South African Class 6Y 2-6-2

The South African Railways Class 6Y 2-6-2 of 1903 was a steam locomotive from the pre-Union era in the Cape of Good Hope.

This article is about one of several different Cape Government Railways locomotive types to be designated "6th Class". For the others, see Cape Government Railways 6th Class locomotives.

CGR 6th Class 2-6-2
SAR Class 6Y 2-6-2
No. 712 at Paardeneiland, c. 1930
Type and origin
Power typeSteam
DesignerCape Government Railways
(H.M. Beatty)
BuilderKitson and Company
Serial number4191-4192
ModelCGR 6th Class 2-6-2
Build date1903
Total produced2
Specifications
Configuration:
​
 • Whyte2-6-2 (Prairie)
 • UIC1'C1'n2
Driver3rd coupled axle
Gauge3 ft 6 in (1,067 mm) Cape gauge
Leading dia.28 1⁄2 in (724 mm)
Coupled dia.60 in (1,524 mm)
Trailing dia.33 in (838 mm)
Tender wheels37 in (940 mm)
Wheelbase46 ft 7 5⁄8 in (14,214 mm)
 • Engine25 ft 9 in (7,849 mm)
 • Coupled10 ft 10 in (3,302 mm)
 • Tender10 ft (3,048 mm)
Wheel spacing
(Asymmetrical)		1-2: 5 ft 7 in (1,702 mm)
2-3: 5 ft 3 in (1,600 mm)
Length:
​
 • Over couplers56 ft 5 3⁄4 in (17,215 mm)
Height12 ft 10 in (3,912 mm)
Frame typeBar
Axle load14 LT 3 cwt (14,380 kg)
 • Leading5 LT 11 cwt (5,639 kg)
 • 1st coupled11 LT 12 cwt (11,790 kg)
 • 2nd coupled13 LT 6 cwt (13,510 kg)
 • 3rd coupled14 LT 3 cwt (14,380 kg)
 • Trailing11 LT 10 cwt (11,680 kg)
 • Tender axleAxle 1: 10 LT 8 cwt (10,570 kg)
Axle 2: 10 LT 15 cwt (10,920 kg)
Axle 3: 10 LT 17 cwt (11,020 kg)
Adhesive weight39 LT 1 cwt (39,680 kg)
Loco weight56 LT 12 cwt (57,510 kg)
Tender weight32 LT (32,510 kg)
Total weight88 LT 12 cwt (90,020 kg)
Tender typeYE (3-axle)
Fuel typeCoal
Fuel capacity5 LT 10 cwt (5.6 t)
Water cap2,825 imp gal (12,800 l)
Firebox typeRound-top
 • Firegrate area26 sq ft (2.4 m2)
Boiler:
​
 • Pitch7 ft 1⁄2 in (2,146 mm)
 • Diameter4 ft 7 3⁄4 in (1,416 mm)
 • Tube plates14 ft 6 1⁄4 in (4,426 mm)
 • Small tubes178: 2 in (51 mm)
Boiler pressure180 psi (1,241 kPa)
Safety valveRamsbottom
Heating surface1,507 sq ft (140.0 m2)
 • Tubes1,397 sq ft (129.8 m2)
 • Firebox110 sq ft (10 m2)
CylindersTwo
Cylinder size18 1⁄2 in (470 mm) bore
26 in (660 mm) stroke
Valve gearStephenson
CouplersJohnston link-and-pin
Performance figures
Tractive effort20,030 lbf (89.1 kN) @ 75%
Career
OperatorsCape Government Railways
South African Railways
ClassCGR 6th Class 2-6-2
SAR Class 6Y
Number in class2
NumbersCGR 901-902
SAR 711-712
Delivered1903
First run1903
Withdrawn1934
The 2nd coupled axle had flangeless wheels

In 1903, the Cape Government Railways placed two 6th Class steam locomotives with a 2-6-2 Prairie type wheel arrangement in service. In 1912, when these locomotives were assimilated into the South African Railways, they were renumbered and designated Class 6Y.[1][2][3]

Manufacturer

The Cape 6th Class 2-6-2 Prairie type locomotive was designed at the Salt River works of the Cape Government Railways (CGR) and was a further development of the 6th Class 2-6-4 Adriatic type. The 2-6-4 locomotive itself came about as an experimental development of the very successful 6th Class 4-6-0 locomotive and was initially also built with a 2-6-2 Prairie wheel arrangement, but eventually modified to a 2-6-4 wheel arrangement.[1]

