South African Class 6A 4-6-0

South African Class 6A 4-6-0
Ex CGR (Western System) Class 6 no. 182, later IMR C509, then SAR Class 6A no. 462, De Aar, 15 April 1978
Power type Steam
Designer Cape Government Railways
Builder Dübs and Company
Sharp, Stewart and Company
Serial number Dübs:
3330, 3332-3335, 3337, 3345-3347, 3437-3439, 3441-3447, 3449-3456, 3460-3466, 3469-3471, 3475-3476
Sharp Stewart:
4116-4119, 4122-4127, 4144
Model CGR Class 6
Build date 1895-1897[1]
Total produced 50
Configuration 4-6-0 "Ten-wheeler" (USA)
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Leading wheel
diameter		 28.5 in (724 mm)
Driver diameter 54 in (1,370 mm)
Wheelbase Total: 42 ft 0.625 in (12.817 m)
Engine:
5 ft 5.5 in (1.664 m) pilot
11 ft (3.353 m) coupled
20 ft 3.75 in (6.191 m) total
Tender:
10 ft (3.048 m)
Length 51 ft 3.625 in (15.637 m)
Height 12 ft 10 in (3.912 m) as built
12 ft 10.75 in (3.931 m) Belpaire
Frame Plate frame
Axle load 11.5 long tons (11.7 t) on 2nd driver as built
13.4 long tons (13.6 t) per driver, Belpaire
Weight on drivers 34 long tons (34.5 t) as built
40.2 long tons (40.8 t) Belpaire
Locomotive weight 45.75 long tons (46.5 t) as built
51.075 long tons (51.9 t) Belpaire
Tender weight 33,056 lb (15.0 t) empty
33.2 long tons (33.7 t) w/o
Locomotive & tender
combined weight		 78.95 long tons (80.2 t) as built
82.225 long tons (83.5 t) Belpaire
Tender type YC - YB, YC, YE, YE1 permitted
* 3 axle tender
* Wheels 37 in (940 mm) dia
* Length 21 ft 2.875 in (6.474 m)
Fuel type Coal
Fuel capacity 7.5 long tons (7.6 t)
Water capacity 2,600 imp gal (12,000 l)
Boiler As built:
4 ft 4 in (1.321 m) int dia
11 ft 2.125 in (3.407 m) int length
6 ft 8 in (2.032 m) pitch
Belpaire:
4 ft 9 in (1.448 m) int dia
11 ft 2.125 in (3.407 m) int length
7 ft (2.134 m) pitch
Boiler pressure 180 psi (1,240 kPa)
Firegrate area 17 sq ft (1.579 m2) as built
16.6 sq ft (1.542 m2) Belpaire
Heating surface:
Tubes		 As built:
185 tubes 1.875 in (47.6 mm) int dia
1,015 sq ft (94.297 m2)
Belpaire:
220 tubes 2 in (50.8 mm) ext dia
1,287.5 sq ft (119.613 m2)
Heating surface:
Firebox		 101 sq ft (9.383 m2) as built
111 sq ft (10.312 m2) Belpaire
Heating surface:
Total		 1,116 sq ft (103.680 m2) as built
1,398.5 sq ft (129.925 m2) Belpaire
Cylinders Two
Cylinder size 17 in (432 mm) bore
26 in (660 mm) stroke
Valve gear Stephenson
Tractive effort 18,780 lbf (83.5 kN) at 75% boiler pressure[2]
Career Cape Government Railways
Imperial Military Railways
Benguela Railway
South African Railways
Sudan Railways
Class CGR Class 6, SAR Class 6A
Number in class 50 CGR, 49 SAR
Number CGR 161-201, 371-376, 660-662
(371-376 renumbered 571-576)
IMR C501, C503, C509 & C510
Benguela 21
SAR 441-489[1][3][4]
Delivered 1896-1897
First run 1896
Withdrawn 1973[5]
Disposition Retired

In 1896 and 1897 the Cape Government Railways placed a second batch of fifty Class 6 4-6-0 steam locomotives in service, forty-one on its Western System, six on its Midland System and three on its Eastern System. During the Second Freedom War four were transferred to the Imperial Military Railways on loan, and in 1907 one was sold to the Benguela Railway in Angola. In 1912, when the remaining forty-nine locomotives were assimilated into the South African Railways, they were renumbered and reclassified to Class 6A.[1][3][5]

Contents

Manufacturers

The Class 6 was designed at the Salt River works of the Cape Government Railways (CGR) at the same time as the Class 7, both according to the specifications of Michael Stephens, then Chief Locomotive Superintendent of the CGR’s Western System, and under the supervision of CGR Locomotive Superintendent H.M. Beatty. Whereas the Class 7 was conceived primarily as a goods locomotive, the Class 6 was intended to be its fast passenger service counterpart.[1]

