MAHLE 14 V Solid-State Voltage Regulator (MX 14 Type) with Brush Holder for Agricultural Alternators - Part Number: 37911125177
The genuine MAHLE integrated solid-state voltage regulator with brush holder assembly (part number 37911125177, manufacturer and OEM references 139515, MX14, MX 14) is an OEM-grade electronic control module engineered to manage rotor field excitation and deliver steady voltage output across 12 V / 14 V charging circuits. Designed specifically for heavy-duty MAHLE / Iskra / Letrika agricultural and industrial alternators, it prevents damaging inductive voltage spikes, protects delicate onboard electronic modules, and maintains dependable battery replenishment during heavy lighting and auxiliary electrical loads. Featuring copper-graphite brushes, calibrated compression springs, and fully resin-potted circuitry, it provides maximum resistance against extreme engine bay temperatures, cyclic vibration, and agricultural dust.
Key Features & Engineering Advantages
- Solid-State Voltage Stabilization: Regulates output to a precision 14.2 V – 14.5 V set-point, ensuring rapid battery charging while eliminating overvoltage hazards to vehicle wiring and sensors.
- Integrated Low-Wear Brush Assembly: Pre-fitted with premium copper-graphite brushes maintaining constant contact pressure on rotor slip rings, preventing arcing and RF interference.
- Heavy-Duty Resin-Sealed Housing: Potted in high-grade dielectric resin to shield sensitive internal semiconductors against airborne field dirt, crop chaff, water spray, and severe vibration.
- Active Thermal Compensation: Automatically trims charging thresholds relative to under-hood temperatures, protecting battery chemistry in severe summer field conditions and ensuring proper charging in winter.
- Direct MAHLE OEM Interchangeability: Built to exact MX14 / MX 14 / 139515 factory specifications for quick bolt-on replacement directly onto the alternator rear housing.
Technical Specifications
| Commercial Part Number |
37911125177 |
| Manufacturer / Quality Brand |
MAHLE (Iskra / Letrika) |
| OEM / Manufacturer References |
139515, MX14, MX 14 |
| Component Classification |
Electronic voltage regulator with integrated brush holder |
| Nominal System Voltage |
14 V (for 12 V vehicle battery electrical systems) |
| Voltage Set-Point |
14.2 V – 14.5 V |
| Brush Gear Assembly |
Pre-installed copper-graphite brushes with calibrated compression springs |
| Mounting Configuration |
Internal/rear-mounted onto the alternator end-shield via threaded bosses |
| Primary Function |
Output voltage regulation and field excitation for MAHLE/Iskra alternators |
Alternator Compatibility & Equipment Guide
| Application Sector |
Supported Alternators & Agricultural Equipment |
| Compatible Alternators |
MAHLE / Iskra / Letrika 14V agricultural and industrial alternators specifying MX14 regulators |
| Tractors & Farm Machinery |
Same, Lamborghini, Deutz-Fahr, Case IH, and Fendt tractors and combine harvesters fitted with MAHLE charging systems |
| Industrial & Stationary Power |
Diesel generators, industrial pumps, wheel loaders, and excavators powered by Deutz, Perkins, and Yanmar engines |
Installation Advice & Workshop Notes: Always disconnect the negative battery terminal before carrying out electrical repairs. Remove the alternator rear shield, unscrew the old regulator, and lift it out gently. Inspect the copper rotor slip rings; if scored or oxidized, lightly clean them with ultra-fine dry abrasive paper. Mount the new MAHLE regulator carefully to avoid chipping the carbon brushes as they slide over the slip rings. Fasten the mounting screws tightly to guarantee solid electrical ground continuity. After installation, reconnect the battery, start the engine, and confirm that battery terminal voltage stabilizes between 14.2 V and 14.5 V at fast idle with the dash warning light extinguished.
