NZASM 32 Tonner 0-4-2RT

The NZASM 32 Tonner 0-4-2RT of 1894 was a South African steam locomotive from the pre-Union era in Transvaal.

In 1894 and 1897, the Nederlandsche-Zuid-Afrikaansche Spoorweg-Maatschappij of the Zuid-Afrikaansche Republiek (Transvaal Republic) placed four rack tank locomotives with a 0-4-2 wheel arrangement in service on the rack section between Waterval Onder and Waterval Boven. Since the railway classified its locomotives according to their weight, these engines were known as the 32 Tonners.^[1][2]

Waterval Onder to Waterval Boven

The construction of the railway line from Delagoa Bay to Pretoria was beset with difficulties, both in terms of disease and engineering. Malaria claimed many lives among the construction crews and some of the terrain was mountainous. In the Elandspruit valley, where the Elands River formed a 295-foot high (90-metre) waterfall, the adjacent cliffs presented a natural barrier to the continuation of the railway from the Eastern Transvaal Lowveld up to the Transvaal Highveld.^[1][2]

In terms of construction, the climb up the escarpment was arguably the most difficult section on the route to be encountered by the railway builders. When the line reached Waterval Onder, they had a choice between a lengthy detour with sharp curves and costly deep cuttings, embankments and viaducts to comply with the agreed upon gradient of 1 in 50 (2%), or a shorter 4 ¹⁄₂-mile long (7.2-kilometre) section, which would entail a gradient of 1 in 20 (5%) over a distance of 2.1 miles (3.4 kilometres) in one place, as well as a 233-yard long (213-metre) tunnel.^[1][2]

The shorter and steeper route was selected. While a gradient of 1 in 20 (5%) is not insurmountable by light trains with orthodox adhesion locomotives, safety and economical considerations led to the decision to install a rack track on the steep section up the escarpment between Waterval Onder and Waterval Boven. The rack track was built to the Riggenbach system which was in use on European mountain railways, with the rack laid between the rails.^[1][2]

Riggenbach rack system

The Riggenbach rack system used a ladder rack, formed of steel channels connected by square rungs at regular intervals, to engage the pinion wheels of the rack engine. The rungs of the NZASM rack track were spaced 4 inches (102 millimetres) apart. To ensure correct meshing of the gears when entering the rack section, engaging pieces of special section, 6 feet 6 ³⁄₄ inches (2,000 millimetres) long and fitted with round-bar rungs, were hinged to each end of the rack, supported by a spiral spring underneath. When the rack engine made contact with the hinged section and the gear wheels did not mesh with the rack correctly, the engaging section would be pressed down until correct meshing was accomplished.^[2][3]

Manufacturer

The line from Delagoa Bay and up the escarpment to Waterval Boven was completed on 20 June 1894. To work on the rack section, the Nederlandsche-Zuid-Afrikaansche Spoorweg-Maatschappij (NZASM) ordered three 0-4-2 rack tank locomotives from Emil Kessler's Maschinenfabrik Esslingen. The three locomotives were delivered in 1894, numbered in the range from 991 to 993. A fourth locomotive, no. 994, was ordered in 1897 and was identical to the other three, except that it had a coal bunker and water tanks with larger capacities, which made it heavier. Since the NZASM classified its locomotives according to their weight, the rack locomotives were known as 32 Tonners. In addition to being numbered, they were all named as well, with the names and numbers cast in brass and mounted on their tank sides.^[1][2][4][5]

Characteristics

The rack locomotive had plate frames, arranged outside the coupled wheels, and was equipped with the Heusinger von Waldegg version of Walschaerts valve gear. The pinion for the rack was mounted between the coupled wheels, just forward of the driving axle. The pinion axle was coupled to the drivers through side rods, with the connecting rods coupled directly to crank disks which were mounted on the ends of the axle, outside the frames. These crank disks were grooved to act as brake drums.^[1][2]

A second free-turning pinion wheel which also meshed with the rack, was mounted on the leading driving axle. It had grooved brake drums bolted to each side and acted as a brake only, with the brakes being applied by a hand mechanism from the footplate. The brakes on the driving and free-turning pinion wheels were separately controlled, while the vacuum brake gear on the engine was only used to control the brakes of the train.^[2]

The main steam cylinders were also used as brakes on the rack section. During descents, the 32 Tonner would be put into reverse with the steam regulator closed and a three-way valve in the exhaust pipe under the smokebox would be closed when brake power was required. The exhaust passages would then be isolated from the blast pipe and air would be admitted to the steam chests. The air would enter the cylinders though the exhaust ports and therefore reversed operations in the cylinders. Used air would be exhausted through the steam inlet ports back into the steam pipe, from where it was led to the rear of the engine by a 1 ¹⁄₂-inch diameter (38-millimetre) branch pipe. This branch pipe had another valve, by which the driver could regulate the amount of compression in the cylinders. Small amounts of water could be admitted into the cylinders to keep them cool.^[1][2]

