South African Class 5B 4-6-2

The South African Railways Class 5B 4-6-2 of 1904 was a steam locomotive from the pre-Union era in the Cape of Good Hope.

In 1904, the Cape Government Railways placed four Karoo Class 4-6-2 Pacific type passenger steam locomotives in service. In 1912, when they were assimilated into the South African Railways, they were renumbered and classified as Class 5B.^[1][2][3][4]

Manufacturer

Following on the success of the first two Karoo Class locomotives of the Cape Government Railways (CGR), a further four were ordered from Beyer, Peacock and Company in 1904 and delivered in that same year. In view of the experience gained with the original two Karoo Class locomotives, their design was modified slightly by CGR Chief Locomotive Superintendent H.M. Beatty.^[1][4][5][6]

They were numbered in the range from 905 to 908 and, like the previous two locomotives, they were also not allocated class numbers by the CGR. Instead, they were also known as the Karoo Class, from the region of the Western System where they were designed to work.^[1]

Characteristics

H.M. Beatty

With these locomotives, Beatty allowed a ¹⁄₂ inch (13 millimetres) increase in the boiler pitch, compared to that of the first two Karoo Class engines, to 7 feet 1 inch (2,159 millimetres) above the railhead.^[4]

This increase still did not allow sufficient clearance between the boiler barrel and the 60 inches (1,524 millimetres) diameter coupled wheels, and pockets in the boiler barrel, similar to those used on the earlier locomotives, were therefore still necessary. The boilers of the first two locomotives, numbers 905 and 906, were fitted with Coale patent safety valves, while numbers 907 and 908 had Ramsbottom safety valves. The eccentrics and motion were actuated from the driving (centre) axle instead of the trailing axle. The firebox had an inside width of 4 feet 2 ¹⁄₂ inches (1,283 millimetres).^[4]

South African Railways

When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (CGR, Natal Government Railways and Central South African Railways) 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 required careful planning and was only implemented with effect from 1 January 1912.^[2][7]

In 1912, these four locomotives were renumbered in the range from 723 to 726 and designated Class 5B on the South African Railways (SAR).^[2][6][8]

Modifications

Piston valves

In the early 1930s, A.G. Watson, CME of the SAR at the time, endeavoured to improve some of the older locomotive classes in various ways. The Class 5B were fitted with piston valves and a redesigned smokebox arrangement, which resulted in an exhaust which has been described as "positively startling" when the regulator was opened up. At the same time, their running boards were raised clear of the coupled wheels. This modification made the as-built wheel fairings on the running boards unnecessary and resulted in a locomotive with a North American rather than a British appearance.^[8]

Trofimoff piston valves

During September 1931, Watson fitted engine no. 726 with Trofimoff type by-pass piston valves as an experiment. The Trofimoff valve was claimed to afford ideal conditions when drifting. On no. 726, the experiment was less than successful and, after having the covers blown off a couple of times through too sudden opening of the regulator, the Trofimoff piston valves were removed.^[8][9]

Trofimoff valve, closed

Trofimoff valve, open

The Trofimoff piston valve consisted of two fixed discs, secured to the valve spindle, and two junk rings, each carrying a Bull ring and four valve rings and both free to move longitudinally on the spindle. When the regulator is opened, steam forces the loose valve bodies against their respective fixed discs, and they then act as units, similar to ordinary piston valves. When steam is shut off, the loose valve heads become detached from their respective discs and remain in their idle positions near the centre of the steam chest, while the valve spindle and fixed disks continue their reciprocating motion, with the spindle sliding freely through the now stationary loose valve heads, and with the steam and exhaust ports now in communication. With both ends of the cylinders now in communication, the use of ordinary by-bass or snifting valves became unnecessary.^[9]

The first such experiment was carried out on Class 16C no. 851. Further similar experiments were carried out on Class 16B no. 805 in July 1932, Class 16DA no. 876 in August 1932, Class 15CA no. 2852 in March 1933 and finally on Class 15A no. 1961. The results of these extended tests did not prove entirely satisfactory and all these engines were gradually refitted with standard piston valves and snifting valves.^[8][9]

Split crossheads

In another experiment, one of the class was fitted with split crossheads. The split was on the vertical centre line and the two halves were bolted together over the end of the piston rod. The end of the piston rod and its nesting inside the crosshead halves were grooved in an arrangement similar to a nut and bolt, but with parallel grooves. The experiment was not a success, since the rods managed to work themselves loose. One of the front cylinder covers was blown off along with parts of the cylinder itself and the idea was abandoned.^[8]

Watson Standard boilers

In the 1930s, many serving locomotives were reboilered with a standard boiler type, designed by Watson as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification.^[3][6]

Three of the Class 5B locomotives, numbers 723, 724 and 725, were eventually reboilered with Watson Standard no. 1 boilers and reclassified to Class 5BR. The reboilering required extensive modifications to the frame under the firebox. The bridle casting was removed and the bar frames extended back to the rear engine buffer beam. Their original boilers were fitted with either Coale or Ramsbottom safety valves, while the Watson Standard boiler was fitted with Pop safety valves.^[6][8]

