South African Class 3A 4-8-2

NGR Class B 4-8-2 1910
South African Class 3A 4-8-2

NGR Class B no. 335, SAR Class 3A no. 1476

Type and origin Power type Steam Designer American Locomotive Company Builder American Locomotive Company Serial number 46176 Model NGR America D Build date 1909 Total produced 1

Specifications Configuration 4-8-2 (Mountain) Driver 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 28 1⁄2 in (724 mm) Coupled dia. 45 1⁄2 in (1,156 mm) Trailing dia. 30 in (762 mm) Tender wheels 30 in (762 mm) Wheelbase 57 ft 7 in (17,551 mm)  • Engine 30 ft 6 in (9,296 mm)  • Leading 6 ft (1,829 mm)  • Coupled 12 ft 9 in (3,886 mm)  • Tender 17 ft 10 in (5,436 mm)  • Tender bogie 5 ft 10 in (1,778 mm) Length: ​  • Over couplers 65 ft 5 7⁄8 in (19,961 mm) Height 12 ft 6 in (3,810 mm) Frame type Bar Axle load 14 LT 11 cwt (14,780 kg)  • Leading 11 LT 16 cwt (11,990 kg)  • 1st coupled 13 LT 14 cwt 2 qtr (13,950 kg)  • 2nd coupled 13 LT 18 cwt 2 qtr (14,150 kg)  • 3rd coupled 13 LT 9 cwt (13,670 kg)  • 4th coupled 14 LT 11 cwt (14,780 kg)  • Trailing 9 LT 1 cwt (9,195 kg)  • Tender bogie Bogie 1: 20 LT 7 cwt (20,680 kg) Bogie 2: 22 LT 10 cwt (22,860 kg) Adhesive weight 55 LT 13 cwt (56,540 kg) Loco weight 76 LT 10 cwt (77,730 kg) Tender weight 42 LT 17 cwt (43,540 kg) Total weight 119 LT 7 cwt (121,300 kg) Tender type 2-axle bogies Fuel type Coal Fuel capacity 8 LT 5 cwt (8.4 t) Water cap 4,000 imp gal (18,200 l) Firebox type Belpaire  • Firegrate area 36.25 sq ft (3.368 m2) Boiler: ​  • Pitch 7 ft 4 in (2,235 mm)  • Diameter 5 ft 4 5⁄8 in (1,641 mm)  • Tube plates 18 ft 7 3⁄8 in (5,674 mm)  • Small tubes 172: 2 1⁄4 in (57 mm)  • Large tubes 15: 5 1⁄4 in (133 mm) Boiler pressure 160 psi (1,103 kPa) Safety valve Ramsbottom Heating surface 2,417 sq ft (224.5 m2)  • Tubes 2,268 sq ft (210.7 m2)  • Firebox 149 sq ft (13.8 m2) Superheater: ​  • Type Cole  • Heating area 457 sq ft (42.5 m2) Cylinders Two Cylinder size 24 in (610 mm) bore 24 in (610 mm) stroke Valve gear Walschaerts Valve type Piston Couplers Johnston link-and-pin AAR knuckle (1930s)

Performance figures Tractive effort 36,460 lbf (162.2 kN) @ 75%

Career Operators Natal Government Railways South African Railways Class NGR Class B SAR Class 3A Number in class 1 Numbers NGR 335, SAR 1476 Nicknames Maud Allan Delivered 1910 First run 1910 Withdrawn 1935

The leading coupled axle had flangeless wheels

The South African Railways Class 3A 4-8-2 of 1910 was a steam locomotive from the pre-Union era in the Colony of Natal.

Early in 1910, the Natal Government Railways commissioned a single American-built Class B 4-8-2 Mountain type locomotive, also known as the America D. It was the first superheated locomotive to be acquired by the Railways in Natal and also the first with a bar frame. In 1912, when it was assimilated into the South African Railways, it was renumbered and designated Class 3A.

As a result of a visit to the United States of America by Natal Government Railways (NGR) Locomotive Superintendent D.A. Hendrie in 1909 to study Mallet type locomotives and also American locomotive design in general, the American Locomotive Company (ALCO) supplied the NGR with two experimental locomotives. These engines represented a radical departure from previous NGR locomotive designs.

One of them was the first Mallet type locomotive in South Africa, later to be designated Class MA on the South African Railways (SAR).

The other was a 4-8-2 Mountain type locomotive which was placed in service early in 1910. It was of very similar general proportions to the NGR Class B of 1909, also known as the Hendrie D. While the ALCO locomotive was also designated Class B, it was commonly known as the America D on the NGR and nicknamed Maud Allan by the enginemen after the Canadian-born dancer.

Like the Class B Hendrie D, the ALCO locomotive also used Walschaerts valve gear, but it had a bar frame, larger 24 inches (610 millimetres) diameter pistons, lower 160 pounds per square inch (1,103 kilopascals) boiler pressure, superheating, an American type cab and some other features which were typical of American design, such as high running boards. It was the first superheated locomotive to be acquired by the NGR and also the first with a bar frame.