South African Class GK 2-6-2+2-6-2

Specifications
Specifications
Configuration:;
• Whyte	2-6-2+2-6-2 (Double Prairie)
• UIC	1’C1’+1’C1’h4
Driver	3rd & 4th coupled axles
Gauge	3 ft 6 in (1,067 mm) Cape gauge
Leading dia.	28+1⁄2 in (724 mm)
Coupled dia.	42+3⁄4 in (1,086 mm)
Trailing dia.	28+1⁄2 in (724 mm)
Wheelbase	56 ft 8 in (17,272 mm)
• Engine	17 ft 8 in (5,385 mm) each
• Coupled	8 ft (2,438 mm) each
Pivot centres	29 ft 8 in (9,042 mm)
Length:;
• Over couplers	63 ft 2+3⁄4 in (19,272 mm)
Height	12 ft 3 in (3,734 mm)
Frame type	Plate
Axle load	10 LT 10 cwt (10,670 kg)
• Leading	8 LT 7 cwt (8,484 kg) front; 8 LT 16 cwt (8,941 kg) rear
• Coupled	10 LT 10 cwt (10,670 kg)
• Trailing	6 LT 16 cwt (6,909 kg) front; 7 LT 19 cwt (8,078 kg) rear
Adhesive weight	63 LT (64,010 kg)
Loco weight	94 LT 18 cwt (96,420 kg)
Fuel type	Coal
Fuel capacity	4 LT (4.1 t)
Water cap.	1,900 imp gal (8,640 L) front; 1,100 imp gal (5,000 L) rear
Firebox:
• Type	Belpaire
• Grate area	34 sq ft (3.2 m2)
Boiler:;
• Pitch	7 ft 3+3⁄8 in (2,219 mm)
• Diameter	5 ft 2 in (1,575 mm)
• Tube plates	11 ft 3+1⁄4 in (3,435 mm)
• Small tubes	225: 1+3⁄4 in (44 mm)
• Large tubes	24: 5+1⁄4 in (133 mm)
Boiler pressure	180 psi (1,241 kPa)
Safety valve	Ramsbottom
Heating surface:
• Firebox	156 sq ft (14.5 m2)
• Tubes	1,531 sq ft (142.2 m2)
• Total surface	1,687 sq ft (156.7 m2)
Superheater:;
• Heating area	300 sq ft (28 m2)
Cylinders	Four
Cylinder size	15 in (381 mm) bore; 22 in (559 mm) stroke
Valve gear	Walschaerts
Valve type	Piston
Couplers	Johnston link-and-pin; AAR knuckle (1930s)

Type and origin
Type and origin
Power type	Steam
Designer	Beyer, Peacock and Company
Builder	Beyer, Peacock and Company
Serial number	6135-6136
Model	NCCR G
Build date	1923
Total produced	2

New Cape Central Garratt 2-6-2+2-6-2
South African Class GK 2-6-2+2-6-2
New Cape Central Garratt 2-6-2+2-6-2; South African Class GK 2-6-2+2-6-2
	NCCR no. G2, later SAR Class GK no. 2341, c. 1925
Power type
Type and origin
Power type	Steam
Designer	Beyer, Peacock and Company
Builder	Beyer, Peacock and Company
Serial number	6135-6136
Model	NCCR G
Build date	1923
Total produced	2
Configuration:;
Specifications
Configuration:;
• Whyte	2-6-2+2-6-2 (Double Prairie)
• UIC	1’C1’+1’C1’h4
Driver	3rd & 4th coupled axles
Gauge	3 ft 6 in (1,067 mm) Cape gauge
Leading dia.	28+1⁄2 in (724 mm)
Coupled dia.	42+3⁄4 in (1,086 mm)
Trailing dia.	28+1⁄2 in (724 mm)
Wheelbase	56 ft 8 in (17,272 mm)
• Engine	17 ft 8 in (5,385 mm) each
• Coupled	8 ft (2,438 mm) each
Pivot centres	29 ft 8 in (9,042 mm)
Length:;
• Over couplers	63 ft 2+3⁄4 in (19,272 mm)
Height	12 ft 3 in (3,734 mm)
Frame type	Plate
Axle load	10 LT 10 cwt (10,670 kg)
• Leading	8 LT 7 cwt (8,484 kg) front; 8 LT 16 cwt (8,941 kg) rear
• Coupled	10 LT 10 cwt (10,670 kg)
• Trailing	6 LT 16 cwt (6,909 kg) front; 7 LT 19 cwt (8,078 kg) rear
Adhesive weight	63 LT (64,010 kg)
Loco weight	94 LT 18 cwt (96,420 kg)
Fuel type	Coal
Fuel capacity	4 LT (4.1 t)
Water cap.	1,900 imp gal (8,640 L) front; 1,100 imp gal (5,000 L) rear
Firebox:
• Type	Belpaire
• Grate area	34 sq ft (3.2 m2)
Boiler:;
• Pitch	7 ft 3+3⁄8 in (2,219 mm)
• Diameter	5 ft 2 in (1,575 mm)
• Tube plates	11 ft 3+1⁄4 in (3,435 mm)
• Small tubes	225: 1+3⁄4 in (44 mm)
• Large tubes	24: 5+1⁄4 in (133 mm)
Boiler pressure	180 psi (1,241 kPa)
Safety valve	Ramsbottom
Heating surface:
• Firebox	156 sq ft (14.5 m2)
• Tubes	1,531 sq ft (142.2 m2)
• Total surface	1,687 sq ft (156.7 m2)
Superheater:;
• Heating area	300 sq ft (28 m2)
Cylinders	Four
Cylinder size	15 in (381 mm) bore; 22 in (559 mm) stroke
Valve gear	Walschaerts
Valve type	Piston
Couplers	Johnston link-and-pin; AAR knuckle (1930s)
Tractive effort
Performance figures
Tractive effort	31,260 lbf (139.1 kN) @ 75%
Operators
Career
Operators	New Cape Central Railways; South African Railways
Class	Class GK
Number in class	2
Numbers	NCCR 12-13, renumbered G1-G2; SAR 2340-2341
Delivered	1923
First run	1923
Withdrawn	1957

