A Major Engineering Milestone

A significant milestone arrived in 1945 when CPH 12 became the first rail motor fitted with a General Motors Detroit Diesel engine and a Twin Disc DFF 10024-TC-1L hydraulic torque converter.

This upgrade delivered impressive results. The new drivetrain package improved reliability, increased efficiency and enhanced overall performance. Consequently, the combination proved so successful that it was adopted across the wider CPH fleet.

Moreover, the Detroit Diesel engine and Twin Disc torque converter helped extend the service life of the rail motors. Together, they delivered the performance and operational flexibility needed to support regional rail services for decades.

The Twin Disc Difference

For operators, the benefits were clear. The Twin Disc hydraulic torque converter provided smooth and efficient power transfer between the engine and drivetrain. In addition, it helped improve vehicle performance while reducing stress on mechanical components.

These advantages contributed to the long-term success of the CPH Class fleet. Furthermore, the proven reliability of the Twin Disc technology helped keep the rail motors operating across New South Wales for more than 60 years.

A Lasting Legacy

More than a century after the first CPH rail motor entered service, the class remains an important part of Australian railway history.

Ultimately, the success of the CPH fleet highlights the value of dependable engineering. The integration of Twin Disc hydraulic torque converter technology helped deliver the reliability and operational performance required to keep regional communities connected for generations. At Twin Disc Pacific, we are proud to celebrate this legacy and the role innovative power transmission technologies continue to play across the transport industry.

Preserving an Important Piece of History

Today, preserved examples continue to tell the story of Australia’s rail heritage. Enthusiasts and railway museums have worked tirelessly to restore and maintain surviving units.

One notable example is CPH 3. It serves as a reminder of the engineering innovation that helped shape regional transport throughout New South Wales. Meanwhile, preservation groups continue to share the history of these iconic rail motors with new generations of rail enthusiasts.

For those interested in exploring the history of the CPH Class in greater detail, the Transport Heritage NSW Rail Motor Society provides a comprehensive class index, vehicle histories and preservation information on its website.

View the CPH Class Index here.