Service

In service, the Class 5B locomotives performed excellently. Beatty’s annual report for 1905 stated that they collectively ran 171,000 miles (275,000 kilometres) without a failure of any description, while their consumption of mixed imported and Colonial coal was 52 pounds (24 kilograms) per train-mile.^[1][4]

They spent a large part of their working lives in the Karoo, working between Beaufort West and De Aar, until they were displaced by larger locomotives and assigned to the Paardeneiland shed in Cape Town. Some remained in service around Cape Town for many years and became familiar sights on the Strand and Stellenbosch suburban trains, until the last locomotive of this Class was withdrawn by 1969.^[3]

Upon withdrawal, no. 723 was plinthed at Strand station. It was subsequently moved to De Aar, where it was observed in April 1980 as part of the well-known and well-maintained collection of preserved locomotives. No. 723, as well as most of the other locomotives in the De Aar collection, were subsequently relocated to Millsite near Krugersdorp.

Illustration

The main picture shows no. 723 while it was still plinthed at Strand station. The first of the following pictures shows the Class 5B, as built with Coale safety valves, in the CGR's green livery with a polished brass dome cover, with its original low running boards with wheel fairings or splashers and its original Type YE1 tender. It is depicted here on a colourised CGR post card which also shows the CGR's crest. The second shows no. 724 in the all-black livery of the SAR, after being equipped with superheating, Ramsbottom safety valves, piston valve cylinders, raised running boards and a modified tender. The third shows Class 5BR no. 725 with Pop safety valves on a Watson Standard no. 1 boiler.

• 
  CGR Karoo Class no. 905, SAR Class 5B no. 723, with Type YE1 tender
• 
  Class 5B no. 724, ex CGR Karoo Class no. 906, with modified Type YC tender, c. 1930
• 
  Class 5BR no. 725, reboilered with a Watson Standard no. 1 boiler, c. 1945

References

Wikimedia Commons has media related to South African Class 5B (4-6-2).

Locomotives of the Cape of Good Hope
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 Cape 0-4-2 Cape 2-4-0T CGR 0-4-0ST Aid
3' 6" gauge	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 2-6-0 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 2-6-0ST CGR 1st Class 4-4-0 CGR 1st Class 4-4-0T CGR 1st Class 4-4-0TT CGR 2nd Class 2-6-2TT CGR 2nd Class 4-4-0T CGR 3rd Class 2-6-0T 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 1890 CGR 5th Class 1891 CGR 6th Class 1893 CGR 6th Class 1896 CGR 6th Class 1897 CGR 6th Class 1898 CGR 6th Class 1900 CGR 6th Class 1901 Baldwin CGR 6th Class 1901 Schenectady CGR 6th Class 1901 Neilson's CGR 6th Class 1902 CGR 6th Class 1904 CGR 6th Class 2-6-2 CGR 6th Class 2-6-4 CGR 7th Class 1892 CGR 7th Class 1896 CGR 7th Class 1902 CGR 8th Class 1901 CGR 8th Class 1902 CGR 8th Class 2-8-0 1903 CGR 8th Class 4-8-0 1903 CGR 8th Class 4-8-0 1903 Exp CGR 8th Class 2-8-0 1904 CGR 8th Class 4-8-0 1904 CGR 9th Class 1903 CGR 9th Class 1906 CGR 10th Class CGR Fairlie CGR Karoo 1903 CGR Karoo 1904 CGR Karoo Compound CGR Kitson-Meyer CGR Mountain 4-8-2 CGR Railmotor CGR Tandem Compound 1902 CGR Tandem Compound 1903 Kowie Railway 0-6-0T Kowie Railway 4-4-0T Metropolitan & Suburban 4-6-2T NCCR 7th Class 1899 NCCR 7th Class 1913 Port Elizabeth 0-4-0ST
2' 6" gauge	Cape Copper 0-6-0T Cape Copper Britannia Cape Copper Caledonia Cape Copper Clara Cape Copper Condenser Cape Copper Scotia Namaqua Copper Pioneer Walvis Bay Hope
2' gauge	CGR Baldwin 2-6-0 CGR NG 0-4-0T CGR NG 0-6-0T CGR NG 4-6-2T CGR Type A CGR Type B CGR Type C
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

South African steam locomotive tenders
Cape gauge	Type CL Type CZ Type ET Type ET1 Type EW Type EW1 Type EW2 Type FT Type GT Type HT Type JT Type JT1 Type JV Type KT Type LP Type MP Type MP1 Type MR Type MS Type MT Type MT1 Type MT2 Type MX Type MY Type MY1 Type SH Type SK Type TJ Type TL Type TM Type WE Type WG Type X-17 Type X-20 Type XC Type XC1 Type XD Type XE Type XE1 Type XF Type XF1 Type XF2 Type XJ Type XM Type XM1 Type XM2 Type XM3 Type XM4 Type XP1 Type XS Type YB Type YC Type YE Type YE1 Type ZA Type ZB Type ZC Type ZE
List of South African locomotive classes South African locomotive history