The AD60 class was a class of steam locomotives operated by the New South Wales Government Railways in Australia. They were built with the 4-8-4+4-8-4 wheel arrangement. They are the most powerful Australian steam locomotives (the NSWGR 57 class was of similar power on paper). They did however have a formidable reputation of being able to lift huge trains single handed over steep grades and in difficult conditions.
This was the first appearance of the Beyer-Garratt type locomotive on the New South Wales Government Railways, although this type of articulated unit had seen considerable use on the narrow gauge lines of other Australian systems for many years. Designed to a light axleload of only 16 tons (16.3 t), they were apparently intended for hauling feeder branch-line services to the main lines where heavier main-line locomotives could continue with the load. Twenty five locomotives, and subsequently a further twenty five, were ordered from Beyer, Peacock and Company, but following the change of policy in favour of diesel traction, attempts were made to cancel part of the order. Forty two complete locomotives were delivered, together with spare parts equating to approximately five further locomotives. Being composed of three distinct sections with live steam connections between, some assembly was required subsequent to delivery. Locomotive 6002 was the first to enter service, it emerging in July 1952. All 42 were in traffic by January 1957.
Whilst there were more powerful Garratts on the narrow gauge lines in Africa, the 60-class were a fairly sizeable locomotive, having a greater tractive effort than any other steam locomotive in Australia, approximately equal in capability to the New South Wales D57 class locomotive. Some modifications were made subsequent to entering service and they became a most useful locomotive. Crews began to express a preference for operating them. The coal bunkers were enlarged from 14 to 18 tons capacity. Ventilation of the cabs caused considerable concern. Consequently, the class was banned from working through single-line tunnels, this ban also being in response to the difficulty crews would have climbing out in the event of failure within such tunnels. Amongst attempts to improve cab ventilation, 6011 was experimentally fitted in September, 1952 with a large tube along the front bunker and boiler to funnel air from the front of the locomotive into the cab. It was unsuccessful and was removed in 1955. Some improvement was obtained by running the locomotives coal-bunker first. Owing to the length and noise of the locomotive, crews found difficulty in hearing warning detonators. To rectify the situation, tubes were fitted to convey the sound from the leading wheels to the cab. It became apparent that the Garratts would see more service on main lines than on the lighter branch lines. It was decided to increase the tractive effort of a number of the class. This was achieved by enlarging the cylinder diameter and by altering the weight distribution by removing liners from the bogies. This increased the axleload on each of the driving wheels by approximately 2 tons. Thirty locomotives were so treated. Due to the lack of suitable turning facilities and the extreme difficulty of observing signals when running coal-bunker first, it was decided to fit dual controls to enable the crew to be positioned on the correct side of the cab and facing the direction of travel. This modification was carried out on the 30 locomotives which had increased tractive effort. The buffer beams were marked with a special symbol next to the number to indicate that the locomotive was so fitted. The train most closely associated with the Garratt locomotives was the ore concentrate train from Broken Hill to Sulphide Junction, near Cockle Creek, known as W44. Another well known duty was the Glenlee, south of Campbelltown, to Rozelle coal traffic which operated prior to electrification of the route and when export coal was handled in Sydney Harbour. When the electrification works were under way and watering facilities had been removed at Campbelltown and Liverpool, 7,000 gallon (31,822 litre) water gins were added between the locomotive and the load. This was the only instance of Australian Garratt locomotives running with water gins. As well as their operation between Molong and Orange on train W44, from early 1966 double-headed Garratts were commonplace between Gosford and Broadmeadow or Port Waratah, the then export coal port near Newcastle. This working lasted right up to the very end of regular steam operations on the N.S.W.G.R. in 1972.
6029 is operated by Transport heritage and is privately own since (Nov 2017) the fall of the Canberra Railway Museum. 6039 and 6042 are with the Dorrigo Steam Railway and Museum and 6040 (the last steam locomotive to enter service with the N.S.W.G.R.) is at the New South Wales Rail Transport Museum which has received some much needed cosmetic work.