The Heisler locomotive was the last variant of the three major types of geared steam locomotive, Charles L. Heisler receiving a patent for the design in 1892 following the construction of a prototype in 1891. Somewhat similar to a Climax locomotive, Heisler's design featured two cylinders canted inwards at a 45-degree angle to form a 'V-twin' arrangement. Power then went to a longitudinal drive shaft in the center of the frame that drove the outboard axle on each powered truck through bevel gears in an enclosed gearcase riding on the axle between the truck frames. The inboard axle on each truck was then driven from the outboard one by external side (connecting) rods.

Built in 1943 by A & G Price of Thames in the North Island to the order of Ogilvie & Co., Gladstone, Westland it ran on their extensive bush tramway until 1958. Approximately 3,500 man hours have been spent on its restoration over a 4 year period. Weight of the loco is 20 tons and the ‘V' type engine has cylinders 10” diameter by 9” stroke and the valve gear actuates piston valves. Boiler pressure is 150 psi and approximately 1 ton of coal is carried in the bunker and 450 gallons of water in the side tanks. Original public domain image from Flickr