South African Class GM 4-8-2+2-8-4

Specifications
Specifications
Configuration:;
• Whyte	4-8-2+2-8-4 (Double Mountain)
• UIC	2'D1'+1'D2'h4t
Driver	3rd & 6th coupled axles
Gauge	3 ft 6 in (1,067 mm) Cape gauge
Leading dia.	28+1⁄2 in (724 mm)
Coupled dia.	54 in (1,372 mm)
Trailing dia.	34 in (864 mm)
Tender wheels	34 in (864 mm)
Wheelbase	86 ft 4 in (26,314 mm)
• Axle spacing; (Asymmetrical)	1-2: 4 ft 10 in (1,473 mm) each; 2-3: 4 ft 9 in (1,448 mm) each; 3-4: 4 ft 10 in (1,473 mm) each
• Engine	29 ft 10 in (9,093 mm) each
• Leading	6 ft 4 in (1,930 mm) each
• Coupled	14 ft 5 in (4,394 mm) each
• Tender	35 ft 9 in (10,897 mm)
• Tender bogie	5 ft 9 in (1,753 mm)
Pivot centres	43 ft (13,106 mm)
Length:;
• Over couplers	93 ft 4+1⁄2 in (28,461 mm) engine; 43 ft 10+4⁄5 in (13,381 mm) tender; 137 ft 3+3⁄10 in (41,841 mm) total
Width	10 ft (3,048 mm)
Height	13 ft (3,962 mm)
Frame type	Bar
Axle load	15 LT (15,240 kg)
• Leading	17 LT 16 cwt (18,090 kg) front; 18 LT 5 cwt (18,540 kg) rear
• 1st coupled	13 LT 15 cwt (13,970 kg)
• 2nd coupled	14 LT 11 cwt (14,780 kg)
• 3rd coupled	14 LT 19 cwt (15,190 kg)
• 4th coupled	14 LT 3 cwt (14,380 kg)
• 5th coupled	14 LT (14,220 kg)
• 6th coupled	15 LT (15,240 kg)
• 7th coupled	14 LT 15 cwt (14,990 kg)
• 8th coupled	13 LT 19 cwt (14,170 kg)
• Trailing	11 LT 13 cwt (11,840 kg) front; 11 LT 10 cwt (11,680 kg) rear
• Tender bogie	24 LT 17 cwt 3 qtr (25,290 kg)
• Tender axle	12 LT 8 cwt 3 qtr (12,640 kg)
Adhesive weight	115 LT 2 cwt (116,900 kg)
Loco weight	174 LT 6 cwt (177,100 kg)
Tender weight	49 LT 15 cwt 3 qtr (50,590 kg)
Total weight	224 LT 1 cwt 3 qtr (227,700 kg)
Tender type	X-17 (2-axle bogies); X-17, X-20 permitted
Fuel type	Coal
Fuel capacity	10 LT (10.2 t)
Water cap.	1,600 imp gal (7,270 L) engine
Tender cap.	6,750 imp gal (30,700 L)
Firebox:
• Type	Round-top
• Grate area	64 sq ft (5.9 m2)
Boiler:;
• Pitch	8 ft 6 in (2,591 mm)
• Diameter	7 ft (2,134 mm)
• Tube plates	13 ft 6+1⁄2 in (4,128 mm)
• Small tubes	255: 2 in (51 mm)
• Large tubes	50: 5+1⁄2 in (140 mm)
Boiler pressure	200 psi (1,379 kPa)
Safety valve	Ross-pop
Heating surface:
• Firebox	281 sq ft (26.1 m2)
• Tubes	2,785 sq ft (258.7 m2)
• Total surface	3,066 sq ft (284.8 m2)
Superheater:;
• Heating area	778 sq ft (72.3 m2)
Cylinders	Four
Cylinder size	20+1⁄2 in (521 mm) bore; 26 in (660 mm) stroke
Valve gear	Walschaerts
Valve type	Piston
Valve travel	6+1⁄2 in (165 mm)
Couplers	AAR knuckle

Type and origin
Type and origin
Power type	Steam
Designer	South African Railways; (W.A.J. Day)
Builder	Beyer, Peacock and Company
Serial number	6883–6898
Model	Class GM
Build date	1938
Total produced	16

