The South Australian Railways Q Class were steam locomotives constructed between 1885 and 1892 by Dübs and Company and James Martin & Co for the South Australian Railways (SAR).[1]

South Australian Railways Q Class
South Australian Railways Q Class No. 86
Type and origin Power type Steam Builder Dübs and Company James Martin & Co Serial number 2030-2044 & 46-51 Build date 1885-1892 Total produced 22
Specifications Configuration: ​  • Whyte 4-4-0  • UIC 2'B 3 Gauge 5 ft 3 in (1,600 mm) Leading dia. 3 ft (914 mm) Driver dia. 5 ft 1 in (1,549 mm) Length 47 ft 2+1⁄4 in (14.383 m) Height 13 ft 3 in (4,038.6 mm) Axle load 11 tons 2 cwt Total weight 58 long tons 13 cwt (131,400 lb or 59.6 t) Fuel type Coal Fuel capacity 5 long tons 12 cwt (12,500 lb or 5.7 t) Water cap. 2,040 imp gal (2,450 US gal; 9,300 L) Firebox type Round-top  • Firegrate area 16.07 sq ft (1.493 m2) Boiler pressure 130 psi (900 kPa) Heating surface:  • Tubes 1,032.7 sq ft (95.94 m2)  • Firebox 89.2 sq ft (8.29 m2) Cylinders 2 Cylinder size 16+1⁄2 in × 24 in (419 mm × 610 mm) Valve gear Stephenson Valve type Piston
Performance figures Tractive effort 11,835 lbs Factor of adh. 4.16
Career Operators South Australian Railways Class Q Number in class 22 Numbers 76-90 & 108-114 First run 1885 Last run 1956 Withdrawn 1923-1956 Scrapped 1923-1956 Disposition All scrapped

History

The first batch of fifteen Q Class locomotives were purchased from Dübs and Company, Scotland to replace the unsuccessful N and O class locomotives on the South Australian Railways "Intercolonial" hills line workings. With the new Q class locomotives being able to haul moderate loads on offer, these locomotives performed very well and the SAR ordered a second batch from the local James Martin & Co. Following the introduction of the more powerful R class locomotives on the southern line, the Q class was put to work on interstate trains from Murray Bridge to Serviceton as well as the northern lines.

These locomotives easily reached speeds of 60 mph (97 km/h), which was required to run these services. They were often seen "double heading" with the S class locomotives on express passenger trains. Q class locomotive No. 90 worked local trains between Murray Bridge and Tailem Bend, and in its final three years of life it spent its time as shunting locomotive at the Islington Railway Workshops.[2]

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