Service

NZASM

The four rack locomotives were all shedded at Waterval Onder. When working a train up to Waterval Boven, a 32 Tonner would be coupled to the rear end of a train as banking engine. When working a descending train, the order of assembly was reversed, with the train's locomotive at the rear end and the rack locomotive in front to act as brake. Loads of 120 to 140 long tons (122 to 142 tonnes) could be handled in this manner.^[1][2]

Imperial Military Railways

All railway operations in the two Boer Republics, the Zuid-Afrikaansche Republiek and the Orange Free State, were taken over by the Imperial Military Railways (IMR) in 1899, during the Second Boer War.^[4]

All four locomotives survived the war.^[5]

Central South African Railways

At the end of the war in 1902, when the IMR was transformed into the Central South African Railways (CSAR), the four 32 Tonners were designated Class G, but retained their original NZASM engine numbers. They remained in banking service on the section between Waterval Boven and Waterval Onder until 1908, when a new alignment with easier gradients, including a new tunnel, was constructed and the rack section could be abandoned.^[1][2]

The original tunnel's portal coordinates are 25°38′17″S 30°20′48″E / 25.638170°S 30.346637°E / -25.638170; 30.346637 (southeastern portal) and 25°38′11″S 30°20′43″E / 25.636465°S 30.345353°E / -25.636465; 30.345353 (northwestern portal). The new 1908 tunnel's portal coordinates are 25°38′01″S 30°20′57″E / 25.633522°S 30.349168°E / -25.633522; 30.349168 (eastern portal) and 25°38′04″S 30°20′42″E / 25.634496°S 30.345066°E / -25.634496; 30.345066 (western portal).

South African Railways

When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (Cape Government Railways, Natal Government Railways and CSAR) were united under a single administration to control and administer the railways, ports and harbours of the Union. Although the South African Railways and Harbours came into existence in 1910, the actual classification and renumbering of all the rolling stock of the three constituent railways was only implemented with effect from 1 January 1912.^[4][6]

In 1912, these four locomotives were taken onto the SAR roster as unclassified engines, since they were considered obsolete. Since they were excluded from the SAR renumbering schedules, they retained their NZASM engine numbers until they were eventually scrapped.^[5][6]

Names and works numbers

The 32 Tonner engine numbers, names, works numbers and years built are listed in the table.^[1]

Illustration

The main picture shows no. 992 Driekleur while the following pictures serve to illustrate the larger coal bunker on the fourth engine.

References

Wikimedia Commons has media related to NZASM 32 Tonner 0-4-2RT.

Locomotives of the Central South African Railways
3' 6" gauge	CSAR 0-6-0ST 1896 CSAR 4-6-0T 1887 CSAR Class 6-L1 CSAR Class 6-L2 CSAR Class 6-L3 CSAR Class 7 CSAR Class 8-L1 CSAR Class 8-L2 CSAR Class 8-L3 CSAR Class 9 CSAR Class 10 1904 CSAR Class 10 1910 CSAR Class 10-2 Saturated CSAR Class 10-2 Superheated CSAR Class 10-C CSAR Class 11 CSAR Class B 0-6-4T CSAR Class C 2-8-4T CSAR Class D CSAR Class E 4-8-0TT CSAR Class E 4-8-2T CSAR Class E 4-10-2T CSAR Class F CSAR Class M CSAR Mallet Saturated CSAR Mallet Stoker CSAR Mallet Superheated CSAR Rack 4-6-4RT CSAR Railmotor IMR 0-6-0ST 1896 IMR 4-6-0T 1887 IMR 46 Tonner 0-6-4T IMR 55 Tonner 2-6-4T IMR 7th Class 4-8-0 IMR 8th Class 4-8-0 IMR Reid Tenwheeler 4-10-2T IMR Western Australian 2-8-4T NZASM 10 Tonner NZASM 13 Tonner NZASM 14 Tonner NZASM 18 Tonner NZASM 19 Tonner NZASM 32 Tonner NZASM 40 Tonner NZASM 46 Tonner OVGS 1st Class 4-4-0TT OVGS 2nd Class 2-6-0 OVGS 2nd Class 2-6-0ST OVGS 3rd Class 4-4-0 OVGS 4th Class G 4-6-0 OVGS 5th Class K 4-6-0 1890 OVGS 5th Class K 4-6-0 1891 OVGS 6th Class L 4-6-0 OVGS 6th Class L2 4-6-0 OVGS 6th Class L3 4-6-0 PPR 0-4-0ST Natal PPR 26 Tonner PPR 35 Tonner Portuguese PPR 55 Tonner
2' gauge	CSAR Pankop
List of South African locomotive classes South African locomotive history

