Chicago Transit Authority 5000 Auxiliary Power Unit, A Success Story for TPS

At the start of the supplier selection process for the 5000 series cars, Chicago Transit Authority narrowed down potential APU suppliers from a worldwide source. This validation process was particularly detailed in the selection of manufacturers who could meet or indeed improve on the CTA specification. The supplier qualification process involved reviewing the design, pedigree and response to detailed questioning on the proposed solutions for the project.
After this rigorous selection process, Turbo Power Systems was selected as one of the two preferred APU suppliers. It was a significant achievement for TPS to gain this credibility against worldwide competition from a demanding customer with a demanding application.

Chicago Transit Authority considers that they have one the most severe track conditions in the USA. This is due to the wide weather extremes, track misalignment and the effects of icing particularly on the elevated sections in the downtown area.
On previous rolling stock they had a difficult history on equipment reliability and most of the new design activities were aimed at mitigating pervious failings.
When Bombardier subsequently won the order TPS were their first choice supplier for the APU.
Even though TPS were the favoured supplier, the competition to select the best design, best company perception and performance with the lowest cost solution was intense. TPS eventually won the project on all counts.

There were several aspects of the Chicago Transit specification that made it more onerous.  Chicago Transit Authority had pushed the boundaries on what would otherwise been considered a ‘standard design’.

  • The Chicago Transit Vehicle is quite compact and there is limited space under floor for mounting equipment.
  • The location for the APU was directly behind the Truck, exposed to spray, debris grease and other contaminants.
  • The wide temperature variations particularly in the summer when the vehicle arrives in a station.
  • The track voltage transients added to shoe bounce particularly in the winter.
  • The specific battery charging regime.

Turbo Power Systems with their pedigree and experience worked closely with both Bombardier and Chicago Transit during the design phase to obtain the best solutions for the particulars of the application outlined above.

Various innovations both in circuits and in packaging were introduced into this design to ensure it meets the stringent environmental and operational conditions dictated by the application.

CTA Unit

When the first 5000 Series production prototypes were manufactured, Turbo Power Systems entered into extensive validation programs with thermal test, vibration, noise and other systems integration test to prove the APUs performance.

Turbo Power Systems has now delivered more than 300 APUs that have demonstrated expected performance and high reliability.

TPS is the UK based supplier of choice of APUs to the rolling stock.

Contact Turbo Power Systems for further information