Case Studies

Whitelegg Supports Alstom DC Motor Repair Facility

Alstom's Train Life Services division, Preston was designated in 2006 as the aftermarket Centre of Excellence for traction motors. This historic 60,000m2 (15 acre) site undertakes servicing and repairs to most of the UK's mainline DC rail traction motors and latterly to AC motors. Whitelegg Machines has a long association with the company and its equipment continues to help Alstom maintain production excellence.

Alstom has a long and continuous association with rail transport engineering. The proud heritage of ownership of the division based in Preston includes names such as English Electric of Deltic fame, AEI and GEC.

The Train Life Services business undertakes repair and refurbishment of DC traction motors for most of the UK train operators in the UK and some for overseas. These typically would be operating on direct 3rd rail electrification or with diesel electric motive power. The plant currently handles suburban stock of 100kW-200kW, the class 90 locos of 800/900kW with the largest being the 1160kW Class 91, built for British Rail in the 1980s, with many in between.

It is this diversity of motors, coupled with the continuous operational efficiency demanded by the rail companies, that places great demands on the high quality engineering output of the company.

Typical Service programme:

On receipt of a motor, with perhaps 4 years main line operation, the armature is fully stripped down for inspection with an evaluation made of its condition; including magnetic particle inspection and washing and stoving.

With the commutator it is virtually certain that wear from the brushes will be seen. This necessitates skimming to return it to a truly circular form ready for the undercutting process which is, in effect, the re-grinding of the longitudinal grooves in the mica to high accuracy, to prevent brush wear.

Alstom's existing undercutter was nearly 20 years old and, with the demands of higher throughput and precision, a more modern machine was deemed necessary.

It was in early 2009 that Whitelegg were called in by Steve Aiton, Motor Cell Manager and, following consultation, a Rimac machine was recommended. Initially a visit was made by Steve and his chief motor machinist Geoff Lowe to the London works of Metronet, the tube train engineering company. Here they saw a similar undercutter in operation. Subsequently a visit was made to Rimac in Italy where they saw the model they desired, in operation at a customer's premises. The decision was made to buy the machine with additional fibre optic to control the rotation of the armature where a laser cannot be used.

The Rimac machine is very operator-friendly and fully computer controlled, with touch screen for easy set up. It can handle armature dimensions between 150 and 1500mm. The bar to bar cutting and indexing is controlled by high accuracy laser. The machine is fitted with a camera and 15inch screen giving a 10x magnification to the area of work; thus greatly improving the ease of use and overall machine accuracy. Once commenced the operation is completely automatic and substantially reduces the time taken when compared to the older machine. The current repair contract places heavy demands on the Rimac. With 20 motors per week being serviced, the machine is in continuous use.