South African Class 6Y 2-6-2

CGR 6th Class 2-6-2 SAR Class 6Y 2-6-2
No. 712 at Paardeneiland, c. 1930
Type and origin Power type Steam Designer Cape Government Railways (H.M. Beatty) Builder Kitson and Company Serial number 4191-4192 Model CGR 6th Class 2-6-2 Build date 1903 Total produced 2
Specifications Configuration: ​  • Whyte 2-6-2 (Prairie)  • UIC 1'C1'n2 Driver 3rd coupled axle Gauge 3 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 wheels 37 in (940 mm) Wheelbase 46 ft 7 5⁄8 in (14,214 mm)  • Engine 25 ft 9 in (7,849 mm)  • Coupled 10 ft 10 in (3,302 mm)  • Tender 10 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 couplers 56 ft 5 3⁄4 in (17,215 mm) Height 12 ft 10 in (3,912 mm) Frame type Bar Axle load 14 LT 3 cwt (14,380 kg)  • Leading 5 LT 11 cwt (5,639 kg)  • 1st coupled 11 LT 12 cwt (11,790 kg)  • 2nd coupled 13 LT 6 cwt (13,510 kg)  • 3rd coupled 14 LT 3 cwt (14,380 kg)  • Trailing 11 LT 10 cwt (11,680 kg)  • Tender axle Axle 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 weight 39 LT 1 cwt (39,680 kg) Loco weight 56 LT 12 cwt (57,510 kg) Tender weight 32 LT (32,510 kg) Total weight 88 LT 12 cwt (90,020 kg) Tender type YE (3-axle) Fuel type Coal Fuel capacity 5 LT 10 cwt (5.6 t) Water cap 2,825 imp gal (12,800 l) Firebox type Round-top  • Firegrate area 26 sq ft (2.4 m2) Boiler: ​  • Pitch 7 ft 1⁄2 in (2,146 mm)  • Diameter 4 ft 7 3⁄4 in (1,416 mm)  • Tube plates 14 ft 6 1⁄4 in (4,426 mm)  • Small tubes 178: 2 in (51 mm) Boiler pressure 180 psi (1,241 kPa) Safety valve Ramsbottom Heating surface 1,507 sq ft (140.0 m2)  • Tubes 1,397 sq ft (129.8 m2)  • Firebox 110 sq ft (10 m2) Cylinders Two Cylinder size 18 1⁄2 in (470 mm) bore 26 in (660 mm) stroke Valve gear Stephenson Couplers Johnston link-and-pin
Performance figures Tractive effort 20,030 lbf (89.1 kN) @ 75%
Career Operators Cape Government Railways South African Railways Class CGR 6th Class 2-6-2 SAR Class 6Y Number in class 2 Numbers CGR 901-902 SAR 711-712 Delivered 1903 First run 1903 Withdrawn 1934
The 2nd coupled axle had flangeless wheels

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.

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.

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.

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.

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.

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.

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.