NZR BB class

NZR B^B class

Type and origin
Power type	Steam
Builder	A & G Price, Thames, NZ
Serial number	63–92
Build date	1915 (12), 1916 (8), 1917 (8), 1918 (2)

Specifications
Configuration	4-8-0
UIC class	2'Dh
Gauge	3 ft 6 in (1,067 mm)
Driver dia.	42.5 in (1.080 m)
Length	52 ft 7 ¹⁄₂ in (16.04 m)
Adhesive weight	32.5 long tons (33.0 t; 36.4 short tons)
Loco weight	43.5 long tons (44.2 t; 48.7 short tons)
Tender weight	25.5 long tons (25.9 t; 28.6 short tons)
Fuel type	Coal
Fuel capacity	4 long tons (4.1 t; 4.5 short tons)
Water cap	1,700 imp gal (7,700 l; 2,000 US gal)
Firebox: • Firegrate area	16.8 sq ft (1.56 m²)
Boiler pressure	175 psi (1.21 MPa)
Heating surface	724 sq ft (67.3 m²)
Superheater:
• Heating area	208 sq ft (19.3 m²)
Cylinders	Two, outside
Cylinder size	17 in × 22 in (432 mm × 559 mm)

Performance figures
Maximum speed	40 mph (64 km/h)
Tractive effort	20,940 lbf (93.1 kN)

Career
Number in class	30
Numbers	55, 109, 143, 144, 147, 167, 169, 171, 197, 222, 618–637
Preserved	1 (B^B 144)
Disposition	One preserved, remainder scrapped

Origin and Design

The B^B class of steam locomotives comprised 30 engines operated by New Zealand Railways in the North Island of New Zealand. Ordered to replace smaller locomotives of several classes in the North Island, they were similar in design and appearance to the preceding B and B^A classes. The first B^B class locomotive entered service in February 1915, with the last to commence operations doing so on 8 March 1917. All were built by A & G Price Ltd of Thames, New Zealand, and as their cylinders had a larger diameter than the B and B^A locomotives they were capable of generating more power to haul heavier trains. The most visible difference however was the roundtop firebox in place of the preceding classes Belpaire design. The B^B class could haul up to 700 long tons (710 t; 780 short tons) of freight on a level railway line, though they were limited to a top speed of around 40 mph (64 km/h).

Service

The B^B class did not solely haul freight trains. They were also utilised to haul passenger trains, generally on branch lines where light track meant trains could not be operated at speeds unattainable for the B^B class. These trains included services for miners working in coal mines along branches in the Waikato region (e.g. Glen Massey Branch). However, they arrived at the same time as the A^B class pacific, and as these proved equally adept at hauling freight trains of similar tonnage they were proliferated while no further B^B types were ordered.

In the later days of steam, powerful locomotives such as the K class were hauling heavy trains that the C class and other shunting locomotives at yards and depots simply could not handle. Accordingly, ten members of the B^B class were modified to perform shunting duties between 1932 and 1938, and they successfully took on the heaviest of roles.

Most B^B locomotives survived into the 1960s. In later years they were concentrated at the yards in Auckland, Frankton and Palmerston North. In the mid 1960s four were sent to Dunedin and Invercargill. During that decade, the complete withdrawal of the class was undertaken progressively, with the last two, B^B 626 and B^B 633, formally removed from service in August 1968. Another one of the last to be withdrawn was B^B 144 in October 1967. It was purchased by Les Hostick. Today it is lease to Ian Welch and is under restoration at the Mainline Steam Heritage Trust's Parnell depot. No other B^B locomotive has been preserved.

Class register

Key:	In service	On lease	Out of service	Preserved	Overhaul/Repair	Scrapped

Road number	In service	Written off	Comments
55	1-1917	7-1965
109	3-1917	31-3-1964
143	4-1917	5-1959
144	7-1917	10-1967	Owned by Les Hostick. Lease to Ian Welch and is under restoration at the Mainline Steam Heritage Trust's Parnell depot.
147	8-1917	12-1965
167	10-1917	12-1965
169	11-1917	12-1960
171	11-1917	12-1965
197	3-1918	12-1962
222	3-1918	4-1966
618	2-1915	5-1966
619	3-1915	5-1959
620	4-1915	7-1965
621	5-1915	9-1959
622	6-1915	5-1959
623	7-1915	8-1959
624	8-1915	6-1957
625	8-1915	9-1962
626	9-1915	8-1968	Transferred to South Island, 1965.
627	11-1915	4-1966
628	12-1915	2-1963
629	12-1915	4-1966
630	2-1916	10-1967	Transferred to South Island, 1965.
631	5-1916	9-1966	Transferred to South Island, 1965.
632	5-1916	8-1959
633	6-1916	8-1968	Transferred to South Island, 1964.
634	6-1916	10-1963
635	9-1916	12-1965
636	9-1916	5-1966
637	11-1916	10-1963

References

Millar, Sean; The NZR Steam Locomotive, NZR&LS, 2012
Palmer, A.N., and Stewart, W.W., Cavalcade of New Zealand Locomotives, A.H. & A.W. Reed, 1965

External links

Rail vehicles of New Zealand

Diesel locomotives

Diesel Multiple Units

Electric locomotives

1500 V DC	E^A (later EO of 1968) E^C E^D E^O of 1923 E^W

25 kV AC	EF

Battery	E E^B

Electric Multiple Units

1500 V DC (Wellington)	"English Electric" D^M (inc. D trailers) "Ganz Mavag" EM (inc. ET trailers) "Matangi" FP (inc. FT trailers)

25 kV AC (Auckland)	AM (inc. AMP, AMT, AMA)

Railcars

RM class	88 seater (also known as Fiats or twinsets) Clayton steam railcar Edison battery-electric railcar Midland railcar Leyland experimental petrol railcar MacEwan-Pratt petrol railcar Model T Ford railcar Sentinel-Cammell steam railcar Silver Fern Standard Thomas Transmission Vulcan Wairarapa Westinghouse

Others	A 88 Buckhurst petrol carriage

Steam locomotives

A of 1873
A of 1906 (inc. A^D)
A^A
A^B
B of 1874
B of 1899
B^A
B^B
B^C
C of 1873
C of 1930
D of 1874
D of 1929
E of 1872 & 1875
E of 1906
F
F^A (inc. F^B)
G of 1874
G Garratt of 1928 (inc. Pacific rebuild)
H
J of 1874
J of 1939
J^A
J^B
K of 1877
K of 1932
K^A
K^B
L
L^A
M
N
N^A
N^C
O
O^A
O^B
O^C
P of 1876
P of 1885
Q of 1878
Q of 1901
R
S
T
U
U^A
U^B
U^C
U^D
V
W
W^A
W^AB
W^B
W^D
W^E
W^F
W^G
W^H
W^J
W^S
W^W
X
Y

Locomotive hauled carriages

See also: Locomotives of New Zealand.

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