NZR B class (1899)

NZR B class (1899)
Power type	Steam
Builder	NZR Addington Workshops (6); Sharp, Stewart & Co. (4)
Build date	1899 (5), 1901 (1), 1902 (2), 1903 (2)
Total produced	10
Configuration	4-8-0
Gauge	3 ft 6 in (1,067 mm)
Driver diameter	42.5 in (1.080 m)
Length	52 ft 1 1⁄2 in (15.89 m)
Weight on drivers	31 tons 14 cwt (71,000 lb or 32.2 t)
Tender weight	25 tons 10 cwt (57,100 lb or 25.9 t)
Locomotive & tender combined weight	68 tons 10 cwt (153,400 lb or 69.6 t)
Fuel type	Coal
Fuel capacity	4 tons 0 cwt (9,000 lb or 4.1 t)
Water capacity	1,700 imperial gallons (7,700 l; 2,000 US gal)
Tender capacity	4.0 tons coal 1,700 gallons water
Boiler pressure	175 lbf/in² (1.21 MPa)
Firegrate area	17.3 sq ft (1.61 m2)
Heating surface: Total	1,037 sq ft (96.3 m2)
Cylinders	Two, outside
Cylinder size	16 × 22 in (406 × 559 mm)
Tractive effort	18,550 lbf (82.5 kN)
Career	NZGR
Number in class	10
Number	178, 198, 302-309
Withdrawn	1960–1967

The B class of 1899 was a class of steam locomotives that operated on New Zealand's national rail network. An earlier B class of Double Fairlies had entered service in 1874, but as they had departed from the ownership of the New Zealand Railways (NZR) by the end of 1896, the B classification was free to be re-used.

Construction

The B class was designed as a larger, more powerful locomotive to handle mainline freight trains that were becoming too heavy for locomotives of the O, P, and T classes. The first was built in NZR's own Addington Workshops in Christchurch and entered service on 4 May 1899, and an order was placed with Sharp, Stewart and Company of Glasgow, Scotland to supply four more. The first engine from Scotland entered service on 20 December 1899, followed by the other three within the next month.

Over the course of 1901–1903, five more Bs were built in Addington Workshops, with the last entering service in May 1903. The locomotives were advanced for their time, featuring a new piston valve design and a modified form of Walschaerts valve gear, and they were designed to haul 600 ton freight trains on flat lines and 220 tons on the hilly section of the Main South Line between Oamaru and Dunedin. For the time, these were quite significant figures. The Addington engines were unusual in the fact that they employed a screw reverse configuration, instead of the standard reversing lever. They also had fold down seats for both driver and fireman.

Interestingly, only a couple of years after their arrival in New Zealand, three of the four Sharp, Stewart models entered NZR's Addington and Hillside (Dunedin) Workshops to be rebuilt, emerging as the 4-6-4T tank locomotives.

Operation and improvement

In their early years, the B class hauled freight trains between Christchurch and Dunedin, with their pulling power a considerable asset. However, they did not last long on this task. In 1906, the A class was introduced, followed by the ubiquitous A^B class in 1915, thus displacing the B class locomotives to branch line trains, and in later years, shunting duties.

In later years, four of the Addington-built members of the B class received upgrades. The first to be upgraded was B 306, re-entering service in March 1930. The overhaul involved the installation of wider fireboxes and superheated boilers, increasing the boiler pressure to 200 psi and generating a tractive effort of 21,200 lbf. B 304 was similarly overhauled in 1931 and B 307 followed in 1935, and then a considerable length of time elapsed until B 303 in 1948 became the fourth and last to be upgraded.

Withdrawal

All members of the B class, including the three converted into W^E tanks, survived until the last decade of steam in New Zealand in the 1960s, with the country's last regular steam-hauled service running on 26 October 1971. B 302 barely made it into the 1960s, becoming the first of the class to be withdrawn on 2 December 1960. B 306 followed the next year, and by the start of 1967, only two Bs were in operation. They were retired in December of that year. The last W^E was taken out of service in March 1969.

No members of either B or W^E classes survived to be preserved, despite the fact they survived into the era of preservation societies.

Similar locomotives

Three similar classes of locomotives operated on NZR, and they accordingly received similar classifications: B^A, B^B, and B^C. Like the B class, the B^A and B^B classes had a wheel arrangement of 4-8-0, but the solitary member of the B^C class was a 2-8-2 locomotive.

External links

• New Zealand Railways Steam Locomotives - B class
• New Zealand Railways Steam Locomotives - W^E class