NZR A class (1906)

NZR A class (1906)
Type and origin
Power type Steam
Builder Addington Workshops (8),
A & G Price (50)
Build date 1906–1914
Total produced 58
Specifications
Configuration 4-6-2
Driver dia. 54 in (1.372 m)
Length 57 ft 2 in (17.42 m)
Adhesive weight 33 long tons 2 cwt (74,100 lb or 33.6 t)
Loco weight 51 long tons 0 cwt (114,200 lb or 51.8 t)
55 long tons 0 cwt (123,200 lb or 55.9 t)(simple)
Tender weight 25 long tons 10 cwt (57,100 lb or 25.9 t)
Fuel type Coal
Fuel capacity 4 long tons 0 cwt (9,000 lb or 4.1 t)
Water cap 1,700 imp gal (7,700 L; 2,000 US gal)
Firebox:
 • Firegrate area		 30 sq ft (2.8 m2)
Boiler pressure 225 psi (1,551 kPa) (as coumpound)
190 psi (1,310 kPa)(simple)
Heating surface 1,724 sq ft (160.2 m2)
Cylinders 2 HP, 2 LP
Cylinder size 18 in × 22 in (457 mm × 559 mm)(simple)
High-pressure cylinder 12 in × 22 in (305 mm × 559 mm)
Low-pressure cylinder 19 in × 22 in (483 mm × 559 mm)
Performance figures
Tractive effort 17,000 lbf (76 kN) (as compound)
20,060 lbf (89.2 kN)(simple)
Career
Operators NZGR
Withdrawn 1954–1969
Preserved Two: 423, 428
Disposition Two preserved, remainder scrapped

The A class were steam locomotives built in 1906 with a 4-6-2 wheel arrangement for New Zealand's national railway network, and described by some as the most handsome engines to run on New Zealand rails. The class should not be confused with the older and more obscure A class of 1873. They were designed by the New Zealand Railways Department's Chief Mechanical Engineer, A. L. Beattie and his Chief Draughtsman, G. A. Pearson to replace less powerful locomotives struggling with increasing loads on the South Island Main Trunk Railway, and in anticipation of the traffic volumes that would be created upon the completion of the North Island Main Trunk Railway.

Origin and Design

The Baldwin Q had established the Pacific as the way forward for Express passenger locomotives, but the C.M.E decided that greater efficiency was needed. The new locomotives were therefore designed as compounds. The Vauclain system had proved ineffective in New Zealand so the type attributed to Frenchman Alfred de Glehn was adopted.

The first four had Stephenson valve gear inside and Walschaerts valve gear outside, while the following 53 had just Walschaerts. The first eight locomotives were built at New Zealand Railways Department's Addington Workshops, the rest by A & G Price of Thames. The first twenty-seven were built with intercepting valves allowing full simple operation. This feature was later removed from all but the first four, and the last thirty were built without and classified as AD until 1915.

Service and Modifications

Initially fifty Price built engines were allocated to the North Island the rest to the South. The class were delivered with 1700 gallon tenders which were inadequate for work on the NIMT. To solve this larger tenders were ordered for the BB class which were given A class tenders. Delivered with saturated boilers, one of the class was given a superheated boiler after two years. Cost meant the rest were converted only as their boilers wore out. From the thirties onward the class were fitted with pressed-steel smokebox doors for Waikato spark arrestors, although not always the arrestors themselves.

Although competent engines the maintenance of the inner cylinders was difficult. In 1941 No. 582 was converted to two cylinder simple arrangement. The last was finished in 1949 and the class remained successful performers thereafter.[1]

Until the arrival of large numbers of the AB class the As' were country's premier express engines. Starting in 1932 thirty-eight of the North Island engines went south. By this time they were being relegated to secondary and branch line service. Despite this the last North Island engine was not withdrawn until 1961 and the last in the south until 1969, near the end of steam. The final A class to be withdrawn was A 428.

Preservation

Two class members have been preserved:

A 409

The eighth locomotive built, A 409, was built in 1908 as a two-cylinder simple-expansion locomotive for comparative purposes against the four-cylinder compounds. Fitted with an ALCO superheater as a trial when built, it was marginally more powerful than the other A class locomotives as a result despite having only two cylinders. Despite its differences, it was classified for a time as AB 409 up until the 1930s along with the mechanically derived AB class locomotives.

A 409 was withdrawn in October 1959 and was scrapped at Linwood locomotive depot as being largely 'non-standard'.

