The Yorkshire Engine Company Janus was a line of 0-6-0 wheel arrangement, diesel-electric locomotives that weighed 48 long tons (49 tonnes; 54 short tons) and had a maximum speed of 23 mph (37 km/h). The two Rolls-Royce C6SFL diesel engines gave a total power output of 400 hp (300 kW). Each engine had its cooling system at the outer end, and the its generator at the inner end. There were two traction motors, each being powered by one generator, thus simplifying the electrical system.