Queensland AC16 class locomotive

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Queensland AC16 class locomotive
Power type Steam
Builder Baldwin Locomotive Works
Serial number 69451–69470
Model USATC S118 Class
Build date 1943
Configuration 2-8-2
UIC classification 1′D1′ h2
Gauge 3 ft 6 in (1,067 mm)
Leading wheel
26 in (0.660 m)
Driver diameter 48 in (1.219 m)
Trailing wheel
30 in (0.762 m)
Length 59 ft 5 12 in (18.12 m)
Weight on drivers 80,000 lb (36.3 tonnes)
Locomotive weight 119,000 lb (54.0 tonnes)
Boiler pressure 185 lbf/in2 (1.28 MPa)
Firegrate area 27.7 sq ft (2.57 m2)
Heating surface:
– Tubes and flues
1,256 sq ft (116.7 m2)
– Firebox 115 sq ft (10.7 m2)
Superheater area 347 sq ft (32.2 m2)
Cylinders Two, outside
Cylinder size 16 in × 24 in (406 mm × 610 mm)
Valve gear Walschaerts
Tractive effort 20,128 lbf (89.53 kN)
Railroad(s) Queensland Railways
Class AC16
Number in class 20
Number 216A–235A
Nicknames "MacArthurs"
Withdrawn Last unit written off June 30, 1969 (218A)
Preserved 218A, 221A
Current owner Zig Zag Railway (218A);
Workshops Rail Museum (221A)
Disposition Both Operational

The Queensland AC16 class locomotive is a 2-8-2 steam locomotive of the Queensland Railways (QR). The locomotives operated on 1,067 mm (3 ft 6 in) gauge.

The Second World War and the occupation by Japanese forces of Pacific Islands and islands to the north of Australia saw Queensland and the north of Australia placed under the threat of imminent attack. This placed a great strain on Queensland Railway’s resources in the movement of wartime supplies and troops.

A request was made in 1941 for further, new C17 Class steam locomotives and the specifications were forwarded to the United States where the United States Army Transportation Corps (USATC) drew up plans for a 2-8-2 with specifications similar to a C17 Class. The locomotives are also known is United States of America as USATC S118 Class steam locomotives. These locomotives were intended as a standard design for use on narrow gauge railways in other parts of the world as a war-time measure. There were twenty engines obtained during World War 2 from USA under “lend lease” arrangements and later purchased. They were the only ones of their type to come to Australia out of a total of 741 similar engines built for US Army Transportation Corps.

With eight coupled wheels the suffix “C” should be first and with sixteen inch diameter cylinders locomotives should have been classified C16 Class steam locomotive but to distinguish them from that existing class they were called American C16 i.e. AC16. The American steam locomotive earned it the nickname of Yank. The engines entered traffic with their US Army road numbers but had “A” appended to differentiate them from existing engines with the same numbers. Road numbers; 216A to 235A.

The engines were supplied with conical profile tyres. These were altered to QR standard cylindrical profile and pressed one-sixteenth of an inch inwards on the wheels to reduce wear. In 1943 the decision was taken to alter the second and third coupled wheels to thin flanges. A number of other modifications were carried out over the years.

The engines were fitted with Walschaerts valve gear. The steam locomotives supplied to Queensland Railway are from Baldwin Locomotive Works, Philadelphia, USA. The original tenders rode poorly and resulted in a speed limit of 30 mph being imposed with a prohibition on passenger train working. The axle load of these tenders also restricted the engines to main line usage. The floor level shovelling plate made the fireman’s work more difficult. One feature that did proved popular was the use of louvre coal boards and these subsequently became standard on all QR steam engines. The headlight mounted on the smokebox door proved to have advantages and was later adopted for some other classes.

In 1958, No. 217A was fitted with a C16 Class steam locomotive type tender taken from a withdrawn locomotive. The previous restrictions were then lifted. All 19 members of the class then remaining in service had been similarly treated by 1963.

After being fitted with these tenders, seven of the class was attached to Alpha where they had a brief period of glory in the early 1960s when they replaced the C17 Class hauling the air-conditioned “Midlander” between Alpha Queensland and Longreach. The American engines with a larger boiler capacity were able to reduce running times in the sections that contained many long banks. 60-ton Diesel Electric Locomotive took over the working in 1963.

The last engine in service was N°218A at Rockhampton. This engine is now at Zig Zag Railway Lithgow where it was restored to operating condition in 2008.

No. 221A is part of the QR Heritage Fleet. It was fitted with a new boiler and restored to working order in 2003. In the course of the overhaul it was fitted with a new tender. Although the external appearance of the tender is similar to the original design, internally it is similar to a standard type with raised shovelling plate.