Class roster

Key: In service On lease Out of service Preserved Overhaul/Repair Scrapped
Number Builder Builder's number Introduced Withdrawn Converted to 2-cylinder simple Comments
71 NZR Addington 70/1906 3-7-1906 3-1969 4-12-1942
161 NZR Addington 71/1906 7-9-1906 10-10-1964 22-12-1942
178 NZR Addington 72/1906 6-5-1907 10-1967 2-12-1943
399 NZR Addington 73/1906 27-3-1907 2-1959 15-11-1946
406 NZR Addington 80/1907 20-12-1907 3-1968 28-5-1943
407 NZR Addington 81/1908 12-3-1908 10-1962 25-6-1943
408 NZR Addington 82/1908 31-3-1908 7-1961 13-9-1946
409 NZR Addington 83/1908 20-7-1908 10-1959 Built as 2-cylinder simple. Originally classed Ab.
410 A & G Price 13/1907 6-12-1907 8-1960 7-11-41
411 A & G Price 14/1908 14-2-1908 8-1966 2-1949
412 A & G Price 15/1908 30-3-1908 7-1961 3-1948
413 A & G Price 16/1908 28-5-1908 23-5-1964 3-1948
414 A & G Price 17/1908 30-6-1908 23-5-1964 29-4-1944
415 A & G Price 18/1908 1-8-1908 7-1962 17-12-1943
416 A & G Price 19/1908 16-9-1908 10-1967 3-1948
417 A & G Price 20/1908 23-9-1908 23-5-1964 9-7-1943
418 A & G Price 21/1908 27-11-1908 3-1965 6-12-1945
419 A & G Price 22/1908 21/12/1908 7-1961 22-12-1941
420 A & G Price 23/1908 12-2-1909 11-1961 16-8-1944
421 A & G Price 24/1909 15-3-1909 3-1965 6-1947
422 A & G Price 25/1909 16-4-1909 20-6-1964 29-9-1942
423 A & G Price 26/1909 15-5-1909 7-1969 20-2-1942 Preserved at Glenbrook Vintage Railway.
424 A & G Price 27/1909 18-6-1909 3-1969 3-1949
425 A & G Price 28/1909 16-7-1909 3-1965 13-7-1945
426 A & G Price 29/1909 27-8-1909 3-1969 7-1948
427 A & G Price 30/1909 20-8-1909 10-10-1964 3-1949
428 A & G Price 31/1909 6-11-1909 7-1969 9-2-1943 Preserved at Weka Pass Railway.
429 A & G Price 32/1909 29-11-1909 9-1959 11-1947
469 A & G Price 33/1910 18-10-1910 7-1961 12-1947
470 A & G Price 34/1910 29-11-1910 12-1965 2-4-1943
471 A & G Price 35/1911 31-1-1911 4-1962 16-2-1944
472 A & G Price 36/1911 13-3-1911 9-1966 31-3-1942
473 A & G Price 37/1911 25-4-1911 2-1959 9-2-1944
474 A & G Price 38/1911 2-6-1911 8-1966 22-5-1942
475 A & G Price 39/1911 14-7-1911 5-1963 14-7-1942
476 A & G Price 40/1911 22-8-1911 7-1961 8-8-1941
477 A & G Price 41/1911 9-10-1911 3-1962 4-1947
478 A & G Price 42/1911 7-11-1911 3-1965 9-1948
578 A & G Price 43/1912 2-7-1912 2-1963 15-10-1943
579 A & G Price 44/1912 6-8-1912 8-1958 5-5-1944
580 A & G Price 45/1912 27-9-1912 12-1967 19-2-1945
581 A & G Price 46/1912 1-11-1912 20-6-1964 8-3-1942
582 A & G Price 47/1912 3-12-1912 7-1961 21-3-1941 Prototype conversion from 4-cyl De Glehn to 2-cyl simple.
583 A & G Price 48/1913 14-2-1913 10-1954 6-8-1945
584 A & G Price 49/1913 25-3-1913 2-1957 12-10-1944
585 A & G Price 50/1913 16-5-1913 3-1957 2-3-1943
586 A & G Price 51/1913 20-6-1913 2-1957 25-5-1945
587 A & G Price 52/1913 13-8-1913 10-1954 11-3-1942
598 A & G Price 53/1913 31-10-1913 10-1968 23-11-1943
599 A & G Price 54/1913 28-11-1913 10-1959 11-12-1944
600 A & G Price 55/1914 19-2-1914 12-1957 7-5-1943
601 A & G Price 56/1914 16-3-1914 6-1961 23-7-1943
602 A & G Price 57/1914 28-4-1914 6-1969 28-10-1943
603 A & G Price 58/1914 30-5-1914 3-1957 4-1948
604 A & G Price 59/1914 10-7-1914 2-1957 15-6-1944
605 A & G Price 60/1914 12-8-1914 12-1957 3-1949
606 A & G Price 61/1914 26-8-1914 2-1957 10-3-1943
607 A & G Price 62/1914 10-10-1914 2-1957 9-11-1945

See also

References

  1. ↑ Millar, Sean (2011). The NZR Steam Locomotive. NZR&LS.

NZR Steam - A/AD class 4-6-2


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