South African Class 7 4-8-0

CGR 7th Class 4-8-0 1892
South African Class 7 4-8-0

Midland System no. 344, SAR no. 975, with type ZA tender, Bloemfontein, 6 April 2006

Type and origin ♠ Type ZA tender (2-axle bogies, Dübs) ♥ Type ZB tender (3-axle, Neilson) ♣ Original locomotive, as built ♦ Locomotive equipped with superheating Power type Steam Designer Cape Government Railways (H.M. Beatty) Builder Dübs and Company Neilson and Company Serial number Dübs 2882-2887 Neilson 4446-4477 Model CGR 7th Build date 1892 Total produced 38

Specifications Configuration 4-8-0 (Mastodon) Driver 2nd coupled axle 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) Tender wheels ♠ 33 1⁄2 in (851 mm) as built ♠ 34 in (864 mm) retyred ♥ 37 in (940 mm) Wheelbase ♠ 41 ft 4 3⁄8 in (12,608 mm) ♥ 46 ft 2 in (14,072 mm)  • Engine 21 ft 3 1⁄2 in (6,490 mm)  • Leading 5 ft 3 in (1,600 mm)  • Coupled 12 ft (3,658 mm)  • Tender ♠ 14 ft 7 in (4,445 mm) ♥ 10 ft (3,048 mm)  • Tender bogie ♠ 4 ft 7 in (1,397 mm) Length: ​  • Over couplers ♠ 51 ft 7 in (15,723 mm) ♥ 50 ft 1 in (15,265 mm) Height ♣ 12 ft 4 1⁄2 in (3,772 mm) ♦ 12 ft 10 in (3,912 mm) Frame type Plate Axle load ♣ 9 LT (9,144 kg) ♦ 9 LT 14 cwt (9,856 kg)  • Leading ♣ 10 LT 9 cwt (10,620 kg) ♦ 11 LT 2 cwt (11,280 kg)  • 1st coupled ♣ 8 LT 14 cwt (8,840 kg) ♦ 9 LT 8 cwt (9,551 kg)  • 2nd coupled ♣ 8 LT 11 cwt (8,687 kg) ♦ 9 LT 14 cwt (9,856 kg)  • 3rd coupled ♣ 9 LT (9,144 kg) ♦ 9 LT 10 cwt (9,652 kg)  • 4th coupled ♣ 8 LT 16 cwt (8,941 kg) ♦ 9 LT 8 cwt (9,551 kg)  • Tender axle ♥ 9 LT 13 cwt 3 qtr (9,843 kg) av. Adhesive weight ♣ 35 LT 1 cwt (35,610 kg) ♦ 38 LT (38,610 kg) Loco weight ♣ 45 LT 10 cwt (46,230 kg) ♦ 49 LT 2 cwt (49,890 kg) Tender weight ♥ 29 LT 1 cwt (29,520 kg) Total weight ♥♣ 74 LT 11 cwt (75,750 kg) ♥♦ 78 LT 3 cwt (79,400 kg) Tender type ZA (2-axle bogies) or ZB (3-axle) ZA, ZB, ZC, ZE permitted Fuel type Coal Fuel capacity ♠ 3 LT 10 cwt (3.6 t) ♥ 5 LT (5.1 t) Water cap ♠ 2,220 imp gal (10,100 l) ♥ 2,370 imp gal (10,800 l) Firebox type Round-top  • Firegrate area ♣ 17.5 sq ft (1.63 m2) ♦ 18 sq ft (1.7 m2) Boiler: ​  • Pitch ♣ 6 ft 6 in (1,981 mm) ♦ 6 ft 10 in (2,083 mm)  • Diameter ♣ 4 ft 2 in (1,270 mm) ♦ 4 ft 6 in (1,372 mm)  • Tube plates ♣♦ 10 ft 9 in (3,277 mm)  • Small tubes ♣ 185: 1 3⁄4 in (44 mm) ♦ 100: 1 7⁄8 in (48 mm)  • Large tubes ♦ 18: 5 1⁄2 in (140 mm) Boiler pressure ♣ 160 psi (1,103 kPa) as built ♣ 170 psi (1,172 kPa) adjusted ♦ 180 psi (1,241 kPa) Safety valve Ramsbottom Heating surface ♣ 1,010 sq ft (94 m2) ♦ 919 sq ft (85.4 m2)  • Tubes ♣ 911 sq ft (84.6 m2) ♦ 806 sq ft (74.9 m2)  • Firebox ♣ 99 sq ft (9.2 m2) ♦ 113 sq ft (10.5 m2) Superheater: ​  • Heating area ♦ 206 sq ft (19.1 m2) Cylinders Two Cylinder size 17 in (432 mm) bore 23 in (584 mm) stroke Valve gear Stephenson Couplers Johnston link-and-pin

