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Carbon Brushes

EMD40025029 Carbon Brush

Part No. EMD40025029

OEM-style replacement carbon brush for the EMD D29 / D31 locomotive traction motor. Triplex (3-wafer) electrographite assembly, 3 × (5.2 × 50.6 × 56) mm, with flexible copper shunt leads; cross-references EMD 40025029, EMD 8430993, EMD 8367716 and Supco SUP-121-040.

Material	Electrographitic (EG)
Dimensions	- Type: Triplex (3-wafer) brush assembly - Per-wafer size: 5.2 × 50.6 × 56 mm (thickness × width × l
Application	Replacement carbon brush for the EMD D29 DC traction motor (also fits D31 per supplier fitment data) used on EMD diesel-electric locomotives; compatible with GE, ALCO and ALSTOM locomotive applications per supplier cross-references. This is a commutator b
Current Density	10–12 A/cm²
Speed	Maximum peripheral speed ≤ 50 m/s
Connection	Flexible copper-braid shunt leads, one per wafer, terminated for bolted connection to the brush holder / machine termina

Compatible Models

EMD 40025029 (OEM part number) EMD 8430993 (superseded / cross-reference) EMD 8367716 (cross-reference) Supco Canada SUP-121-040 (aftermarket ISO 9001:2015) BroadCarbon EMD40025029 / EMD8430993 (aftermarket) EMD D29 / D31 traction motor applications

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Technical Specifications

Specification	Value
OEM Part Number	EMD 40025029
Cross References	EMD 8430993 · EMD 8367716
Aftermarket References	Supco SUP-121-040 · BroadCarbon EMD40025029/8430993
Product Type	Locomotive traction-motor carbon brush (triplex)
Material	Electrographitic (EG)
Grade	DE7000 (supplier designation)
Wafer Configuration	Triplex, 3 wafers
Per-Wafer Size	5.2 × 50.6 × 56 mm (T × W × L)
Total Assembly Thickness	≈15.6 mm (3 × 5.2 mm)
Lead Type	Flexible tinned copper braid shunt leads, one per wafer
Voltage	Not rated (N/A)
Current Density	10–12 A/cm² (typical, electrographite group)
Max Surface Speed	≤50 m/s (typical, electrographite group)
Hardness	Not published (typical electrographite Shore 30–50)
Spring	Not included (brush-holder supplied)
Application	EMD D29 / D31 traction motors (locomotive)
Compatible Platforms	EMD / GE / ALCO / ALSTOM locomotives (per supplier fitment)

Compatible Models

This EMD40025029 Carbon Brush is designed as a direct replacement for the following machine models and series:

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Description

This EMD 40025029 carbon brush is a direct replacement for the EMD D29 (and D31) DC traction motors fitted to EMD diesel-electric locomotives. The brush is supplied as a triplex assembly — three electrographite wafers (each 5.2 × 50.6 × 56 mm) with individual flexible copper-braid leads — matching the OEM multi-wafer configuration used in the D29 brush box for high-current traction duty. Electrographite material provides stable commutation, low friction and even wear under the heavy vibration and thermal cycling of railway service.

Features & benefits:

OEM-matched triplex configuration — 3 × (5.2 × 50.6 × 56) mm wafer assembly, drop-in fit for EMD D29/D31 brush holders.
Electrographite material — low electrical loss, medium contact drop, low friction; suited to high-current traction duty.
Individual shunt leads per wafer — flexible copper-braid leads with terminals for reliable, balanced current sharing.
Cross-referenced part numbers — EMD 40025029, EMD 8430993, EMD 8367716, Supco SUP-121-040.
Typical applications — EMD D29/D31 locomotive traction motors; compatible GE/ALCO/ALSTOM locomotive applications.
Quality-inspected before dispatch: wafer dimensional check, lead crimp integrity, and surface condition per batch.