Development

Good though the 6th Class 4-6-0 locomotives were, the requirement grew for larger and more powerful engines. It was becoming increasingly apparent at the time that such locomotives would require fireboxes with larger grate areas, which was not possible with the existing type of frame.[1]

H.M. Beatty

To overcome this problem, CGR Chief Locomotive Superintendent H.M. Beatty prepared designs for a new locomotive with a 2-6-2 Prairie wheel arrangement in which the frame terminated in front of the firebox, where it connected to a casting which he termed the "bridle casting". This casting extended out on either side and had wider spaced frames attached to it, which allowed a wider and deeper firebox.[1][3]

Because of the widened frames and larger firebox, trailing carrier wheels were incorporated to take the weight of the firebox. The coupled wheels were also located further forward to accommodate the deeper firebox and, as a result, the leading bogie was replaced by a single axle bissel truck.[1][3]

The first four locomotives of this design, later to be designated Class 6Z by the South African Railways (SAR), were placed in service in 1901. They displayed a tendency to be unsteady at speed and the design was therefore modified to a 2-6-4 Adriatic type wheel arrangement. Another four locomotives which incorporated this improvement were ordered in 1902, while the first four locomotives were modified accordingly.[1]

In spite of their totally different appearance and wheel arrangement, the CGR designated them as 6th Class as well, possibly because they were intended as an improved 6th Class.[2][4]

Redesign

With an improved design of bissel truck, another two locomotives were ordered from Kitson and Company in 1903 and were once again built with a 2-6-2 Prairie wheel arrangement. They had larger boilers as well as larger 60-inch diameter (1,524-millimetre) coupled wheels, compared to the 54-inch diameter (1,372-millimetre) coupled wheels of all other 6th Class locomotives. Numbered 901 and 902 for the Western System of the CGR, these two engines did not display the tendency to sway at speed and therefore retained their 2-6-2 wheel arrangement.[1][2]

Class 6 sub-classes

When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (CGR, Natal Government Railways and Central South African Railways) were united under a single administration to control and administer the railways, ports and harbours of the Union. Although the South African Railways and Harbours came into existence in 1910, the actual classification and renumbering of all the rolling stock of the three constituent railways were only implemented with effect from 1 January 1912.[2][5]

In 1912, these two locomotives were renumbered 711 and 712 and designated Class 6Y on the SAR. The rest of the CGR's 6th Class locomotives, together with the Central South African Railways Classes 6-L1 to 6-L3 locomotives which had been inherited from the Oranje-Vrijstaat Gouwermentspoorwegen via the Imperial Military Railways, were grouped into thirteen more sub-classes by the SAR. The 4-6-0 locomotives became SAR Classes 6, 6A to 6H and 6J to 6L, and the eight 2-6-4 locomotives became Class 6Z.[2][4][6]

Service

In service, these two locomotives proved to be very successful, being fast, powerful, and good steamers. The experience which was gained with these two engines led to the introduction of the Karoo Class 4-6-2 Pacific type later in 1903. The two engines spent practically their entire working lives on the Cape mainline in the Karoo region, until they were withdrawn and scrapped in 1934.[3][4]

Illustration
  • CGR 6th Class 2-6-2 at Three Sisters, c. 1905
  • Ex CGR 6th Class no. 901, SAR Class 6Y no. 711, at Touws River, c. 1930
  • Ex CGR 6th Class 2-6-2, SAR Class 6Y, c. 1930

References
  1. Holland, D.F. (1971). Steam Locomotives of the South African Railways. 1: 1859–1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 52–54, 56. ISBN 978-0-7153-5382-0.
  2. Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer's Office, Pretoria, January 1912, pp. 8, 12, 14, 34 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  3. Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. p. 45. ISBN 0869772112.
  4. Holland, D. F. (1972). Steam Locomotives of the South African Railways. 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. p. 138. ISBN 978-0-7153-5427-8.
  5. The South African Railways - Historical Survey. Editor George Hart, Publisher Bill Hart, Sponsored by Dorbyl Ltd., Published c. 1978, p. 25.
  6. South African Railways and Harbours Locomotive Diagram Book, 2'0" & 3'6" Gauge Steam Locomotives, 15 August 1941, as amended
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