South African Class 8E 4-8-0

CGR 8th Class 4-8-0 1903 Experimental South African Class 8E 4-8-0
CGR 8th Class no. 814, SAR Class 8E no. 1231
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 Serial number 6309-6312 Model CGR 8th Build date 1903 Total produced 4
Specifications Configuration: ​  • Whyte 4-8-0 (Mastodon)  • UIC ♠ 2'Dn2 - ♥ 2'Dh2 Driver 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 28 1⁄2 in (724 mm) Coupled dia. 48 in (1,219 mm) Tender wheels 33 1⁄2 in (851 mm) as built 34 in (864 mm) retyred Wheelbase 46 ft 10 1⁄2 in (14,288 mm)  • Engine 23 ft 3 in (7,087 mm)  • Leading 6 ft (1,829 mm)  • Coupled 13 ft 6 in (4,115 mm)  • Tender 14 ft 7 in (4,445 mm)  • Tender bogie 4 ft 7 in (1,397 mm) Length: ​  • Over couplers ♠ 54 ft 2 1⁄4 in (16,516 mm) ♥ 54 ft 5 1⁄8 in (16,589 mm) Height 12 ft 10 in (3,912 mm) Frame type Bar Axle load ♠ 11 LT 14 cwt (11,890 kg) ♥ 12 LT (12,190 kg)  • Leading ♠ 12 LT 9 cwt (12,650 kg) ♥ 12 LT 15 cwt (12,950 kg)  • Coupled ♠ 11 LT 14 cwt (11,890 kg) ♥ 12 LT (12,190 kg)  • Tender bogie Bogie 1: 17 LT 13 cwt (17,930 kg) Bogie 2: 18 LT 16 cwt (19,100 kg)  • Tender axle 9 LT 8 cwt (9,551 kg) Adhesive weight ♠ 46 LT 16 cwt (47,550 kg) ♥ 48 LT (48,770 kg) Loco weight ♠ 59 LT 5 cwt (60,200 kg) ♥ 60 LT 15 cwt (61,720 kg) Tender weight 36 LT 9 cwt (37,030 kg) Total weight ♠ 95 LT 14 cwt (97,240 kg) ♥ 97 LT 4 cwt (98,760 kg) Tender type XE1 (2-axle bogies) XC, XC1, XD, XE, XE1, XF, XF1, XF2, XJ, XM, XM1, XM2, XM3 permitted Fuel type Coal Fuel capacity 10 LT (10.2 t) Water cap 2,855 imp gal (13,000 l) Firebox type Round-top  • Firegrate area ♠ 27.5 sq ft (2.55 m2) ♥ 21 sq ft (2.0 m2) Boiler: ​  • Pitch ♠ 7 ft 2 1⁄2 in (2,197 mm) ♥ 7 ft 3 in (2,210 mm)  • Diameter 5 ft (1,524 mm)  • Tube plates ♠ 11 ft 1⁄4 in (3,359 mm) ♥ 11 ft 3⁄8 in (3,362 mm)  • Small tubes ♠ 205: 2 in (51 mm) ♥ 115: 2 in (51 mm)  • Large tubes ♥ 18: 5 1⁄2 in (140 mm) Boiler pressure 180 psi (1,241 kPa) Safety valve Ramsbottom Heating surface ♠ 1,321 sq ft (122.7 m2) ♥ 1,081 sq ft (100.4 m2)  • Tubes ♠ 1,184 sq ft (110.0 m2) ♥ 950 sq ft (88 m2)  • Firebox ♠ 137 sq ft (12.7 m2) ♥ 131 sq ft (12.2 m2) Superheater: ​  • Heating area ♥ 214 sq ft (19.9 m2) Cylinders Two Cylinder size ♠ 18 1⁄2 in (470 mm) bore 24 in (610 mm) stroke ♥ 19 in (483 mm) bore 24 in (610 mm) stroke Valve gear Stephenson Valve type ♠ Slide - ♥ Piston Couplers Johnston link-and-pin AAR knuckle (1930s)
Performance figures Tractive effort ♠ 23,110 lbf (102.8 kN) @ 75% ♥ 24,370 lbf (108.4 kN) @ 75%
Career Operators Cape Government Railways South African Railways Class CGR 8th Class, SAR Class 8E Number in class 4 Numbers CGR 813-816 SAR 1230-1233 Delivered 1903 First run 1903
As built, the leading coupled axle had flangeless wheels

The South African Railways Class 8E 4-8-0 of 1903 was a steam locomotive from the pre-Union era in the Cape of Good Hope.

In 1903, at the same time that the Cape Government Railways ordered its second batch of 38 8th Class 4-8-0 Mastodon type steam locomotives, four additional experimental locomotives of the same class were ordered, built to modified specifications to accommodate a larger firegrate area. In 1912, when these four locomotives were assimilated into the South African Railways, they were renumbered and designated Class 8E.

The first Cape Government Railways (CGR) 8th Class locomotive was a 2-8-0 Consolidation type, designed by H.M. Beatty, the CGR's Chief Locomotive Superintendent from 1896 to 1910. These locomotives were later to become the South African Railways (SAR) Class 8X. While these first Schenectady- and ALCO-built 2-8-0 locomotives were being subjected to exhaustive testing on all types of traffic and under varying conditions, some trouble was experienced with the leading two-wheeled pony truck and, when designs were prepared at Salt River for a later order for more locomotives, the pony truck was replaced with a four-wheeled bogie, which resulted in the CGR's 4-8-0 Mastodon type 8th Class.

In spite of the difference in wheel arrangements, the CGR's 2-8-0 Consolidations and post-7th Class 4-8-0 Mastodons were all grouped together as the 8th Class.

In 1902, when a second batch of 38 8th Class 4-8-0 locomotives was ordered, later to become the Class 8D on the SAR, an additional four engines were ordered. These were of an experimental design, built to modified specifications.

Beatty believed that, while the earlier 8th Class locomotives (later the SAR Class 8) steamed well, they would steam even better if they had a larger firegrate area. He was hampered by the fact that the firebox wrapper plates had to fit between the rearmost coupled wheels. The result was that the greatest inside width obtainable on a firebox which was arranged between the wheels of a Cape gauge locomotive was 27 ¹⁄₂ inches (698 millimetres). He overcame this by designing an 8th Class locomotive with a deep curve in the foundation ring (mud ring) to clear the intermediate coupled wheels and a steep slope towards the rear to clear the trailing wheels. In the process he was able to increase the firegrate area from 21 to 27.5 square feet (1.951 to 2.555 square metres).