The fifty locomotives in this second group were built between 1895 and 1897 by Dübs and Company and Sharp, Stewart and Company and were delivered in 1896 and 1897, numbered 161 to 201 for the CGR’s Western System, 371 to 376 for the Midland System and 660 to 662 for the Eastern System.[1]

These locomotives differed from the previous order in having slightly larger boilers with an increased heating surface and higher coal capacity Type YC tenders.[1]

Class 6 sub-classes

When all but one of these fifty locomotives were assimilated into the newly established South African Railways (SAR) in 1912, they were reclassified to Class 6A and renumbered 441 to 489.[2][3][4]

The rest of the CGR’s Class 6 locomotives, together with the Class 6-L1 to 6-L3 locomotives inherited by the Central South African Railways (CSAR) from the Oranje-Vrijstaat Gouwermentspoorwegen (OVGS) via the Imperial Military Railways (IMR), were grouped into thirteen more sub-classes by the SAR. The 4-6-0 locomotives became SAR Classes 6, 6B to 6H and 6J to 6L, the 2-6-2 locomotives became Class 6Y and the 2-6-4 locomotives became Class 6Z.[2][3][4]

Modifications

Several of the CSAR’s Class 6-L1 to 6-L3 locomotives were modified by P.A Hyde, Chief Mechanical Engineer (CME) of the CSAR, by having their round top fireboxes replaced with larger boilers and Belpaire fireboxes and by having larger, more sheltered cabs installed. This conversion improved their performance tremendously and resulted in several of the Class 6, 6A and 6B locomotives being similarly modified by the SAR in later years, but without altering their classifications.[5]

During the 1930s many of them were modified once again, when the CME of the SAR at the time, A.G. Watson, displayed his aversion to Belpaire fireboxes and reboilered them with round-topped fireboxes again, but retaining the larger cabs. Once again, they retained their classifications.[2][5]

Service

South Africa

The Class 6 series of locomotives were introduced primarily as passenger locomotives, but when the class became displaced by larger and more powerful locomotive classes, it literally became a "Jack-of-all-trades" that proved itself as one of the most useful and successful locomotive classes ever to be designed at the Salt River shops. It went on to see service in all parts of the country except Natal and was used on all types of traffic.[1]

In Cape Town they held a monopoly over the suburban services until electrification arrived in 1928, and on the Reef they also worked these services between Randfontein and Springs until the loads became too heavy for them. They were employed on branch lines all over the country, Natal excluded, and practically every big station and many smaller ones had its quota of these locomotives to work the local passenger, goods and shunting services.[1]

Like the Class 7, the Class 6 family gave good service for many years. By the time the last ones were eventually retired in 1973, the Class 6 series had achieved a service life of eighty years, a performance that can be matched by few, if any, other locomotive classes world wide.[1]

IMR, Angola and Sudan

One of these locomotives was sold to the Benguela Railway in Angola, while another four saw service with the IMR during the Second Freedom War.[1][5]

During World War II sixteen of the Classes 6 to 6D were transferred to the Middle East to assist with the war effort during the North African Campaign. The four Class 6A locomotives in this group were numbers 465, 472, 475 and 479. They were sold to the Sudan Railways Corporation in 1942 and renumbered M707 to M710, in the same order as their former SAR running numbers.[1][5][6]

Renumberings

During their long service lives some of the Class 6A locomotives underwent multiple renumberings. All were initially numbered into the CGR’s Western, Midland and Eastern Systems rosters. The Midland System’s locomotives, 371 to 376, were later renumbered 571 to 576. These then unused running numbers, 371 to 376, were later re-allocated to Class 8D locomotives, delivered in 1902.[1]

The four locomotives loaned to the IMR were renumbered C501, C503, C509 and C510 for the duration of their military service, while the one sold to Angola became Benguela Railway’s number 21.[1]

The remaining forty-nine locomotives were eventually renumbered into the SAR’s roster in 1912, becoming SAR 441 to 489. The table reflects all these renumberings as well as their builders and works numbers.[1][3][4]

Gallery

The main picture shows Sharp Stewart built ex CGR (Western System) Class 6 182, later IMR C509, then SAR Class 6A 462, with a Belpaire firebox, at De Aar on 15 April 1978.

Round-top fireboxes

Belpaire fireboxes

See also

References

  1. ^ a b c d e f g h i j k l m n Holland, D.F. (1971). Steam Locomotives of the South African Railways, Volume 1: 1859-1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 45-46, 57. ISBN 0715353829. 
  2. ^ a b c d South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
  3. ^ a b c d e Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912, pp. 8, 12, 14, 28-30 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  4. ^ a b c d Holland, D.F. (1972). Steam Locomotives of the South African Railways, Volume 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 137-138. ISBN 0715354272. 
  5. ^ a b c d e f Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 41-44. ISBN 0869772112. 
  6. ^ Class 6 to 6D sold to Sudan Railways during the WWII North African Campaign, list compiled by Austrian locomotive historian Reimar Holzinger