NZR DM Class - Technical Details

Technical Details

Motor cars have 54 seats and trailers 70 seats (originally 56 and 72 seats). Originally there was a double seat alongside the driver's cab. During renovations this seat was removed, reducing the seating by two, and a barrier was installed level with the back of the cab.

Some motor cars had the double seats in the rear section in front of the luggage compartment removed and the seats parallel with the sides extended to provide space for prams.

Motor cars originally had a driver's cab at each end, but extra space was needed in the luggage compartment and the cab there was removed. Initially a single motor car had been used on the Johnsonville line for the all-night service, and this was considered for the Melling line.

Each car had ten 150 V electric heaters in series run off the 1500 V supply, so a 1500 V connection was required between motor cars and trailers. 46 stock differed from 36/42 stock in some respects:

• 36/42 stock motor cars had a 120 V DC motor-generator set supplying power for lights, signal circuits and brake & door operation; 46 stock set was larger, to supply two trailers rather than one.
• 36/42 stock bogie wheelbase was 7 ft 6 in (2.3 m); 46 stock 8 ft (2.4 m).
• 36/42 stock had ventilation louvres in the doors; 46 stock had taller windows.
• 36/42 stock had one coach-mounted brake cylinder only; 46 stock had Westinghouse electro-pneumatic air brakes and automatic brake equipment.

Because of their shorter wheelbase and the smaller motor-generator set designed for one trailer only, 36/42 stock units were kept for the Johnsonville line as much as possible.