Performance figures Tractive effort ♣ 18,660 lbf (83.0 kN) @ 75% ♣ 19,810 lbf (88.1 kN) @ 75% adjusted ♦ 22,240 lbf (98.9 kN) @ 75% Factor of adh. 4.20

Career Operators Cape Government Railways Imperial Military Railways South African Railways Zambesi Saw Mills Class Class 7 Number in class 38 Numbers CGR 315-352 17 renumbered 701-717 IMR C520, C521 & C524 SAR 950-987 Delivered 1892-1893 First run 1892 Withdrawn 1972

The leading coupled axle had flangeless wheels

The South African Railways Class 7 4-8-0 of 1892 was a steam locomotive from the pre-Union era in the Cape of Good Hope.

In 1892, the Cape Government Railways placed six 7th Class steam locomotives with a 4-8-0 Mastodon type wheel arrangement in service and, until 1893, another 32 were acquired. They were initially placed in service on the Midland System, but were later distributed between the Midland and Eastern Systems. The locomotives were renumbered in 1912, when they were assimilated into the South African Railways, but retained their Class 7 classification.

In 1890, Michael Stephens, then Chief Locomotive Superintendent of the Cape Government Railways (CGR), accompanied General Manager C.B. Elliot on a visit to Durban, to examine and report on the new Dübs A 4-8-2T (later NGR Class D) tank locomotives which had been placed in service by the Natal Government Railways (NGR) in 1888. In Elliot's subsequent report, he stated his conviction that locomotives with eight-coupled wheels should be adopted for the coastal sections of the Midland and Eastern Systems, where fog and the damp atmosphere were detrimental to tractive adhesion at night in the summer months.

Following this report, a complete design for such a locomotive was prepared at the Salt River works, under the supervision of Western System Locomotive Superintendent H.M. Beatty. The last six of an order for 36 Cape 5th Class 4-6-0 locomotives from Dübs and Company were cancelled and substituted with an order for six of these new 7th Class locomotives. They were delivered in 1892, numbered in the range from 315 to 320 for the Midland System. Two of them, numbers 318 and 320, were later renumbered to 701 and 702 and re-allocated to the Eastern System.

These six locomotives were equipped with type ZA tenders which rode on two two-axle bogies, the first proper bogie tenders to enter service in South Africa. They had a capacity of 3 long tons 10 hundredweight (3.6 tonnes) coal and 2,220 imperial gallons (10,100 litres) water.

The first six locomotives were followed by an order for another 32 of these engines, which were delivered from Neilson and Company in 1892 and 1893. These engines were initially numbered in the range from 321 to 352 for the Midland System. Fifteen of them were later renumbered in the range from 703 to 717 and re-allocated to the Eastern System. They were equipped with type ZB tenders, which rode on three-axle bogies. They had a larger capacity of 5 long tons (5.1 tonnes) coal and 2,370 imperial gallons (10,800 litres) water, with an average maximum axle load of 9 long tons 13 hundredweight 3 quarters (9,843 kilograms).