South African Class 3A 4-8-2

South African Class 3A 4-8-2
NGR Class American D 335, later SAR Class 3A 1476
Power type Steam
Designer Natal Government Railways
Builder American Locomotive Company
Serial number 46176[1]
Model NGR American D
Build date 1909
Total produced 1
Configuration 4-8-2 "Mountain"
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Leading wheel
diameter		 28.5 in (724 mm)
Driver diameter 45.5 in (1,160 mm)
Trailing wheel
diameter		 30 in (762 mm) trailing & tender
Wheelbase Total: 57 ft 7 in (17.551 m)
Engine:
6 ft (1.829 m) pilot
12 ft 9 in (3.886 m) coupled
30 ft 6 in (9.296 m) total
Tender:
5 ft 10 in (1.778 m) bogie
17 ft 10 in (5.436 m) total
Length 65 ft 5.875 in (19.961 m)
Height 12 ft 6 in (3.810 m)
Frame Bar frame
Axle load 14.55 long tons (14.8 t) on 4th driver
Weight on drivers 55.65 long tons (56.5 t)
Locomotive weight 76.5 long tons (77.7 t)
Tender weight 42.85 long tons (43.5 t)
Locomotive & tender
combined weight		 119.35 long tons (121.3 t)
Tender type 2 axle bogies
Wheels 30 in (762 mm) dia
Fuel type Coal
Fuel capacity 8.25 long tons (8.4 t)
Water capacity 4,000 imp gal (18,000 l)
Boiler 5 ft 4.625 in (1.641 m) int dia
18 ft 7.375 in (5.674 m) int length
7 ft 4 in (2.235 m) pitch
Boiler pressure 160 psi (1,100 kPa)
Firegrate area 36.25 sq ft (3.368 m2)
Heating surface:
Tubes		 172 tubes 2.25 in (57.2 mm) ext dia
15 tubes 5.25 in (133 mm) ext dia
2,268 sq ft (210.704 m2)
Heating surface:
Firebox		 149 sq ft (13.843 m2)
Heating surface:
Total		 2,417 sq ft (224.547 m2)
Superheater type Cole
Superheater area 457 sq ft (42.457 m2)
Cylinders Two
Cylinder size 24 in (610 mm) bore
24 in (610 mm) stroke
Valve gear Walschaerts
Tractive effort 36,460 lbf (162.2 kN) at 75% boiler pressure[1]
Career Natal Government Railways
South African Railways
Class NGR Class American D
SAR Class 3A
Number in class 1
Number NGR 335, SAR 1476[1][2]
Nicknames Maude Allen
Delivered 1910
First run 1910
Withdrawn 1935
Disposition Retired

Early in 1910 the Natal Government Railways placed a single Class American D 4-8-2 locomotive in service. In 1912, when it was assimilated into the South African Railways, it was renumbered and classified as Class 3A.[1][2][3]

Contents

Manufacturer

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 represented a radical departure from previous NGR locomotive designs.[1][3]

One of these was the first Mallet type in South Africa, later to become the Class MA on the South African Railways (SAR). The other was a 4-8-2 Mountain type locomotive, placed in service early in 1910, of very similar general proportions to the Class Hendrie D. Officially known as the Class American D, it was nicknamed "Maude Allen" by the enginemen.[1][3]

Characteristics

Like the Class Hendrie D, the locomotive also used Walschaerts valve gear, but had a bar frame, larger 24 inches (610 millimetres) diameter pistons, lower 160 pounds per square inch (1,100 kilopascals) boiler pressure, superheating, an American type cab and some other features typical of American design.[1][3]

It was the first superheated locomotive to be acquired by the NGR. The superheater was of the Cole type, having two headers on either side of the smokebox. Experience with the Class American D proved that, when compared with the saturated steam Class Hendrie D, it was more economical in fuel and water consumption.[1][3]

However, the factor of adhesion was found to be on the low side for the service for which it was required and the locomotive was prone to slipping when the rails were wet, which often happened in Natal when the weather was misty.[1]

Service

The locomotive joined the Hendrie D locomotives working between Estcourt and Charlestown on the Transvaal border. In 1912, when it was taken onto the SAR roster, it was renumbered 1476 and classified as the sole Class 3A. It was withdrawn from service in 1935.[1][2][3]

See also

References

  1. ^ a b c d e f g h i j Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 103-105. ISBN 0715353829. 
  2. ^ a b c Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 7, 12, 15, 46 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  3. ^ a b c d e f Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. p. 37. ISBN 0869772112.