# Indian locomotive class YAM-1

> class of 20 Indian metre-gauge AC electric mixed-traffic locomotives

**Wikidata**: [Q18395737](https://www.wikidata.org/wiki/Q18395737)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Indian_locomotive_class_YAM-1)  
**Source**: https://4ort.xyz/entity/indian-locomotive-class-yam-1

## Summary
The Indian locomotive class YAM-1 is a class of 20 metre-gauge AC electric mixed-traffic locomotives operated by Indian Railways. Manufactured in Japan by Mitsubishi, Hitachi, and Toshiba, these locomotives entered service in 1964 and were utilized for both passenger and freight operations until their retirement in June 2004.

## Key Facts
*   **Class Type:** Metre-gauge (1000 mm) AC electric mixed-traffic locomotive.
*   **Fleet Size:** A total of 20 locomotives were produced.
*   **Operators:** Indian Railways (Service period: 1964 – June 2004).
*   **Country of Origin:** Japan.
*   **Manufacturers:** Mitsubishi, Hitachi, and Toshiba.
*   **Technical Specification:** Equipped with a B′B′ wheel arrangement.
*   **Electrification System:** Designed for 25 kV, 50 Hz AC railway electrification.
*   **Fleet Numbers:** 21904 – 21923.
*   **Manufacturer Numbers (Mitsubishi):** 1238–1255 and 1378–1379 (built 1964–1966).

## FAQs
### Q: What was the primary use of the YAM-1 locomotive?
A: The YAM-1 was a mixed-traffic locomotive, meaning it was designed to haul both passenger trains and freight cargo on Indian Railways' metre-gauge lines.

### Q: Who manufactured the YAM-1 class locomotives?
A: The locomotives were built in Japan by three major manufacturers: Mitsubishi, Hitachi, and Toshiba.

### Q: How long did the YAM-1 class serve Indian Railways?
A: The class served for approximately 40 years, entering service in 1964 and retiring in June 2004.

## Why It Matters
The YAM-1 class holds a distinct place in the history of Indian Railways as a specialized import designed to modernize metre-gauge operations. Introduced in 1964, these locomotives represented a significant technological collaboration between India and Japan, utilizing advanced electric traction technology from Japanese industrial giants like Toshiba, Hitachi, and Mitsubishi.

Their four-decade service life highlights their durability and the critical role they played in transitioning rail transport on metre-gauge lines from steam or diesel to more efficient electric power. As a mixed-traffic class, they provided versatile operational capability, handling both heavy freight and passenger loads. Their existence illustrates the complexity of maintaining a diverse railway network (metre-gauge vs. broad gauge) and the specific engineering solutions required to electrify the 1000 mm tracks with 25 kV AC power systems before the eventual consolidation and retirement of this gauge in many sectors.

## Notable For
*   **Gauge Specificity:** It was a specialized electric locomotive class built exclusively for the 1000 mm (metre-gauge) network, distinguishing it from the standard broad-gauge fleet.
*   **Japanese Origin:** It is a notable example of mid-20th-century rolling stock imported from Japan, involving a consortium of major Japanese manufacturers (Mitsubishi, Hitachi, Toshiba).
*   **Mixed Traffic Versatility:** The class was designed to handle dual roles (passenger and freight), a requirement that necessitated a robust B′B′ wheel arrangement.
*   **Fleet Identification:** The class maintained a tight, sequential numbering block (21904–21923) within the Indian Railways fleet.

## Body

### Design and Manufacture
The Indian locomotive class YAM-1 was manufactured by a collaboration of Japanese engineering firms. The primary contract was shared among **Mitsubishi**, **Hitachi**, and **Toshiba**. Mitsubishi specifically produced units corresponding to manufacturer numbers 1238–1255 and 1378–1379 between 1964 and 1966. The locomotives were classified as electric locomotives under the subclass of mixed-traffic engines, indicating their ability to generate sufficient tractive effort for freight while maintaining speeds necessary for passenger service.

### Technical Specifications
The YAM-1 class was built to operate on the **1000 mm track gauge** (metre gauge). The locomotives utilized a **B′B′ wheel arrangement**, a Bo-Bo configuration where two bogies each have two powered axles, providing good adhesion and ride quality for mixed traffic. They were engineered to operate under the **25 kV, 50 Hz AC** railway electrification standard used by Indian Railways.

### Operational History
The fleet of 20 locomotives was assigned the registration numbers **21904 through 21923**. They entered service with **Indian Railways** in **1964**. For nearly 40 years, these units operated on electrified metre-gauge routes across India. The class was officially retired from service in **June 2004**, marking the end of the operational life for this specific Japanese-imported electric class on the Indian network.