Superstructure.

The superstructure of the vehicle, consisting of a tower and accommodation at each end for the driver, has been designed by the chief mechanical engineer of the railways (Mr. G. S. Lynde), and will be constructed in the New Zealand Government Railway workshops. It will be approximately 15ft long and 8ft wide, and will house the driver, the engine, and repair material for the overhead cable. The gauge of the car is 3ft 6in, and the wheel-base 10ft, and it will be required to operate on a 3 per cent. up-grade with a total load of 9000lb on the chassis and a gross training load of 14,000lb at a speed of 15 miles an hour. All controls are duplicated at each end to allow the vehicle to be operated in both directions with the full trailing load.

The car has a 6-cylinder engine with cylinders 100mm. bore by 140mm. stroke, developing 80 b.h.p. at 2000 r.p.m. The valves are placed on one side and are of large diameter—inlet valve of nickel steel and exhaust valves of stainless steel. The crank-case is of valves of stainless steel. The crank-case is of aluminium, and the capacity of the sump is three gallons. Lubrication is by gear pump through a large strainer to the main and cam-shaft bearings, and through the crank-shaft to the big end bearings, efficient relief valves being fitted to the whole system. Ignition is by high tension magneto, and an electric starter and lighting are also fitted. Efficient cooling is secured by two gilled tube radiators with cast tanks and side brackets mounted one at each end of the vehicle, circulation being carried through the engine and the two radiators in series by a large capacity rotary pump. A fan is also mounted at the engine end.