Cummins Diesel Engine Spare Parts Spline Adapter 212639

The Cummins Spline Adapter 212639 is an OEM grade power transmission component specifically engineered for QSB6.7 (6.7L) and QSL9 (9L) engines. It addresses the challenge of synchronized torque transmission between the high pressure oil pump, air compressor, and crankshaft. With a centering accuracy of 0.02 mm and a torque capacity of 1,850 N·m, it prevents power interruptions caused by spline wear in applications such as 5ton loaders, 200kVA generator sets, and 30ton mining dump trucks. Each adapter undergoes 1 million torsional fatigue cycles (simulating 15,000 operational hours), and its double in volute spline design compensates for ±2° of crankshaft oscillation, serving as the "power fuse" for QSB/QSL engines.

Part No. ： 212639 (REV D, 2025 heat treatment process)

Engine Compatibility ： QSB6.7 (2018+), QSL9 (2020+)

Torque Rating ： 1,850 N·m (continuous) / 2,700 N·m (10sec peak)

Speed Range ： 03,000 rpm (QSB6.7) / 02,600 rpm (QSL9)

Dimensions ：φ82 mm x 115 mm (QSB6.7) / φ95 mm x 132 mm (QSL9)

Weight ： 1.6 kg (QSB) / 2.1 kg (QSL)

Service Life ：12,000hour bench validation (equivalent to 300,000 km highway)

Balance Class ：G2.5 (ISO 1940)

99% Torque Transmission Efficiency

Aftermarket adapters with 0.08 mm flank clearance cause 12% torque loss, while 212639 achieves zero clearance through precision machining.

Field data: QSL9 generator sets using 212639 show 3.2% fuel efficiency improvement (saving 1.1L/hour).

40% Extended Accessory Life

Bench tests: 212639 radial run out (0.03 mm) is 1/5 of aftermarket parts (0.15 mm).

Jiangsu port trial: Bearing replacement intervals extended from 800 to 1,120 hours.

Full Operational Adaptability

40°C cold start: Inner Mongolia winter tests confirm spline oil film formation in 10 seconds (vs. 30 seconds for aftermarket).

50°C high temperature endurance: 500hour Middle East oilfield operation with 18°C temperature rise (vs. 35°C for aftermarket).

Installation Requirements

1. Cleanliness: Use Cummins cleaner P/N 4922458 to ensure spline groove debris <50 μm.

2. Taper inspection: Verify diameters with micrometer (QSB6.7: φ82.0582.07 mm). Reject out of tolerance units.

3. Hydraulic mounting: Apply 80 MPa pressure via KT212639 tool (3minute hold). Never use impact tools.

Maintenance Schedule

1,000hour intervals: Infrared temperature check (normal <85°C; investigate if >100°C).

3,000hour intervals: Spline wear inspection (replace if flank clearance exceeds 0.05 mm).

Lubrication: Exclusive use of Cummins Transmission Oil 50 (P/N 4922393, viscosity index 170).

Critical Note for QSL9 Users

Synchronize replacement of front oil seal (P/N 212640) to prevent timing belt damage from oil leakage.