South African Class 3B 4-8-2

South African Classes 3B & 3BR 4-8-2
No. 1486 Maureen at Kloof, 6 June 2010
Type and origin ♠ Class 3B as built with a Belpaire firebox ♥ Class 3BR rebuilt with a Watson Standard boiler ♣ Steel firebox - ♦ Copper firebox Power type Steam Designer Natal Government Railways (D.A. Hendrie) Builder North British Locomotive Company Serial number 19597-19601, 19688-19692 Model Class 3B Build date 1911-1912 Total produced 10
Specifications Configuration: ​  • Whyte 4-8-2 (Mountain)  • UIC 2'D1'h2 Driver 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 28 1⁄2 in (724 mm) Coupled dia. 45 1⁄2 in (1,156 mm) as built 46 in (1,168 mm) retyred Trailing dia. 30 in (762 mm) Tender wheels 30 in (762 mm) Wheelbase 55 ft 8 in (16,967 mm)  • Engine 30 ft 9 in (9,373 mm)  • Leading 6 ft (1,829 mm)  • Coupled 12 ft 9 in (3,886 mm)  • Tender 16 ft 6 in (5,029 mm)  • Tender bogie 4 ft 6 in (1,372 mm) Length: ​  • Over couplers 63 ft 2 3⁄4 in (19,272 mm) Height ♠ 12 ft 6 in (3,810 mm) ♥ 12 ft 4 3⁄4 in (3,778 mm) Frame type Plate Axle load ♠ 15 LT 12 cwt (15,850 kg) ♥♦ 15 LT 11 cwt (15,800 kg)  • Leading ♠ 14 LT 2 cwt (14,330 kg) ♥♦ 14 LT 1 cwt (14,280 kg)  • 1st coupled ♠ 14 LT 10 cwt (14,730 kg) ♥♦ 14 LT 15 cwt (14,990 kg)  • 2nd coupled ♠ 15 LT 12 cwt (15,850 kg) ♥♦ 15 LT 11 cwt (15,800 kg)  • 3rd coupled ♠ 15 LT (15,240 kg) ♥♦ 15 LT 2 cwt (15,340 kg)  • 4th coupled ♠ 15 LT (15,240 kg) ♥♦ 14 LT 11 cwt (14,780 kg)  • Trailing ♠ 9 LT 10 cwt (9,652 kg) ♥♦ 10 LT 6 cwt (10,470 kg)  • Tender bogie Bogie 1: 21 LT 14 cwt (22,050 kg) Bogie 2: 21 LT 16 cwt (22,150 kg)  • Tender axle 10 LT 18 cwt (11,070 kg) Adhesive weight ♠ 60 LT 2 cwt (61,060 kg) ♥♦ 59 LT 19 cwt (60,910 kg) Loco weight ♠ 83 LT 14 cwt (85,040 kg) ♥♦ 84 LT 14 cwt (86,060 kg) Tender weight 43 LT 10 cwt (44,200 kg) Total weight ♠ 127 LT 4 cwt (129,200 kg) ♥♦ 128 LT 4 cwt (130,300 kg) Tender type TM (2-axle bogies) TJ, TL, TM permitted Fuel type Coal Fuel capacity 8 LT 5 cwt (8.4 t) Water cap 4,000 imp gal (18,200 l) Firebox type ♠ Belpaire - ♥ Round-top  • Firegrate area ♠ 34 sq ft (3.2 m2) ♥ 37 sq ft (3.4 m2) Boiler: ​  • Model ♥ Watson Standard no. 2  • Pitch ♠ 7 ft 4 1⁄2 in (2,248 mm) ♥ 7 ft 5 1⁄2 in (2,273 mm)  • Diameter ♠ 5 ft 6 1⁄8 in (1,680 mm) ♥ 5 ft 7 1⁄2 in (1,714 mm)  • Tube plates ♠ 18 ft 6 in (5,639 mm) ♥♣ 19 ft 4 in (5,893 mm) ♥♦ 19 ft 3 5⁄8 in (5,883 mm)  • Small tubes ♠ 135: 2 1⁄4 in (57 mm) ♥ 87: 2 1⁄2 in (64 mm)  • Large tubes ♠ 24: 5 1⁄2 in (140 mm) ♥ 30: 5 1⁄2 in (140 mm) Boiler pressure ♠ 185 psi (1,276 kPa) ♥ 190 psi (1,310 kPa) Safety valve ♠ Ramsbottom ♥ Pop Heating surface ♠ 2,245 sq ft (208.6 m2) ♥ 2,075 sq ft (192.8 m2)  • Tubes ♠ 2,110 sq ft (196 m2) ♥ 1,933 sq ft (179.6 m2)  • Firebox ♠ 135 sq ft (12.5 m2) ♥ 142 sq ft (13.2 m2) Superheater: ​  • Heating area ♠ 617 sq ft (57.3 m2) ♥ 492 sq ft (45.7 m2) Cylinders Two Cylinder size 22 in (559 mm) bore 24 in (610 mm) stroke Valve gear Walschaerts Valve type Piston Couplers Johnston link-and-pin AAR knuckle (1930s)
Performance figures Tractive effort ♠ 35,030 lbf (155.8 kN) @ 75% ♥ 35,980 lbf (160.0 kN) @ 75%
Career Operators South African Railways Class Class 3B & 3BR Number in class 10 Numbers 1479-1488 Delivered 1912 First run 1912 Withdrawn 1976
The leading coupled axle had flangeless wheels

