When I was looking at the workshop plans for Diesel and Electric Locomotives I came across these two "Mini Railmotor" plans.
Does anyone know about these proposed carriages?
All I know is that they bear a resemblance to the 900 class and they are small two car sets. The second one appears to have to have a six - wheeled articulated bogie between the two cars whereas the first has two four wheeled ones.
What was the intended for and why was it cancelled?
To find them see pages 43 and 44 of the link inserted below.
These are not rail motors but are locomotives.
They are related to the drawing immediately following, the cab unit with cardan shaft drive from four body mounted traction motors. This was intended to be equivalent to the SAR 900 class, fitted with an English Electric 16 SVT engine of 1760 BHP, giving an input to the generator of about 1600 HP.
The big clue as to why this didn't go ahead can be seen in the estimated weights which were significantly less than the similarly powered SAR 900 class.
The next step was to add a seventh axle, which resulted in the unusual A1' A1A' 1A' wheel arrangement, with the engine in the left unit and the radiators, fuel and electrical gear in the right side unit. The outline of the engine is visible in the drawing of the left unit.
This probably couldn't be made to work, and yet another version, with eight axles but with two eight cylinder in-line engines in a matched pair of A1' 1A' units.
While the third version might have worked, by this time they had ordered the V-16 engines (at least, according to contemporary "Railway Transportation" magazines) and the 40 class had arrived, and proved that nothing needed to be invented.
The drawing above/before those three appears to be the AI&S 800 HP diesel electric shunter built by Comeng which used the same engine as the twin units.
The original idea was to produce a passenger locomotive for use on the North Coast line which had deteriorated badly under wartime traffic and was limited to 32 class locomotives until track repairs could be made. Trials were made with the 40 class before the end of 1952 which showed that they could do the job, but they were too valuable on freight traffic to be spared for North Coast passenger traffic.
The arrangement of traction motors on the cab unit was eventually used by GEC in the UK on the class 91 electric locomotives.