DC Motor Compressor Conversion

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Angel Trains / Merseyrail



The Problem:

The train operator was looking to extend the working live of Class 508/509 EMUs. These were fitted with a very old design of reciprocating compressor. Whilst the DC motors were satisfactory, the compressors were life expired. The situation was complicated in that the motors and compressors were designed as an integrated unit.

KSL Solution:

KSL undertook a design study to evaluate the possibility of reusing the existing motors with a replacement compressor. A concept design was developed where the principle components of the motor were re-used – thus avoiding costly approvals – and created a mechanical interface for a replacement compressor. This included the design of new support bearings/housings and the motor drive end shield / support brackets.


1000 l/min @ 7.6 bar


The project was deemed technically and financially feasible and would have offered a cost effective method of extending the vehicle lives. The project was discontinued due to the rolling stock being replaced with new trains.
A similar project is currently underway to extend the lives of 32x EMUs fitted with DC compressor motors.

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