Junior Railway Challenge

A course for schoolchildren run this summer at Huddersfield University could attract more young people to careers on the railway.

The course for schoolchildren in years 11 and 12 was one of a series run by the Smallpeice Trust. The trust is an independent educational charity that runs hands-on science, technology, engineering and maths (STEM) activities for pupils in years 5 to 10 and residential courses for years 8 to 12 pupils.

The trust promotes engineering as a career choice for young people. It was started in 1966 by Dr Cosby Smallpeice who founded Martonair, a company specialising in pneumatic equipment for the machine tools industry. When the company was floated, he used the proceeds to set up the trust.

Amongst the wide range of courses it offers is a four-day residential railway systems engineering course. This year these were run at the universities of Huddersfield and Birmingham.

The course at the University of Huddersfield took place from 13-16 July and had 44 pupils formed into nine teams. They came from all parts of the UK and were studying science subjects but had yet to decide their university courses. It gave them an insight into university life from their stay in the university’s halls of residence and by attending lectures on railway engineering given by staff of the Institute of Railway Research (IRR) and industry experts.

Kit built locomotives

Those on the course were split up into nine teams, each of which had to build the best locomotive based on its performance at the lowest cost. The teams also had to sell their locomotives with an eye-catching poster and give a presentation explaining the ideas behind their design.

Before doing this, they were given useful background information from their lectures that included rail vehicle dynamics, power, traction and braking and crashworthiness. They were also provided with equations useful for the design of their locomotive.

The teams had a budget of £400 from which they bought component parts from a catalogue that had all they needed to build their locomotives. For example, wheelsets were £15.50, axle boxes £6.95, gears and pulleys ranged in price from £6.51 to £12.95 and a 500 mm length of 20×20 aluminium profile for the chassis was £1.45. All teams had to purchase a 3.3 Ah battery pack and Reventon electric motor for £82.99. Their radio-control system, however, came free.

Their problem was to take the power from the motor shaft to the wheels in a drivetrain suited for two performance challenges. To do this the teams had to undertake calculations to optimise tractive effort and acceleration for the sprint and tug-of-war challenges that required different torque characteristics.

In the sprint challenge, the locomotives had to get from the start of the track to a marked ‘red area’ in the fastest time. In the tug-of-war challenge, locomotives were tied to each other with string and with the objective of pulling their opponent over a marked centre line. This was a knockout competition done in a series of heats.

All done by gears

For some teams, the performance trials did not go well when their locomotives remained stationary. On one locomotive a motor failed as it was not aligned with its output shaft, on others as gears and drive belts slipped.

Thus the need for the drivetrain to be secure and properly aligned was a lesson learnt. One team had anticipated this problem and used a double-frame section below the motor to provide a four-point mounting.

The trials proved that gear ratios were the key to success. These varied from 8.4:1 to 24:1. The team with the 24:1 gear ratio wanted their locomotive to have high torque for the tug-of-war challenge. They reasoned that for the sprint challenge the low top speed from this ratio would not be a great disadvantage as locomotives spend most of their time accelerating and relatively little time at top speed.

Another team designed their locomotive so that gear ratio could quickly be changed from 12.5 to 16.6 to 1. The winning team had a 9:1 gear ratio and a single drive train to minimise losses.

All locomotives, except one, had just four wheels. One team decided that their locomotive should have six wheels as they felt that this would give extra adhesion in the tug of war challenge. Unfortunately, this theory did not work as it lost the first heat of this challenge. However, with its extra axle, it almost won the sprint challenge. This locomotive also won the engineering excellence award.

Valuable lessons learnt

After the trials, prizes were given for first, second and third places. There were also prizes for best teamwork and engineering excellence. These were awarded by the University of Huddersfield’s Professor Andrew Ball who had been impressed by the teams’ motivation and effort. He noted that Britain had a critical shortage of engineers and was glad to see the Smallpeice Trust organising courses such as this one to encourage young people to choose engineering as a career.

Speaking to the teams, it was clear that they had enjoyed seeing their locomotives progress from concept to hardware. One comment was how the mathematics just seemed to work as the locomotive behaved as they thought it would. A number of pupils commented that they had expected to find the course interesting but not as interesting as this.

The Smallpeice Trust and the Universities of Huddersfield and Birmingham are to be congratulated in providing these courses to attract schoolchildren to engineering careers. In this, they seem to have succeeded.

Written by David Shirres