NZR class G (1928)

from Wikipedia, the free encyclopedia
NZR class G (1928)
NZR class G (1928)
NZR class G (1928)
Numbering: 98-100
Number: 3
Manufacturer: Beyer-Peacock
Year of construction (s): 1928
Retirement: 1931 (converted to Pacifics in 1937)
Type : (2'C1 ') (1'C2') h6
Gauge : 1067 mm ( cape track )
Length over coupling: 25,698 mm
Service mass: 148.1 t
Friction mass: 89.1 t
Wheel set mass : 15.1 t
Driving wheel diameter: 1447 mm
Cylinder diameter: 419 mm
Piston stroke: 610 mm
Boiler overpressure: 137.34 N / cm²
Grate area: 5.9 m²
Radiant heating surface: 22.76 m²
Tubular heating surface: 206 m²
Superheater area : 50.3 m²

The 1928-built vehicles of class G of the New Zealand National Railways ( New Zealand Government Railways , NZR) were steam locomotives of the type Garratt . They were the first and only Garratt locomotives to operate in New Zealand and the largest locomotives ever built for that country. However, they could not convince and were taken out of service after a few years. In 1937, six conventional locomotives, which were also designated as class G , were built from the engine frames of the three locomotives .

history

After the New Zealand State Railroad had already experimented with articulated locomotives of the Fairlie and Mallet types with limited success , three Garratt locomotives were purchased by Beyer-Peacock in 1928 . You should reduce the pushing operation on the steep stretches of the North Island . The machines were given the class designation G , which had previously been carried by a number of tank locomotives built in 1873 (see NZR class G (1873) ).

The Garratts were also unsuccessful as they suffered from several problems, but only in part were due to design flaws.

The couplings used in New Zealand were too weak for the trains the Garratts could pull, and the station and sidings were too short. The stoker jammed easily, the Garratt design was unfamiliar to the maintenance staff, and the three-cylinder engine, also unfamiliar in New Zealand, was difficult to adjust. All of this meant that the locomotives were retired as early as 1931, making them one of the few Garratt locomotives that were unsuccessful.

In 1937 the parked locomotives were dismantled, and parts of them were used to create six Pacific locomotives (further referred to as class G ), with the running gear and engines being reused in particular (with the exception of the inner running axles). These locomotives not only retained their class designation, but three of the six also retained the Garratt's operating numbers. They too suffered from the problems of the three-cylinder engine that was retained during the conversion and were therefore retired in 1956, as the first main-line locomotives to make way for the emerging diesel locomotives.

The Class G Garratts remained the only locomotives of this type used in New Zealand. Some Garratt designs for use on the Rimutaka partial ramp were worked out, but none of them were implemented. One of the designs was a locomotive for the Fell system , another envisaged a reduction in the speed of the drive wheels compared to the engine via gear transmission.

Technical features

The locomotives had three-cylinder engines of the Gresley type , in which the control of the inner cylinder was derived from that of the outer cylinder via transverse levers. Only one other Garratt in the world was equipped with such an engine, locomotive No. 2395 of the LNER (class U1 ). The outer cylinders were also inclined so as not to violate the clearance profile . All cylinders worked on the central coupling axis.

The coal box, which was not built on the rear engine frame, but on the main frame, was also unusual. This made it easier to install the stoker because there was no relative movement between the boiler and the coal box. The locomotives were thus an intermediate form between normal Garratts and the Union Garrats, in which the rear plenum tank was also attached to the main frame (e.g. class U of the South African Railways).

literature

Web links