The South African Railways Class GK 2-6-2+2-6-2 of 1923 was an articulated steam locomotive from the New Cape Central Railway era.

In 1923, the New Cape Central Railway placed two Garratt articulated steam locomotives with a 2-6-2+2-6-2 Double Prairie type wheel arrangement in service. In 1925, when the New Cape Central Railway was amalgamated into the South African Railways, the two Garratts were renumbered and designated Class GK.^[1]^[2]^[3]^[4]

New Cape Central Railway

The New Cape Central Railway (NCCR) was an independent privately owned railway company who operated between Worcester and Mossel Bay. It was formed in January 1893 when it purchased all the assets of the bankrupted Cape Central Railway (CCR) who had constructed a railway from Worcester via Robertson to Roodewal.^[1]^[4]

In 1894, the NCCR began work to extend the railway to Swellendam. From there it continued via Heidelberg to Riversdale, which was reached on 3 December 1903. Voorbaai, outside Mossel Bay, was reached in 1906.^[1]^[4]

When the Cape Government Railways linked up with the NCCR at Mossel Bay on 23 September 1907, the NCCR undertook to operate the 32+1⁄2-mile long (52.3-kilometre) section to George.^[2]

Unlike many other privately owned railways in South Africa, the NCCR prospered and was well and efficiently run. Prior to 1917 dividends were small, but from 1917 to 1925 dividends of 4½% were declared each year. The NCCR was the last component railway to be added to the South African Railways (SAR) when it was liquidated and amalgamated in May 1925. All the NCCR locomotives which came onto the SAR roster continued to give good service for many years.^[1]^[2]

Manufacturer

Increasing traffic and heavier loads led to the decision by the NCCR in 1922 to place an order with Beyer, Peacock and Company for two Garratt 2-6-2+2-6-2 Double Prairie type locomotives. The locomotives were built to the design of the Class GB of the SAR and were also superheated, with Belpaire fireboxes, plate frames, piston valves and Walschaerts valve gear, but they were heavier and had larger cylinders. They were delivered in 1923 and were initially numbered 12 and 13, but were later renumbered G1 and G2. The Garratts were the last new locomotives to be acquired by the company.^[1]^[4]^[5]

Service

New Cape Central Railway

In service on the NCCR, each Garratt could replace two of the railway’s older Class 7 locomotives, one 95 long tons (97 tonnes) Garratt being able to do the work of altogether 166 long tons (169 tonnes) worth of tender locomotives while saving 5 long tons (5 tonnes) of coal and one crew's wages in the process. The Garratts eliminated the need to double-head passenger trains which often consisted of eight bogie carriages.^[1]^[2]

South African Railways

When the NCCR was amalgamated into the SAR in 1925, the two Garratt locomotives were renumbered 2340 and 2341 on the SAR roster and designated Class GK.^[1]^[2]^[4]

The locomotives were initially transferred to Cape Town and later joined the Class GD Garratts on the Overberg branch line to Caledon for a brief period. Since they were much lighter than the Class GD, they were less useful as traffic engines. They were then sent to Natal where they remained in service on the Donnybrook to Underberg branch until they were withdrawn from service by 1957.^[4]^[6]

Illustration

NCCR no. G1, later SAR Class GK no. 2340, as delivered c. 1923

References

^ ^a ^b ^c ^d ^e ^f ^g Holland, D.F. (1971). Steam Locomotives of the South African Railways. Vol. 1: 1859–1910 (1st ed.). Newton Abbott, England: David & Charles. pp. 79–80. ISBN 978-0-7153-5382-0.
^ ^a ^b ^c ^d ^e Espitalier, T.J.; Day, W.A.J. (1944). The Locomotive in South Africa - A Brief History of Railway Development. Chapter II - The Cape Government Railways (Continued). South African Railways and Harbours Magazine, April 1944. pp. 253-257.
^ South African Railways and Harbours Locomotive Diagram Book, 2'0" & 3'6" Gauge Steam Locomotives, 15 August 1941, as amended
^ ^a ^b ^c ^d ^e ^f Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 93–94. ISBN 0869772112.
^ Hamilton, Gavin N., The Garratt Locomotive - Garratt Locomotives produced by Beyer, Peacock, retrieved 10 November 2012
^ Soul of A Railway, System 1, Part 7: The Caledon train. Caption 42 (Accessed on 29 November 2016)