Railway Challenge at Sheffield (RCAS) is an extracurricular activity for undergraduate students, and is the University of Sheffield’s entry into the IMechE Railway Challenge competition, held annually in June at Stapleford Miniature Railway in Leicestershire. The team is currently composed of around 35 engineers from across the Faculty of Engineering, including; Mechanical, Automatic Control and Systems, Aerospace, General, Civil, Electrical, and Computer Science Engineering. Supporting the team are four PhD students from the School of Mechanical, Aerospace and Civil (MAC) Engineering. An academic supervisor, Professor Roger Lewis, provides additional support.
The competition requires teams of students and recent graduates from across the globe to design and manufacture a 10¼” gauge (5th-scale) locomotive to compete in a wide variety of dynamic, on-track challenges intended to replicate real challenges faced in the rail industry. The teams also compete in paperwork challenges designed to reflect the demands placed on an engineering team in industry. This year marks the team’s eleventh year involved in the competition and will be our tenth competing locomotive. The team has always had a strong track record of results but were finally crowned Grand Champions in 2024, as well as winning several individual challenges. Due to the success of this tenth anniversary locomotive, the team has elected to retain it in full competition specification to train new team members, support the University, and exhibit at STEM outreach and other widening participation events to promote engineering to younger audiences.
As such, a brand new locomotive is being designed and built for the 2025 Competition; shown below as computer aided design render.
This provides a fantastic opportunity for the team to design, build, test and implement long-desired changes to our locomotive - in an effort to learn and develop further. Sponsorship from RS through the Student Project Fund has enabled the ambition for the 2025 locomotive to be the most radical in the team’s history, whilst (hopefully) retaining the success of its predecessors. The progress of building the locomotive, as well as many of the team, in April 2025 can be seen below.
Principally this support has helped drive a change to the locomotive’s powertrain. The team’s basic powertrain design and philosophy has not changed since 2014, albeit with several successful iterations. In brief, this comprises a brushed DC motor driving two wheelsets through an intermediate shaft either using chains or belts. Relatively simple motor controllers are used to control this system. Although this system works, it is now very conventional. The concept also has significant limitations with respect to the speed, safety, and ease of wheelset removal, which negatively affects performance in the competition’s ‘Maintainability Challenge’. An alternative system has been conceived, designed, developed, and implemented which includes major mechanical changes to incorporate direct drive gearing to simplify wheelset removal. Implementation of a new powertrain design concept also allows the incorporation of new motors with more sophisticated motor controllers. This alteration delivers a step change in locomotive performance which should provide a more capable and reliable vehicle. A high-level outline of the overall powertrain design can be seen below.
The student fund has been used to acquire numerous components for the overall powertrain including universal joints, and for each individual gearbox including taperlocks, taper roller bearings, plain bearings. This support has also meant that other funds could be used to acquire new wheelsets to support the goal of retaining the previous winning locomotive in full running specification for use in STEM outreach events. An example application of a universal joint within the powertrain is shown below. This joint allows a flexible connection between the motor-brake assembly and the gearbox mounted on an axle.
Through participation in the railway challenge competition, the team now has a network of over 100 practising engineers in sectors including rail, automotive, energy, aerospace, and academia. Individual testimony has highlighted that RCAS, and ultimately the railway challenge competition, has been instrumental in many alumni securing their current roles. RCAS also has an extremely high rate of members who join ‘Year in Industry’ and ‘Summer Placement’ programmes in a multitude of sectors; 2023 saw a 100% success rate. These statistics serve to highlight how well RCAS has taken on the goal of ‘allowing aspiring engineers to build and showcase their skills, expertise, knowledge, and business acumen’ which is core to the Railway Challenge competition; the delivery of this mission will only be enhanced through sponsorship from RS Components for the 2025 Railway Challenge competition.
The team is immensely thankful for this support from RS Components, and all look forward to continuing our partnership. Progress of the locomotive at the Railway Challenge competition can be followed across our social media pages (LinkedIn, Facebook: @Railway Challenge at Sheffield; Instagram: @railchallatsheff) at the end of June 2025.
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