Design and construction

During the design phase, different bogies were tested for the trailer cars. Two SDS cars were fitted with new bogies to test the ride quality. SDS2245 received the prototypes of the Comeng CT22 bogie, and SDS2252 received imported British Rail BT10 bogies.

All photos below are builder's photos. Click on the thumbnails to enlarge.

Prototype CT22 under SDS2245.								Production CT22 at Granville factory.

The test train ran to Armidale on 14/4/80. The consist was 42205-4470-DMC1902-SDS2252-SDS2245-LTC1903-NVEF11567.

Comeng was the first engineering company in Australia to indroduce Computer Aided Design (CAD). The XPTs were some of the first rail vehicles designed by CAD.

XPT power car being designed on computer.

Automated drawing production on the CAD plotter.

Styling and exterior colour scheme in preparation.

Full size timber mockup of XPT power car nose.

Full size cab mockup.

The power bogies are similar to the British BP10 as used on the HST, but have increased vertical movement on the primary suspension and softer secondary suspension. The secondary suspension also has more lateral movement to cope with local track conditions. The weight of the power car is more evenly distributed than on the HST. The coupler heights are lower than the HST.

As originally (re)designed, the XP was to have an 8-notch controller and standard multiple unit jumpers. This would, at least theoretically, allow it to run in multiple with existing locomotives if required. The Public Transport Commission, fearing that XPs might end up hauling freight, overruled this and decreed that the 5-notch controller from the HST was to be fitted.