D77/D78/ D87 Commutator for EMD Traction Motor

The D77, D78, and D87 commutators from Qingfeng Commutator are precision-machined copper segments designed for use in EMD traction motors, with each segment insulated by mica and bonded under high pressure. The nominal diameter ranges from 185 mm to 220 mm depending on the model, and segment height is typically 12 mm to 16 mm, with a tolerance of ±0.05 mm. These units are manufactured using high-purity electrolytic copper with a conductivity rating of at least 99.9% IACS, consistent with industrial standards for traction applications.

The insulation system uses compressed mica paper with a thickness of 0.15 mm to 0.20 mm, standard for high-vibration environments. Segment undercut depth is 0.8 mm to 1.2 mm, ensuring proper brush contact and minimizing arcing. Surface finish on the commutator segments is ground to a Ra value of 0.4 micrometers or better, a typical requirement for motors operating above 1,500 RPM. The assembly is balanced to a residual unbalance limit of 2 g·mm, aligned with IEEE 115 standards for rotating machinery.

These commutators are primarily purchased by locomotive maintenance depots, railway overhaul facilities, and industrial motor rebuilders serving mining, rail, and heavy machinery sectors. They are supplied loose in anti-corrosion paper wraps, packed 5 to 10 units per carton, depending on size. Lead time is typically 4 to 6 weeks after order confirmation, and delivery terms are FOB Changzhou Port. Buyers should confirm segment count and brush holder compatibility before ordering, as variations exist between EMD motor generations.

Qingfeng Commutator operates from Changzhou, Jiangsu Province, with manufacturing facilities in the Qianhuang Industrial Park. The supplier has specialized in commutators for traction and industrial motors for over three decades, with documented production history for D-series and GE-series units. There is no public information on company size, revenue, or employee count, and no third-party certifications are listed in the source profile.

The supplier responds to inquiries with low frequency, and no verified response rate or average reply time is available. Their listing emphasizes production capability over compliance claims, and no export history, client names, or quality certifications are referenced. Buyers should treat all technical claims as supplier assertions pending independent verification.