If the N, Z and H Cars are not suitable for higher speed than 115kmh why were some of the N class locos regeared for 130kmh operation?
Two issues here.
1. As originally purchased the N class locos were used for both passenger & freight duties and as such the gearing chosen was a compromise of 115kmh to suit passenger , and grunt at low speed for freight . Now they are used exclusively on VLP passenger services as there is a need to fit new traction motors the decision was taken to fit those motors with gearing suitable for 130kmh operation, if and when that became possible on Class-1 track . Class 1 track only exists in selected sections of the RFR lines so far .
2. The intention with the Nth East standardization was to achieve Class 1 track standard on the East Line at least . As such and in anticipation of that track standard being achieved by ARTC three N class locos already regeared for 130kmh, and the 3 x 6 car sg N sets all were said to have had bogie modifications (brake rigging,, springing and dampener improvements) to allow 130kmh running for the sg N sets only .
The botched tie renewal by ARTC the on going track stability issues on both the East & West lines have not as yet achieved a Class-1 track , so current speeds are restricted to loco hauled 115kmh and lower in many places, plus a plethora of semi permanent speed restrictions on the West line especially.