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Wheels keep turning

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The wheels on the UK’s largest light rail network will continue turning, thanks to the early completion of a brand new lathe. The flanged wheels of all rail vehicles, while they may look superficially quite simple in shape, are actually machined to closely controlled tolerances. The profile of a wheel is matched to the profile of the rail it runs on to minimise wear and to ensure smooth running. If the profiles on either component are out of tolerance, excessive wear takes place, which necessitates expensive replacement, and even derailments can result.

Manchester Metrolink’s fleet of M5000 trams, which was introduced into service between 2009 and 2016, runs on-street and on dedicated lines. When sharing public roads with pedestrians and vehicles, grooved rails are used, embedded into the tarmac of the roads. Off-street, they are conventional railway lines.

To take account of these two environments, and the different speeds used on and off-street, the profiles on the trams’ wheels have to be carefully controlled. When they wear, they need to be re-machined to restore the profile. For that, Metrolink operator RATP Dev, who facilitated the works, providing technical help and support, needed a good quality, precise and efficient wheel lathe that could machine the correct profile into a tram’s wheels while they are still fitted to the vehicle.


New lathe for Trafford

Sheffield-based rail depot equipment specialist Mechan helped Polish wheel lathe experts Koltech obtain an order from Transport for Greater Manchester (TfGM) for the provision and assisted installation of a new TUP 650 lathe by assisting with the tender and contract negotiations. Mechan, as the sole UK and Irish supplier of Koltech product, will have responsibility for servicing the lathe once installed and commissioned.

Cairn Cross Civil Engineering, working in partnership with Metrolink, Koltech and Mechan, started work on installing the new wheel lathe at Metrolink’s Trafford depot in June 2016. Cairn Cross, a multi-disciplinary design-and-build specialist with over 25 years of experience within the rail sector, has successfully installed wheel lathes throughout the UK, from London to Edinburgh, since 2012.

This latest project is the seventh lathe to have been installed in five years. The Koltech underfloor wheel lathe can be used to recondition the wheel profiles of any rail vehicle without removing them from the carriage. The Trafford depot order has internal axle box supports to fix the trams to the machine and is equipped with a swarf crusher and conveyor to remove all waste metal produced during the turning process.

All the design work was completed by the Cairn Cross in-house team, providing the client with a comprehensive design package and liaising with Koltech throughout the programme. The work called for structural modifications to an existing pit – the floor had to be raised by 1.5 meters – along with reinforced concrete plinths to seat the new wheel lathe.


Service and safety

To service the wheel lathe, the client required the installation of a new 1.5 tonne jib crane working at a six-metre radius. This is integrated into the existing steel building structure.

An interlocking system was incorporated as an extension of the existing depot protection to provide safety and security for operational staff working on the lathe. Interlocking allows users to safely operate the machinery in a controlled and safe manner. The system was extended to include the battery shunter, overhead line, jib crane and road protection. There is a complementary fume and dust extractor and the installation of a lone worker alarm system provides operators with an additional safety mechanism in case of any emergencies.

Cairn Cross’s electrical team provided distribution boards and electrical cabling to power the lathe, including the use of Endurance luminaires to provide appropriate working lux levels within the pit. These provide the depot with three hours of emergency lighting should it be subject to power failure. The existing bonding system was modified to ensure safety of the machine and associated equipment from potential DC stray currents within the existing system.

Aaron Morgan, Cairn Cross Civil Engineering’s site manager said: “The early completion of this wheel lathe installation has come about due to the fantastic working relationship between all stakeholders”.


Tram on lathe.

Transport for Greater Manchester’s head of Metrolink, Danny Vaughan added: “Having just opened the brand new Second City Crossing and started work on a new line out to the Trafford Centre, it’s more important than ever before that we maintain our 120-strong fleet to the highest standards.

“This new lathe will ensure a more efficient way of working and is therefore a hidden benefit that the customer won’t be aware of but that will ultimately help us to keep them, and the network, moving.

“I’d like to thank all involved for their work in procuring and installing the new wheel lathe.”


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