NSWGR class AD60

NSWGR class AD60
	AD60 No. 6042 in front of a freight train
Numbering:	6001-6042
Number:	42 (+5 in parts)
Manufacturer:	Beyer-Peacock
Year of construction (s):	1952-1954, 1956
Retirement:	1972
Type :	(2'D2 ') (2'D2') h4 (Garratt)
Gauge :	1435 mm ( standard gauge )
Length over coupling:	33,120 mm
Service mass:	264.1 (268.7) t
Friction mass:	128 (130) tons
Wheel set mass :	16.0 (16.3) tons
Driving wheel diameter:	1,397 mm
Cylinder diameter:	489 (505) mm
Piston stroke:	660 mm
Boiler overpressure:	137 N / cm²
Grate area:	5.9 m²
Radiant heating surface:	22.1 m²
Tubular heating surface:	259.0 m²
Superheater area :	69.7 m²
	Brackets apply to the AD60 ++

The locomotives of the class AD60 of the New South Wales Government Railways (NSWGR) were steam locomotives of the Garratt design . The machines were the heaviest steam locomotives in the southern hemisphere and the most powerful in Australia.

history

The New South Wales Government Railways were the last rail company in Australia to purchase Garratt locomotives. For heavy coal and ore trains on branch lines with a lighter superstructure, the railway ordered 60 Garratts from Beyer-Peacock in the early 1950s . Rigid locomotives for the desired area of application would have required six coupling axles, which was out of the question because of the tight curve radii.

In 1952, when the switch to diesel locomotives was already underway on the main lines , the first examples were delivered. This resulted in operational and maintenance difficulties, and the order was reduced to 50 locomotives, the last 5 of which were delivered unassembled as spare parts. The initial problems were resolved, however, and the AD60 was able to hold on to tracks that were too weak for American diesel locomotives until the early 1970s, particularly in northern New South Wales . Not infrequently, the machines were also used in prestressing operations.

In 1969 locomotive no. 6042, which would have required major repairs, was rebuilt as a practically new locomotive from the existing spare parts; the total number of locomotives built is therefore actually 43.

Four AD60s have been preserved; one of them, No. 6029, has been operational again since 2015.

Technology and modifications

The "back" of the AD60 No. 6003

The AD60 had the wheel arrangement (2'D2) (2'D2 '), so they had 2 × 4 coupling axles and 4 two-axle running bogies . Only half of the 16 axles were driven.

In terms of design, the AD60 were state-of-the-art. The drive frames were built on cast steel frames , and all axles as well as the drive pins were equipped with roller bearings . Operation has been made easier by a stoker and power reversal.

In 29 locomotives, designated as AD60 ++, the pulling force was increased by an enlarged cylinder diameter and an increased coupling axle load. These locomotives were also given a second set of controls on the back of the driver's cab because the driver's view of the signals when "reversing" was very poor and the driver's union requested the conversion.

Because the length of the Garratt-style locomotive made it difficult to hear bang capsules from the driver's cab , special tubes were later installed that led from the front wheels to the driver's cab and transmitted the bang.

Comparison with other Garratts

The wheel arrangement (2'D2) (2'D2 ') was only used very rarely worldwide; except for the AD60, only the meter-gauge class EC3 of the Kenya-Uganda Railway (KUR) and the almost identical class 58 of the East African Railways (EAR).

The AD60s were the heaviest, but not - as can be read in some publications - the most powerful steam locomotives in the southern hemisphere. Some Garratt series in Africa and South America, which had a higher axle load, were superior to some of the Garratt series in Africa and South America, both in terms of the tensile force, which is calculated from the boiler pressure, piston diameter, piston stroke and coupling wheel diameter, as well as in the grate area and thus the boiler output. EAR class 59 is the largest garratt in the southern hemisphere ; The GL class of South African Railways (SAR) had the highest tractive effort .