The South African Railways Class 3B 4-8-2 of 1912 was a steam locomotive.

In 1912, the South African Railways took delivery of ten Class 3B steam locomotives with a 4-8-2 Mountain type wheel arrangement which had been ordered by the Natal Government Railways the year before.

With the experience gained from the sole experimental Class B American D locomotive, Natal Government Railways (NGR) Locomotive Superintendent D.A. Hendrie redesigned his Class Hendrie D and placed orders for ten locomotives with the North British Locomotive Company on 29 March 1911. These locomotives, which would have become the NGR's Class Superheated Hendrie D, were built in two batches of five and were all delivered in 1912 after the renumbering and reclassification of the locomotives of the constituent former Colonial railways into the South African Railways (SAR). Upon delivery, they were therefore taken directly onto the SAR roster, numbered in the range from 1479 to 1488 and designated Class 3B. The first of these engines entered service in February 1912.

Like the NGR Class Hendrie D which it was based on and which was later designated the SAR Class 3, the Class 3B had plate frames, Walschaerts valve gear and Belpaire fireboxes. They were the first of Hendrie's designs to have superheaters and, as a result, piston valves instead of slide valves. They also sported a new design of leading bogie with cast-steel framing and three-point suspension links.

To accommodate the redesigned cylinders and the necessary alteration to the Walschaerts valve gear, the running boards had to be raised to clear the steam chests and motion. This resulted in the gentle sweeps at either end where the running boards dropped down to the buffer beam and below the cab. These curves became a Hendrie hallmark and enhanced the appear­ance of the locomotive. In other respects, however, they were practically identical to the Class 3.

The locomotives were delivered with Type TM tenders with an 8 long tons 5 hundredweight (8.4 tonnes) coal capacity and a 4,000 imperial gallons (18,200 litres) water capacity. When the coupled wheels were retyred, their diameter on tread was increased from 45 ¹⁄₂ to 46 inches (1,156 to 1,168 millimetres). This reduced their tractive effort to 35,030 pounds-force (155.8 kilonewtons) at 75% of boiler pressure, which was set at 185 pounds per square inch (1,276 kilopascals). The engines, as built, had flangeless wheels on the leading coupled axle, but these were subsequently also flanged as shown in official SAR dimensional locomotive drawings.