Locomotives of South Africa
Steam	7' ¼" gauge East London 0-4-0VB Table Bay 0-4-0ST Table Bay 0-4-0T Table Bay 0-4-0WT 4' 8½" gauge Cape 0-4-0T Blackie Cape 0-4-2 Cape 2-4-0T CGR 0-4-0ST Aid Natal 0-4-0ST Durban Natal 0-4-0WT Natal Natal 4-4-0T Perseverance 3' 6" gauge Tank engines CGR 0-4-0ST 1873 CGR 0-4-0ST 1874 CGR 0-4-0ST 1881 CGR 0-4-0ST 1881 Coffee Pot CGR 0-6-0ST CGR 0-6-0T CGR 2-6-0ST 1900 CGR 2-6-0ST 1902 CGR 1st Class 0-4-0ST 1875 CGR 1st Class 0-4-0ST 1876 CGR 1st Class 2-6-0ST CGR 1st Class 4-4-0T CGR 2nd Class 4-4-0T CGR 3rd Class 2-6-0T CGR Railmotor CSAR Class C CSAR Class E CSAR Rack 4-6-4RT CSAR Railmotor Durban's Congella Durban's Edward Innes Durban's John Milne Durban's Sir Albert Port Elizabeth 0-4-0ST Kowie Railway 0-6-0T Kowie Railway 4-4-0T Metropolitan & Suburban 4-6-2T NGR 2-6-0T Durban & Pietermaritzburg NGR Class I 2-6-2T NGR Class K 0-4-0ST NGR Class K 0-6-0ST NGR Class K 2-6-0T NZASM 10 Tonner NZASM 13 Tonner NZASM 14 Tonner NZASM 18 Tonner NZASM 19 Tonner NZASM 32 Tonner NZASM 40 Tonner PPR 26 Tonner PPR 35 Tonner Portuguese SAR Class A SAR Class B SAR Class C SAR Class C1 SAR Class C2 SAR Class D SAR Class E SAR Class F SAR Class G SAR Class H SAR Class H1 SAR Class H2 SAR Class J SAR Class K SAR Railmotor SAR Dock 0-4-0ST SAR Dock 0-4-0T SWA 2-8-0T 3' 6" gauge Tender engines CGR 1st Class 2-6-0 1876 BP CGR 1st Class 2-6-0 1876 Kitson CGR 1st Class 2-6-0 1879 CGR 1st Class 2-6-0 1891 CGR 1st Class 4-4-0 CGR 1st Class 4-4-0TT CGR 2nd Class 2-6-2TT CGR 3rd Class 4-4-0 1883 CGR 3rd Class 4-4-0 1884 CGR 3rd Class 4-4-0 1889 CGR 3rd Class 4-4-0 1898 CGR 3rd Class 4-4-0 1901 CGR 3rd Class 4-4-0 1903 CGR 4th Class 4-4-2 CGR 4th Class 4-6-0TT 1880 CGR 4th Class 4-6-0TT 1882 CGR 4th Class 4-6-0TT 1882 Joy CGR 4th Class 4-6-0TT 1884 CGR 5th Class 4-6-0 1890 CGR 5th Class 4-6-0 1891 NGR Havelock NGR Class I SAR Class Exp 1 SAR Class Exp 2 SAR Class Exp 3 SAR Class Exp 4 SAR Class Exp 5 SAR Class Exp 6 SAR Class S SAR Class S1 SAR Class S2 SAR Class 1 SAR Class 1A SAR Class 1B SAR Class 2 SAR Class 2C SAR Class 3 SAR Class 3A SAR Class 3B SAR Class 4 SAR Class 4A SAR Class 5 SAR Class 5A SAR Class 5B SAR Class 6 SAR Class 6A SAR Class 6B SAR Class 6C SAR Class 6D SAR Class 6E SAR Class 6F SAR Class 6G SAR Class 6H SAR Class 6J SAR Class 6K SAR Class 6L SAR Class 6Y SAR Class 6Z SAR Class 7 SAR Class 7A SAR Class 7B SAR Class 7C SAR Class 7D SAR Class 7E SAR Class 7F SAR Class 8 SAR Class 8A SAR Class 8B SAR Class 8C SAR Class 8D SAR Class 8E SAR Class 8F SAR Class 8R SAR Class 8X SAR Class 8Y SAR Class 8Z SAR Class 9 SAR Class 10 SAR Class 10A SAR Class 10B SAR Class 10C SAR Class 10D SAR Class 11 SAR Class 12 SAR Class 12A SAR Class 12B SAR Class 13 SAR Class 14 SAR Class 14A SAR Class 14B SAR Class 14C 1st SAR Class 14C 2nd SAR Class 14C 3rd SAR Class 14C 4th SAR Class 15 SAR Class 15A SAR Class 15B SAR Class 15C SAR Class 15CA SAR Class 15E SAR Class 15F SAR Class 16 SAR Class 16A SAR Class 16B SAR Class 16C SAR Class 16D SAR Class 16DA 1928 SAR Class 16DA 1930 SAR