South African Class 7D 4-8-0

Rhodesia Railways 7th Class
South African Class 7D 4-8-0

RR 7th Class no. MR11, then no. MR18, then no. RRM67, then SAR Class 7D no. 1353

Type and origin ♠ Original locomotive, as built ♥ Locomotive equipped with superheating Power type Steam Designer Cape Government Railways (H.M. Beatty) Builder Neilson, Reid and Company Kitson and Company North British Locomotive Company Order number NR E834 & E835 (1899), E851 (1900) NBL L313 & L322 (1903) Serial number NR 5675-5686, 5791-5802, 5817 Kitson 4062-4069 NBL 16085-16094, 16171-16180 Model CGR 7th Class Build date 1899-1903 Total produced 52

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 Wheelbase 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 16 ft 1 in (4,902 mm)  • Tender bogie 4 ft 7 in (1,397 mm) Length: ​  • Over couplers 53 ft 5 1⁄4 in (16,288 mm) Height 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 14 cwt (10,870 kg) ♥ 11 LT 2 cwt (11,280 kg)  • 1st coupled ♠ 9 LT (9,144 kg) ♥ 9 LT 8 cwt (9,551 kg)  • 2nd coupled ♠ 9 LT (9,144 kg) ♥ 9 LT 14 cwt (9,856 kg)  • 3rd coupled ♠ 8 LT 18 cwt (9,043 kg) ♥ 9 LT 10 cwt (9,652 kg)  • 4th coupled ♠ 8 LT 18 cwt (9,043 kg) ♥ 9 LT 8 cwt (9,551 kg)  • Tender axle 8 LT 10 cwt 2 qtr (8,662 kg) av. Adhesive weight ♠ 35 LT 16 cwt (36,370 kg) ♥ 38 LT (38,610 kg) Loco weight ♠ 46 LT 10 cwt (47,250 kg) 44 LT 7 cwt (45,060 kg) Kitson ♥ 49 LT 2 cwt (49,890 kg) Tender weight 34 LT 2 cwt (34,650 kg) Total weight ♠ 80 LT 12 cwt (81,890 kg) 78 LT 9 cwt (79,710 kg) Kitson ♥ 83 LT 4 cwt (84,540 kg) Tender type ZC (2-axle bogies) ZA, ZB, ZC, ZE permitted Fuel type Coal Fuel capacity 5 LT 10 cwt (5.6 t) Water cap 2,600 imp gal (11,800 l) Firebox type Round-top or Belpaire  • Firegrate area ♠ 17.5 sq ft (1.63 m2) ♥ 18 sq ft (1.7 m2) Boiler: ​  • Pitch ♠ 6 ft 8 in (2,032 mm) ♥ 6 ft 10 in (2,083 mm)  • Diameter ♠ 4 ft 4 in (1,321 mm) ♥ 4 ft 6 in (1,372 mm)  • Tube plates ♠ 10 ft 9 in (3,277 mm) ♥ 10 ft 9 in (3,277 mm)  • Small tubes ♠ 185: 1 7⁄8 in (48 mm) ♥ 100: 1 7⁄8 in (48 mm)  • Large tubes ♥ 18: 5 1⁄2 in (140 mm) Boiler pressure ♠ 160 psi (1,103 kPa) 170 psi (1,172 kPa) adjusted ♥ 180 psi (1,240 kPa) Safety valve Ramsbottom Heating surface ♠ 1,078 sq ft (100.1 m2) 1,088 sq ft (101.1 m2) Kitson ♥ 919 sq ft (85.4 m2)  • Tubes ♠ 976 sq ft (90.7 m2) ♥ 806 sq ft (74.9 m2)  • Firebox ♠ 102 sq ft (9.5 m2) 112 sq ft (10.4 m2) Kitson ♥ 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 Valve type ♠ Slide - ♥ Piston Couplers Johnston link-and-pin AAR knuckle (1930s)

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. NR & NBL-built: 4.32 Kitson-built: 4.531

Career Operators Imperial Military Railways Mashonaland Railways Rhodesia Railways Northern Ext Rhodesia Railways South African Railways Class IMR, MR, RRM & RR 7th Class SAR Class 7D Number in class RR 52, SAR 5 Numbers BR 7-8, RR 1-50, IMR 110 SAR 1351-1355 Delivered 1899-1903 to RR, 1915 to SAR First run 1899 Withdrawn 1972

The leading coupled axle had flangeless wheels

The South African Railways Class 7D 4-8-0 of 1915 was a steam locomotive.

Between 1899 and 1903, the Rhodesia Railways placed 52 Cape 7th Class 4-8-0 Mastodon steam locomotives in service. During the Second Boer War, one more was obtained from the Imperial Military Railways in March 1901, as replacement for a locomotive which was damaged beyond local repair capabilities as a result of hostilities during delivery.

In May 1915, five of these locomotives were sold to the South African Railways, where they were renumbered and reclassified, four of them to Class 7D and the remaining one erroneously to Class 7B. At the same time, the ex Imperial Military Railways locomotive was also sold back to South Africa and was, also erroneously, designated Class 7D.

The original Cape 7th Class locomotive had been designed in 1892 by H.M. Beatty, at the time the Cape Government Railways Western System Locomotive Superintendent.

Between 1899 and 1903, 52 such Cape 7th Class 4-8-0 steam locomotives were built for the Beira and Mashonaland and Rhodesia Railways (BMR), later the Rhodesia Railways (RR). These locomotives were acquired by Southern Rhodesia at the time when railways were still expanding from South Africa via the Bechuanaland Protectorate into Southern Rhodesia in the southwest, and from Beira in Mozambique to Umtali in the east, and while the Second Boer War was in progress. At the time, the system was composed of several smaller railways, still largely under construction, which were eventually all linked up in 1902. These were:

The 52 locomotives were ordered in five batches from three British manufacturers.

In May 1915, six of the Neilson, Reid-built 7th Class locomotives were purchased by the South African Railways (SAR) to augment its locomotive stock, which was being taxed severely due to war conditions at the time. These six locomotives included the war-damaged no. RR8 which had still not been repaired and consequently never ran a mile in revenue service in Rhodesia, as well as the ex IMR locomotive which had been transferred to Rhodesia as compensation for the damaged no. RR8.

These locomotives were initially referred to as Class RR, until they were later designated SAR Class 7D. Five of them were renumbered in the range from 1351 to 1355 on the SAR roster. The sixth, SAR no. 949, was erroneously designated Class 7B.