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Natal Government Railways class C 4-10-2-T

South African class H

South Africa 1899 101 produced
NGR Class C No. 171, later SAR Class H No. 253 J. Stuart Grossert collection PD

The NGR class C, also known as “Reid Tenwheeler”, was a 4-10-2T tank locomotive introduced by G.W. Reid in 1899. It was designed for Cape gauge lines with curves with a radius of 300 feet and inclines of 1 in 30, where the 4-8-2T classes D1 and D2 had to be used double-headed. The requirements called for a locomotive that had 1.5 times the power of the D1 and D2. At the same time, the axle load was limited to 14 tons.

Initially, only few believed that a tank locomotive with ten coupled wheels would work in reality. So Reid initially only ordered a single prototype that was built in 1899 by Dübs. With its flangeless wheels on the first and fifth driving axles and the leading bogie with a side play of four inches, its running characteristics were found to be sufficient. Only later it became evident that it tended to derail when running backwards through sharp turnouts due to the missing flanges on the last driving axle, but this problem was addressed by widening the tires on that axle.

100 more were ordered from Dübs, of which the last five were delivered in 1903 by the new company of North British. The Imperial Military Railways ordered 35 more and the Witbank Colliery got one. The NGR used the Reid Tenwheelers in passenger and freight service. When some were transferred to shunting service, they still derailed sometimes and so the NGR started to remove the last driving axle, what resulted in the 4-8-2T wheel arrangement.

When South African Railways were founded in 1912, they took over 93 of the unrebuilt variant and designated them class H. Five which had been rebuilt to 4-8-2T became class H2 and the SAR rebuilt more in this way. The locomotives of the Imperial Military Railway had become class H1. The last ones were used for shunting at Durban Harbour in the middle of the seventies. Three have been preserved, but are not operational.

Identical Witbank Colliery No. 1 flickr/Historical Railway Images

Technical data

General

Built
1899-1903
Manufacturers
Dübs & Co., North British
Wheel arrangement
4-10-2T (Reid Tenwheeler)
Gauge
1,067 mm (Cape gauge)

Dimensions and weights

Length
11.43 m
Wheelbase
9.30 m
Service mass
70 t
Adhesion mass
55.7 t
Rigid wheelbase
5.08 m
Axle load
12.4 t
Water capacity
8,547 l
Fuel capacity
4.1 t (coal)

Boiler

Grate area
1.965 m²
Firebox surface
10.034 m²
Tube heating surface
138.797 m²
Evaporative heating surface
148.831 m²
Total heating surface
148.8 m²

Power plant

Driver diameter
1,143 mm
Boiler pressure
12.1 bar
Expansion type
simple expansion
Cylinders
two, 483 x 686 mm

Power

Power source
steam
Estimated power
485 kW (659 PS)
Starting effort
143.3 kN

Calculated values

Factor of adhesion
1 : 3.81
Optimal speed
21 km/h
Power-to-weight ratio
6.9 kW/t
Heating Surface Equivalent
199.0 m²
Cylinder volume/HSE
1 : 1,260.77
Adhesive weight/Total
1 : 1.26
Tractive force/Heating surface
1 : 20.11
Grate area/Heating surface
1 : 75.74
Firebox/Tube surface
1 : 13.83
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