Class 16E SAR Class 17 SAR Class 18 SAR Class 19 SAR Class 19A SAR Class 19B SAR Class 19C SAR Class 19D SAR Class 20 SAR Class 21 SAR Class 23 SAR Class 24 SAR Class 25 SAR Class 25NC SAR Class 26 SAR Katanga SWA 2-8-0 3' 6" gauge Articulated engines CGR Fairlie CGR Kitson-Meyer SAR Class FC SAR Class FD SAR Class GA SAR Class GB SAR Class GC SAR Class GCA SAR Class GD SAR Class GDA SAR Class GE SAR Class GEA SAR Class GF SAR Class GG SAR Class GH SAR Class GK SAR Class GL SAR Class GM SAR Class GMA SAR Class GO SAR Class HF SAR Class KM SAR Class MA SAR Class MB SAR Class MC SAR Class MC1 SAR Class MD SAR Class ME SAR Class MF SAR Class MG SAR Class MH SAR Class MJ SAR Class MJ1 SAR Class U 2' 6" gauge Cape Copper John King & Miner Cape Copper Britannia Cape Copper Caledonia Cape Copper Clara Cape Copper Condenser Cape Copper Scotia Namaqua Copper Pioneer Walvis Bay 2-4-2T Hope 2' & 600mm gauges ACR Class NG-G16A CGR NG 0-4-0T CGR NG 0-6-0T CGR NG 4-6-2T CGR Type A 2-6-4T CGR Type C 0-4-0T NGR Class N 4-6-2T SAR Dutton SAR NG 0-4-0T SAR Class NG1 SAR Class NG2 SAR Class NG3 SAR Class NG4 SAR Class NG5 SAR Class NG6 SAR Class NG7 SAR Class NG8 SAR Class NG9 SAR Class NG10 SAR Class NG-G11 SAR Class NG-G12 SAR Class NG-G13 SAR Class NG-G14 SAR Class NG15 SAR Class NG-G16 SWA Class Ha SWA Class Hb SWA Class Hc SWA Class Hd SWA Jung SWA Zwillinge
Electric	Amcoal Class E38 SAR Class ES SAR Class ES1 SAR Class Exp-AC SAR Class 1E SAR Class 2E SAR Class 3E SAR Class 4E SAR Class 5E s1 SAR Class 5E s2 SAR Class 5E s3 SAR Class 5E1 s1 SAR Class 5E1 s2 SAR Class 5E1 s3 SAR Class 5E1 s4 SAR Class 5E1 s5 SAR Class 6E SAR Class 6E1 s1 SAR Class 6E1 s2 SAR Class 6E1 s3 SAR Class 6E1 s4 SAR Class 6E1 s5 SAR Class 6E1 s6 SAR Class 6E1 s7 SAR Class 6E1 s8 SAR Class 6E1 s9 SAR Class 6E1 s10 SAR Class 6E1 s11 SAR Class 7E SAR Class 7E1 SAR Class 7E2 s1 SAR Class 7E2 s2 SAR Class 7E3 s1 SAR Class 7E3 s2 Spoornet Class 7E4 SAR Class 8E SAR Class 9E s1 SAR Class 9E s2 SAR Class 10E SAR Class 10E1 s1 Spoornet Class 10E1 s2 SAR Class 10E2 SAR Class 11E SAR Class 12E Spoornet Class 14E Spoornet Class 14E1 TFR Class 15E Spoornet Class 16E Spoornet Class 17E Spoornet Class 18E s1 TFR Class 18E s2 TFR Class 19E TFR Class 20E TFR Class 21E TFR Class 22E
Gas-electric	SAR Gas-electric
Diesel	3' 6" gauge Diesel-electric PRASA Class Afro 4000 SAR Class DS SAR Class DS1 SAR Class 31-000 SAR Class 32-000 SAR Class 32-200 SAR Class 33-000 SAR Class 33-200 SAR Class 33-400 SAR Class 34-000 SAR Class 34-200 SAR Class 34-400 SAR Class 34-500 SAR Class 34-600 SAR Class 34-800 SAR Class 34-900 SAR Class 35-000 SAR Class 35-200 SAR Class 35-400 SAR Class 35-600 TFR Class 35-800 SAR Class 36-000 SAR Class 36-200 SAR Class 37-000 Spoornet Class 39-000 TFR Class 39-200 TFR Class 43-000 TFR Class 44-000 2' gauge Diesel-electric SAR Class 91-000 3' 6" gauge Diesel-hydraulic SAR Class 61-000 3' 6" gauge Electro-diesel Spoornet Class 38-000
List of South African locomotive classes South African locomotive numbering and classification