RR class 20 / 20A
| RR class 20 / 20A ZR class 20 / 20A NRZ class 20 / 20A |
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|---|---|
 20A 747 at the coal mine in Dete; July 1990
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| Numbering: | originally 700-760 NRZ: 730-737, 740-750 |
| Number: | 61 |
| Manufacturer: | Beyer-Peacock |
| Year of construction (s): | 1954, 1957 |
| Retirement: | approx. 1970-1992 |
| Type : | (2'D1 ') (1'D2') h4 (Garratt) |
| Gauge : | 1067 mm ( cape track ) |
| Length over coupling: | 31,450 mm |
| Service mass: | 219.9 / 222 t |
| Friction mass: | 134.1 t |
| Wheel set mass : | 16.7 / 16.9 t |
| Top speed: | 70 km / h |
| Driving wheel diameter: | 1,295 mm |
| Impeller diameter: | k. A. |
| Cylinder diameter: | 508 mm |
| Piston stroke: | 660 mm |
| Boiler overpressure: | 138 N / cm² |
| Grate area: | 5.86 m² |
| Radiant heating surface: | 21.6 m² |
| Tubular heating surface: | 259.2 m² |
| Superheater area : | 69.5 m² |
| Train brake: | Suction air brake |
The vehicles of classes 20 and 20A of the former Rhodesian Railways (RR) or the Zambia Railways (ZR) and the National Railways of Zimbabwe (NRZ) are articulated locomotives of the Garratt design . They are among the largest and most powerful steam locomotive designs that have been used in the southern hemisphere.
With 61 built, the locomotives were the fourth largest Garratt type after class GMA / GMAM of the SAR (120), class 15 / 15A of RR (74) and class GF of SAR (65). Beyer-Peacock delivered 14 class 20 locomotives in 1954, followed by 6 more class 20 and class 40 locomotives in 1957.
technology
The locomotives have the wheel arrangement (2'D1 ') (1'D2'), also called "Double Mountain ". Most of the other large Garratt series also have this wheel arrangement, as it combines good running properties with the tractive power of eight coupling axles even at higher speeds .
The axle load, which was significantly higher than that of the previous Garratt models of the RR, enabled a considerable increase in performance, even if part of the permissible additional weight was used in favor of larger stocks.
As the first and only Rhodesian class, the machines were given a stoker fire. Further technical features were the bar frame, power reversal, pivot pins with independent adjustment and fire screen water pipes.
Class 20A differs from class 20 only in the size of the inner running wheels, which in class 20 are slightly larger than those of the bogies , and in class 20A just as big. In addition, the class 20A machines have a slightly higher total weight.
The front water tanks, which extend almost the full width of the vehicle, are sloped at the top to improve the view of the locomotive driver. This characteristic feature is otherwise only found in the very similar but slightly larger class 59 of the EAR, which was created around the same time, and in the class AD 60 of the New South Wales Government Railways .
The first years
The use of the class 20 / 20A was initially not a good star. The locomotives were plagued by teething troubles; there were breaks in the frames of the engine frames and damage to the fire boxes . Unlike the SAR class GMA / GMAM, which was created at the same time and which was already equipped with a more stable cast steel frame, the class 20 / 20A still had a conventional bar frame. The damage to the fire boxes, on the other hand, was difficult to explain because those of the South African locomotives were almost identical and did not cause any problems.
Two locomotives, coincidentally the first (No. 700) and the last (No. 760), had to be scrapped after a short time after collisions.
Aside from these problems, the locomotives lived up to expectations. They were by far the most powerful locomotives on the railroad and could move trains weighing 1270 t over an incline of 15.5 ‰.
Zambia becomes independent
In 1964, Northern Rhodesia became independent. After the resulting division of the country into Zambia and Southern Rhodesia , only 15 of the 59 remaining locomotives remained in Southern Rhodesia; four more were later acquired after Zambia introduced diesel traction. These 19 machines with the numbers 705, 707, 709, 710, 714, 716, 717 and 718 (class 20) as well as 723, 724, 726, 727, 729, 738, 746, 747, 749, 753 and 756 (class 20A ) were mainly used in coal transport from Thomson Junction to Bulawayo and Victoria Falls .
At least a part of the 20 / 20A remaining in Zambia was retired as early as 1970 and replaced by diesel locomotives.
reconstruction
Because of the rising oil prices after the oil crisis of 1978 , the NRZ decided in 1978 a reconstruction program for steam locomotives because they could be operated with cheaper domestic coal. From 1980 to 1983 the still existing Garratt locomotives were completely overhauled and some points were modernized, including the installation of roller bearings . The task was entrusted to private companies, in particular to the RESSCO plants in Bulawayo.
Work on two class 20 / 20A machines was completed in 1980; however, most of the class was not reconstructed until the end of the program until April 1983.
The ZR also put one or two 20 / 20A back into operation during this period, and at least consideration was given to modernizing them by installing roller bearings. However, there is no more detailed information on this.
Because the locomotives that remained in Zambia left larger gaps in the numbering, the reconstructed locomotives were given new numbers. Class 20 machines were given the numbers 730 to 737, those of class 20A were given numbers 740 to 750. Three locomotives, numbers 746, 747 and 749, kept their old numbers.
