding peak cylinder pressures up to 200 bar. The WEICHAI WP12 Crankshaft Group features induction-hardened journal surfaces and micro-alloyed steel construction, delivering exceptional fatigue resistance and a service life exceeding 1.5 million kilometers in line-haul applications.
The WEICHAI WP12 Crankshaft Group comprises the forged steel crankshaft, six counterweights, main bearing shells, thrust washers, and a rear oil seal assembly – all pre-assembled and dynamically balanced as a set. This group forms the backbone of the engine’s rotating assembly, transmitting over 2,000 Nm of torque to the flywheel while enduring extreme bending and torsional stresses. Each crankshaft is forged from 42CrMoA alloy steel, then normalized, quenched, and tempered to achieve a tensile strength of 980 MPa and a yield strength of 835 MPa.
The crankshaft features eight counterweights (six integral and two bolt-on) to neutralize primary and secondary imbalances, resulting in smooth operation up to 2,200 rpm. All main and connecting rod journals are induction-hardened to a depth of 4–6 mm with a hardness of 55–60 HRC, then superfinished to a mirror-like surface finish of 0.2 Ra. This reduces friction against the bearing shells and extends oil film life. The group also includes precision-ground thrust washers that control axial play within 0.10–0.25 mm, critical for maintaining timing gear alignment.
Unlike conventional crankshafts, the WP12 unit incorporates fillet rolling on all journal radii, which introduces compressive residual stress and increases fatigue strength by 30%. The group is balanced to ISO 1940 G2.5 grade, ensuring vibration-free operation even at redline. Each journal is micro-drilled with cross-drilled oil passages that feed pressurized oil to the connecting rod bearings. The rear flange includes a pilot bearing bore for the transmission input shaft, machined to a tolerance of H7.
Every WEICHAI WP12 Crankshaft Group undergoes 100% magnetic particle inspection (MPI) to detect surface cracks, followed by an ultrasonic test for internal flaws. A computerized balancing machine then verifies residual unbalance below 30 g·mm. The assembly is then coated with anti-rust oil and sealed in a vacuum bag to prevent corrosion during storage. This meticulous process ensures that each crankshaft group meets the highest OE durability standards for heavy-duty truck, bus, and construction machinery applications.
Product Parameters of WEICHAI WP12 Crankshaft Group
NO.
Part NO.
Description
1
612630390671
Crankshaft Forging (42CrMoA, 12.5 kg)
2
612630400688
Main Bearing Set (6 pcs, Trimetal Copper-Lead)
3
612630410692
Thrust Washer Set (Upper/Lower, Steel-Bronze)
4
612630420705
Connecting Rod Bearing Set (6 pcs, Tin-Aluminum)
5
612630430718
Rear Oil Seal Housing with PTFE Seal
6
612630440722
Front Oil Seal (Viton, 85x105x12 mm)
7
612630450735
Flywheel Mounting Flange (12x M12 Studs)
8
612630460749
Crankshaft Gear (60 Teeth, Induction Hardened)
9
612630470753
Bolt-on Counterweight (2 pcs, Forged Steel)
10
612630480766
Main Bearing Cap Bolts (10.9 Grade, Set of 14)
11
612630490770
Pilot Bearing (Deep Groove Ball, 6204)
12
612630500783
Complete Crankshaft Group (Balanced & Sealed)
Why Choose Our WEICHAI WP12 Crankshaft Group?
Our WEICHAI WP12 Crankshaft Group is sourced directly from the same Tier-1 forging house that supplies Weichai Power’s original assembly line. This guarantees identical material chemistry, heat treatment profile, and dimensional tolerances. Each group is delivered with a certificate of conformance that includes individual journal measurements, hardness test results, and balancing report. Unlike rebuilt or reground crankshafts, our group uses only virgin steel and new bearings, eliminating the risk of hidden fatigue cracks or undersized journals.
We offer a complete “one-box” solution: the crankshaft, bearings, thrust washers, seals, and mounting hardware are all included. This saves your workshop from sourcing components from multiple vendors, reducing procurement errors and assembly downtime. The bearings are color-coded by size grade (A/B/C) to match your engine block’s main bore classification, ensuring proper oil clearance between 0.05–0.09 mm. Our technical support team provides free access to torque sequences and plastigage procedures via a QR code on the box.
Price competitiveness is a major advantage. By cutting out dealer markups and maintaining a direct supply chain, we price our WEICHAI WP12 Crankshaft Group 25–35% below typical OEM list prices, while still offering a 24-month or 200,000 km warranty. For fleet operators, we offer core exchange programs and volume discounts. Every group is packed in a heavy-duty wooden crate with foam inserts to prevent shipping damage. We also stock both standard and 0.25mm undersize bearing sets for blocks that have been line-bored.
Our global warehouse network (USA, UAE, Germany, China) ensures that 95% of orders are dispatched within 24 hours. Real-time tracking and insurance are standard. Independent dyno tests have proven that our crankshaft group exhibits identical torsional vibration characteristics and bearing oil film thickness as the genuine part at full load (350 kW / 2200 rpm). When you need to rebuild a WP12 engine with absolute confidence, our crankshaft group provides the reliability, value, and support you deserve.
What are the Routine Maintenance Considerations for the WEICHAI WP12 Crankshaft Group?
Maintain strict oil change intervals (max 50,000 km or 500 hours) using API CK-4 15W-40 oil. Contaminated or degraded oil accelerates bearing wear and can cause crankshaft journal scoring. During each oil change, cut open the oil filter and inspect for metallic flakes; copper-colored particles indicate main bearing wear, while steel particles suggest crankshaft surface damage. If any debris is found, perform an oil pressure test and consider removing the oil pan for visual inspection of the crankshaft group.
Check crankshaft end play annually using a dial gauge against the flywheel. The permissible axial movement is 0.10–0.30 mm. Excessive end play points to worn thrust washers, which can lead to timing gear misalignment and crankshaft position sensor errors. Also, listen for a deep knocking noise that increases under load – this often indicates failed main bearings or a cracked crankshaft. Never ignore such symptoms; immediate teardown can save the cylinder block from catastrophic damage.
When replacing the rear oil seal, always use genuine PTFE seals and lubricate the sealing lip with clean engine oil before installation. Avoid touching the seal lip with bare hands (oils from skin degrade PTFE). Torque the flywheel bolts to 240 Nm + 90° in a cross pattern. An improperly installed rear seal is the number one cause of oil leaks after an overhaul. Similarly, the front seal must be installed with a protective sleeve to prevent lip damage over the keyway.
If storing a spare WEICHAI WP12 Crankshaft Group, keep it in its original anti-rust packaging in a climate-controlled environment (10–30°C, <60% humidity). Rotate the crankshaft 180° every three months to redistribute the protective oil film. Before installation, verify that all oil passages are unobstructed using a soft brush and compressed air. Never use a hammer or impact wrench to install the crankshaft gear; press it on using a proper tool. Adhering to these maintenance guidelines ensures that your crankshaft group delivers maximum durability and engine uptime.
If you have any questions about our products, services, or anything related to what we offer, please don’t hesitate to leave us a message—our dedicated team is always ready to provide prompt and helpful responses to address your concerns. What’s more, when you become our valued customer, we’re delighted to offer you complimentary catalog services, giving you access to detailed, up-to-date information on our full range of products, specifications, and offerings to help you make informed decisions.
