NZR D class (1929)
      
NZR D class| | Type and origin | 
|---|
 | Builder | Clayton(1) | 
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 | Build date | 1929 | 
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 | 
| | Specifications | 
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 | Configuration | 0-4-0 | 
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 | Driver dia. | 42 | 
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 | Loco weight | 25.7 long tons (26.1 t; 28.8 short tons) | 
|---|
 | Firebox: • Firegrate area
 | 12.5 sq ft (1.16 m2) | 
|---|
 | Boiler pressure | 300 lbf/in2 (2.07 MPa) | 
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 | Heating surface | 320 sq ft (30 m2) | 
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 | Cylinders | 4, vertical | 
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 | Cylinder size | 7 in × 10 in (178 mm × 254 mm) | 
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 | 
| | Career | 
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 | Operators | NZR | 
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 | Disposition | Scrapped | 
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 | 
The NZR D class of 1929 comprised one 0-4-0 tank locomotive that was built for the New Zealand Railways Department by the Clayton Wagons Ltd in Lincoln, England.
 History 
Originally, D 1 was purchased for railcar type service but it was not successful. It had a White-Forster type boiler designed for a working pressure of 300 psi (2,068 kPa), had four vertical cylinders housed in the rear of the cab and was high geared. At a normal engine speed of 400 rpm, the unit was calculated to develop 200 horsepower (150 kW). The engine drove a central transverse jackshaft through reduction gearing, the drive from the jackshaft being transmitted to the wheels through conventional side rods.
 Working Life 
On arrival in New Zealand, D 1 was found to be more than 25 percent heavier than the specified maximum of 20 long tons (20.3 t; 22.4 short tons) and after trials in Wellington was allocated for use as a shunting engine at the Otahuhu workshops. However it never proved satisfactory and was written off in 1936 and scrapped and  D 1 did not survive to be preserved.
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