In addition, the reconstructed locomotives of classes 15 / 15A and 20 / 20A were given names, with class 20 being named Matabele regiments and class 20A names being given to rivers. The only exception is locomotive no. 747, which was given the name " Jumbo ".
Operation after the reconstruction
The reconstructed class 20 / 20A locomotives, like all Garratts, were stationed at the Bulawayo railway junction and used on the routes from there.
Because of the continued difficult economic situation in Zimbabwe, the reconstructed steam locomotives remained in service longer than originally planned. It was not until the turn of the millennium that the end of steam operation was decided, and the locomotives were only used for as long as the term of the boiler certificates allowed and as long as no major damage occurred. Most of the class 20 / 20A machines were taken out of service as early as 1992 because a Canadian loan to finance 60 diesel locomotives from EMD required the locomotives to be scrapped. However, some were still used sporadically afterwards when there was an acute shortage of locomotives. The parked locomotives then served as spare parts donors, but were not scrapped.
Contrary to the plans, about ten locomotives of the smaller classes 14A , 15A and 16A were refurbished again in 2006/2007, so that further use is possible at least in shunting service and in front of suburban and special trains. However, this is not planned for class 20 / 20A because steam locomotives are no longer planned to be used in front of heavy freight trains.
Whereabouts
In both Zambia and Zimbabwe, the locomotives were shut down after they were taken out of service and not scrapped. The 20 / 20A of the NRZ are at the depot in Bulawayo. Some machines are preserved in museums or as monument locomotives.
# 708 is in the Livingstone Railway Museum , 741 is at Ndola Station, and # 758 is at Kitwe Station . Locomotive No. 730 (formerly No. 705) belongs to the Bulawayo Railway Museum and is currently the only locomotive of the class that is still operational or that only needs minor repairs.
Overview table
The following table contains all locomotives that have remained in Southern Rhodesia and Zimbabwe as well as the locomotives in Zambia for which information is available about their whereabouts.
| RR / ZR no. | NRZ no. | Whereabouts |
|---|---|---|
| 700 | - | scrapped after an accident in the 1950s |
| 702 | - | Ndola locomotive cemetery , ready for scrap |
| 703 | - | Lusaka , parked ready for scrap |
| 704 | - | Lusaka, parked ready for scrap |
| 705 | 730 | Bulawayo Railway Museum (probably the best preserved example) |
| 707 | 731 | Bulawayo depot, parked |
| 708 | - | Livingstone Railway Museum |
| 709 | 732 | Bulawayo depot, parked |
| 710 | 733 | Bulawayo depot, parked |
| 714 | 734 | Bulawayo depot, parked |
| 716 | 735 | Bulawayo depot, parked |
| 717 | 736 | Bulawayo (was in the museum until 2004, is now in the depot) |
| 718 | 737 | Bulawayo depot, parked |
| 721 | - | ZCCM copper mine in Mufulira (condition unknown) |
| 723 | 740 | Bulawayo (was a museum locomotive and was operational until 2001; after a cylinder damage it is now used as a stationary steam boiler in the depot) |
| 724 | 741 | Bulawayo depot, parked |
| 726 | 742 | Bulawayo depot, parked |
| 727 | 743 | Bulawayo depot, parked |
| 728 | - | One of the locomotives that were put back into service in 1980 (whereabouts unknown) |
| 729 | 744 | Bulawayo depot, parked |
| 733 | - | Lusaka, parked ready for scrap |
| 735 | - | Ndola locomotive cemetery, ready for scrap |
| 738 | 745 | Bulawayo depot, parked |
| 740 | - | Ndola locomotive cemetery, ready for scrap |
| 741 | - | Monument locomotive at Ndola station |
| 746 | 746 | Bulawayo depot, parked |
| 747 | 747 | Bulawayo depot, parked |
| 748 | - | Ndola locomotive cemetery, ready for scrap |
| 749 | 749 | Bulawayo depot, parked |
| 753 | 748 | Bulawayo depot, parked |
| 755 | - | In operation until at least 1971, whereabouts unknown |
| 756 | 750 | Bulawayo depot, parked |
| 758 | - | Monument locomotive at Kitwe station |
| 760 | - | scrapped after an accident in the 1950s |
literature
- Anthony E. Durrant: Garratt locomotives of the world ("Garratt locomotives of the world"). Pawlak Verlag, Herrsching 1991, ISBN 3-88199-847-0 (reprint of the Basel edition 1984).
- Günter Koch: The development of the Garratt locomotive in Rhodesia . In: Horst J. Obermayer (Ed.): Lok-Magazin . No. 140 . Franckh'sche Verlagshandlung, W. Keller & Co. , 1986, ISSN 0458-1822 , p. 343-352 .
Individual evidence
- ↑ Here Durrant gives 14 + 4 on p. 178, so a total of 18. In the redrawing table, however, 19 machines are listed. So it could have been 14 + 5 machines.
- ↑ Pictures from 1972 show at least three locomotives in a locomotive cemetery near Livingstone ( Memento of the original from May 3, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Michael Bleckmann: The decline of the railroad in Zimbabwe . Extract from the magazine "Lok-Report" on the website of a tour operator, accessed on August 19, 2014.
- ↑ a b c d e f g h i Pictures of parked locomotives in Zambia
- ↑ a b c 15 ° 24 ′ 39.3 ″ S , 28 ° 16 ′ 57.4 ″ E
- ↑ Photograph of No. 755 from 1971