South African Class GM 4-8-2+2-8-4
South African Class GM 4-8-2+2-8-4
	No. 2298 at Krugersdorp, 23 April 1970
Power type
Type and origin
Power type	Steam
Designer	South African Railways; (W.A.J. Day)
Builder	Beyer, Peacock and Company
Serial number	6883–6898
Model	Class GM
Build date	1938
Total produced	16
Configuration:;
Specifications
Configuration:;
• Whyte	4-8-2+2-8-4 (Double Mountain)
• UIC	2'D1'+1'D2'h4t
Driver	3rd & 6th coupled axles
Gauge	3 ft 6 in (1,067 mm) Cape gauge
Leading dia.	28+1⁄2 in (724 mm)
Coupled dia.	54 in (1,372 mm)
Trailing dia.	34 in (864 mm)
Tender wheels	34 in (864 mm)
Wheelbase	86 ft 4 in (26,314 mm)
• Axle spacing; (Asymmetrical)	1-2: 4 ft 10 in (1,473 mm) each; 2-3: 4 ft 9 in (1,448 mm) each; 3-4: 4 ft 10 in (1,473 mm) each
• Engine	29 ft 10 in (9,093 mm) each
• Leading	6 ft 4 in (1,930 mm) each
• Coupled	14 ft 5 in (4,394 mm) each
• Tender	35 ft 9 in (10,897 mm)
• Tender bogie	5 ft 9 in (1,753 mm)
Pivot centres	43 ft (13,106 mm)
Length:;
• Over couplers	93 ft 4+1⁄2 in (28,461 mm) engine; 43 ft 10+4⁄5 in (13,381 mm) tender; 137 ft 3+3⁄10 in (41,841 mm) total
Width	10 ft (3,048 mm)
Height	13 ft (3,962 mm)
Frame type	Bar
Axle load	15 LT (15,240 kg)
• Leading	17 LT 16 cwt (18,090 kg) front; 18 LT 5 cwt (18,540 kg) rear
• 1st coupled	13 LT 15 cwt (13,970 kg)
• 2nd coupled	14 LT 11 cwt (14,780 kg)
• 3rd coupled	14 LT 19 cwt (15,190 kg)
• 4th coupled	14 LT 3 cwt (14,380 kg)
• 5th coupled	14 LT (14,220 kg)
• 6th coupled	15 LT (15,240 kg)
• 7th coupled	14 LT 15 cwt (14,990 kg)
• 8th coupled	13 LT 19 cwt (14,170 kg)
• Trailing	11 LT 13 cwt (11,840 kg) front; 11 LT 10 cwt (11,680 kg) rear
• Tender bogie	24 LT 17 cwt 3 qtr (25,290 kg)
• Tender axle	12 LT 8 cwt 3 qtr (12,640 kg)
Adhesive weight	115 LT 2 cwt (116,900 kg)
Loco weight	174 LT 6 cwt (177,100 kg)
Tender weight	49 LT 15 cwt 3 qtr (50,590 kg)
Total weight	224 LT 1 cwt 3 qtr (227,700 kg)
Tender type	X-17 (2-axle bogies); X-17, X-20 permitted
Fuel type	Coal
Fuel capacity	10 LT (10.2 t)
Water cap.	1,600 imp gal (7,270 L) engine
Tender cap.	6,750 imp gal (30,700 L)
Firebox:
• Type	Round-top
• Grate area	64 sq ft (5.9 m2)
Boiler:;
• Pitch	8 ft 6 in (2,591 mm)
• Diameter	7 ft (2,134 mm)
• Tube plates	13 ft 6+1⁄2 in (4,128 mm)
• Small tubes	255: 2 in (51 mm)
• Large tubes	50: 5+1⁄2 in (140 mm)
Boiler pressure	200 psi (1,379 kPa)
Safety valve	Ross-pop
Heating surface:
• Firebox	281 sq ft (26.1 m2)
• Tubes	2,785 sq ft (258.7 m2)
• Total surface	3,066 sq ft (284.8 m2)
Superheater:;
• Heating area	778 sq ft (72.3 m2)
Cylinders	Four
Cylinder size	20+1⁄2 in (521 mm) bore; 26 in (660 mm) stroke
Valve gear	Walschaerts
Valve type	Piston
Valve travel	6+1⁄2 in (165 mm)
Couplers	AAR knuckle
Tractive effort
Performance figures
Tractive effort	60,700 lbf (270 kN) @ 75%
Operators
Career
Operators	South African Railways
Class	Class GM
Number in class	16
Numbers	2291–2306
Delivered	1938–1939
First run	1938
Withdrawn	1974

The South African Railways Class GM 4-8-2+2-8-4 of 1938 was an articulated steam locomotive.

During 1938 and 1939, the South African Railways placed sixteen Class GM Garratt articulated steam locomotives with a 4-8-2+2-8-4 Double Mountain type wheel arrangement in goods train service on the Mafeking line out of Johannesburg.