NZR DB class

New Zealand DB/DBR class
DBR 1199 at Westfield
Type and origin Power type Diesel-electric Builder General Motors Diesel Canada (builder) Clyde Engineering, Australia (rebuilder) Model EMD G8 Build date 1965–1966 (built) 1980–1982 (rebuilt)
Specifications Configuration: ​  • UIC A1A-A1A Gauge 3 ft 6 in (1,067 mm) Length 14.0 m (45 ft 11 in) Adhesive weight DB 47.0 t (46.3 long tons; 51.8 short tons) DBR 46.0 t (45.3 long tons; 50.7 short tons) Loco weight DB 69.0 t (67.9 long tons; 76.1 short tons) DBR 68.0 t (66.9 long tons; 75.0 short tons) Prime mover DB GM 8-567C DBR GM 8-645C Engine type V8 Diesel engine Aspiration Roots-type supercharger Displacement DB 74.33 litres (4,536 cu in) DBR 84.56 litres (5,160 cu in) Traction motors Four EMD D29 Cylinders 8 Cylinder size 9 1⁄16 in (230 mm) x 10 in (250 mm)
Performance figures Maximum speed 100 km/h (62 mph) Power output DBR 709 kW (951 hp) Tractive effort 100 kN (22,000 lbf)
Career Number in class 17 Numbers DB 1000–1016 (original) DB 1001–1180 (TMS) DBR 1199–1295 First run DB 1965 – 1966 DBR 1980 – 1982 Last run DB 1986 – 1989 DBR 2002 - 2017 Disposition 6 DBRs stored 7 DBs and 2 DBRs scrapped 2 DBRs preserved

The New Zealand DB class and DBR class locomotive is a type of diesel-electric locomotive built for service on New Zealand's rail network. They were built by General Motors Diesel (GMD) of Canada as a narrow-gauge version of the EMD G8 model, with seventeen locomotives constructed. Ten of these were later rebuilt into the DBR class. All now have been withdrawn.

The DB class was introduced to the rail network in 1965-1966 as a result of a requirement for a modern locomotive that could operate on the North Island lines that the D^A class was excluded from due to their weight and axle load. While these were mainly branch lines, it also applied to the East Coast Main Trunk line, particularly the section beyond Paeroa through the Karangahake and Athenree gorges, until the opening of the Kaimai Tunnel in 1978. The class was virtually indistinguishable externally from the D^A class, being of the same basic design and dimensions, and wearing the same livery. They were some 13 tonnes lighter with a V8 prime as opposed to a V12, though they shared the same A1A-A1A wheel configuration and traction motors for commonality with the D^A fleet.

In the late 1970s the decision was undertaken to rebuild the D^B class along similar lines to that being undertaken for the D^A class into the DC class. However, as the rebuild was not as extensive and did not involve conversion into another GMD model the rebuilt D^B units were designated as DBR (R = rebuild). The work was undertaken by Clyde Engineering in Australia and involved the lowering of the short hood to improve visibility for the driver, new cabs and the installation of a new EMD 8-645 engine. Ten units were rebuilt between 1980 and 1982.

The D^B class was employed primarily freight duties, though they did also see occasional service hauling passenger trains. As lines and bridges were upgraded, and in the case of the ECMT the Kaimai Tunnel opening, the weight advantage the locomotives had over other classes used in the North Island became less of a factor and the locomotives were operated as part of a general pool. The lightweight nature of the locomotives was called upon again however to operate some South Island lines following the withdrawal of the D^I and D^J classes. The last DBR returned north from the South Island around 2007.