[4] The typical role of a TR was at small stations where a normal shunting locomotive was not needed due to light traffic.

NZR's operating rules allowed TRs to be driven by staff who were not members of the locomotive branch, saving on wages.

Other roles have included shunting at railway workshops and depots, and most of the remaining locomotives can still be found at these locations.

There are very few stations where they are still in use owing to rationalisations of freight terminals, the trend towards containerisation of traffic, and roving shunting services.

Although A & G Price built similar locomotives for NZR, plus a J & F Howard's former Public Works Department shunter no.

These locomotives were never owned by New Zealand Railways Department or their successors and thus their TR classification and numbers are historically fictitious.

[6] The first TR shunting locomotive built was TR1, constructed at Petone Workshops, New Zealand in July 1924.

It was built from a standard Fordson 22 hp tractor, which was attached to a patent underframe supplied by the Adamson Motor Company of Birmingham, Alabama.

The locomotives were built at various United Kingdom works including Vulcan Foundry and Robert Stephenson and Hawthorns.

The McLaren engines were unsuccessful, so from 1973 TR 150-154 were re-engined with the Gardner 6LX with Twin Disc torque converters.

The long-established New Zealand engineering firm A & G Price of Thames supplied a total of 39 TRs, making them the largest single builder.

[12] In the 1960s Hitachi received an order for six TRs, 177-182, at a time when NZR was turning away from traditional English suppliers and purchasing an increased number of vehicles from Asia.

[4] The locomotives were equipped with a Cummins 6-cylinder engine developing 138 kW (185 hp) and Niigata torque converter, making them the most powerful TRs.

The design is an unusual (for a TR) centre-cab style with a single Gardner 6LX engine and Rolls-Royce torque converter.